acro (29apr20)

git-svn-id: svn://tug.org/texlive/trunk@54937 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 4463 insertions, 3136 deletions

diff --git a/Master/texmf-dist/tex/latex/acro/acro.sty b/Master/texmf-dist/tex/latex/acro/acro.sty
index 5209dda3ca9..d1761cf0052 100644
--- a/Master/texmf-dist/tex/latex/acro/acro.sty
+++ b/Master/texmf-dist/tex/latex/acro/acro.sty
@@ -5,7 +5,7 @@
 % 
 % --------------------------------------------------------------------------
 % Clemens Niederberger
-% Web:    https://bitbucket.org/cgnieder/acro/
+% Web:    https://github.com/cgnieder/acro/
 % E-Mail: contact@mychemistry.eu
 % --------------------------------------------------------------------------
 % Copyright 2011--2020 Clemens Niederberger
@@ -30,15 +30,15 @@
 % If you have any ideas, questions, suggestions or bugs to report, please
 % feel free to contact me.
 % --------------------------------------------------------------------------
-\RequirePackage{expl3,xparse,xtemplate,l3keys2e}
-\RequirePackage{etoolbox} % for the document hooks
-
+\RequirePackage{expl3,xparse,l3keys2e}
 \ExplSyntaxOn
 
-\tl_const:Nn \c_acro_date_tl                 {2020/03/07}
-\tl_const:Nn \c_acro_version_major_number_tl {2}
-\tl_const:Nn \c_acro_version_minor_number_tl {11}
-\tl_const:Nn \c_acro_version_subrelease_tl   {d}
+% setup package:
+\tl_const:Nn \c_acro_package_name_tl {acro}
+\tl_const:Nn \c_acro_date_tl {2020/04/29}
+\tl_const:Nn \c_acro_version_major_number_tl {3}
+\tl_const:Nn \c_acro_version_minor_number_tl {0}
+\tl_const:Nn \c_acro_version_subrelease_tl   {}
 \tl_const:Nx \c_acro_version_number_tl
   {
     \c_acro_version_major_number_tl .
@@ -49,3448 +49,4199 @@
     \c_acro_version_number_tl
     \c_acro_version_subrelease_tl
   }
-\tl_const:Nn \c_acro_info_tl {Typeset~ Acronyms}
+\tl_const:Nn \c_acro_info_tl {typeset~ acronyms~ and~ other~ abbreviations}
 
 \ProvidesExplPackage
-  {acro}
+  {\c_acro_package_name_tl}
   {\c_acro_date_tl}
   {\c_acro_version_tl}
   {\c_acro_info_tl}
 
 % --------------------------------------------------------------------------
-% warning and error messages:
-\msg_new:nnn {acro} {undefined}
-  {
-    You've~ requested~ acronym~ `#1'~ \msg_line_context: \ but~ you~
-    apparently~ haven't~ defined~ it,~ yet! \\
-    Maybe~ you've~ misspelled~ `#1'?
-  }
+% document hooks:
+\tl_new:N \g_acro_end_document_hook_tl
+\tl_new:N \g_acro_begin_document_hook_tl
 
-\msg_new:nnn {acro} {macro}
-  {
-    A~ macro~ with~ the~ csname~ `#1'~ already~ exists! \\
-    Unless~ you~ set~ acro's~ option~ `strict'~ I~ won't~ redefine~ it~
-    \msg_line_context: .
-  } 
+\AtBeginDocument { \tl_use:N \g_acro_begin_document_hook_tl }
+\AtEndDocument   { \tl_use:N \g_acro_end_document_hook_tl }
+
+\cs_new_protected:Npn \acro_at_begin_document:n #1
+  { \tl_gput_right:Nn \g_acro_begin_document_hook_tl {#1} }
 
-\msg_new:nnn {acro} {replaced}
+\cs_new_protected:Npn \acro_at_end_document:n #1
+  { \tl_gput_right:Nn \g_acro_end_document_hook_tl {#1} }
+
+% --------------------------------------------------------------------------
+% load-time messages:
+\msg_new:nnn {acro} {load-time-option}
   {
-    The~ #1~ `#2' ~you ~used~ \msg_line_context: \ is~ deprecated~ and~ has~
-    been~ replaced~ by~ `#3'. ~Since~ I~ will~ not~ guarantee~ that~ #1~ `#2'~
-    will~ be~ kept~ forever~ I~ strongly~ encourage~ you~ to~ switch!
+    `#1'~ is~ a~ load-time~ option! \\
+    You~ cannot~ set~ it~ with~ \token_to_str:N \acsetup ! \\
+    You~ need~ to~ use~ \token_to_str:N \usepackage [#1] {acro} .
   }
 
-\msg_new:nnn {acro} {deprecated}
+\msg_new:nnn {acro} {unknown-option}
   {
-    The~ #1~ `#2'~ you~ used~ \msg_line_context: \ is~ deprecated~and~ there~
-    is~ no~ replacement.~ Since~ I~ will~ not~ guarantee~ that~ #1~ `#2'~
-    will~ be~ kept~ forever~ I~ strongly~ encourage~ you~ to~ remove~ it~
-    from~ your~ document.
+    Unknown~ option~ `#1' \\
+    I~ dont'~ know~ the~ option~ `#1'.~ Please~ make~ sure~ there~ is~ no~
+    typo.~ Check~ the~ manual~ for~ help.
   }
 
-\msg_new:nnn {acro} {substitute-short}
+% --------------------------------------------------------------------------
+% re-compile mechanism:
+\bool_new:N \g__acro_rerun_bool
+\tl_new:N \g__acro_rerun_message_tl
+
+\tl_const:Nn \l__acro_rerun_general_tl
+  { Rerun~ to~ get~ `acro'~ synchronized. }
+
+\tl_const:Nn \l__acro_rerun_property_tl
   {
-    There~ is~ no~ short~ form~ set~ for~ acronym~ `#1'! \\
-    I~ am~ setting~ the~ short~ form~ equal~ to~ the~ ID~ `#1'. \\
-    If~ that~ is~ not~ what~ you~ want~ make~ sure~ to~ add~ an~ explicit~
-    short~ form.
+    Acronym~ properties~ may~ have~ changed.~ Rerun~ to~ get~ them~
+    synchronized.
   }
-\msg_new:nnn {acro} {ending-exists}
+
+\tl_const:Nn \l__acro_rerun_list_tl
   {
-    An~ ending~ with~ the~ name~ `#1'~ already~ exists! \\ \\
-    I~ am~ overwriting~ the~ defaults.
+    Empty~ acronym~ list.~ If~ you~ have~ used~ acronyms~ then~ re-compile~
+    to~ get~ the~ list~ filled.~ Otherwise~ remove~ \token_to_str:N
+    \printacronyms
   }
 
-\msg_new:nnn {acro} {ending-before-acronyms}
+\msg_new:nnn {acro} {rerun} { \use:c {l__acro_rerun_#1_tl} }
+
+\prg_new_conditional:Npnn \acro_if_rerun: {p,T,F,TF}
   {
-    You~ are~ using~ \token_to_str:N \ProvideAcroEnding \ after~ you've~
-    declared~ at~ least~ one~ acronym.~ This~ will~ lead~ to~ trouble! \\
-    Make~ sure~ to~ define~ endings~ before~ *any*~ acronym~ declarations!
+    \bool_if:NTF \g__acro_rerun_bool
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-\msg_new:nnn {acro} {no-alternative}
+\cs_new_protected:Npn \acro_rerun:n #1
   {
-    There~ is~ no~ alternative~ form~ for~ acronym~ `#1'! \\ \\
-    I~ am~ using~ the~ short~ form~ instead.
+    \bool_gset_true:N \g__acro_rerun_bool
+    \tl_map_inline:Nn \g__acro_rerun_message_tl
+      {
+        \tl_if_eq:nnT {##1} {#1}
+          { \tl_map_break:n { \use_none:nn } }
+      }
+    \use:n { \tl_gput_right:Nn \g__acro_rerun_message_tl {{#1}} }
   }
 
-\msg_new:nnn {acro} {unknown}
+\cs_new_protected:Npn \acro_do_rerun:
   {
-    You're~ trying~ to~ use~ the~ #1~ `#2'~ \msg_line_context: . \\
-    However,~ I~ do~ not~ know~ #1~ `#2'! \\
-    If~ this~ is~ no~ typo~ please~ contact~ the~ package~ author. \\ \\
-    I~ am~ going~ to~ use~ the~ #1~ `#3'~ instead.
+    \acro_if_rerun:T
+      {
+        \tl_map_inline:Nn \g__acro_rerun_message_tl
+          {
+            \str_case:nnTF {##1}
+              {
+                {property} { \msg_warning:nnn {acro} {rerun} {property} }
+                {list} { \msg_warning:nnn {acro} {rerun} {list} }
+                {general} { \msg_warning:nnn {acro} {rerun} {general} }
+              }
+              { \tl_map_break: }
+              { \msg_warning:nnn {acro} {rerun} {general} }
+          }
+      }
   }
-\msg_new:nnn {acro} {definitions-missing}
+
+% --------------------------------------------------------------------------
+% debugging mechanism:
+\bool_new:N \g__acro_debug_bool
+
+\prg_new_conditional:Npnn \acro_if_debug: {p,T,F,TF}
   {
-    I~ cannot~ find~ the~ file~ \c_acro_definition_file_name_tl
-    .\c_acro_definition_file_extension_tl !~ This~ file~ contains~ all~
-    essential~ user~ commands~ of~ acro~ and~ is~ a~ crucial~ part~ of~ the~
-    package!~ Please~ check~ your~ installation.
+    \bool_if:NTF \g__acro_debug_bool
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
 % --------------------------------------------------------------------------
-% temporary variables
-\tl_new:N   \l__acro_tmpa_tl
-\tl_new:N   \l__acro_tmpb_tl
-\tl_new:N   \l__acro_tmpc_tl
-\prop_new:N \l__acro_tmpa_prop
-\prop_new:N \l__acro_tmpb_prop
-\seq_new:N  \l__acro_tmpa_seq
-\seq_new:N  \l__acro_tmpb_seq
-\int_new:N  \l__acro_tmpa_int
-\int_new:N  \l__acro_tmpb_int
-\int_new:N  \l__acro_tmpc_int
-\int_new:N  \l__acro_tmpd_int
+% check for stuff changed in the new version:
+\bool_new:N \g__acro_upgrade_bool
 
-% --------------------------------------------------------------------------
-% variants of kernel commands
-\cs_generate_variant:Nn \quark_if_no_value:nTF  {V}
-\cs_generate_variant:Nn \tl_put_right:Nn        {NV,Nv}
-\cs_generate_variant:Nn \tl_if_eq:nnT           {V}
-\cs_generate_variant:Nn \tl_if_eq:nnF           {V}
-\cs_generate_variant:Nn \seq_use:Nnnn           {c}
-\cs_generate_variant:Nn \seq_gset_split:Nnn     {c}
-\cs_generate_variant:Nn \seq_set_split:Nnn      {NnV}
-\cs_generate_variant:Nn \seq_if_in:NnT          {NV}
-\cs_generate_variant:Nn \seq_if_in:NnTF         {Ne}
-\cs_generate_variant:Nn \prop_put:Nnn           {NnV,cnx,cnv}
-\cs_generate_variant:Nn \prop_get:NnNTF         {cnc}
-\cs_generate_variant:Nn \prop_get:NnNF          {cn,cnc}
-\cs_generate_variant:Nn \prop_get:NnN           {cnc}
-\cs_generate_variant:Nn \cs_generate_variant:Nn {c}
-\cs_generate_variant:Nn \str_case:nn            {V}
+\prg_new_conditional:Npnn \acro_if_upgrade: {p,T,F,TF}
+  {
+    \bool_if:NTF \g__acro_upgrade_bool
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
 % --------------------------------------------------------------------------
-% variables:
-\bool_new:N      \l__acro_acc_supp_bool
-\bool_new:N      \l__acro_addto_index_bool
-\bool_new:N      \l__acro_capitalize_list_bool
-\bool_new:N      \g__acro_case_sensitive_bool
-\bool_new:N      \l__acro_citation_all_bool
-\bool_new:N      \l__acro_citation_first_bool
-\bool_set_true:N \l__acro_citation_first_bool
-\bool_new:N      \l__acro_create_macros_bool
-\bool_new:N      \l__acro_custom_alt_format_bool
-\bool_new:N      \l__acro_custom_long_format_bool
-\bool_new:N      \l__acro_custom_short_format_bool
-\bool_new:N      \l__acro_custom_foreign_format_bool
-\bool_new:N      \l__acro_extra_punct_bool
-\bool_new:N      \l__acro_extra_use_brackets_bool
-\bool_new:N      \g__acro_first_acronym_declared_bool
-\bool_new:N      \l__acro_first_instance_bool
-\bool_new:N      \l__acro_first_only_short_bool
-\bool_new:N      \l__acro_first_only_long_bool
-\bool_new:N      \l__acro_first_reversed_bool
-\bool_new:N      \l__acro_first_switched_bool
-\bool_new:N      \l__acro_first_use_brackets_bool
-\bool_new:N      \l__acro_first_upper_bool
-\bool_new:N      \l__acro_following_page_bool
-\bool_new:N      \l__acro_following_pages_bool
-\bool_new:N      \l__acro_foreign_bool
-\bool_set_true:N \l__acro_foreign_bool
-\bool_new:N      \l__acro_group_citation_bool
-\bool_new:N      \l__acro_hyperref_loaded_bool
-\bool_new:N      \l__acro_hyperref_use_bool
-\bool_new:N      \l__acro_include_endings_format_bool
-\bool_new:N      \l__acro_indefinite_bool
-\bool_new:N      \l__acro_in_list_bool
-\bool_new:N      \l__acro_is_included_bool
-\bool_new:N      \l__acro_is_excluded_bool
-\bool_new:N      \l__acro_list_all_pages_bool
-\bool_set_true:N \l__acro_list_all_pages_bool
-\bool_new:N      \l__acro_list_reverse_long_extra_bool
-\bool_new:N      \l__acro_log_acronyms_bool
-\bool_new:N      \l__acro_log_acronyms_verbose_bool
-\bool_new:N      \l__acro_mark_as_used_bool
-\bool_new:N      \g__acro_mark_first_as_used_bool
-\bool_new:N      \l__acro_override_list_format_bool
-\bool_new:N      \l__acro_page_brackets_bool
-\bool_new:N      \l__acro_page_display_bool
-\bool_new:N      \l__acro_page_punct_bool
-\bool_new:N      \l__acro_place_label_bool
-\bool_new:N      \l__acro_print_only_used_bool
-\bool_set_true:N \l__acro_print_only_used_bool
-\bool_new:N      \g__acro_rerun_bool
-\bool_new:N      \g__acro_reset_at_barrier_bool
-\bool_new:N      \l__acro_silence_bool
-\bool_new:N      \l__acro_single_use_bool
-\bool_new:N      \l__acro_sort_bool
-\bool_set_true:N \l__acro_sort_bool
-\bool_new:N      \l__acro_strict_bool
-\bool_new:N      \l__acro_trailing_tokens_bool
-\bool_new:N      \l__acro_tooltip_bool
-\bool_new:N      \l__acro_tooltip_inside_bool
-\bool_new:N      \l__acro_upper_indefinite_bool
-\bool_new:N      \l__acro_upper_short_bool
-\bool_new:N      \l__acro_use_acronyms_bool
-\bool_set_true:N \l__acro_use_acronyms_bool
-\bool_new:N      \l__acro_use_barrier_bool
-\bool_new:N      \g__acro_use_barriers_bool
-\bool_new:N      \l__acro_use_ending_form_bool
-\bool_new:N      \l__acro_use_note_bool
-\bool_new:N      \l__acro_xspace_bool
-
-\str_new:N \l__acro_current_id_str
-
-\tl_new:N  \l__acro_list_entries_tl
-\tl_new:N  \l__acro_endings_tl
-\tl_new:N  \l__acro_trailing_tokens_tl
-\tl_new:N  \l__acro_included_classes_tl
-\tl_new:N  \l__acro_excluded_classes_tl
-\tl_new:N  \l__acro_ignore_tl
-\tl_new:N  \l__acro_default_indefinite_tl
-\tl_set:Nn \l__acro_default_indefinite_tl {a}
-\tl_new:N  \l__acro_foreign_sep_tl
-\tl_new:N  \l__acro_extra_instance_tl
-\tl_set:Nn \l__acro_extra_instance_tl {default}
-\tl_new:N  \l__acro_page_instance_tl
-\tl_set:Nn \l__acro_page_instance_tl  {none}
-\tl_new:N  \l__acro_page_name_tl
-\tl_new:N  \l__acro_pages_name_tl
-\tl_new:N  \l__acro_next_page_tl
-\tl_new:N  \l__acro_next_pages_tl
-\tl_new:N  \l__acro_list_instance_tl
-\tl_set:Nn \l__acro_list_instance_tl  {description}
-\tl_new:N  \l__acro_list_type_tl
-\tl_new:N  \l__acro_list_heading_cmd_tl
-\tl_set:Nn \l__acro_list_heading_cmd_tl {section*}
-\tl_new:N  \l__acro_list_name_tl
-\tl_new:N  \l__acro_list_before_tl
-\tl_new:N  \l__acro_list_after_tl
-\tl_new:N  \l__acro_custom_short_format_tl
-\tl_new:N  \l__acro_first_between_tl
-\tl_new:N  \l__acro_citation_connect_tl
-\tl_new:N  \l__acro_between_group_connect_citation_tl
-\tl_new:N  \l__acro_extra_brackets_tl
-\tl_new:N  \l__acro_extra_punct_tl
-\tl_new:N  \l__acro_first_brackets_tl
-\tl_new:N  \l__acro_page_punct_tl
-\tl_new:N  \l__acro_page_brackets_tl
-\tl_new:N  \l__acro_last_page_tl
-\tl_new:N  \l__acro_current_page_tl
-\tl_new:N  \l__acro_list_table_tl
-\tl_new:N  \l__acro_list_table_spec_tl
-\tl_new:N  \l__acro_acc_supp_tl
-\tl_new:N  \l__acro_acc_supp_options_tl
-\tl_new:N  \l__acro_label_prefix_tl
-\tl_set:Nn \l__acro_label_prefix_tl {ac:}
-\tl_new:N  \l__acro_index_short_tl
-\tl_new:N  \l__acro_first_instance_tl
-\tl_set:Nn \l__acro_first_instance_tl {default}
-\tl_new:N  \l__acro_short_tl
-\tl_new:N  \l__acro_short_format_tl
-\tl_new:N  \l__acro_list_short_format_tl
-\tl_new:N  \l__acro_alt_tl
-\tl_new:N  \l__acro_alt_format_tl
-\tl_new:N  \l__acro_long_tl
-\tl_new:N  \l__acro_long_format_tl
-\tl_new:N  \l__acro_list_long_format_tl
-\tl_new:N  \l__acro_single_form_tl
-\tl_set:Nn \l__acro_single_form_tl {long}
-\tl_new:N  \l__acro_extra_format_tl
-\tl_new:N  \l__acro_foreign_format_tl
-\tl_new:N  \l__acro_foreign_list_format_tl
-\tl_set:Nn \l__acro_foreign_list_format_tl { \acroenparen }
-\tl_new:N  \l__acro_index_format_tl
-
-\skip_new:N \l__acro_page_space_skip
-
-\dim_new:N  \l__acro_short_width_dim
-\dim_set:Nn \l__acro_short_width_dim {3em}
-
-\int_new:N  \g__acro_barrier_int
-
-\seq_new:N \l__acro_endings_seq
-\seq_new:N \l__acro_actions_seq
-\seq_new:N \g__acro_declared_acronyms_seq
-
-\prop_new:N \l__acro_citation_prop
-\prop_new:N \l__acro_citation_pre_prop
-\prop_new:N \l__acro_citation_post_prop
-\prop_new:N \l__acro_pdfstring_alt_prop
-\prop_new:N \l__acro_pdfstring_short_prop
-\prop_new:N \g__acro_properties_prop
-\prop_new:N \l__acro_trailing_tokens_prop
-\prop_new:N \l__acro_trailing_actions_prop
-\prop_new:N \l__acro_list_styles_prop
-\prop_new:N \l__acro_list_headings_prop
-\prop_new:N \l__acro_first_styles_prop
-\prop_new:N \l__acro_extra_styles_prop
-\prop_new:N \l__acro_page_styles_prop
+% 
+\bool_new:N \g__acro_final_bool
 
-% --------------------------------------------------------------------------
-% logging:
-\prg_new_conditional:Npnn \acro_if_log: {p,T,F,TF}
+\prg_new_conditional:Npnn \acro_if_final: {p,T,F,TF}
   {
-    \bool_if:NTF \l__acro_log_acronyms_bool
+    \bool_if:NTF \g__acro_final_bool
       { \prg_return_true: }
       { \prg_return_false: }
   }
 
-\keys_define:nn {acro}
+% --------------------------------------------------------------------------
+% load-time options:
+% #1: message name
+\cs_new_protected:Npn \__acro_loadtime_error:n #1
+   { \msg_error:nnV {acro} {#1} \l_keys_key_str }
+
+\cs_new_protected:Npn \__acro_loadtime_warning:n #1
+   { \msg_warning:nnV {acro} {#1} \l_keys_key_str }
+
+\cs_generate_variant:Nn \msg_error:nnn {nnV}
+\cs_generate_variant:Nn \msg_warning:nnn {nnV}
+
+\int_new:N \g__acro_version_int
+
+\keys_define:nn {acro/package}
   {
-    log           .choice: ,
-    log / true    .code:n    =
-      \bool_set_true:N \l__acro_log_acronyms_bool
-      \bool_set_false:N \l__acro_log_acronyms_verbose_bool ,
-    log / silent  .meta:n    = { log = true } ,
-    log / verbose .code:n    =
-      \bool_set_true:N \l__acro_log_acronyms_bool
-      \bool_set_true:N \l__acro_log_acronyms_verbose_bool ,
-    log / false   .code:n    =
-      \bool_set_false:N \l__acro_log_acronyms_bool
-      \bool_set_false:N \l__acro_log_acronyms_verbose_bool ,
-    log           .default:n = true ,
-    log           .initial:n = false
-  }
-
-\cs_new:Npn \__acro_write_log:nn #1#2 { \ \ \ #1 ~ = ~ {#2} }
-\cs_new:Npn \__acro_write_log_property:nnn #1#2#3
-  { \__acro_write_log:nn {#2} { \__acro_property_get:nn {#3} {#1} } }
-
-\cs_new:Npn \__acro_ending_log_entry:nn #1#2
-  {
-    | \\
-    | \__acro_write_log_property:nnn {#1} {short-#2} {short_#2} \\
-    | \__acro_write_log_property:nnn {#1} {short-#2-form} {short_#2_form} \\
-    | \__acro_write_log_property:nnn {#1} {long-#2} {long_#2} \\
-    | \__acro_write_log_property:nnn {#1} {long-#2-form} {long_#2_form} \\
-    | \__acro_write_log_property:nnn {#1} {alt-#2} {alt_#2} \\
-    | \__acro_write_log_property:nnn {#1} {alt-#2-form} {alt_#2_form} \\
-    | \__acro_write_log_property:nnn {#1} {foreign-#2} {foreign_#2} \\
-    | \__acro_write_log_property:nnn {#1} {foreign-#2-form} {foreign_#2_form} \\
+    debug       .bool_gset:N = \g__acro_debug_bool ,
+    debug       .initial:n   = false ,
+    upgrade     .bool_gset:N = \g__acro_upgrade_bool ,
+    upgrade     .initial:n   = true ,
+    final       .bool_set:N  = \g__acro_final_bool ,
+    final       .initial:n   = false ,
+    version     .choice: ,
+    version / 2 .code:n      = \int_set:Nn \g__acro_version_int {2} ,
+    version / 3 .code:n      = \int_set:Nn \g__acro_version_int {3} ,
+    version     .initial:n   = 3 ,
+    unknown     .code:n      = \__acro_loadtime_warning:n {unknown-option}
   }
-  
-\msg_new:nnn {acro} {log-acronym-verbose}
-  {
-    ================================================= \\
-    | ~ \msg_info_text:n {acro}~ --~ defining~ new~ acronym: \\
-    | \__acro_write_log:nn {ID} {#1} \\
-    | \__acro_write_log_property:nnn {#1} {short} {short} \\
-    | \__acro_write_log_property:nnn {#1} {long} {long} \\
-    | \__acro_write_log_property:nnn {#1} {alt} {alt} \\
-    | \__acro_write_log_property:nnn {#1} {sort} {sort} \\
-    | \__acro_write_log_property:nnn {#1} {class} {class} \\
-    | \__acro_write_log_property:nnn {#1} {list} {list} \\
-    | \__acro_write_log_property:nnn {#1} {extra} {extra} \\
-    | \__acro_write_log_property:nnn {#1} {foreign} {foreign} \\
-    | \__acro_write_log_property:nnn {#1} {single} {single} \\
-    | \__acro_write_log_property:nnn {#1} {pdfstring} {pdfstring} \\
-    | \__acro_write_log_property:nnn {#1} {accsupp} {accsupp} \\
-    | \__acro_write_log_property:nnn {#1} {tooltip} {tooltip} \\
-    | \\
-    | \__acro_write_log_property:nnn {#1} {short-indefinite} {short_indefinite} \\
-    | \__acro_write_log_property:nnn {#1} {long-indefinite} {long_indefinite} \\
-    | \__acro_write_log_property:nnn {#1} {alt-indefinite} {alt_indefinite} \\
-    \seq_map_function:NN \l__acro_endings_seq \__acro_ending_log_entry:n
-    | \\
-    | \__acro_write_log_property:nnn {#1} {short-format} {short_format} \\
-    | \__acro_write_log_property:nnn {#1} {long-format} {long_format} \\
-    | \__acro_write_log_property:nnn {#1} {first-long-format} {first_long_format} \\
-    | \__acro_write_log_property:nnn {#1} {single-format} {single_format} \\
-    | \__acro_write_log_property:nnn {#1} {foreign-lang} {foreign_lang} \\    
-    | \\
-    | \__acro_write_log_property:nnn {#1} {cite} {citation} \\
-    | \__acro_write_log_property:nnn {#1} {before-citation} {before_citation} \\
-    | \__acro_write_log_property:nnn {#1} {after-citation} {after_citation} \\
-    | \__acro_write_log_property:nnn {#1} {index} {index} \\
-    | \__acro_write_log_property:nnn {#1} {index-sort} {index_sort} \\
-    | \\
-    | \__acro_write_log_property:nnn {#1} {long-pre} {long_pre} \\
-    | \__acro_write_log_property:nnn {#1} {long-post} {long_post} \\
-    | \__acro_write_log_property:nnn {#1} {post} {post} \\
-    | \__acro_write_log_property:nnn {#1} {index-cmd} {index_cmd} \\
-    | \__acro_write_log_property:nnn {#1} {first-style} {first_style} \\
-    =================================================
-  }
-
-\msg_new:nnn {acro} {log-acronym-silent}
-  {
-    ================================================= \\
-    | ~ \msg_info_text:n {acro}~ --~ defining~ new~ acronym: \\
-    | \__acro_write_log:nn {ID} {#1} \\
-    | \__acro_write_log_property:nnn {#1} {short} {short} \\
-    | \__acro_write_log_property:nnn {#1} {long} {long} \\
-    | \__acro_write_log_property:nnn {#1} {alt} {alt} \\
-    | \__acro_write_log_property:nnn {#1} {sort} {sort} \\
-    | \__acro_write_log_property:nnn {#1} {class} {class} \\
-    | \__acro_write_log_property:nnn {#1} {list} {list} \\
-    | \__acro_write_log_property:nnn {#1} {extra} {extra} \\
-    | \__acro_write_log_property:nnn {#1} {foreign} {foreign} \\
-    | \__acro_write_log_property:nnn {#1} {cite} {citation} \\
-    =================================================
+
+\ProcessKeysPackageOptions {acro/package}
+
+\int_compare:nNnT \g__acro_version_int = 2
+  {
+    \RequirePackage {acro2}
+    \file_input_stop:
   }
-  
-\cs_new_protected:Npn \__acro_log_acronym:n #1
+
+\keys_define:nn {acro/package}
   {
-    \bool_if:NT \l__acro_log_acronyms_bool
-      {
-        \cs_set:Npn \__acro_ending_log_entry:n ##1
-          { \__acro_ending_log_entry:nn {#1} {##1} }
-        \bool_if:NTF \l__acro_log_acronyms_verbose_bool
-          { \msg_log:nnn {acro} {log-acronym-verbose} {#1} }
-          { \msg_log:nnn {acro} {log-acronym-silent} {#1} }
-      }
-  }   
+    debug   .code:n = \__acro_loadtime_error:n {load-time-option} ,
+    upgrade .code:n = \__acro_loadtime_error:n {load-time-option} ,
+    final   .code:n = \__acro_loadtime_error:n {load-time-option}
+  }
 
-% --------------------------------------------------------------------------
-% message macros:
-\cs_new:Npn \__acro_remove_backslash:N #1
-  { \exp_after:wN \use_none:n \token_to_str:N #1 }
+% ----------------------------------------------------------------------------
+% temporary variables:
+\tl_new:N \l__acro_tmpa_tl
+\tl_new:N \l__acro_tmpb_tl
+\tl_new:N \l__acro_tmpc_tl
+
+\str_new:N \l__acro_tmpa_str
+\str_new:N \l__acro_tmpb_str
+\str_new:N \l__acro_tmpc_str
+
+\bool_new:N \l__acro_tmpa_bool
+\bool_new:N \l__acro_tmpb_bool
+\bool_new:N \l__acro_tmpc_bool
+
+\seq_new:N \l__acro_tmpa_seq
+\seq_new:N \l__acro_tmpb_seq
+\seq_new:N \l__acro_tmpc_seq
+
+\int_new:N \l__acro_tmpa_int
+\int_new:N \l__acro_tmpb_int
+\int_new:N \l__acro_tmpc_int
+\int_new:N \l__acro_tmpd_int
+
+\clist_new:N \l__acro_tmpa_clist
+\clist_new:N \l__acro_tmpb_clist
+\clist_new:N \l__acro_tmpc_clist
 
-\cs_new_protected:Npn \acro_new_message_commands:Nnnn #1#2#3#4
+% ----------------------------------------------------------------------------
+% module mechanism:
+\msg_new:nnn {acro} {module-missing}
   {
-    \clist_map_inline:nn {#2}
+    You've~ requested~ the~ acro~ module~ `#1'~ but~ it~ appears~ to~
+    be~ missing~ on~ your~ system.~ Maybe~ you've~ misspelled~ the~ name?~
+    Loading~ the~ module~ will~ abort~ \msg_line_context:
+  }
+
+\msg_new:nnn {acro} {loading-module}
+  { Loading~ module~ `#1'~ ... }
+
+\msg_new:nnn {acro} {wrong-module-name}
+  { The~ module~ file~ name~ is~ `#2'~ but~ it~ provides~ module~ `#1'. }
+
+\msg_new:nnn {acro} {forbidden-module}
+  {
+    You've~ requested~ the~ acro~ module~ `modules'~ \msg_line_context: .~
+  This~ module~ is~ a~ pseudo~ module~ which~ may~ not~ be~ loaded~ through~
+  the~ module~ loading~ mechansim.
+  }
+
+% ----------------------------------------------------------------------------
+\cs_generate_variant:Nn \str_if_eq:nnF {xx}
+\cs_generate_variant:Nn \msg_error:nnnn {nnnx}
+
+\prg_new_conditional:Npnn \acro_package_if_loaded:n #1 {p,T,F,TF}
+  {
+    \cs_if_exist:cTF {ver@#1.sty}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+
+% ----------------------------------------------------------------------------
+% this is for external file modules called "styles":
+\tl_const:Nn \c__acro_module_extension_tl {code.tex}
+\tl_const:Nn \c__acro_module_prefix_tl    {acro}
+
+\tl_new:N \g__acro_modules_loaded_tl
+
+\cs_new_protected:Npn \acro_modules_load:n #1
+  { \clist_map_inline:nn {#1} { \acro_module_load:n {##1} } }
+
+\cs_new_protected:Npn \acro_module_load:n #1
+  {
+    \tl_set:Nx \l_tmpa_tl { \tl_trim_spaces:n {#1} }
+    \str_if_eq:VnTF \l_tmpa_tl {modules}
+      { \msg_error:nn {acro} {forbidden-module} }
+      {  \__acro_module_load:V \l_tmpa_tl }
+  }
+
+\cs_new_protected:Npn \__acro_module_load:n #1
+  {
+    \acro_if_module_loaded:nF {#1}
       {
-        \cs_new_protected:cpn { \__acro_remove_backslash:N #1 ##1 }
+        \acro_module_if_exist:nTF {#1}
           {
-            \bool_if:NTF \l__acro_silence_bool
-              { \use:c { \__acro_remove_backslash:N #3 n##1 } {acro} }
-              { \use:c { \__acro_remove_backslash:N #4 n##1 } {acro} }
+            \__acro_module_hook_use:nn {#1} {before}
+            \msg_info:nnn {acro} {loading-module} {#1}
+            \@onefilewithoptions
+              {\c__acro_module_prefix_tl.#1}[][]
+              \c__acro_module_extension_tl
+            \__acro_module_hook_use:nn {#1} {after}
           }
+          { \msg_error:nnn {acro} {module-missing} {#1} }
       }
   }
+\cs_generate_variant:Nn \__acro_module_load:n {V}
 
-\acro_new_message_commands:Nnnn \acro_serious_message: {n,nn,nnn}
-  { \msg_warning: }
-  { \msg_error: }
+\prg_new_conditional:Npnn \acro_if_module_loaded:n #1 {p,T,F,TF}
+  {
+    \tl_if_in:NnTF \g__acro_modules_loaded_tl {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-\acro_new_message_commands:Nnnn \acro_harmless_message: {n,nn,nnn,nnnn}
-  { \msg_info: }
-  { \msg_warning: }
+\prg_new_conditional:Npnn \acro_module_if_exist:n #1 {p,T,F,TF}
+  {
+    \file_if_exist:nTF
+      {\c__acro_module_prefix_tl.#1.\c__acro_module_extension_tl}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-\cs_new_protected:Npn \acro_option_deprecated:nn #1#2
+% --------------------------------------------------------------------------
+% module hooks:
+% #1: module
+% #2: code
+\cs_new_protected:Npn \acro_module_after:nn #1#2
   {
-    \tl_if_blank:nTF {#2}
-      { \acro_harmless_message:nnn  {deprecated} {option} {#1} }
-      { \acro_harmless_message:nnnn {replaced}   {option} {#1} {#2} }
+    \acro_if_module_loaded:nTF {#1}
+      {#2}
+      { \__acro_add_to_module_hook:nnn {#1} {after} {#2} }
   }
-\cs_new_protected:Npn \acro_option_deprecated:n #1
-  { \acro_option_deprecated:nn {#1} {} }
 
-\cs_new_protected:Npn \acro_command_deprecated:NN #1#2
+% #1: module
+% #2: code
+\cs_new_protected:Npn \acro_module_before:nn #1#2
   {
-    \tl_if_blank:nTF {#2}
+    % TODO: error in T case?
+    \acro_if_module_loaded:nF {#1}
+      { \__acro_add_to_module_hook:nnn {#1} {before} {#2} }
+  }
+
+% #1: module
+% #2: hook name
+% #3: code
+\cs_new_protected:Npn \__acro_add_to_module_hook:nnn #1#2#3
+  {
+    \acro_if_module_loaded:nF {#1}
       {
-        \acro_harmless_message:nnn {deprecated} {command}
-          { \token_to_str:N #1 }
+        \tl_if_exist:cF {g__acro_module_hook_#1_#2_tl}
+          { \tl_new:c {g__acro_module_hook_#1_#2_tl} }
+        \tl_gput_right:cn {g__acro_module_hook_#1_#2_tl} {#3}
       }
+  }
+
+% #1: module
+% #2: hook name
+\cs_new_protected:Npn \__acro_module_hook_use:nn #1#2
+  {
+    \tl_if_exist:cT {g__acro_module_hook_#1_#2_tl}
       {
-        \acro_harmless_message:nnnn {replaced} {command}
-          { \token_to_str:N #1 }
-          { \token_to_str:N #2 }
+        \tl_use:c {g__acro_module_hook_#1_#2_tl}
+        \tl_gclear:c {g__acro_module_hook_#1_#2_tl}
       }
   }
+\cs_generate_variant:Nn \__acro_module_hook_use:nn {V}
 
 % --------------------------------------------------------------------------
-% small commands for use at various places
-\cs_new:Npn \acro_no_break: { \tex_penalty:D 10000 \scan_stop: }
+\tl_new:N \l__acro_module_date_tl
+\tl_new:N \l__acro_module_version_tl
 
-\cs_new_protected:Npn \__acro_first_upper_case:n #1
-  { \text_titlecase_first:n {#1} }
-\cs_generate_variant:Nn \__acro_first_upper_case:n {x}
+\tl_set_eq:NN \l__acro_module_date_tl \c_acro_date_tl
+\tl_set_eq:NN \l__acro_module_version_tl \c_acro_version_tl
 
-\cs_new_eq:NN \acro_first_upper_case:n \__acro_first_upper_case:n
+\cs_new_protected:Npn \__acro_module:nn #1#2
+  {
+    \tl_gput_right:Nn \g__acro_modules_loaded_tl {{#1}}
+    \str_if_eq:xxF
+      {\c__acro_module_prefix_tl.#1.\c__acro_module_extension_tl}
+      {\@currname.\@currext}
+      {
+        \msg_error:nnnxx {acro} {wrong-module-name}
+          {#1}
+          {\@currname.\@currext}
+      }
+    \ProvidesFile
+      {\c__acro_module_prefix_tl.#1.\c__acro_module_extension_tl}
+      [
+        \l__acro_module_date_tl
+        \c_space_tl
+        v \l__acro_module_version_tl
+        \c_space_tl
+        acro~ style~ file~ `#1'~ (#2)
+      ]
+  }
 
 % --------------------------------------------------------------------------
-\tl_new:N \l_acro_config_file_name_tl
-\tl_new:N \l_acro_config_file_extension_tl
+% define internal acro modules:
+\tl_new:N \g_acro_module_tl
+\tl_new:N \g__acro_module_stop_tl
 
-\tl_set:Nn \l_acro_config_file_name_tl      {acro}
-\tl_set:Nn \l_acro_config_file_extension_tl {cfg}
+\cs_new_protected:Npn \acro_stop_module:n #1
+  { \tl_gput_right:Nn \g__acro_module_stop_tl {{#1}} }
+
+% #1: name
+% #2: description
+\cs_new_protected:Npn \AcroModule #1#2
+  {
+    \msg_log:nnnn {acro} {loading-module} {#1} {#2}
+    \tl_gput_right:Nn \g__acro_modules_loaded_tl {{#1}}
+    \tl_gset:Nn \g_acro_module_tl {#1}
+    \__acro_module_hook_use:nn {#1} {before}
+    \tl_map_inline:Nn \g__acro_module_stop_tl
+      {
+        \str_if_eq:nnT {##1} {#1}
+          { \tl_map_break:n { \__acro_gobble_module:w } }
+      }
+  }
+
+\cs_new_protected:Npn \AcroModuleEnd
+  { \__acro_module_hook_use:Vn \g_acro_module_tl {after} }
+
+\cs_new_protected:Npn \__acro_gobble_module:w #1 \AcroModuleEnd {}
+
+\bool_lazy_or:nnT
+  { \acro_if_final_p: }
+  { !\acro_if_upgrade_p: }  
+  { \acro_stop_module:n {upgrade} }
+
+% --------------------------------------------------------------------------
+% style files
+\NewDocumentCommand \AcroStyle {smO{}}
+  {
+    \__acro_module:nn {style.#2} {#3}
+    \IfBooleanT {#1} { \ExplSyntaxOn }
+  }
+
+\cs_new_protected:Npn \acro_style_load:n #1
+  { \clist_map_inline:nn {#1} { \acro_module_load:n {style.##1} } }
 
-% options:
 \keys_define:nn {acro}
+  { load-style .code:n = \acro_style_load:n {#1} }
+
+% --------------------------------------------------------------------------
+\acro_if_debug:TF
+  {
+    \cs_new_protected:Npn \__acro_debug_start:n #1
+      {
+        \iow_term:n {}
+        \iow_term:n {#1}
+        \acro_package_if_loaded:nT {l3benchmark} { \benchmark_tic: }
+      }
+    \cs_new_protected:Npn \__acro_debug_stop:
+      { \acro_package_if_loaded:nT {l3benchmark} { \benchmark_toc: } }
+  }
   {
-    messages          .choice: ,
-    messages / silent .code:n     =
-      \bool_set_true:N \l__acro_silence_bool ,
-    messages / loud .code:n       =
-      \bool_set_false:N \l__acro_silence_bool ,
-    messages          .value_required:n = true ,
-    config-file-name  .tl_set:N   = \l_acro_config_file_name_tl ,
-    config-file-name  .initial:n  = acro ,
-    config-file-extension .tl_set:N  = \l_acro_config_file_extension_tl ,
-    config-file-extension .initial:n = cfg ,
-    accsupp           .bool_set:N = \l__acro_acc_supp_bool ,
-    accsupp-options   .tl_set:N   = \l__acro_acc_supp_options_tl ,
-    tooltip           .bool_set:N = \l__acro_tooltip_bool ,
-    tooltip-cmd       .code:n     = \cs_set:Npn \__acro_tooltip_cmd:nn {#1} ,
-    tooltip-cmd       .value_required:n = true ,
-    macros            .bool_set:N = \l__acro_create_macros_bool ,
-    xspace            .bool_set:N = \l__acro_xspace_bool ,
-    % xspace            .code:n     = \acro_option_deprecated:nn {xspace} {} ,
-    strict            .bool_set:N = \l__acro_strict_bool ,
-    case-sensitive    .bool_set:N = \g__acro_case_sensitive_bool ,
-    case-sensitive    .initial:n  = true ,
-    sort              .bool_set:N = \l__acro_sort_bool ,
-    short-format      .code:n     =
-      \tl_set:Nn \l__acro_short_format_tl {#1}
-      \tl_set_eq:NN \l__acro_alt_format_tl \l__acro_short_format_tl
-      \tl_set:Nn \l__acro_list_short_format_tl {#1} ,
-    short-format      .value_required:n = true ,
-    alt-format        .tl_set:N   = \l__acro_alt_format_tl ,
-    alt-format        .value_required:n = true ,
-    long-format       .code:n     =
-      \tl_set:Nn \l__acro_long_format_tl {#1}
-      \tl_set:Nn \l__acro_first_long_format_tl {#1}
-      \tl_set:Nn \l__acro_list_long_format_tl {#1} ,
-    long-format       .value_required:n = true ,
-    first-long-format .code:n     =
-      \tl_set:Nn \l__acro_first_long_format_tl {#1} ,
-    first-long-format .value_required:n = true ,
-    single-format     .tl_set:N   = \l__acro_single_format_tl ,
-    single-format     .value_required:n = true ,
-    format-include-endings .bool_set:N = \l__acro_include_endings_format_bool ,
-    display-foreign   .bool_set:N = \l__acro_foreign_bool ,
-    foreign-format    .tl_set:N   = \l__acro_foreign_format_tl ,
-    foreign-format    .value_required:n = true ,
-    list-short-format .tl_set:N   = \l__acro_list_short_format_tl ,
-    list-short-format .value_required:n = true ,
-    list-short-width  .dim_set:N  = \l__acro_short_width_dim ,
-    list-short-width  .value_required:n = true ,
-    list-long-format  .tl_set:N   = \l__acro_list_long_format_tl ,
-    list-long-format  .value_required:n = true ,
-    list-foreign-format .tl_set:N = \l__acro_foreign_list_format_tl ,
-    list-foreign-format .value_required:n = true ,
-    override-list-format .bool_set:N = \l__acro_override_list_format_bool ,
-    override-list-format .initial:n  = true ,
-    extra-format      .tl_set:N   = \l__acro_extra_format_tl ,
-    extra-format      .value_required:n = true ,
-    single            .bool_set:N = \l__acro_single_use_bool ,
-    single-form       .tl_set:N   = \l__acro_single_form_tl ,
-    single-form       .value_required:n = true ,
-    first-style       .code:n     = \acro_set_first_style:n {#1} ,
-    first-style       .value_required:n = true ,
-    extra-style       .code:n     = \acro_set_extra_style:n {#1} ,
-    extra-style       .value_required:n = true ,
-    label             .bool_set:N = \l__acro_place_label_bool ,
-    label-prefix      .tl_set:N   = \l__acro_label_prefix_tl ,
-    label-prefix      .value_required:n = true ,
-    pages             .choice: ,
-    pages / all       .code:n     =
-      \bool_set_true:N \l__acro_list_all_pages_bool ,
-    pages / first     .code:n     =
-      \bool_set_true:N \l__acro_place_label_bool
-      \bool_set_false:N \l__acro_list_all_pages_bool ,
-    pages             .value_required:n = true ,
-    page-ref          .code:n     =
-      \acro_option_deprecated:nn {page-ref} {page-style}
-      \acro_set_page_style:n {#1} ,
-    page-style        .code:n     = \acro_set_page_style:n {#1} ,
-    page-style        .value_required:n = true ,
-    page-name         .tl_set:N   = \l__acro_page_name_tl ,
-    page-name         .value_required:n = true ,
-    pages-name        .tl_set:N   = \l__acro_pages_name_tl ,
-    pages-name        .value_required:n = true ,
-    following-page    .bool_set:N = \l__acro_following_page_bool ,
-    following-pages   .bool_set:N = \l__acro_following_pages_bool ,
-    following-pages*  .meta:n     =
-      { following-page = #1 , following-pages = #1 } ,
-    following-pages*  .default:n  = true ,
-    next-page         .tl_set:N   = \l__acro_next_page_tl ,
-    next-page         .value_required:n = true ,
-    next-pages        .tl_set:N   = \l__acro_next_pages_tl ,
-    next-pages        .value_required:n = true ,
-    list-style        .code:n     = \acro_set_list_style:n {#1} ,
-    list-style        .value_required:n = true ,
-    list-heading      .code:n     = \acro_set_list_heading:n {#1} ,
-    list-heading      .value_required:n = true ,
-    list-name         .tl_set:N   = \l__acro_list_name_tl ,
-    list-name         .value_required:n = true ,
-    hyperref          .bool_set:N = \l__acro_hyperref_use_bool ,
-    only-used         .bool_set:N = \l__acro_print_only_used_bool ,
-    mark-as-used      .choice: ,
-    mark-as-used / first .code:n  =
-      \bool_gset_true:N \g__acro_mark_first_as_used_bool ,
-    mark-as-used / any   .code:n  =
-      \bool_gset_false:N \g__acro_mark_first_as_used_bool ,
-    mark-as-used      .default:n  = any ,
-    list-caps         .bool_set:N = \l__acro_capitalize_list_bool ,
-    cite              .choice: ,
-    cite / all        .code:n     =
-      \bool_set_true:N \l__acro_citation_all_bool
-      \bool_set_true:N \l__acro_citation_first_bool ,
-    cite / none       .code:n     =
-      \bool_set_false:N \l__acro_citation_all_bool
-      \bool_set_false:N \l__acro_citation_first_bool ,
-    cite / first      .code:n     =
-      \bool_set_false:N \l__acro_citation_all_bool
-      \bool_set_true:N  \l__acro_citation_first_bool ,
-    cite              .default:n  = all ,
-    cite-cmd          .code:n     =
-      \cs_set:Npn \__acro_citation_cmd:w {#1} ,
-    cite-cmd          .value_required:n = true ,
-    group-cite-cmd    .code:n     =
-      \cs_set:Npn \__acro_group_citation_cmd:w {#1} ,
-    group-cite-cmd    .value_required:n = true ,
-    group-citation    .bool_set:N = \l__acro_group_citation_bool ,
-    cite-connect      .tl_set:N   = \l__acro_citation_connect_tl ,
-    cite-connect      .initial:n  = \nobreakspace ,
-    cite-connect      .value_required:n = true ,
-    group-cite-connect .tl_set:N = \l__acro_between_group_connect_citation_tl ,
-    group-cite-connect .initial:n = {,\nobreakspace} ,
-    group-cite-connect .value_required:n = true ,
-    index             .bool_set:N = \l__acro_addto_index_bool ,
-    index-cmd         .code:n     =
-      \cs_set:Npn \__acro_index_cmd:n {#1} ,
-    index-cmd         .value_required:n = true ,
-    uc-cmd            .code:n     =
-      \cs_set_eq:NN \__acro_first_upper_case:n #1 ,
-    uc-cmd            .value_required:n = true ,
-    uppercase-short   .bool_set:N = \l__acro_upper_short_bool ,
-    uppercase-short   .initial:n  = true
-  }
-
-\AtBeginDocument
-  {
-    \bool_if:NTF \l__acro_xspace_bool
-      {
-        \@ifpackageloaded {xspace}
-          { }
-          { \RequirePackage {xspace} }
-        \cs_new_eq:NN \acro_xspace: \xspace
-      }
-      { \cs_new:Npn \acro_xspace: {} }
+    \cs_new_protected:Npn \__acro_debug_start:n #1 {}
+    \cs_new_protected:Npn \__acro_debug_stop: {}
   }
+% --------------------------------------------------------------------------
+\AcroModule{base}{basic functionality of the package}
 
 % --------------------------------------------------------------------------
-% we use xtemplate for different object types and with a different number of
-% arguments; let's declare functions for usage later so we don't have to
-% bother
+% variants of kernel functions:
+\cs_generate_variant:Nn \bool_lazy_any:nTF {e}
+\cs_generate_variant:Nn \bool_lazy_all:nTF {e}
+\cs_generate_variant:Nn \seq_gset_split:Nnn {cVx}
+\cs_generate_variant:Nn \seq_use:Nn {cV}
+\cs_generate_variant:Nn \seq_set_split:Nnn {Nnx}
+\cs_generate_variant:Nn \seq_if_in:NnTF {Ne}
+\cs_generate_variant:Nn \seq_if_in:NnF {ceF}
+\cs_generate_variant:Nn \seq_gremove_all:Nn {cV}
+\cs_generate_variant:Nn \seq_put_right:Nn {Ne}
+\cs_generate_variant:Nn \seq_gput_right:Nn {Ne,ce}
+\cs_generate_variant:Nn \seq_set_split:Nnn {Nne}
+\cs_generate_variant:Nn \clist_if_empty:nTF {e}
+\cs_generate_variant:Nn \clist_item:nn {e}
+\cs_generate_variant:Nn \int_set:Nn {Nx}
+\cs_generate_variant:Nn \tl_set:Nn {Ne}
+\cs_generate_variant:Nn \tl_remove_all:Nn {NV}
+\cs_generate_variant:Nn \tl_remove_once:Nn {NV}
+\cs_generate_variant:Nn \tl_if_in:NnF {NV}
+\cs_generate_variant:Nn \tl_put_right:Nn {Ne}
+\cs_generate_variant:Nn \clist_set:Nn {Ne}
+\cs_generate_variant:Nn \str_if_eq:nnT {x}
+\cs_generate_variant:Nn \str_fold_case:n {e}
+\cs_generate_variant:Nn \str_lowercase:n {e}
+\cs_generate_variant:Nn \msg_error:nnnnn {nnnxx}
+\cs_generate_variant:Nn \msg_warning:nn {nV}
+\cs_generate_variant:Nn \msg_error:nnnn {nne}
+\cs_generate_variant:Nn \prg_new_conditional:Npnn {c}
+\cs_generate_variant:Nn \file_get_mdfive_hash:nN {V}
+\cs_generate_variant:Nn \iow_open:Nn {NV}
+\cs_generate_variant:Nn \use_ii:nn {ne}
+\cs_generate_variant:Nn \keys_set:nn {nV}
+
+% --------------------------------------------------------------------------
+\prg_new_conditional:Npnn \acro_class_if_loaded:n #1 {p,T,F,TF}
+  {
+    \cs_if_exist:cTF {ver@#1.cls}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-% objects with one argument:
-\cs_new_protected:Npn \acro_page_number_instance:nn #1#2
-  { \UseInstance {acro-page-number} {#1} {#2} }
-\cs_generate_variant:Nn \acro_page_number_instance:nn {V}
+\prg_new_conditional:Npnn \acro_if_komascript: {p,T,F,TF}
+  {
+    \cs_if_exist:NTF \KOMAClassName
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-\cs_new_protected:Npn \acro_extra_instance:nn #1#2
-  { \UseInstance {acro-extra} {#1} {#2} }
-\cs_generate_variant:Nn \acro_extra_instance:nn {VV}
+% --------------------------------------------------------------------------
+% attributes instead of property lists:
+\msg_new:nnn {acro} {attribute-not-set}
+  { The~ attribute~ `#1'~ is~ not~ set~ \msg_line_context: }
 
-\cs_new_protected:Npn \acro_title_instance:nn #1#2
-  { \UseInstance {acro-title} {#1} {#2} }
-\cs_generate_variant:Nn \acro_title_instance:nn {VV}
+\msg_new:nnn {acro} {attribute-defined}
+  { The~ attribute~ `#1'~ is~ already~ defined~ \msg_line_context: }
 
-% objects with two arguments:
-\cs_new_protected:Npn \acro_list_instance:nnn #1#2#3
-  { \UseInstance {acro-list} {#1} {#2} {#3} }
-\cs_generate_variant:Nn \acro_list_instance:nnn {VVV}
+\msg_new:nnn {acro} {attribute-undefined}
+  { The~ attribute~ `#1'~ is~ not~ yet~ defined~ \msg_line_context: }
 
-\cs_new_protected:Npn \acro_first_instance:nn #1#2
+\prg_new_conditional:Npnn \acro_attribute_if_exist:n #1 {p,T,F,TF}
   {
-    \acro_property_if_set:nnTF {#1} {first-style}
+    \cs_if_exist:cTF {____acro_attribute_main_ \tl_to_str:n {#1} :}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+
+% #1: attribute
+\cs_new_protected:Npn \acro_attribute_new:n #1
+  {
+    \acro_attribute_if_exist:nTF {#1}
+      { \msg_error:nnn {acro} {attribute-defined} {#1} }
+      { \cs_gset:cpx {____acro_attribute_main_ \tl_to_str:n {#1} :} {} }
+  }
+  
+% #1: attribute
+% #2: item
+% #3: value
+\cs_new_protected:Npn \acro_attribute_set:nnn #1#2#3
+  {
+    \acro_attribute_if_exist:nTF {#1}
       {
-        \tl_set_eq:NN
-          \l__acro_tmpa_tl
-          \l__acro_first_style_tl
+        \cs_gset:cpx
+          {____acro_attribute_ \tl_to_str:n {#1::#2} :}
+          { \exp_not:n { \exp_not:n {#3} } }
       }
+      { \msg_error:nnn {acro} {attribute-undefined} {#1} }
+  }
+\cs_generate_variant:Nn \acro_attribute_set:nnn {nnx,nne}
+
+% #1: attribute
+% #2: item
+\cs_new_protected:Npn \acro_attribute_unset:nn #1#2
+  { \cs_undefine:c {____acro_attribute_ \tl_to_str:n {#1::#2} :} }
+  
+% #1: attribute
+% #2: item
+\cs_new:Npn \acro_attribute_get:nn #1#2
+  {
+    \acro_attribute_if_exist:nTF {#1}
       {
-        \tl_set_eq:NN
-          \l__acro_tmpa_tl
-          \l__acro_first_instance_tl
+        \cs_if_exist:cTF {____acro_attribute_ \tl_to_str:n {#1::#2} :}
+          { \use:c {____acro_attribute_ \tl_to_str:n {#1::#2} :} }
+          {
+            \acro_if_debug:T
+              { \msg_expandable_error:nnn {acro} {attribute-not-set} {#1::#2} }
+          }
       }
-    \acro_if_defined:nT {#1}
+      { \msg_expandable_error:nnn {acro} {attribute-undefined} {#1} }
+  }
+\cs_generate_variant:Nn \acro_attribute_get:nn {ne}
+
+% #1: attribute
+% #2: item
+\prg_new_conditional:Npnn \acro_attribute_if_set:nn #1#2 {p,T,F,TF}
+  {
+    \acro_attribute_if_exist:nTF {#1}
       {
-        \use:x {
-          \UseInstance {acro-first}
-            { \exp_not:V \l__acro_tmpa_tl }
-            { \exp_not:n {#1} }
-            { \exp_not:n {#2} }
-          }
+        \cs_if_exist:cTF {____acro_attribute_ \tl_to_str:n {#1::#2} :}
+          { \prg_return_true: }
+          { \prg_return_false: }
       }
+      { \prg_return_false: }
   }
-\cs_generate_variant:Nn \acro_first_instance:nn {nV}
+\prg_generate_conditional_variant:Nnn \acro_attribute_if_set:nn {ne} {p,T,F,TF}
 
-% --------------------------------------------------------------------------
-% hyperref support
-\cs_new_eq:NN \acro_hyper_target:nn \use_ii:nn
-\cs_new_eq:NN \acro_hyper_link:nn   \use_ii:nn
+% #1: attribute
+% #2: item
+\prg_new_conditional:Npnn \__acro_if_attribute_eq:nnn #1#2#3 {p,T,F,TF}
+  {
+    \tl_if_eq:enTF
+      { \use:c {____acro_attribute_ \tl_to_str:n {#1::#2} :} }
+      {#3}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-\cs_new_protected:Npn \acro_activate_hyperref_support:
+% #1: attribute
+% #2: item
+\cs_new_protected:Npn \acro_attribute_show:nn #1#2
   {
-    \bool_lazy_and:nnT
-      { \l__acro_hyperref_loaded_bool }
-      { \l__acro_hyperref_use_bool }
+    \acro_attribute_if_exist:nTF {#1}
       {
-        \sys_if_engine_xetex:TF
+        \iow_term:n {}
+        \iow_term:x
           {
-            \cs_set:Npn \acro_hyper_link:nn ##1##2
-              { \hyperlink {##1} { \XeTeXLinkBox {##2} } }
+            \c_space_tl \c_space_tl
+            \tl_to_str:n {#1::#2}
+            \c_space_tl \c_space_tl == \c_space_tl \c_space_tl
+            {\use:c {____acro_attribute_ \tl_to_str:n {#1::#2} :}}
           }
-          { \cs_set_eq:NN \acro_hyper_link:nn \hyperlink }
-        \cs_set:Npn \acro_hyper_target:nn ##1##2
-          { \raisebox {3ex} [0pt] { \hypertarget {##1} { } } ##2 }
+        \iow_term:n {}
       }
+      { \msg_error:nnn {acro} {attribute-undefined} {#1} }
   }
 
-% #1: id
-% #2: text
-\cs_new_protected:Npn \__acro_make_link:nn #1#2
+% ----------------------------------------------------------------------------
+% option setup:
+\cs_new_protected:Npn \acro_setup:n #1
+  { \keys_set:nn {acro} {#1} }
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{interface}{definitions of user commands}
+
+% --------------------------------------------------------------------------
+% helper commands
+\NewDocumentCommand \AcroAddRow {+m}
   {
-    \bool_lazy_and:nnTF
-      { \l__acro_hyperref_use_bool }
-      { \l__acro_hyperref_loaded_bool }
+    \tl_put_right:Ne \AcronymTable
       {
-         \acro_hyper_link:nn {#1} { \phantom {#2} }
-         \acro_if_is_single:nTF {#1}
-           { \hbox_overlap_left:n {#2} }
-           { \acro_color_link:n { \hbox_overlap_left:n {#2} } }
-       }
-       {#2}
+        \exp_not:n { \tl_gset:Nn \AcronymID } { \AcronymID }
+        \exp_not:n {#1}
+      }
   }
 
-\cs_new:Npn \acro_color_link:n #1
+\NewDocumentCommand \AcroRerun {}
+  { \acro_rerun:n {list} }
+
+\NewDocumentCommand \AcroPropertiesMap {+m}
+  { \acro_properties_map:n {#1} }
+
+\NewDocumentCommand \AcroMap {m+m}
+  { \acro_list_map:nn {#1} {#2} }
+
+\NewDocumentCommand \AcroNeedPackage {m}
   {
-    \cs_if_exist:NTF \hypersetup
-      {
-        \ifHy@colorlinks
-          \exp_after:wN \use_i:nn
-        \else
-          \ifHy@ocgcolorlinks
-            \exp_after:wN \use_i:nn
-          \else
-            \exp_after:wN \exp_after:wN \exp_after:wN \use_ii:nn
-          \fi
-        \fi
-        { \textcolor { \@linkcolor } {#1} }
-        {#1}
-      }
-      {#1}
+    \acro_package_if_loaded:nF {m}
+      { \msg_error:nnen {acro} {package-needed} { \TemplateName } {#1} }
   }
 
-\AtBeginDocument{
-  \cs_if_exist:NF \textcolor { \cs_new_eq:NN \textcolor \use_ii:nn }
-}
+% --------------------------------------------------------------------------
+% general commands:
+\NewDocumentCommand \acsetup {+m}
+  { \acro_setup:n {#1} }
+
+\NewDocumentCommand \acroloadstyle {m}
+  { \acro_style_load:n {#1} }
+
+\NewExpandableDocumentCommand \acroifusedTF {m}
+  { \acro_boolean_property_if:nnTF {#1} {used} }
+
+\NewDocumentCommand \acuse {m}
+  { \acro_use:n {#1} }
+
+\NewDocumentCommand \acuseall {}
+  { \acro_use_all: }
+
+\NewDocumentCommand \acreset {m}
+  { \acro_reset:n {#1} }
+
+\NewDocumentCommand \acresetall {}
+  { \acro_reset_all: }
+
+\NewExpandableDocumentCommand \acsimple {mm}
+  { \acro_pdfstring_template:nn {#1} {#2} }
+
+\NewDocumentCommand \acbarrier {}
+  { \acro_barrier: }
+
+\NewDocumentCommand \acswitchoff {}
+  { \acro_switch_off: }
+
+\NewDocumentCommand \acswitchon {}
+  { \acro_switch_on: }
 
 % --------------------------------------------------------------------------
-% output style of the first time an acronym is used
+\NewDocumentCommand \DeclareAcroProperty {st?t!t|m}
+  { \acro_property_declare:nnnnn {#1} {#2} {#3} {#4} {#5} }
 
-% helper macros for the styles
-% #1: short|long
-% #2: id
-% #3: long
-\cs_new_protected:Npn \__acro_print_form_and_indefinite:nnn #1#2#3
+\NewDocumentCommand \DeclareAcroPropertyAlias {st?t!t|mm}
   {
-    \group_begin:
-      \acro_for_all_trailing_tokens_do:n
-        { \acro_deactivate_trailing_action:n {##1} }
-      \str_case:nn {#1}
-        {
-          {long} {
-            \bool_lazy_or:nnT
-              { \l__acro_first_only_long_bool }
-              {  !\l__acro_first_only_short_bool }
-              {
-                \acro_write_indefinite:nn {#2} {long}
-                \acro_write_expanded:nnn {#2} {first-long} {#3}
-              }
-          }
-          {short} {
-            \bool_lazy_or:nnT
-              { !\l__acro_first_only_long_bool }
-              { \l__acro_first_only_short_bool }
-              {
-                \acro_soft_upper:
-                \acro_write_indefinite:nn {#2} {short}
-                \acro_write_compact:nn {#2} {short}
-              }
-          }
-        }
-    \group_end:
+    \acro_property_declare:nnnnn {#1} {#2} {#3} {#4} {#5}
+    \acro_property_make_alias:nn {#5} {#6}
   }
 
-\cs_new_protected:Npn \__acro_open_bracket:
+\NewDocumentCommand \MakeAcroPropertyAlias {mm}
+  { \acro_property_make_alias:nn {#1} {#2} }
+
+\NewDocumentCommand \UseAcroTemplate {O{acronym}mO{1}}
+  { \acro_template_use:nnn {#3} {#1} {#2} }
+
+\NewDocumentCommand \NewAcroTemplate {O{acronym}m+m}
+  { \use:c {acro_#1_template_new:nn} {#2} {#3} }
+
+\NewDocumentCommand \RenewAcroTemplate {O{acronym}m+m}
+  { \use:c {acro_#1_template_renew:nn} {#2} {#3} }
+
+\NewDocumentCommand \DeclareAcronym {m+m}
+  { \acro_declare_acronym:nn {#1} {#2} }
+
+\NewDocumentCommand \DeclareAcroEnding {mmm}
+  { \acro_declare_ending:nnn {#1} {#2} {#3} }
+
+\NewDocumentCommand \DeclareAcroArticle {mm}
+  { \acro_article_declare:nn {#1} {#2} }
+
+\NewDocumentCommand \DeclareAcroTranslation {m+m}
+  { \acro_declare_translations:nn {#1} {#2} }
+
+\NewDocumentCommand \AddAcroTranslations {m+m}
+  { \acro_add_translations:nn {#1} {#2} }
+
+\NewExpandableDocumentCommand \acrotranslate {m}
+  { \acro_translate:n {#1} }
+
+\NewExpandableDocumentCommand \aciftrailing {}
+  { \acro_trailing_if_tokens:nTF }
+
+\NewDocumentCommand \acfootnote {m}
+  { \acro_footnote:n {#1} }
+
+\NewDocumentCommand \acgobbletrail {}
+  { \bool_gset_true:N \g__acro_gobble_trail_bool }
+
+\NewExpandableDocumentCommand \acdot   {} { \acro_dot: }
+\NewExpandableDocumentCommand \acspace {} { \acro_space: }
+\NewExpandableDocumentCommand \abbrdot {} { .\@ }
+
+\NewDocumentCommand \acroupper {} { \acro_upper: }
+\NewDocumentCommand \acrofull {} { \acro_first: }
+
+\NewDocumentCommand \printacronyms {o}
   {
-    \bool_lazy_and:nnT
-      { !\l__acro_first_only_long_bool }
-      { !\l__acro_first_only_short_bool }
-      {
-        \acro_space:
-        \tl_if_blank:VF \l__acro_first_between_tl
-          {
-            \tl_use:N \l__acro_first_between_tl
-            \acro_space:
-          }
-        \bool_if:NT \l__acro_first_use_brackets_bool
-          { \tl_head:N \l__acro_first_brackets_tl }
-      }
+    \group_begin:
+      \IfNoValueF {#1}
+        { \keys_set:nn {acro/list} {#1} }
+      \acro_list:
+    \group_end:
   }
 
-\cs_new_protected:Npn \__acro_close_bracket:
+% --------------------------------------------------------------------------
+% commands for list templates
+\NewDocumentCommand \acroheading  {} { \acro_heading: }
+\NewDocumentCommand \acropreamble {} { \acro_preamble: }
+
+\NewExpandableDocumentCommand \acrolistname {}
+  { \tl_use:N \l__acro_list_name_tl }
+
+% --------------------------------------------------------------------------
+% cmmands for use in templates:
+\NewDocumentCommand \acronymsmapTF {+m+m+m}
   {
-    \bool_lazy_all:nT
+    \acro_acronyms_map:nTF
       {
-        { \l__acro_first_use_brackets_bool }
-        { !\l__acro_first_only_short_bool }
-        { !\l__acro_first_only_long_bool }
+        \tl_set:Nn \AcronymID {##1}
+        #1
       }
-      { \tl_tail:N \l__acro_first_brackets_tl }
+      {#2}
+      {#3}
   }
-  
-% #1: short|long
-% #2: id
-% #3: long
-\cs_new_protected:Npn \__acro_print_form:nnn #1#2#3
+
+\NewDocumentCommand \acronymsmapT {+m+m}
+  { \acronymsmapTF {#1} {#2} {} }
+
+\NewDocumentCommand \acronymsmapF {+m+m}
+  { \acronymsmapTF {#1} {} {#2} }
+
+\NewDocumentCommand \acronymsmap {+m}
+  { \acronymsmapTF {#1} {} {} }
+
+\NewExpandableDocumentCommand \acrofield {mm}
+  { \acro_property_get:nn {#1} {#2} }
+
+\NewDocumentCommand \acroprintfield {mm}
   {
-    \str_case:nn {#1}
+    \acro_property_if_eq:nnTF {#2} {list}
       {
-        {long} {
-          \bool_lazy_or:nnT
-            { \l__acro_first_only_long_bool }
-            { !\l__acro_first_only_short_bool }
-            {
-              \group_begin:
-                \bool_set_false:N \l__acro_first_upper_bool
-                \acro_write_expanded:nnn {#2} {first-long} {#3}
-              \group_end:
-            }
-        }
-        {short} {
-          \bool_lazy_or:nnT
-            { !\l__acro_first_only_long_bool }
-            { \l__acro_first_only_short_bool }
-            {
-              \group_begin:
-                \acro_soft_upper:
-                \acro_write_compact:nn {#2} {short}
-              \group_end:
-            }
-        }
+        \bool_if:NT \l__acro_upper_list_bool { \acro_upper: }
+        \acro_write:en {#1} {#2}
       }
+      { \acro_write:en {#1} {#2} }
   }
 
-% #1: id
-\cs_new_protected:Npn \__acro_foreign_sep:n #1
+\NewExpandableDocumentCommand \acrofieldifTF {+m+m+m+m}
+  { \acro_property_if_set:nnTF {#1} {#2} {#3} {#4} }
+
+\NewDocumentCommand \acroifanyfieldTF {mm+m+m}
+  { \acro_property_if_any:nnTF {#1} {#2} {#3} {#4} }
+
+\NewDocumentCommand \acroifallfieldsTF {mm+m+m}
+  { \acro_property_if_all:nnTF {#1} {#2} {#3} {#4} }
+
+\NewExpandableDocumentCommand \acroifpagefieldTF {m}
+  { \acro_if_pages:nTF {#1} }
+
+\NewDocumentCommand \acrowrite {m}
+  { \acroprintfield { \AcronymID } {#1} }
+
+\NewDocumentCommand \acroshow {m}
+  { \acro_property_show:en { \AcronymID } {#1} }
+
+\NewDocumentCommand \acrodonotuse {}
+  { \acro_use_false: }
+
+\NewDocumentCommand \acroformat {mm}
+  { \acro_format:enn { \AcronymID } {#1} {#2} }
+
+\NewDocumentCommand \acrogroupcite {}
   {
-    \bool_lazy_all:nT
+    \bool_if:NT \l__acro_cite_group_bool
       {
-        { \l__acro_foreign_bool }
-        { !\l__acro_first_only_short_bool }
-        { !\l__acro_first_only_long_bool }
+        \tl_set_eq:NN \l__acro_cite_pre_tl \l__acro_cite_between_tl
+        \cs_set_eq:NN \__acro_cite_cmd:w \__acro_cite_group_cmd:w
+        \acro_cite_if:neT { \l__acro_star_bool } { \AcronymID }
+          { \acro_cite:e { \AcronymID } }
       }
-      { \acro_if_foreign:nT {#1} { \tl_use:N \l__acro_foreign_sep_tl } }
   }
-  
-% #1: id
-\cs_new_protected:Npn \__acro_print_foreign:n #1
+
+\NewDocumentCommand \acrocite {}
+  { \bool_set_true:N \l__acro_cite_always_bool }
+
+\NewDocumentCommand \acroifTF {m+m+m}
+  { \acro_property_if_set:enTF { \AcronymID } {#1} {#2} {#3} }
+\NewDocumentCommand \acroifT {m+m}
+  { \acro_property_if_set:enTF { \AcronymID } {#1} {#2} {} }
+\NewDocumentCommand \acroifF {m+m}
+  { \acro_property_if_set:enTF { \AcronymID } {#1} {} {#2} }
+
+\NewDocumentCommand \acroifanyTF {m+m+m}
+  { \acro_property_if_any:enTF { \AcronymID } {#1} {#2} {#3} }
+\NewDocumentCommand \acroifanyT {m+m}
+  { \acro_property_if_any:enTF { \AcronymID } {#1} {#2} {} }
+\NewDocumentCommand \acroifanyF {m+m}
+  { \acro_property_if_any:enTF { \AcronymID } {#1} {} {#2} }
+
+\NewDocumentCommand \acroifallTF {m+m+m}
+  { \acro_property_if_all:enTF { \AcronymID } {#1} {#2} {#3} }
+\NewDocumentCommand \acroifallT {m+m}
+  { \acro_property_if_all:enTF { \AcronymID } {#1} {#2} {} }
+\NewDocumentCommand \acroifallF {m+m}
+  { \acro_property_if_all:enTF { \AcronymID } {#1} {} {#2} }
+
+\NewDocumentCommand \acroifsingleTF {+m+m}
+  { \acro_if_single:eTF { \AcronymID } {#1} {#2} }
+\NewDocumentCommand \acroifsingleT {+m}
+  { \acro_if_single:eTF { \AcronymID } {#1} {} }
+\NewDocumentCommand \acroifsingleF {+m}
+  { \acro_if_single:eTF { \AcronymID } {} {#1} }
+
+\NewDocumentCommand \acroiffirstTF {+m+m}
+  { \acro_if_first:eTF { \AcronymID } {#1} {#2} }
+\NewDocumentCommand \acroiffirstT {+m}
+  { \acro_if_first:eTF { \AcronymID } {#1} {} }
+\NewDocumentCommand \acroiffirstF {+m}
+  { \acro_if_first:eTF { \AcronymID } {} {#1} }
+
+\NewDocumentCommand \acroiftagTF {m+m+m}
+  { \acro_if_tag:enTF { \AcronymID } {#1} {#2} {#3} }
+\NewDocumentCommand \acroiftagT {m+m}
+  { \acro_if_tag:enT { \AcronymID } {#1} {#2} }
+\NewDocumentCommand \acroiftagF {m+m}
+  { \acro_if_tag:enF { \AcronymID } {#1} {#2} }
+
+\NewDocumentCommand \acropages {mm}
+  { \acro_print_pages:enn { \AcronymID } {#1} {#2} }
+
+\NewDocumentCommand \acronopagerange {}
+  { \acro_no_page_ranges:e { \TemplateName } }
+
+\NewDocumentCommand \acropagefill {}
+  { \acro_if_pages:eT  { \AcronymID } { \tl_use:N \l__acro_pages_fill_tl } }
+
+\NewExpandableDocumentCommand \acroifpagesTF {}
+  { \acro_if_pages:eTF { \AcronymID } }
+
+\NewExpandableDocumentCommand \acroifpagesT {}
+  { \acro_if_pages:eT { \AcronymID } }
+
+\NewExpandableDocumentCommand \acroifpagesF {}
+  { \acro_if_pages:eF { \AcronymID } }
+
+\NewExpandableDocumentCommand \acroifchapterTF {}
+  { \cs_if_exist:NTF \chapter }
+
+\NewExpandableDocumentCommand \acroifchapterT {}
+  { \cs_if_exist:NT \chapter }
+
+\NewExpandableDocumentCommand \acroifchapterF {}
+  { \cs_if_exist:NF \chapter }
+
+% --------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{aux}{usage of auxiliary files}
+
+\cs_new_protected:Npn \ACRO #1 { \use:c {__acro_aux_#1:} }
+
+\cs_new_protected:Npn \__acro_auxlist_field_new:cpn #1
+  { \cs_new_protected:cpn {__acro_aux_#1:} }
+
+\cs_new_protected:Npn \acro_auxlist_to_aux:nn #1#2
+  { \acro_write_to_aux:x { \token_to_str:N \ACRO {#1} #2 } }
+
+\tl_const:Nx \c_acro_auxfile_tl { \c_sys_jobname_str .acr }
+
+\iow_new:N \l__acro_aux_file_iow
+\tl_new:N \g__acro_mdfive_hash_tl
+
+\acro_at_begin_document:n
   {
-    \acro_if_foreign:nT {#1}
+    \legacy_if:nT {@filesw}
       {
-        \bool_lazy_all:nT
-          {
-            { \l__acro_foreign_bool }
-            { !\l__acro_first_only_short_bool }
-            { !\l__acro_first_only_long_bool }
-          }
-          {
-            \acro_write_foreign:n {#1}
-            \acro_endings:nn {#1} {foreign}
-          }
+        \iow_now:Nx \@auxout
+          { \token_to_str:N \providecommand \token_to_str:N \ACRO [1] {} }
       }
+    \file_get_mdfive_hash:VN
+      \c_acro_auxfile_tl
+      \g__acro_mdfive_hash_tl
+    \iow_open:NV \l__acro_aux_file_iow \c_acro_auxfile_tl
   }
 
-\cs_new_protected:Npn \__acro_print_citation:n #1
+\cs_new_protected:Npn \acro_close_aux:
   {
-    \bool_if:NT \l__acro_group_citation_bool
-      { \acro_group_cite:n {#1} }
+    \iow_close:N \l__acro_aux_file_iow
+    \file_get_mdfive_hash:VN
+      \c_acro_auxfile_tl
+      \l__acro_tmpa_tl
+    \tl_if_eq:NNF \g__acro_mdfive_hash_tl \l__acro_tmpa_tl
+      { \acro_rerun:n {general} }
+    \legacy_if:nT {@filesw}
+      { \iow_now:Nx \@auxout { \token_to_str:N \ACRO {readaux} } }
   }
 
-\cs_new_protected:Npn \__acro_finalize_first:n #1
+\cs_new_protected:Npn \acro_write_to_aux:n #1
   {
-    \bool_if:NF \l__acro_group_citation_bool
-      { \acro_cite_if:Nn \l__acro_citation_first_bool {#1} }
-    \acro_index_if:Nn \l__acro_addto_index_bool {#1}
-    \acro_property_get:nnT {#1} {post}
-      { \tl_use:N \l__acro_post_tl }
+    \legacy_if:nT {@filesw}
+      { \iow_now:Nn \l__acro_aux_file_iow {#1} }
   }
+\cs_generate_variant:Nn \acro_write_to_aux:n {x}
 
-% --------------------------------------------------------------------------
-% the `acro-first' object, templates, instances:
-% #1: id
-% #2: long
-\DeclareObjectType {acro-first} {2}
-
-% template for inline appearance:
-\DeclareTemplateInterface {acro-first} {inline} {2}
-  {
-    brackets      : boolean   = true  ,
-    brackets-type : tokenlist = ()    ,
-    only-short    : boolean   = false ,
-    only-long     : boolean   = false ,
-    reversed      : boolean   = false ,
-    between       : tokenlist         ,
-    foreign-sep   : tokenlist = {,~}
-  }
-\DeclareTemplateCode {acro-first} {inline} {2}
-  {
-    brackets      = \l__acro_first_use_brackets_bool ,
-    brackets-type = \l__acro_first_brackets_tl       ,
-    only-short    = \l__acro_first_only_short_bool   ,
-    only-long     = \l__acro_first_only_long_bool    ,
-    reversed      = \l__acro_first_reversed_bool     ,
-    between       = \l__acro_first_between_tl        ,
-    foreign-sep   = \l__acro_foreign_sep_tl
-  }
-  {
-    \AssignTemplateKeys
-    \bool_set_true:N \l__acro_first_instance_bool
-    \bool_if:NTF \l__acro_first_reversed_bool
-      { % zuerst kurze Form, dann lange Form:
-        \__acro_print_form_and_indefinite:nnn {short} {#1} {#2}
-        \__acro_open_bracket:
-        \__acro_print_foreign:n {#1}
-        \__acro_foreign_sep:n {#1}
-        \__acro_print_form:nnn {long} {#1} {#2}
-        \__acro_print_citation:n {#1}
-        \__acro_close_bracket:
-        \__acro_finalize_first:n {#1}
-      }
-      { % zuerst lange Form, dann kurze Form:
-        \__acro_print_form_and_indefinite:nnn {long} {#1} {#2}
-        \__acro_open_bracket:
-        \__acro_print_foreign:n {#1}
-        \__acro_foreign_sep:n {#1}
-        \__acro_print_form:nnn {short} {#1} {#2}
-        \__acro_print_citation:n {#1}
-        \__acro_close_bracket:
-        \__acro_finalize_first:n {#1}
-      }
-  }
-  
-% template for footnotes, sidenotes, ...
-\cs_new:Npn \__acro_note_command:n #1 {#1}
-\DeclareTemplateInterface {acro-first} {note} {2}
+\__acro_auxlist_field_new:cpn {readaux}
   {
-    use-note     : boolean    = true ,
-    note-command : function 1 = \footnote {#1} ,
-    foreign-sep  : tokenlist  = {,~} ,
-    reversed      : boolean   = false ,
+    \file_if_exist:nT { \c_sys_jobname_str .acr }
+      { \file_input:n { \c_sys_jobname_str .acr } }
   }
 
-\DeclareTemplateCode {acro-first} {note} {2}
+% ----------------------------------------------------------------------------
+% list for recording values that need to be written to the aux file and
+% updated at begin document
+
+\str_new:N \l__acro_auxlist_split_str
+\keys_define:nn {acro}
   {
-    use-note     = \l__acro_use_note_bool  ,
-    note-command = \__acro_note_command:n  ,
-    foreign-sep  = \l__acro_foreign_sep_tl ,
-    reversed     = \l__acro_first_reversed_bool
+    auxlist-split .code:n    = \str_set:Nn \l__acro_auxlist_split_str {#1} ,
+    auxlist-split .initial:n = ||
   }
-  {
-    \AssignTemplateKeys
-    \bool_if:NTF \l__acro_first_reversed_bool
-      { % long in text and short in note
-        \__acro_print_form_and_indefinite:nnn {long} {#1} {#2}
-        \bool_if:NT \l__acro_use_note_bool
+
+% define list:
+% #1: name
+\cs_new_protected:Npn \__acro_auxlist_new:n #1
+  {
+    % entries collected during the run:
+    \seq_new:c {g__acro_auxlist_#1_seq}
+    % entries read from the auxfile:
+    \seq_new:c {g__acro_auxlist_recorded_#1_seq}
+    \acro_attribute_new:n {#1}
+    \__acro_auxlist_field_new:cpn {#1} ##1
+      {
+        \tl_if_blank:nF {##1}
           {
-            \__acro_note_command:n
-              {
-                \__acro_print_foreign:n {#1}
-                \__acro_foreign_sep:n {#1}
-                \__acro_print_form:nnn {short} {#1} {#2}
-                \__acro_print_citation:n {#1}
-                \__acro_finalize_first:n {#1}
-              }
+            \seq_gset_split:cVx {g__acro_auxlist_#1_seq}
+              \l__acro_auxlist_split_str
+              { \tl_to_str:n {##1} }
+            \seq_map_inline:cn {g__acro_auxlist_#1_seq}
+              { \acro_attribute_set:nnn {#1} {####1} {} }
           }
       }
-      { % short in text and long in note
-        \__acro_print_form_and_indefinite:nnn {short} {#1} {#2}
-        \bool_if:NT \l__acro_use_note_bool
+    \acro_at_begin_document:n
+      {
+        \seq_gclear:c {g__acro_auxlist_recorded_#1_seq}
+        \seq_set_eq:Nc \l__acro_tmpa_seq {g__acro_auxlist_#1_seq}
+        \seq_map_inline:Nn \l__acro_tmpa_seq
           {
-            \__acro_note_command:n
-              {
-                \__acro_print_foreign:n {#1}
-                \__acro_foreign_sep:n {#1}
-                \__acro_print_form:nnn {long} {#1} {#2}
-                \__acro_print_citation:n {#1}
-                \__acro_finalize_first:n {#1}
-              }
+            \str_set:Nn \l__acro_tmpa_str {##1}
+            \seq_gput_right:cV {g__acro_auxlist_recorded_#1_seq} \l__acro_tmpa_str
           }
+        \seq_gremove_duplicates:c {g__acro_auxlist_recorded_#1_seq}        
       }
   }
 
-% --------------------------------------------------------------------------
-% declare new first styles:
-\cs_new_protected:Npn \acro_declare_first_style:nnn #1#2#3
+% add to or remove from list:
+% #1: name
+% #2: entry
+\cs_new_protected:Npn \__acro_auxlist_add:nn #1#2
   {
-    \DeclareInstance {acro-first} {#1} {#2} {#3}
-    \prop_put:Nnn \l__acro_first_styles_prop  {#1} {#2}
+    \str_set:Nn \l__acro_tmpa_str {#2}
+    \acro_attribute_set:nnn {#1} {#2} {}
+    \seq_if_in:cVT {g__acro_auxlist_#1_seq} \l__acro_tmpa_str
+      { \seq_gremove_all:cV {g__acro_auxlist_#1_seq} \l__acro_tmpa_str }
+    \seq_gput_right:cV {g__acro_auxlist_#1_seq} \l__acro_tmpa_str
   }
+\cs_generate_variant:Nn \__acro_auxlist_add:nn {nx}
 
-% set a list style
-\cs_new_protected:Npn \acro_set_first_style:n #1
+% #1: name
+% #2: entry
+\cs_new_protected:Npn \__acro_auxlist_remove:nn #1#2
   {
-    \prop_if_in:NnTF \l__acro_first_styles_prop {#1}
-      { \__acro_set_first_style:n {#1} }
-      {
-        \msg_warning:nnnnn {acro} {unknown}
-          {first~ style}
-          {#1}
-          {default}
-        \__acro_set_first_style:n {default}
-      }
+    \str_set:Nn \l__acro_tmpa_str {#2}
+    \acro_attribute_if_set:nnT {#1} {#2}
+      { \acro_attribute_unset:nn {#1} {#2} }
+    \seq_if_in:cVT {g__acro_auxlist_#1_seq} \l__acro_tmpa_str
+      { \seq_gremove_all:cV {g__acro_auxlist_#1_seq} \l__acro_tmpa_str }
+    \seq_if_in:cVT {g__acro_auxlist_recorded#1_seq} \l__acro_tmpa_str
+      { \seq_gremove_all:cV {g__acro_auxlist_recorded_#1_seq} \l__acro_tmpa_str }
   }
+\cs_generate_variant:Nn \__acro_auxlist_remove:nn {nx}
 
-\cs_new_protected:Npn \__acro_set_first_style:n #1
+% check if in list:
+% #1: name
+% #2: entry
+\prg_new_conditional:Npnn \__acro_auxlist_if_in:nn #1#2 {p,T,F,TF}
   {
-    \tl_set:Nn \l__acro_first_instance_tl {#1}
-    \prop_get:NnN \l__acro_first_styles_prop {#1} \l__acro_tmpa_tl
+    \acro_attribute_if_set:nnTF {#1} {#2}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
+\prg_generate_conditional_variant:Nnn \__acro_auxlist_if_in:nn {nx} {T,TF}
 
-% --------------------------------------------------------------------------
-% formatting the extras information:
-\DeclareObjectType {acro-extra} {1}
+\bool_new:N \l__acro_auxlists_clear_bool
+\cs_new_protected:Npn \acro_auxlists_clear:
+  { \bool_set_true:N \l__acro_auxlists_clear_bool }
 
-\DeclareTemplateInterface {acro-extra} {inline} {1}
-  {
-    punct         : boolean   = false ,
-    punct-symbol  : tokenlist = {,}   ,
-    brackets      : boolean   = true  ,
-    brackets-type : tokenlist = ()
+% update list (should be used inside \acro_at_end_document:n):
+% #1: name
+\cs_new_protected:Npn \__acro_auxlist_update:n #1
+  {
+    \seq_remove_duplicates:c {g__acro_auxlist_#1_seq}
+    \seq_remove_duplicates:c {g__acro_auxlist_recorded_#1_seq}
+    \str_set:Nx \l__acro_tmpa_str
+      { \seq_use:cn {g__acro_auxlist_#1_seq} {} }
+    \str_set:Nx \l__acro_tmpb_str
+      { \seq_use:cn {g__acro_auxlist_recorded_#1_seq} {} }
+    \str_if_eq:NNF \l__acro_tmpa_str \l__acro_tmpb_str
+      { \acro_rerun:n {property} }
+    \bool_if:NF \l__acro_auxlists_clear_bool
+      {
+        \acro_auxlist_to_aux:nn {#1}
+          { { \seq_use:cV {g__acro_auxlist_#1_seq} \l__acro_auxlist_split_str } }
+      }
   }
 
-\DeclareTemplateCode {acro-extra} {inline} {1}
-  {
-    punct         = \l__acro_extra_punct_bool        ,
-    punct-symbol  = \l__acro_extra_punct_tl          ,
-    brackets      = \l__acro_extra_use_brackets_bool ,
-    brackets-type = \l__acro_extra_brackets_tl
-  }
-  {
-    \AssignTemplateKeys
-    \bool_if:NT \l__acro_extra_punct_bool
-      { \tl_use:N \l__acro_extra_punct_tl \tl_use:N \c_space_tl }
-    \bool_if:NT \l__acro_extra_use_brackets_bool
-      { \tl_head:N \l__acro_extra_brackets_tl }
-    \acro_write_long:Vn \l__acro_extra_format_tl {#1}
-    \bool_if:NT \l__acro_extra_use_brackets_bool
-      { \tl_tail:N \l__acro_extra_brackets_tl }
-  }
+% loop over list:
+% #1: name
+% #2: code
+\cs_new_protected:Npn \__acro_auxlist_foreach_entry:nn #1#2
+  { \seq_map_inline:cn {g__acro_auxlist_recorded_#1_seq} {#2} }
+
+\cs_new_protected:Npn \__acro_auxlist_foreach_new_entry:nn #1#2
+  { \seq_map_inline:cn {g__acro_auxlist_#1_seq} {#2} }
+
+% length of a list:
+% #1: name
+\cs_new:Npn \__acro_auxlist_count:n #1
+  { \seq_count:c {g__acro_auxlist_recorded_#1_seq} }
+
+% item of a list:
+% #1: name
+% #2: integer
+\cs_new:Npn \__acro_auxlist_item:nn #1#2
+  { \seq_item:cn {g__acro_auxlist_recorded_#1_seq} {#2} }
 
-% declare new extra styles:
-\cs_new_protected:Npn \acro_declare_etxra_style:nnn #1#2#3
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{properties}{properties of acronyms}
+
+% ----------------------------------------------------------------------------
+% messages:
+\msg_new:nnn {acro} {unknown-property}
   {
-    \DeclareInstance {acro-etxra} {#1} {#2} {#3}
-    \prop_put:Nnn \l__acro_etxra_styles_prop  {#1} {#2}
+    You~ tried~ to~ set~ the~ property~ `#1'~ \msg_line_context: . \\
+    This~ property~ does~ not~ exist.~ Check~ for~ a~ typo~ or~ \\
+    define~ the~ property~ yourself.
   }
 
-% set an extra style
-\cs_new_protected:Npn \acro_set_extra_style:n #1
+\msg_new:nnn {acro} {property-unique}
   {
-    \prop_if_in:NnTF \l__acro_extra_styles_prop {#1}
-      { \__acro_set_extra_style:n {#1} }
-      {
-        \msg_warning:nnnnn {acro} {unknown}
-          {extra~ style}
-          {#1}
-          {default}
-        \__acro_set_extra_style:n {default}
-      }
+    You~ tried~ to~ set~ the~ property~ `#1'~ \msg_line_context: . \\
+    This~ property~ has~ to~ have~ a~ unique~ value~ and~ thus~ \\
+    cannot~ be~ set~ to~ `#2'~ since~ this~ value~ is~ already~ talen.
   }
 
-\cs_new_protected:Npn \__acro_set_extra_style:n #1
+\msg_new:nnn {acro} {no-boolean-property}
   {
-    \tl_set:Nn \l__acro_extra_instance_tl {#1}
-    \prop_get:NnN \l__acro_extra_styles_prop {#1} \l__acro_tmpa_tl
+    You~ tried~ to~ check~ the~ boolean~ value~ of~ property~ `#1'~
+    \msg_line_context: . \\
+    However,~ property~ `#1'~ is~ not~ a~ boolean~ property!
   }
 
-\cs_new_protected:Npn \acro_declare_extra_style:nnn #1#2#3
+\msg_new:nnn {acro} {unbalanced-property-list}
   {
-    \DeclareInstance {acro-extra} {#1} {#2} {#3}
-    \prop_put:Nnn \l__acro_extra_styles_prop  {#1} {#2}
+    There~ is~ a~ mis-match~ in~ the~ property~ list: \\
+    `#1' \\
+    \msg_line_context:
   }
 
-% --------------------------------------------------------------------------
-% outputting the page numbers:
-\RequirePackage {zref-abspage}
-
-\cs_new_protected:Npn \__acro_create_page_records:n #1
+\msg_new:nnn {acro} {value-required}
   {
-    \seq_new:c { g__acro_#1_pages_seq }
-    \tl_new:c  { g__acro_#1_recorded_pages_tl }
+    The~ property~ `#2'~ for~ acroynm~ `#1'~ \msg_line_context: \
+    needs~ a~ (possibly~ empty)~ value!
   }
+  
 
-\cs_new_protected:Npn \acro_hyper_page:n #1 { \use:n {#1} }
-
-\cs_new:Npn \acro_get_thepage:nnn #1#2#3 { \acro_hyper_page:n {#1} }
-\cs_new:Npn \acro_get_thepage_from:N #1
-  { \exp_after:wN \acro_get_thepage:nnn #1 }
+% ----------------------------------------------------------------------------
+% declare properties:
+\seq_new:N \l__acro_properties_seq
 
-\cs_new:Npn \acro_get_page_number:nnn #1#2#3 {#2}
-\cs_new:Npn \acro_get_page_number_from:N #1
-  { \exp_after:wN \acro_get_page_number:nnn #1 }
+\cs_new_protected:Npn \acro_properties_map:n #1
+  { \seq_map_inline:Nn \l__acro_properties_seq {#1} }
 
-\cs_new:Npn \acro_get_abspage:nnn #1#2#3 {#3}
-\cs_new:Npn \acro_get_abspage_from:N #1
-  { \exp_after:wN \acro_get_abspage:nnn #1 }
+\acro_attribute_new:n {boolean}
+\acro_attribute_new:n {unique}
+\acro_attribute_new:n {mandatory}
+\acro_attribute_new:n {dynamic}
 
-\cs_new:Npn \acro_page_range_comma: {}
+% \seq_new:N \l__acro_mandatory_properties_seq
+\tl_new:N \l__acro_mandatory_properties_tl
 
-\cs_new_protected:Npn \acro_print_page_numbers:n #1
+% new property:
+% #1: boolean (true = unique)
+% #2: boolean (true = boolean)
+% #3: boolean (true = mandatory)
+% #4: boolean (true = static != dynamic)
+% #5: property name
+\cs_new_protected:Npn \acro_property_declare:nnnnn #1#2#3#4#5
   {
-    \seq_if_empty:cF {g__acro_#1_pages_seq}
+    \acro_property_if_exist:nF {#5}
       {
-        \bool_if:NTF \l__acro_list_all_pages_bool
+        \seq_put_right:Ne \l__acro_properties_seq { \tl_to_str:n {#5} }
+        \acro_attribute_new:n {property::#5}
+        \bool_if:nF {#4}
+          { \acro_attribute_set:nnn {dynamic} {#5} {true} }
+        \__acro_auxlist_new:n {#5}
+        \bool_if:nT {#3}
           {
-            % have the numbers changed?
-            \tl_set:Nx \l__acro_tmpa_tl
-              { \seq_use:cn {g__acro_#1_pages_seq} {|} }
-            \tl_if_eq:cNF {g__acro_#1_recorded_pages_tl} \l__acro_tmpa_tl
-              {
-                \@latex@warning@no@line
-                  {Rerun~to~get~page~numbers~of~acronym~#1~in~acronym~list~right}
-              }
-            \tl_clear:N \l__acro_write_pages_tl
-            \tl_clear:N \l__acro_last_page_tl
-            \tl_clear:N \l__acro_current_page_tl
-            \seq_set_eq:Nc \l__acro_tmpb_seq { g__acro_#1_pages_seq }
-            \seq_remove_duplicates:N \l__acro_tmpb_seq
-            \seq_clear:N \l__acro_tmpa_seq
-            \cs_set_protected:Npn \acro_page_range_comma:
-              { \cs_set:Npn \acro_page_range_comma: { ,~ } }
-            % get the numbers:
-            \int_compare:nNnTF { \seq_count:N \l__acro_tmpb_seq } = { 1 }
-              {
-                \tl_use:N \l__acro_page_name_tl
-                \seq_get_right:cN { g__acro_#1_pages_seq } \l__acro_tmpa_tl
-                \acro_get_thepage_from:N \l__acro_tmpa_tl
-              }
-              {
-                \tl_use:N \l__acro_pages_name_tl
-                \seq_map_inline:cn { g__acro_#1_pages_seq }
-                  {
-                    \tl_if_blank:VTF \l__acro_last_page_tl
-                      {% we're at the beginning
-                        \seq_put_right:Nn \l__acro_tmpa_seq {##1}
-                        \tl_set:Nn \l__acro_last_page_tl {##1}
-                      }
-                      {% we'at least at the second page
-                         % current page:
-                         \tl_set:Nn  \l__acro_current_page_tl {##1}
-                         % last page:
-                         \seq_get_right:NN \l__acro_tmpa_seq \l__acro_last_page_tl
-                         \tl_if_eq:NNTF \l__acro_current_page_tl \l__acro_last_page_tl
-                           {% there were more than one appearance on the current page
-                             \seq_put_right:Nn \l__acro_tmpa_seq {##1}
-                           }
-                           {% new page
-                             \acro_determine_page_ranges:NNn
-                               \l__acro_tmpa_seq
-                               \l__acro_write_pages_tl
-                               {##1}
-                           }
-                      }
-                  }
-                \seq_if_empty:NF \l__acro_tmpa_seq
-                  {
-                    \acro_determine_page_ranges:NNV
-                      \l__acro_tmpa_seq
-                      \l__acro_write_pages_tl
-                      \l__acro_current_page_tl
-                  }
-                \tl_use:N \l__acro_write_pages_tl
-                \tl_clear:N \l__acro_write_pages_tl
-              }
+            \acro_attribute_set:nnn {mandatory} {#5} {true}
+            % \seq_put_right:Nn \l__acro_mandatory_properties_seq {#5}
+            \tl_put_right:Nn \l__acro_mandatory_properties_tl {{#5}}
           }
+        \bool_if:nT {#2}
+          { \acro_attribute_set:nnn {boolean} {#5} {true} }
+        \bool_if:nT {#1}
           {
-            \tl_use:N \l__acro_page_name_tl
-            \pageref{\l__acro_label_prefix_tl #1}
-          }
-      }
-    \seq_clear:N \l__acro_tmpa_seq
-    \seq_clear:N \l__acro_tmpb_seq
-  }
-
-\cs_new:Npn \acro_determine_page_ranges:NNn #1#2#3
-  {
-    \seq_remove_duplicates:N #1
-    % current page:
-    \int_set:Nn \l__acro_tmpa_int { \acro_get_abspage:nnn #3 }
-    \int_set:Nn \l__acro_tmpb_int { \acro_get_page_number:nnn #3 }
-    % last page:
-    \seq_get_right:NN #1 \l__acro_last_page_tl
-    \int_set:Nn \l__acro_tmpc_int
-      { \acro_get_abspage_from:N \l__acro_last_page_tl }
-    \int_set:Nn \l__acro_tmpd_int
-      { \acro_get_page_number_from:N \l__acro_last_page_tl }
-    \bool_lazy_and:nnTF
-      {
-        \int_compare_p:nNn
-          { \l__acro_tmpa_int - \l__acro_tmpc_int }
-           =
-          { \l__acro_tmpb_int - \l__acro_tmpd_int }
-      }
-      {
-        \int_compare_p:nNn
-        { \l__acro_tmpb_int - \l__acro_tmpd_int } = {1}
-      }
-      {% same kind of page numbering, one page ahead
-       % => possible range
-         \seq_put_right:Nn #1 {#3}
-      }
-      {% any possible range ended
-        \tl_put_right:Nn #2 { \acro_page_range_comma: }
-        \int_compare:nNnTF
-          { \seq_count:N #1 } > {2}
-          {% real range
-            \seq_get_left:NN #1 \l__acro_tmpa_tl
-            \tl_put_right:Nx #2 { \acro_get_thepage_from:N \l__acro_tmpa_tl }
-            \bool_if:NTF \l__acro_following_pages_bool
-              { \tl_put_right:Nn #2 { \l__acro_next_pages_tl } }
-              {
-                \tl_put_right:Nn #2 { -- }
-                \seq_get_right:NN #1 \l__acro_tmpa_tl
-                \tl_put_right:Nx #2 { \acro_get_thepage_from:N \l__acro_tmpa_tl }
-              }
+            \acro_attribute_set:nnn {unique} {#5} {true}
+            \seq_new:c {l__acro_unique_#5_seq}
           }
+        \bool_if:nT {#4}
           {
-            \int_compare:nNnTF
-              { \seq_count:N #1 } = {2}
-              {% range of two pages
-                \seq_get_left:NN #1 \l__acro_tmpa_tl
-                \tl_put_right:Nx #2 { \acro_get_thepage_from:N \l__acro_tmpa_tl }
-                \bool_if:NTF \l__acro_following_page_bool
-                  { \tl_put_right:Nn #2 { \l__acro_next_page_tl } }
-                  {
-                    \tl_put_right:Nn #2 { ,~ }
-                    \seq_get_right:NN #1 \l__acro_tmpa_tl
-                    \tl_put_right:Nx #2 { \acro_get_thepage_from:N \l__acro_tmpa_tl }
-                  }
-              }
-              {% no range at all
-                \seq_get_right:NN #1 \l__acro_tmpa_tl
-                \tl_put_right:Nx #2 { \acro_get_thepage_from:N \l__acro_tmpa_tl }
-              }
+            \AtEndDocument { \__acro_auxlist_update:n {#5} }
+            \acro_at_begin_document:n { \__acro_property_set_from_auxlist:n {#5} }
           }
-        \seq_clear:N #1
-        \seq_put_right:Nn #1 {#3}
       }
   }
-\cs_generate_variant:Nn \acro_determine_page_ranges:NNn {NNV}
-
-% --------------------------------------------------------------------------
-\DeclareObjectType {acro-page-number} {1}
 
-\DeclareTemplateInterface {acro-page-number} {inline} {1}
+% ----------------------------------------------------------------------------
+% property conditionals:
+\prg_new_conditional:Npnn \acro_property_if_exist:n #1 {T,F,TF}
   {
-    display       : boolean   = true  ,
-    punct         : boolean   = false ,
-    punct-symbol  : tokenlist = {,}   ,
-    brackets      : boolean   = false ,
-    brackets-type : tokenlist = ()    ,
-    space         : skip      = .333333em plus .166666em minus .111111em
+    \acro_attribute_if_exist:nTF {property::#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
+\cs_generate_variant:Nn \acro_property_if_exist:nTF {x}
 
-\DeclareTemplateCode {acro-page-number} {inline} {1}
+% #1: id
+% #2: property
+\prg_new_conditional:Npnn \acro_property_if_set:nn #1#2 {p,T,F,TF}
   {
-    display       = \l__acro_page_display_bool  ,
-    punct         = \l__acro_page_punct_bool    ,
-    punct-symbol  = \l__acro_page_punct_tl      ,
-    brackets      = \l__acro_page_brackets_bool ,
-    brackets-type = \l__acro_page_brackets_tl   ,
-    space         = \l__acro_page_space_skip
+    \acro_attribute_if_set:neTF {#2} { \acro_case_insensitive:n {#1} }
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
-  {
-    \AssignTemplateKeys
-    \bool_if:NT \l__acro_page_display_bool
-      {
-        \bool_if:NT \l__acro_page_punct_bool
-          { \tl_use:N \l__acro_page_punct_tl }
-        % \tl_use:N \c_space_tl
-        \dim_compare:nNnF { \l__acro_page_space_skip } = { 0pt }
-          { \skip_horizontal:N \l__acro_page_space_skip }
-        \bool_if:NT \l__acro_page_brackets_bool
-          { \tl_head:N \l__acro_page_brackets_tl }
-        \acro_print_page_numbers:n {#1}
-        \bool_if:NT \l__acro_page_brackets_bool
-          { \tl_tail:N \l__acro_page_brackets_tl }
-      }
+\prg_generate_conditional_variant:Nnn \acro_property_if_set:nn
+  {nx,xx,nV,e,ne}
+  {p,T,F,TF}
+
+
+% #1: id
+% #2: properties
+\prg_new_protected_conditional:Npnn \acro_property_if_any:nn #1#2 {T,F,TF}
+  {
+    \seq_set_from_clist:Nn \l__acro_tmpa_seq {#2}
+    \seq_set_map:NNn \l__acro_tmpa_seq \l__acro_tmpa_seq
+      { { \exp_not:N \acro_property_if_set_p:nn {#1} {##1} } }
+    \bool_lazy_any:eTF
+      { \seq_use:Nn \l__acro_tmpa_seq {} }
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
+\prg_generate_conditional_variant:Nnn \acro_property_if_any:nn {e} {TF}
 
-% declare new page styles:
-\cs_new_protected:Npn \acro_declare_page_style:nnn #1#2#3
-  {
-    \DeclareInstance {acro-page-number} {#1} {#2} {#3}
-    \prop_put:Nnn \l__acro_page_styles_prop  {#1} {#2}
+% #1: id
+% #2: properties
+\prg_new_protected_conditional:Npnn \acro_property_if_all:nn #1#2 {T,F,TF}
+  {
+    \seq_set_from_clist:Nn \l__acro_tmpa_seq {#2}
+    \seq_set_map:NNn \l__acro_tmpa_seq \l__acro_tmpa_seq
+      { { \exp_not:N \acro_property_if_set_p:nn {#1} {##1} } }
+    \bool_lazy_all:eTF
+      { \seq_use:Nn \l__acro_tmpa_seq {} }
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
+\prg_generate_conditional_variant:Nnn \acro_property_if_all:nn {e} {TF}
 
-% set a page style
-\cs_new_protected:Npn \acro_set_page_style:n #1
+\prg_new_conditional:Npnn \acro_property_if_eq:nn #1#2 {p,T,F,TF}
   {
-    \prop_if_in:NnTF \l__acro_page_styles_prop {#1}
-      { \__acro_set_page_style:n {#1} }
-      {
-        \msg_warning:nnnnn {acro} {unknown}
-          {page~ style}
-          {#1}
-          {none}
-        \__acro_set_page_style:n {none}
-      }
+    \str_if_eq:nnTF {#1} {#2}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-\cs_new_protected:Npn \__acro_set_page_style:n #1
+\prg_new_conditional:Npnn \acro_property_if_mandatory:n #1 {p,T,F,TF}
   {
-    \tl_set:Nn \l__acro_page_instance_tl {#1}
-    \prop_get:NnN \l__acro_page_styles_prop {#1} \l__acro_tmpa_tl
+    \acro_attribute_if_set:nnTF {mandatory} {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
+\cs_generate_variant:Nn \acro_property_if_mandatory:nF {V}
 
-% --------------------------------------------------------------------------
-% the title of the list:
-\cs_new:Npn \acro_list_title_format:n #1 {#1}
-
-\DeclareObjectType {acro-title} {1}
+\cs_new_protected:Npn \acro_property_foreach_mandatory:n #1
+  { \tl_map_inline:Nn \l__acro_mandatory_properties_tl {#1} }
 
-\DeclareTemplateInterface {acro-title} {sectioning} {1}
-  { name-format : function 1 = #1 }
+\prg_new_conditional:Npnn \acro_property_if_boolean:n #1 {p,T,F,TF}
+  {
+    \acro_attribute_if_set:nnTF {boolean} {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
 
-\DeclareTemplateCode {acro-title} {sectioning} {1}
-  { name-format = \acro_list_title_format:n }
+\prg_new_conditional:Npnn \acro_property_if_unique:n #1 {p,T,F,TF}
   {
-    \AssignTemplateKeys
-    \acro_list_title_format:n {#1}
+    \acro_attribute_if_set:nnTF {unique} {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-% set a list heading:
-\cs_new_protected:Npn \acro_set_list_heading:n #1
+% #1: property
+% #2: value
+\prg_new_protected_conditional:Npnn \acro_property_if_unique_value:nn #1#2 {T,F,TF}
   {
-    \prop_if_in:NnTF \l__acro_list_headings_prop {#1}
-      { \__acro_set_list_heading:n {#1} }
+    \acro_property_if_unique:nTF {#1}
       {
-        \msg_warning:nnnnn {acro} {unknown}
-          {list~ heading}
-          {#1}
-          {section*}
-        \__acro_set_list_heading:n {section*}
+        \seq_if_in:cnTF {l__acro_unique_#1_seq} {#2}
+          { \prg_return_true: }
+          { \prg_return_false: }
       }
+      { \prg_return_false: }
   }
 
-\cs_new_protected:Npn \__acro_set_list_heading:n #1
-  { \tl_set:Nn \l__acro_list_heading_cmd_tl {#1} }
-  
-\cs_new_protected:Npn \acro_declare_list_heading:nn #1#2
+% #1: id
+% #2: property
+\prg_new_conditional:Npnn \acro_property_get_if_set:nn #1#2 {T,F,TF}
   {
-    \prop_put:Nnn \l__acro_list_headings_prop {#1} {#2}
-    \DeclareInstance {acro-title} {#1} {sectioning}
-      { name-format = #2 {##1} }
+    \acro_property_if_set:nnTF {#1} {#2}
+      {
+        \acro_property_get:nn {#1} {#2}
+        \prg_return_true:
+      }
+      { \prg_return_false: }
   }
-
-% --------------------------------------------------------------------------
-% typesetting the acronym list
-\DeclareObjectType {acro-list} {2}
+\prg_generate_conditional_variant:Nnn \acro_property_if_set:nn {V} {TF}
 
 % #1: id
-% #2: excluded classes
-\prg_new_protected_conditional:Npnn \acro_if_is_excluded:nn #1#2 {T,F,TF}
+% #2: property
+\prg_new_conditional:Npnn \acro_boolean_property_if:nn #1#2 {p,T,F,TF}
   {
-    \bool_set_false:N \l__acro_is_excluded_bool
-    \tl_if_blank:nF {#2}
+    \acro_property_if_exist:nTF {#2}
       {
-        \acro_property_get:nnT {#1} {class}
+        \acro_property_if_boolean:nTF {#2}
           {
-            \seq_set_split:NnV \l__acro_tmpa_seq {,} \l__acro_class_tl
-            \clist_map_inline:nn {#2}
+            \acro_property_if_set:nnTF {#1} {#2}
               {
-                \seq_if_in:NnT \l__acro_tmpa_seq {##1}
-                  { \bool_set_true:N \l__acro_is_excluded_bool }
+                \bool_if:cTF
+                  {c_ \acro_property_get:nn {#1} {#2} _bool}
+                  { \prg_return_true: }
+                  { \prg_return_false: }
               }
+              { \prg_return_false: }
           }
+          { \prg_return_false: }
       }
-    \bool_if:NTF \l__acro_is_excluded_bool
-      { \prg_return_true: }
       { \prg_return_false: }
   }
+\cs_generate_variant:Nn \acro_boolean_property_if:nnTF {oo}
+\cs_generate_variant:Nn \acro_boolean_property_if:nnF  {nV}
 
+% ----------------------------------------------------------------------------
+% set properties:
 % #1: id
-% #2: included classes
-\prg_new_protected_conditional:Npnn \acro_if_is_included:nn #1#2 {T,F,TF}
+% #2: property
+% #3: value
+\cs_new_protected:Npn \acro_property_set:nnn #1#2#3
   {
-    \bool_set_false:N \l__acro_is_included_bool
-    \tl_if_blank:nTF {#2}
-      { \bool_set_true:N \l__acro_is_included_bool }
+    \acro_property_if_exist:nTF {#2}
       {
-        \acro_property_get:nnT {#1} {class}
+        \acro_property_if_set:nnTF {#1} {#2}
+          {
+            \acro_property_if_unique:nTF {#2}
+              {
+                \acro_property_if_unique_value:nnTF {#2} {#3}
+                  { \__acro_unique_property_set:nnn {#1} {#2} {#3} }
+                  { \msg_warning:nnnn {acro} {property-unique} {#2} {#3} }
+              }
+              {
+                \acro_property_if_boolean:nTF {#2}
+                  { \__acro_boolean_property_set:nnn {#1} {#2} {#3} }
+                  { \__acro_property_set:nnn {#1} {#2} {#3} }
+              }
+          }
           {
-            \seq_set_split:NnV \l__acro_tmpa_seq {,} \l__acro_class_tl
-            \clist_map_inline:nn {#2}
+            \acro_property_if_boolean:nTF {#2}
+              { \__acro_boolean_property_set:nnn {#1} {#2} {#3} }
               {
-                \seq_if_in:NnT \l__acro_tmpa_seq {##1}
-                  { \bool_set_true:N \l__acro_is_included_bool }
+                \acro_property_if_unique:nTF {#2}
+                  { \__acro_unique_property_set:nnn {#1} {#2} {#3} }
+                  { \__acro_property_set:nnn {#1} {#2} {#3} }
               }
           }
       }
-    \bool_if:NTF \l__acro_is_included_bool
-      { \prg_return_true: }
-      { \prg_return_false: }
+      { \msg_error:nnn {acro} {unknown-property} {#2} }  
   }
+\cs_generate_variant:Nn \acro_property_set:nnn {nnV,nxx,nnx,e,nne,nnv}
 
 % #1: id
-\cs_new_protected:Npn \__acro_list_entry_short:n #1
+% #2: property
+% #3: value
+\cs_new_protected:Npn \__acro_boolean_property_set:nnn #1#2#3
   {
-    \group_begin:
-      \acro_get:n {#1}
-      \acro_hyper_target:nn
-        {#1}
-        {
-          \acro_acc_supp:nn
-            {#1}
-            {
-              \bool_lazy_and:nnTF
-                { \l__acro_custom_short_format_bool }
-                { \l__acro_override_list_format_bool }
-                { \l__acro_custom_short_format_tl }
-                { \l__acro_list_short_format_tl }
-              { \__acro_property_get:nn {short} {#1} }
-            }
-        }
-    \group_end:
+    \str_case_e:nnTF { \str_lowercase:n {#3} }
+      {
+        {} {}
+        {true} {}
+      }
+      { \__acro_property_set:nnn {#1} {#2} {true} }
+      { \__acro_property_set:nnn {#1} {#2} {false} }
   }
 
 % #1: id
-\cs_new_protected:Npn \__acro_list_entry_long:n #1
+% #2: property
+% #3: value
+\cs_new_protected:Npn \__acro_unique_property_set:nnn #1#2#3
+  { \__acro_property_set:nnn {#1} {#2} {#3} }
+
+% #1: id
+% #2: property
+\cs_new_protected:Npn \__acro_property_unset:nn #1#2
   {
-    \group_begin:
-      \bool_if:NT \l__acro_capitalize_list_bool
-        { \bool_set_true:N \l__acro_first_upper_bool }
-      \acro_write_long:Vf \l__acro_list_long_format_tl
-        {
-          \prop_if_in:NnTF \l__acro_list_prop {#1}
-            { \__acro_property_get:nn {list} {#1} }
-            { \__acro_property_get:nn {long} {#1} }
-        }
-    \group_end:
-    \bool_if:NT \l__acro_foreign_bool
-      { \acro_get_foreign:n {#1} }
-    \acro_cite_if:Nn \l__acro_citation_all_bool {#1}
+    \__acro_property_remove_from_auxlist:nn {#1} {#2}
+    \acro_attribute_unset:nn {#2} {#1}
   }
 
 % #1: id
-\cs_new_protected:Npn \__acro_list_entry_extra:n #1
+% #2: property
+\cs_new_protected:Npn \acro_property_unset:nn #1#2
   {
-    \acro_property_get:nnT {#1} {extra}
-      {
-        \acro_extra_instance:VV
-          \l__acro_extra_instance_tl
-          \l__acro_extra_tl
-      }
+    \acro_property_if_exist:nTF {#2}
+      { \__acro_property_unset:nn {#1} {#2} }
+      { \msg_error:nnn {acro} {unknown-property} {#2} }
   }
+\cs_generate_variant:Nn \acro_property_unset:nn {nx,nV}
 
 % #1: id
-\cs_new_protected:Npn \__acro_list_entry_page:n #1
+% #2: property
+% #3: value
+\cs_new_protected:Npn \__acro_property_set:nnn #1#2#3
   {
-    \cs_if_exist:cT {acro@#1@once}
-      {
-        \acro_page_number_instance:Vn
-          \l__acro_page_instance_tl
-          {#1}
-      }
+    \__acro_property_remove_from_auxlist:nn {#1} {#2}
+    % now we can safely add the property to the list:
+    \__acro_auxlist_add:nn {#2} {#1=={#3}}
+    \acro_attribute_set:nnn {#2} {#1} {#3}
   }
-  
-% macro for retrieval of items in the list:
-% #1: property
-% #2: id
-\cs_new_protected:Npn \acro_list_entry:nn #1#2
+\cs_generate_variant:Nn \__acro_property_set:nnn {VnV,nne}
+
+\tl_set:Nx \l__acro_tmpa_tl { \cs_to_str:N \{ }
+\tl_set:Nx \l__acro_tmpb_tl { \cs_to_str:N \} }
+\use:x
   {
-    \str_case:nnF {#1}
-      {
-        {short} { \__acro_list_entry_short:n {#2} }
-        {long}  { \__acro_list_entry_long:n {#2} }
-        {extra} { \__acro_list_entry_extra:n {#2} }
-        {page}  { \__acro_list_entry_page:n {#2} }
-      }
-      { \__acro_property_get:nn {#1} {#2} }
+    \cs_new_protected:Npn
+    \exp_not:N \__acro_property_extract_auxlist_entry:NNww
+    ##1##2##3 == \l__acro_tmpa_tl ##4 \l__acro_tmpb_tl
+    \exp_not:N \q_stop
+  }
+  {
+    \str_set:Nn #1 {#3}
+    \str_set:Nn #2 {#4}
   }
 
-% this macro may/should be redefined in templates:
-% #1: short
-% #2: long
-% #3: extra
-% #4: page number(s)
-\cs_new_protected:Npn \acro_print_list_entry:nnnn #1#2#3#4
-  { #1 #2 #3 #4 }
-
-\cs_new_protected:Npn \acro_for_all_acronyms_do:n #1
-  { \prop_map_inline:Nn \l__acro_short_prop {#1} }
-
-% test, if acronyms should be printed or not; needs testing for in/excluded
-% classes and options `only-used' and `single' -- this macro should be used in
-% the template code for retrieving the list
-  
 % #1: id
-% #2: included classes
-% #3: excluded classes
-\prg_new_protected_conditional:Npnn \acro_if_entry:nnn #1#2#3 {T,F,TF}
+% #2: property
+\cs_new_protected:Npn \__acro_property_remove_from_auxlist:nn #1#2
   {
-    \bool_lazy_or:nnTF
-      {
-        \bool_lazy_and_p:nn
-          { !\l__acro_single_use_bool }
-          { !\l__acro_print_only_used_bool }
-      }
+    % make sure we change the entry if it has been recorded previously:
+    \__acro_auxlist_foreach_entry:nn {#2}
       {
-        \bool_lazy_and_p:nn
-          { \bool_if_p:c {g__acro_#1_in_list_bool} }
+        \__acro_property_extract_auxlist_entry:NNww
+          \l__acro_tmpa_str \l__acro_tmpb_str ##1 \q_stop
+        \str_if_eq:xnT { \l__acro_tmpa_str } {#1}
           {
-            \bool_lazy_or_p:nn
-              {
-                \bool_lazy_and_p:nn
-                  { \l__acro_single_use_bool }
-                  { \cs_if_exist_p:c {acro@#1@twice} }
-              }
-              {
-                \bool_lazy_all_p:n
-                  {
-                    { !\l__acro_single_use_bool }
-                    { \cs_if_exist_p:c {acro@#1@once} }
-                    { \l__acro_print_only_used_bool }
-                  }
-              }
+            \__acro_auxlist_remove:nx {#2}
+              { #1 == {\l__acro_tmpb_str} }
           }
       }
+    % make sure we change the entry if it has been set during the current run:
+    \__acro_auxlist_foreach_new_entry:nn {#2}
       {
-        \acro_if_is_excluded:nnTF {#1} {#3}
-          { \prg_return_false: }
+        \__acro_property_extract_auxlist_entry:NNww
+          \l__acro_tmpa_str \l__acro_tmpb_str ##1 \q_stop
+        \str_if_eq:xnT { \l__acro_tmpa_str } {#1}
           {
-            \acro_if_is_included:nnTF {#1} {#2}
-              {
-                \bool_lazy_and:nnTF
-                  { \g__acro_use_barriers_bool }
-                  { \l__acro_use_barrier_bool }
-                  {
-                    \acro_if_in_barrier:nxTF {#1}
-                      { \int_use:N \g__acro_barrier_int }
-                      { \prg_return_true: }
-                      { \prg_return_false: }
-                  }
-                  { \prg_return_true: }
-              }
-              { \prg_return_false: }
+            \__acro_auxlist_remove:nx {#2}
+              { #1 == {\l__acro_tmpb_str} }
           }
       }
-      { \prg_return_false: }
   }
 
-% this macro is used in templates for fetching all items to be printed; it
-% collects all entries in a tl which then is used where needed
-%
-% #1: tl containing the entries
-% #2: included classes
-% #3: excluded classes
-\cs_new_protected:Npn \acro_build_list_entries:Nnn #1#2#3
+% #1: property
+\cs_new_protected:Npn \__acro_property_set_from_auxlist:n #1
   {
-    \tl_clear:N #1
-    \acro_for_all_acronyms_do:n
-      {% ##1: id; ##2: short form
-        \group_begin:
-          \acro_get:n {##1}
-          \acro_if_entry:nnnT {##1} {#2} {#3}
-            {
-              \tl_gput_right:Nn #1
-                {
-                  \acro_print_list_entry:nnnn
-                    { \acro_list_entry:nn {short} {##1} }
-                    { \acro_list_entry:nn {long} {##1} }
-                    { \acro_list_entry:nn {extra} {##1} }
-                    { \acro_list_entry:nn {page} {##1} }
-                }
-            }
-        \group_end:  
+    \__acro_auxlist_foreach_entry:nn {#1}
+      {
+        \__acro_property_extract_auxlist_entry:NNww
+          \l__acro_tmpa_str \l__acro_tmpb_str ##1 \q_stop
+        \tl_set_rescan:Nnx \l__acro_tmpa_tl {} { \l__acro_tmpb_str }
+        \__acro_property_set:VnV \l__acro_tmpa_str {#1} \l__acro_tmpa_tl
       }
   }
 
-% this macro is used in templates for fetching all items to be printed:
-\cs_new_protected:Npn \acro_list_items:nn #1#2
-  {
-    \acro_build_list_entries:Nnn \l__acro_list_entries_tl {#1} {#2}
-    \tl_use:N \l__acro_list_entries_tl
-  }
-  
-% --------------------------------------------------------------------------
-% declare templates for the list:
-% `list' template:
-\DeclareTemplateInterface {acro-list} {list} {2}
+% set properties:
+% #1: id
+% #2: csv list of properties
+\cs_new_protected:Npn \acro_properties_set:nn #1#2
   {
-    foreign-sep : tokenlist = {~} ,
-    list        : tokenlist = {description} ,
-    reverse     : boolean   = false ,
-    before      : tokenlist = ,
-    after       : tokenlist =
+    \cs_set_protected:Npn \__acro_parse_property:nn ##1##2
+      { \acro_property_set:nnn {#1} {##1} {##2} }
+    \cs_set_protected:Npn \__acro_parse_property:n ##1
+      {
+        \acro_property_if_boolean:nTF {##1}
+          { \acro_property_set:nnn {#1} {##1} {true} }
+          { \msg_error:nnnn {acro} {value-required} {#1} {##1} }
+      }
+    \keyval_parse:NNn
+      \__acro_parse_property:n
+      \__acro_parse_property:nn
+      {#2}
   }
+\cs_generate_variant:Nn \acro_properties_set:nnn {nnx,nxx,nV,nVx}
 
-\DeclareTemplateCode {acro-list} {list} {2}
-  {
-    foreign-sep = \l__acro_foreign_sep_tl ,
-    list        = \l__acro_list_tl ,
-    reverse     = \l__acro_list_reverse_long_extra_bool ,
-    before      = \l__acro_list_before_tl ,
-    after       = \l__acro_list_after_tl
-  }
+% ----------------------------------------------------------------------------
+% inspect properties:
+\cs_new_protected:Npn \acro_property_show:nn #1#2
   {
-    \AssignTemplateKeys
-    \bool_set_true:N \l__acro_in_list_bool
-    \acro_activate_hyperref_support:
-    \bool_if:NTF \l__acro_list_reverse_long_extra_bool
+    \acro_property_if_set:nnT {#1} {#2}
       {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { \item [##1] ##3 ##2 ##4 }
-      }
-      {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { \item [##1] ##2 ##3 ##4 }
-      }
-    \use:x
-      {
-        \exp_not:V \l__acro_list_before_tl
-        \exp_not:N \begin { \exp_not:V \l__acro_list_tl }
-          \exp_not:n { \acro_list_items:nn {#1} {#2} }
-        \exp_not:N \end { \exp_not:V \l__acro_list_tl }
-        \exp_not:V \l__acro_list_after_tl
+        \iow_term:x
+          {
+            \c_space_tl \c_space_tl
+            \tl_to_str:n {#2}
+            \c_space_tl \c_space_tl => \c_space_tl \c_space_tl
+            { \acro_property_get:nn {#1} {#2} }
+          }
       }
   }
+\cs_generate_variant:Nn \acro_property_show:nn {e}
 
-% `list-of' template:
-\DeclareTemplateInterface {acro-list} {list-of} {2}
+% ----------------------------------------------------------------------------
+% alias properties:
+\tl_new:N \g__acro_property_aliases_tl
+
+% #1: property
+\prg_new_conditional:Npnn \acro_property_if_alias:n #1 {p,T,F,TF}
   {
-    foreign-sep : tokenlist = {~} ,
-    style       : tokenlist = {toc} ,
-    reverse     : boolean   = false ,
-    before      : tokenlist = ,
-    after       : tokenlist =
+    \tl_map_tokens:Nn \g__acro_property_aliases_tl
+      { \__acro_property_if_alias:nn {#1} }
+    \use_ii:nn
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-\DeclareTemplateCode {acro-list} {list-of} {2}
+% #1: tl
+% #2: tl
+\cs_new:Npn \__acro_property_if_alias:nn #1#2
   {
-    foreign-sep = \l__acro_foreign_sep_tl ,
-    style       = \l__acro_list_of_style ,
-    reverse     = \l__acro_list_reverse_long_extra_bool ,
-    before      = \l__acro_list_before_tl ,
-    after       = \l__acro_list_after_tl
+    \str_if_eq:nnT {#1} {#2}
+      { \tl_map_break:n { \use_ii:nnn } }
   }
+
+% #1: property
+\cs_new:Npn \acro_property_alias:n #1
+  { \acro_attribute_get:nn {#1} {alias} }
+\cs_generate_variant:Nn \acro_property_alias:n {e}
+
+% #1: property
+% #2: alias of
+\cs_new_protected:Npn \acro_property_make_alias:nn #1#2
   {
-    \AssignTemplateKeys
-    \bool_set_true:N \l__acro_in_list_bool
-    \tl_if_eq:VnT \l__acro_page_instance_tl {none}
-      { \tl_set:Nn \l__acro_page_instance_tl {plain} }
-    \tl_set:Nn \l__acro_page_name_tl {}
-    \tl_set:Nn \l__acro_pages_name_tl {}
-    \acro_activate_hyperref_support:
-    \str_case:Vn \l__acro_list_of_style
+    \acro_property_if_alias:nF {#1}
       {
-        {toc}
-        { % similar to the table of contents
-          \bool_if:NTF \l__acro_list_reverse_long_extra_bool
-            {
-              \cs_if_exist:NTF \chapter
-                {
-                  \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                    {
-                      \contentsline{chapter}{##1}{}{}
-                      \contentsline{section}{##3##2}{##4}{}
-                    } 
-                }
-                {
-                  \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                    {
-                      \contentsline{section}{##1}{}{}
-                      \contentsline{subsection}{##3##2}{##4}{}
-                    }
-                }
-            }
-            {
-              \cs_if_exist:NTF \chapter
-                {
-                  \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                    {
-                      \contentsline{chapter}{##1}{}{}
-                      \contentsline{section}{##2##3}{##4}{}
-                    } 
-                }
-                {
-                  \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                    {
-                      \contentsline{section}{##1}{}{}
-                      \contentsline{subsection}{##2##3}{##4}{}
-                    }
-                }
-            }
-        }
-        {lof}
-        { % similar to the list of figures
-          \cs_set_protected:Npn \l@acro
-            { \@dottedtocline {1} {1.5em} {\l__acro_short_width_dim} }
-          \bool_if:NTF \l__acro_list_reverse_long_extra_bool
-            {
-              \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                { \contentsline{acro}{\numberline{##1}{##3##2}}{##4}{} }
-            }
-            {
-              \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-                { \contentsline{acro}{\numberline{##1}{##2##3}}{##4}{} }
-            }
-        }
+        \acro_attribute_set:nnn {#1} {alias} {#2}
+        \tl_gput_right:Nn \g__acro_property_aliases_tl {{#1}}
       }
-    \use:x
-      {
-        \exp_not:V \l__acro_list_before_tl
-        \exp_not:n { \acro_list_items:nn {#1} {#2} }
-        \exp_not:V \l__acro_list_before_tl
-      }
-  }
-  
-% `table' template:
-\DeclareTemplateInterface {acro-list} {table} {2}
-  {
-    table       : tokenlist = tabular ,
-    table-spec  : tokenlist = lp{.7\linewidth} ,
-    foreign-sep : tokenlist = {~} ,
-    reverse     : boolean   = false ,
-    before      : tokenlist = ,
-    after       : tokenlist = 
   }
 
-\DeclareTemplateCode {acro-list} {table} {2}
-  {
-    table       = \l__acro_list_table_tl      ,
-    table-spec  = \l__acro_list_table_spec_tl ,
-    foreign-sep = \l__acro_foreign_sep_tl ,
-    reverse     = \l__acro_list_reverse_long_extra_bool ,
-    before      = \l__acro_list_before_tl ,
-    after       = \l__acro_list_after_tl
-  }
+% #1: id
+% #2: alias property
+\cs_new_protected:Npn \acro_property_set_alias:nn #1#2
   {
-    \AssignTemplateKeys
-    \acro_activate_hyperref_support:
-    \bool_if:NTF \l__acro_list_reverse_long_extra_bool
-      {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { ##1 & ##3 ##2 ##4 \tabularnewline }
-      }
+    \acro_property_if_set:nnF {#1} {#2}
       {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { ##1 & ##2 ##3 ##4 \tabularnewline }
-      }
-    \acro_build_list_entries:Nnn \l__acro_list_entries_tl {#1} {#2}
-    \use:x
-      {
-        \exp_not:V \l__acro_list_before_tl
-        \exp_not:N \begin { \exp_not:V \l__acro_list_table_tl }
-          { \exp_not:V \l__acro_list_table_spec_tl }
-        \exp_not:V \l__acro_list_entries_tl
-        \exp_not:N \end { \exp_not:V \l__acro_list_table_tl }
-        \exp_not:V \l__acro_list_after_tl
+        \acro_property_if_set:neT {#1} { \acro_property_alias:n {#2} }
+          { 
+            \__acro_property_set:nne {#1} {#2}
+              { \acro_property_get:ne {#1} { \acro_property_alias:n {#2} } }
+          }
       }
   }
 
-% `extra-table' template:
-\DeclareTemplateInterface {acro-list} {extra-table} {2}
+% #1: id
+\cs_new_protected:Npn \acro_property_set_aliases:n #1
   {
-    table       : tokenlist = tabular ,
-    table-spec  : tokenlist = llll ,
-    foreign-sep : tokenlist = {~} ,
-    reverse     : boolean   = false ,
-    before      : tokenlist = ,
-    after       : tokenlist = 
+    \tl_map_inline:Nn \g__acro_property_aliases_tl
+      { \acro_property_set_alias:nn {#1} {##1} }
   }
 
-\DeclareTemplateCode {acro-list} {extra-table} {2}
+% ----------------------------------------------------------------------------
+% retrieve properties:
+% #1: id
+% #2: property
+\cs_new:Npn \acro_property_get:nn #1#2
+  {  \acro_attribute_get:ne {#2} { \acro_case_insensitive:n {#1} } }
+\cs_generate_variant:Nn \acro_property_get:nn {nx,ne,V}
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+% ----------------------------------------------------------------------------
+% the ACRO package - acronyms module
+% 
+%   Typeset Acronyms
+% 
+% --------------------------------------------------------------------------
+% Clemens Niederberger
+% Web:    https://github.com/cgnieder/acro/
+% E-Mail: contact@mychemistry.eu
+% --------------------------------------------------------------------------
+% Copyright 2011--2020 Clemens Niederberger
+% 
+% This work may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either version 1.3
+% of this license or (at your option) any later version.
+% The latest version of this license is in
+%   http://www.latex-project.org/lppl.txt
+% and version 1.3 or later is part of all distributions of LaTeX
+% version 2005/12/01 or later.
+% 
+% This work has the LPPL maintenance status `maintained'.
+% 
+% The Current Maintainer of this work is Clemens Niederberger.
+% --------------------------------------------------------------------------
+% If you have any ideas, questions, suggestions or bugs to report, please
+% feel free to contact me.
+% --------------------------------------------------------------------------
+\AcroModule{acronyms}{define acronyms}
+
+% --------------------------------------------------------------------------
+\msg_new:nnn {acro} {undefined}
   {
-    table       = \l__acro_list_table_tl      ,
-    table-spec  = \l__acro_list_table_spec_tl ,
-    foreign-sep = \l__acro_foreign_sep_tl ,
-    reverse     = \l__acro_list_reverse_long_extra_bool ,
-    before      = \l__acro_list_before_tl ,
-    after       = \l__acro_list_after_tl
+    You've~ requested~ acronym~ `#1'~ \msg_line_context: \ but~ you~
+    apparently~ haven't~ defined~ it,~ yet! \\
+    Maybe~ you've~ misspelled~ `#1'?
   }
+
+\msg_new:nnn {acro} {mandatory}
   {
-    \AssignTemplateKeys
-    \acro_activate_hyperref_support:
-    \bool_if:NTF \l__acro_list_reverse_long_extra_bool
-      {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { ##1 & ##3 & ##2 & ##4 \tabularnewline }
-      }
-      {
-        \cs_set_protected:Npn \acro_print_list_entry:nnnn ##1##2##3##4
-          { ##1 & ##2 & ##3 & ##4 \tabularnewline }
-      }
-    \acro_build_list_entries:Nnn \l__acro_list_entries_tl {#1} {#2}
-    \use:x
-      {
-        \exp_not:V \l__acro_list_before_tl
-        \exp_not:N \begin { \exp_not:V \l__acro_list_table_tl }
-          { \exp_not:V \l__acro_list_table_spec_tl }
-        \exp_not:V \l__acro_list_entries_tl
-        \exp_not:N \end { \exp_not:V \l__acro_list_table_tl }
-        \exp_not:V \l__acro_list_after_tl
-      }
+    You~ forgot~ to~ set~ the~ mandatory~ property~ `#2'~ for~ acronym~
+    `#1'~ \msg_line_context:
   }
 
 % --------------------------------------------------------------------------
-% declare new list styles:
-\cs_new_protected:Npn \acro_declare_list_style:nnn #1#2#3
-  {
-    \DeclareInstance {acro-list} {#1} {#2} {#3}
-    \prop_put:Nnn \l__acro_list_styles_prop  {#1} {#2}
-  }
+% short and long list:
+\tl_new:N \l__acro_short_tl
+\tl_new:N \l__acro_long_tl
 
-% set a list style
-\cs_new_protected:Npn \acro_set_list_style:n #1
+\cs_new_protected:Npn \acro_list_add:nn #1#2
   {
-    \prop_if_in:NnTF \l__acro_list_styles_prop {#1}
-      { \__acro_set_list_style:n {#1} }
+    \clist_map_inline:nn {#2}
       {
-        \msg_warning:nnnnn {acro} {unknown}
-          {list~ style}
-          {#1}
-          {description}
-        \__acro_set_list_style:n {description}
+        \tl_put_right:cn {l__acro_#1_tl} {{##1}}
+        \cs_set:cpn {____acro_#1::##1____:} {}
       }
   }
 
-\cs_new_protected:Npn \__acro_set_list_style:n #1
+\cs_new_protected:Npn \acro_list_map:nn #1#2
+  { \tl_map_inline:cn {l__acro_#1_tl} {#2} }
+
+\prg_new_conditional:Npnn \acro_if_short:n #1 {p,T,F,TF}
   {
-    \tl_set:Nn \l__acro_list_instance_tl {#1}
-    \prop_get:NnN \l__acro_list_styles_prop {#1} \l__acro_list_type_tl
+    \cs_if_exist:cTF {____acro_short::#1____:}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-% --------------------------------------------------------------------------
-% case insensitivity of the ID:
-\cs_new:Npn \acro_case_insensitive:n #1
+\prg_new_conditional:Npnn \acro_if_long:n #1 {p,T,F,TF}
   {
-    \bool_if:NTF \g__acro_case_sensitive_bool
-      { \tl_to_str:n {#1} }
-      { \str_lowercase:n {#1} }
+    \cs_if_exist:cTF {____acro_long::#1____:}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-\cs_new_protected:Npn \acro_protected_case_insensitive:n #1
-  { \acro_case_insensitive:n {#1} }
-
-\cs_new:Npn \acro_case_insensitive:Nn #1#2
-  { \exp_args:Ne #1 { \acro_case_insensitive:n {#2} } }
+% --------------------------------------------------------------------------
+% define necessary properties:
+% short and long properties:
+\acro_list_add:nn {short} {short,alt}
+\acro_list_add:nn {long}  {long,foreign,single,extra,list}
+
+% meta information:
+\DeclareAcroProperty*!{id}
+\DeclareAcroProperty ?{used}
+\DeclareAcroProperty |{usage}
+\DeclareAcroProperty |{pages}
+\DeclareAcroProperty |{barriers}
+\DeclareAcroProperty* {label}
+
+% main properties:
+\DeclareAcroProperty !{short}
+\DeclareAcroProperty  {alt}
+\DeclareAcroProperty !{long}
+
+% sorting, indexing, ... :
+\DeclareAcroPropertyAlias {sort} {short}
+\DeclareAcroProperty {index}
+\DeclareAcroProperty?{no-index}
+\DeclareAcroPropertyAlias {index-sort} {sort}
+\DeclareAcroProperty {index-cmd}
+\DeclareAcroProperty {tag}
+\DeclareAcroProperty {cite}
+\DeclareAcroProperty {before-citation}
+\DeclareAcroPropertyAlias {pdfstring} {short}
+\DeclareAcroProperty {pdfcomment}
+
+% locale:
+\DeclareAcroProperty {foreign}
+\DeclareAcroProperty {foreign-babel}
+\DeclareAcroProperty {foreign-locale}
+
+% additional properties:
+\DeclareAcroPropertyAlias {single} {long}
+\DeclareAcroPropertyAlias {list} {long}
+\DeclareAcroPropertyAlias {first-long} {long}
+\DeclareAcroProperty {extra}
+\DeclareAcroProperty {post}
+\DeclareAcroProperty {long-post}
+\DeclareAcroProperty {first-style}
+\DeclareAcroProperty {single-style}
+
+% formatting:
+\DeclareAcroProperty {format}
+\DeclareAcroPropertyAlias {short-format} {format}
+\DeclareAcroProperty {alt-format}
+\DeclareAcroPropertyAlias {long-format}  {format}
+\DeclareAcroPropertyAlias {first-long-format} {long-format}
+\DeclareAcroProperty {foreign-format}
+\DeclareAcroProperty {single-format}
+\DeclareAcroProperty {list-format}
+\DeclareAcroProperty {extra-format}
+
+% Accessibility:
+\acro_list_map:nn {short}
+  {
+    \DeclareAcroPropertyAlias {#1-acc} {#1}
+    \acro_list_add:nn {short} {#1-acc}
+  }
+
+\DeclareAcroPropertyAlias {single-acc} {long-acc}
+\acro_list_map:nn {long}
+  {
+    \DeclareAcroPropertyAlias {#1-acc} {#1}
+    \acro_list_add:nn {long} {#1-acc}
+  }
 
-\cs_new:Npn \acro_case_insensitive:Nnn #1#2#3
-  { \exp_args:Ne #1 { \acro_case_insensitive:n {#2} } {#3} }
+% --------------------------------------------------------------------------
+% use id as short entry:
+\bool_new:N \g__acro_use_id_bool
 
-\cs_new_protected:Npn \acro_case_insensitive_command:Nnnn #1#2#3#4
-  { \exp_args:Nnnx #1 {#2} {#3} { \acro_case_insensitive:n {#4} } }
-\cs_generate_variant:Nn \acro_case_insensitive_command:Nnnn {c}
+\keys_define:nn {acro}
+  {
+    use-id-as-short         .choice: ,
+    use-id-as-short / true  .code:n =
+      \bool_gset_true:N \g__acro_use_id_bool ,
+    use-id-as-short / false .code:n =
+      \bool_gset_false:N \g__acro_use_id_bool ,
+    use-id-as-short         .default:n = true
+  }
 
 % --------------------------------------------------------------------------
-% automatic typesetting, the internals of \ac:
-% #1: id
+% declaration of acronyms:
+\seq_new:N \g__acro_acronyms_seq
 
-\cs_new_protected:Npn \acro_soft_upper:
+\tl_new:N \l__acro_first_style_tl
+
+\acro_attribute_new:n {acronyms}
+
+\keys_define:nn {acro}
   {
-    \bool_if:NF \l__acro_upper_short_bool
-      { \bool_set_false:N \l__acro_first_upper_bool }
+    first-style .tl_set:N  = \l__acro_first_style_tl ,
+    first-style .initial:n = long-short
   }
 
-\cs_new_protected:Npn \acro_use:n #1
+\cs_new_protected:Npn \acro_declare_acronym:nn #1#2
+  { \acro_case_insensitive:Nn \__acro_declare_acronym:nn {#1} {#2} }
+
+% #1: id
+% #2: properties
+\cs_new_protected:Npn \__acro_declare_acronym:nn #1#2
   {
-    % get the acronym and the plural settings:
-    \acro_get:n {#1}
-    \acro_is_used:nTF {#1}
+    \int_new:c {g__acro_#1_int}
+    \seq_new:c {g__acro_#1_pages_seq}
+    \seq_new:c {g__acro_#1_barriers_seq}
+    \acro_at_begin_document:n
       {
-        \acro_soft_upper:
-        % this is not the first time
-        \acro_write_indefinite:nn {#1} {short}
-        \acro_write_compact:nn {#1} {short}
-        \acro_after:n {#1}
+        \intarray_new:cn
+          {g__acro_#1_barriers_intarray}
+          { \g_acro_barrier_total_int }
       }
+    \seq_gput_right:Nn \g__acro_acronyms_seq {#1}
+    \acro_attribute_set:nnn {acronyms} {#1} {}
+    % set defaults:
+    \__acro_set_article_defaults:n {#1}
+    % set user input:
+    \acro_properties_set:nn {#1} {#2}
+    % set defaults which must not be overwritten:
+    \acro_property_set:nnn {#1} {usage} {0}
+    \bool_lazy_and:nnT
+      { \g__acro_use_id_bool }
+      { !\acro_property_if_set_p:nn {#1} {short} }
+      { \acro_property_set:nnn {#1} {short} {#1} }
+    \acro_property_set:nnn {#1} {id} {#1}
+    \acro_property_set_aliases:n {#1}
+    % check mandatory properties:
+    \acro_property_foreach_mandatory:n
       {
-        % this is the first time
-        \bool_gset_true:c { g__acro_#1_first_use_bool }
-        \acro_if_is_single:nTF {#1}
-          { \acro_single:n {#1} }
-          { \acro_first_instance:nV {#1} \l__acro_long_tl }
+        \acro_property_if_set:nnF {#1} {##1}
+          { \msg_error:nnnn {acro} {mandatory} {#1} {##1} }
       }
+    % set endings:
+    \acro_set_endings:n {#1}
+    \acro_at_end_document:n
+      {
+        \acro_property_set:nnx {#1} {usage} { \int_use:c {g__acro_#1_int} }
+        \acro_set_barriers:n {#1}
+      }
+  }
+
+\prg_new_conditional:Npnn \acro_if_defined:n #1 {p,T,F,TF}
+  {
+    \acro_attribute_if_set:neTF {acronyms}
+      { \acro_case_insensitive:n {#1} }
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-% single appearances:
-\cs_new_protected:Npn \acro_single:n #1
+\cs_new_protected:Npn \acro_check_definition:n #1
   {
-    \acro_cite:
-    \acro_single_form:nV {#1} \l__acro_single_form_tl
-    \acro_after:n {#1}
+    \acro_if_defined:nF {#1}
+      { \msg_error:nnn {acro} {undefined} {#1} }
   }
 
-% #1: ID
-% #2: long|first|<other>
-\cs_new_protected:Npn \acro_single_form:nn #1#2
+% --------------------------------------------------------------------------
+% use and reset:
+\bool_new:N \l__acro_use_bool
+\bool_set_true:N \l__acro_use_bool
+
+\cs_new_protected:Npn \acro_use_false:
+  { \bool_set_false:N \l__acro_use_bool }
+
+\cs_new_protected:Npn \__acro_use:n #1
   {
-    \acro_write_indefinite:nn {#1} {#2}
-    \str_case:nnF {#2}
+    \bool_if:NT \l__acro_use_bool
       {
-        {long} {
-          \tl_if_blank:VT \l__acro_single_format_tl
-            {
-              \bool_if:NTF \l__acro_custom_long_format_bool
-                {
-                  \tl_set_eq:NN
-                    \l__acro_single_format_tl
-                    \l__acro_custom_long_format_tl
-                }
-                {
-                  \tl_set_eq:NN
-                    \l__acro_single_format_tl
-                    \l__acro_long_format_tl
-                }
-            }
-          \tl_if_blank:VT \l__acro_single_tl
-            { \tl_set_eq:NN \l__acro_single_tl \l__acro_long_tl }
-          % BUG: should that be \acro_write_expanded:nn ?
-          % \acro_write_expanded:nnn {#1} {#2} {\l__acro_single_tl}
-          \acro_write_long:VV \l__acro_single_format_tl \l__acro_single_tl
-          \acro_endings:nn {#1} {single}
-          \l__acro_long_post_tl
-        }
-        {first} {
-          \tl_if_blank:VF \l__acro_single_format_tl
-            {
-              \tl_set_eq:NN
-                \l__acro_first_long_format_tl
-                \l__acro_single_format_tl
-            }
-          \tl_if_blank:VT \l__acro_single_tl
-            { \tl_set_eq:NN \l__acro_single_tl \l__acro_long_tl }
-          \acro_first_instance:nV {#1} \l__acro_single_tl
-        }
-      }
-      { % other (e.g. short)
-        \acro_soft_upper:
-        \tl_if_blank:VF \l__acro_single_tl
-          { \tl_set_eq:cN {l__acro_#2_tl} \l__acro_single_tl }
-        \tl_if_blank:VF \l__acro_single_format_tl
-          { \tl_set_eq:cN {l__acro_#2_format_tl} \l__acro_single_format_tl }
-        \acro_write_compact:nn {#1} {#2}
+        \acro_property_set:nnn {#1} {used} {true}
+        \acro_step:n {#1}
       }
   }
-\cs_generate_variant:Nn \acro_single_form:nn {nV}
 
-\prg_new_conditional:Npnn \acro_if_is_single:n #1 { p,T,TF }
+\cs_new_protected:Npn \acro_use:n #1
+  { \clist_map_inline:nn {#1} { \__acro_use:n {#1} } }
+\cs_generate_variant:Nn \acro_use:n {e}
+
+\cs_new_protected:Npn \acro_use_all:
+  { \seq_map_inline:Nn \g__acro_acronyms_seq { \__acro_use:n {##1} } }
+
+\cs_new_protected:Npn \__acro_reset:n #1
   {
-    \bool_lazy_or:nnTF
-      { !\l__acro_single_use_bool }
-      { \cs_if_exist_p:c {acro@#1@twice} }
-      { \prg_return_false: }
-      { \prg_return_true: }
+    \acro_property_set:nnn {#1} {used} {false}
+    \int_gzero:c {g__acro_ \acro_case_insensitive:n {#1} _int}
+    \int_compare:nNnF
+      { \acro_property_get:nn {#1} {usage} } > 0
+      { \acro_property_set:nnn {#1} {usage} {0} }
   }
 
-\cs_new_protected:Npn \acro_use_acronym:n #1
-  { \use:c {bool_set_#1:N} \l__acro_mark_as_used_bool }
+\cs_new_protected:Npn \acro_reset:n #1
+  { \clist_map_inline:nn {#1} { \__acro_reset:n {##1} } }
+
+\cs_new_protected:Npn \acro_reset_all:
+  { \seq_map_inline:Nn \g__acro_acronyms_seq { \__acro_reset:n {##1} } }
+
+\cs_new_protected:Npn \acro_switch_off:
+  { \bool_set_false:N \l__acro_use_bool }
+
+\cs_new_protected:Npn \acro_switch_on:
+  { \bool_set_true:N \l__acro_use_bool }
 
 % --------------------------------------------------------------------------
-% some helpers we'll need more often:
-\prg_new_conditional:Npnn \acro_if_defined:n #1 {p,T,F,TF}
+% check for tags:
+% #1: id
+% #2: tag
+\prg_new_protected_conditional:Npnn \acro_tag_if:nn #1#2 {T,F,TF}
   {
-    \seq_if_in:NeTF \g__acro_declared_acronyms_seq
-      { \acro_case_insensitive:n {#1} }
+    \clist_set:Ne \l__acro_tmpa_clist { \acro_property_get:nn {#1} {tag} }
+    \clist_if_in:NnTF \l__acro_tmpa_clist {#2}
       { \prg_return_true: }
       { \prg_return_false: }
   }
+\prg_generate_conditional_variant:Nnn \acro_tag_if:nn {en} {T,F,TF}
 
-\cs_new_protected:Npn \acro_defined:n #1
+% --------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{formatting}{formatting of acronyms}
+% --------------------------------------------------------------------------
+% formatting:
+\bool_new:N \l__acro_format_replace_bool
+
+% sets the format from the global option:
+% #1: property
+\cs_new:Npn \__acro_global_format:n #1
   {
-    \acro_if_defined:nF {#1}
-      { \acro_serious_message:nn {undefined} {#1} }
+    \acro_property_if_alias:nTF {#1}
+      {
+        \tl_if_empty:cTF {l__acro_format_ #1 _tl}
+          { \__acro_use_global_format:n { \acro_property_alias:n {#1} } }
+          { \__acro_use_global_format:n {#1} }
+      }
+      { \__acro_use_global_format:n {#1} }
   }
 
-% expandably gets property but doesn't transform property name -- internal
-% name is needed
 % #1: property
-% #2: id
-\cs_new:Npn \__acro_property_get:nn #1#2
-  { \prop_item:cn {l__acro_#1_prop} {#2} }
+\cs_new:Npn \__acro_use_global_format:n #1
+  {
+    \tl_if_exist:cT {l__acro_format_ #1 _tl}
+      { \tl_use:c {l__acro_format_ #1 _tl} }
+  }
 
 % #1: id
 % #2: property
-% #3: set case
-% #4: not set case
-\prg_new_protected_conditional:Npnn \acro_property_get:nn #1#2 {T,F,TF}
-  {
-    \tl_set:Nn \l__acro_tmpa_tl {#2}
-    \tl_replace_all:Nnn \l__acro_tmpa_tl {-} {_}
-    \prop_get:cncTF
-      {l__acro_ \l__acro_tmpa_tl _prop}
-      {#1}
-      {l__acro_ \l__acro_tmpa_tl _tl}
-      { \prg_return_true: }
+% #3: insert if false
+\cs_new:Npn \__acro_property_format:nnF #1#2#3
+  {
+    \acro_property_if_set:nnTF {#1} {#2-format}
+      { \acro_property_get:nn {#1} {#2-format} }
+      {
+        \acro_if_format_alias:nnTF {#1} {#2}
+          {
+            \acro_property_get:nn {#1}
+              { \acro_property_alias:n {#2} -format }
+          }
+          {#3}
+      }
+  }
+
+% #1: id
+% #1: property
+\prg_new_conditional:Npnn \acro_if_format_alias:nn #1#2 {TF}
+  {
+    \acro_property_if_alias:nTF {#2}
+      {
+        \acro_property_if_set:nnTF {#1}
+          { \acro_property_alias:n {#2} -format }
+          { \prg_return_true: }
+          { \prg_return_false: }
+      }
       { \prg_return_false: }
   }
 
-\cs_new_protected:Npn \acro_property_get:nn #1#2
-  { \acro_property_get:nnTF {#1} {#2} {} {} }
-\cs_generate_variant:Nn \acro_property_get:nn {V}
+% #1: id
+% #1: property
+\cs_new:Npn \__acro_property_format:nn #1#2
+  { \__acro_property_format:nnF {#1} {#2} {} }
 
-% within this command one can refer to the current id with `#1'
-\cs_new_protected:Npn \acro_add_action:n #1
-  { \seq_put_right:Nn \l__acro_actions_seq {#1} }
+% sets the individual format:
+% #1: id
+% #2: property
+% #3: text
+\cs_new:Npn \acro_format:nnn #1#2#3
+  {
+    {
+      \bool_if:NTF \l__acro_format_replace_bool
+        {
+          \__acro_property_format:nnF {#1} {#2}
+            { \__acro_global_format:n {#2} }
+          {#3}
+        }
+        {
+          \__acro_global_format:n {#2}
+            {
+              \__acro_property_format:nn {#1} {#2}
+              {#3}
+            }
+        }
+    }
+  }
+\cs_generate_variant:Nn \acro_format:nnn {e}
 
-\cs_new_protected:Npn \__acro_get_actions:n #1
+% #1: property:
+\cs_new_protected:Npn \acro_new_format:n #1
   {
-    \seq_map_inline:Nn \l__acro_actions_seq
+    \tl_new:c {l__acro_format_#1_tl}
+    \keys_define:nn {acro/format}
       {
-        \cs_set:Npn \__acro_action:n ####1 {##1}
-        \__acro_action:n {#1}
+        #1 .tl_set:c  = l__acro_format_#1_tl ,
+        #1 .initial:n =
       }
   }
 
-\cs_new_protected:Npn \acro_get:n #1
+\acro_new_format:n {short}
+\acro_new_format:n {long}
+\acro_new_format:n {alt}
+\acro_new_format:n {extra}
+\acro_new_format:n {foreign}
+\acro_new_format:n {list}
+\acro_new_format:n {first-long}
+
+\keys_define:nn {acro}
+  {
+    format .meta:n = { format/short = #1 , format/long = #1 } ,
+    format / replace .bool_set:N = \l__acro_format_replace_bool ,
+    format / replace .initial:n  = false
+  }
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{ppfixes}{pre- and postfixes to acronyms}
+% --------------------------------------------------------------------------
+% articles
+\bool_new:N \l__acro_article_bool
+\tl_new:N \g__acro_articles_tl
+
+% #1: name
+% #2: default
+\cs_new_protected:Npn \acro_article_declare:nn #1#2
   {
-    \bool_if:NF \l__acro_in_list_bool { \leavevmode }
-    \acro_activate_hyperref_support:
-    % short:
-    \acro_property_get:nn {#1} {short}
-    % alt:
-    \acro_property_get:nnF {#1} {alt}
-      { \tl_set_eq:NN \l__acro_alt_tl \l__acro_short_tl }
-    % long:
-    \acro_property_get:nn {#1} {long}
-    % foreign:
-    \acro_property_get:nn {#1} {foreign}
-    % foreign-lang:
-    \acro_property_get:nn {#1} {foreign-lang}
-    % extra:
-    \acro_property_get:nn {#1} {extra}
-    % single:
-    \acro_property_get:nn {#1} {single}
-    % first-style:
-    \acro_property_get:nn {#1} {first-style}
-    % formatting
-    \acro_property_get:nnTF {#1} {long-format}      
-      {
-        \tl_set_eq:NN \l__acro_custom_long_format_tl \l__acro_long_format_tl
-        \bool_set_true:N  \l__acro_custom_long_format_bool
-      }
-      { \bool_set_false:N \l__acro_custom_long_format_bool }
-    \acro_property_get:nn {#1} {first-long-format}
-    \acro_property_get:nnTF {#1} {format}
+    \tl_gput_right:Nn \g__acro_articles_tl {{#1}}
+    \acro_property_declare:nnnnn
+      { \c_false_bool } { \c_false_bool } { \c_false_bool } { \c_false_bool }
+      {#1}
+    \acro_list_map:nn {short}
       {
-        \tl_set_eq:NN \l__acro_custom_short_format_tl \l__acro_format_tl
-        \bool_set_true:N \l__acro_custom_short_format_bool
+        \DeclareAcroPropertyAlias {##1-#1} {#1}
+        \str_if_in:nnF {##1} {-acc}
+          { \DeclareAcroPropertyAlias {##1-acc-#1} {##1-#1} }
       }
-      { \bool_set_false:N \l__acro_custom_short_format_bool }
-    \acro_property_get:nnTF {#1} {alt-format}
+    \acro_list_map:nn {long}
       {
-        \tl_set_eq:NN \l__acro_custom_alt_format_tl \l__acro_alt_format_tl
-        \bool_set_true:N \l__acro_custom_alt_format_bool
+        \DeclareAcroPropertyAlias {##1-#1} {#1}
+        \str_if_in:nnF {##1} {acc}
+          { \DeclareAcroPropertyAlias {##1-acc-#1} {##1-#1} }
       }
-      { \bool_set_false:N \l__acro_custom_alt_format_bool }
-    \acro_property_get:nnTF {#1} {foreign-format}
+    \bool_new:c {l__acro_article_#1_bool}
+    \tl_new:c {l__acro_article_#1_tl}
+    \exp_args:Nc \NewDocumentCommand {acro#1} {} { \use:c {acro_#1:} }
+    \cs_new_protected:cpn {acro_#1:}
       {
-        \tl_set_eq:NN \l__acro_custom_foreign_format_tl \l__acro_foreign_format_tl
-        \bool_set_true:N \l__acro_custom_foreign_format_bool
+        \bool_if:NF \l__acro_article_bool
+          {
+            \bool_set_true:c {l__acro_article_#1_bool}
+            \bool_set_true:N \l__acro_article_bool
+          }
       }
-      { \bool_set_false:N \l__acro_custom_foreign_format_bool }
-    \acro_property_get:nn {#1} {single-format}
-    \acro_for_endings_do:n
+    \keys_define:nn {acro}
       {
-        \bool_if:cT {l__acro_##1_bool}
-          { \__acro_set_ending_for:nnn {##1} {#1} {long} }
+        #1 .tl_set:c  = {l__acro_article_#1_tl} ,
+        #1 .initial:n = #2
       }
-    \acro_property_get:nnF {#1} {long-post}
-      { \tl_clear:N \l__acro_long_post_tl }
-    \acro_property_get:nnT {#1} {long-pre}
-      { \tl_put_left:NV \l__acro_long_tl \l__acro_long_pre_tl }
-    \__acro_get_actions:n {#1}
   }
 
+% #1: id
+\cs_new_protected:Npn \__acro_set_article_defaults:n #1
+  {
+    \tl_map_tokens:Nn \g__acro_articles_tl
+      { \__acro_default_article:nn {#1} }
+  }
+
+% #1: id
+% #2: article
+\cs_new_protected:Npn \__acro_default_article:nn #1#2
+  { \acro_property_set:nnv {#1} {#2} {l__acro_article_#2_tl} }
+
 % --------------------------------------------------------------------------
-% plural endings and similar concepts:
+% mechanism for endings:
+\tl_new:N \l__acro_endings_tl
 
-\cs_new_protected:Npn \acro_for_endings_do:n #1
-  { \seq_map_inline:Nn \l__acro_endings_seq {#1} }
+\bool_new:N \l__acro_ending_bool
 
-% #1: ending
-% #2: ID
-\cs_new_protected:Npn \__acro_set_ending:nn #1#2
+\acro_attribute_new:n {short:endings}
+\acro_attribute_new:n {long:endings}
+
+\cs_new_protected:Npn \__acro_declare_ending_properties:n #1
   {
-    \bool_if:cT {l__acro_#1_bool}
-      {
-        \__acro_set_ending_for:nnn {#1} {#2} {short}
-        \__acro_set_ending_for:nnn {#1} {#2} {alt}
-        \__acro_set_ending_for:nnn {#1} {#2} {long}
-        \__acro_set_ending_for:nnn {#1} {#2} {foreign} % XXX
-      }
+    \acro_property_declare:nnnnn
+      { \c_false_bool } { \c_false_bool } { \c_false_bool } { \c_false_bool }
+      {#1}
+    \acro_property_declare:nnnnn
+      { \c_false_bool } { \c_false_bool } { \c_false_bool } { \c_false_bool }
+      {#1-form}
   }
 
-% this does nothing if a non-existent ending (#1) or non-existent form (#3) is
-% input
 % #1: ending
-% #2: id
-% #3: short|alt|long|foreign
-\cs_new_protected:Npn \__acro_set_ending_for:nnn #1#2#3
+% #2: short default
+% #3: long default
+\cs_new_protected:Npn \acro_declare_ending:nnn #1#2#3
   {
-    \acro_if_ending_form_exist:nnT {#1} {#3}
+    \bool_new:c {l__acro_ending_#1_bool}
+    \exp_args:Nc \NewDocumentCommand {acro#1} {} { \use:c {acro_#1:} }
+    \cs_new_protected:cpn {acro_#1:}
+      {
+        \bool_if:NF \l__acro_ending_bool
+          {
+            \bool_set_true:c {l__acro_ending_#1_bool}
+            \bool_set_true:N \l__acro_ending_bool
+          }
+      }
+    \prg_new_conditional:cpnn {acro_if_#1:} {p,T,F,TF}
+      {
+        \bool_if:cTF {l__acro_ending_#1_bool}
+          { \prg_return_true: }
+          { \prg_return_false: }
+      }
+    \tl_put_right:Nn \l__acro_endings_tl {{#1}}
+    \keys_define:nn {acro}
+      {
+        short-#1-ending .code:n =
+          \acro_attribute_set:nnn {short:endings} {#1} {##1} ,
+        short-#1-ending .initial:n = #2 ,
+        long-#1-ending .code:n =
+          \acro_attribute_set:nnn {long:endings} {#1} {##1} ,
+        long-#1-ending .initial:n = #3
+      }
+    \__acro_declare_ending_properties:n {#1}% plural + plural-form
+    \acro_list_map:nn {short}
       {
-        \bool_if:cTF
-          { c_ \prop_item:cn {l__acro_#3_#1_form_prop} {#2} _bool }
-          { \prop_get:cnc {l__acro_#3_#1_prop} {#2} {l__acro_#3_tl}  }
-          { \prop_get:cnc {l__acro_#3_#1_prop} {#2} {l__acro_#3_#1_tl} }
+        % short-plural + short-plural-form
+        \__acro_declare_ending_properties:n {##1-#1}
+        % short-plural = plural
+        \acro_property_make_alias:nn {##1-#1} {#1}
+      }
+    \acro_list_map:nn {long}
+      {
+        % long-plural + long-plural-form
+        \__acro_declare_ending_properties:n {##1-#1}
+        % long-plural = plural
+        \acro_property_make_alias:nn {##1-#1} {#1}
+        % long-plural-form = plural-form
+        \acro_property_make_alias:nn {##1-#1-form} {#1-form}
       }
   }
 
-\cs_new_protected:Npn \__acro_set_endings:n #1
+% #1: id
+% #2: short|long
+\cs_new_protected:Npn \__acro_set_endings:nn #1#2
   {
-    \acro_for_endings_do:n
-      { \__acro_set_ending:nn {##1} {#1} }
+    \acro_list_map:nn {#2}
+      {
+         \tl_map_inline:Nn \l__acro_endings_tl
+           { \__acro_set_ending:nnnn {#1} {#2} {##1} {####1} }
+      }
   }
 
 % #1: id
-% #2: short|alt|…
-\cs_new_protected:Npn \acro_get_ending_form:nn #1#2
+% #2: short|long
+% #3: property
+% #4: ending
+\cs_new_protected:Npn \__acro_set_ending:nnnn #1#2#3#4
   {
-    \acro_for_endings_do:n
+    \acro_property_if_set:nnF {#1} {#3-#4-form}
       {
-        \acro_if_ending_form_exist:nnT {##1} {#2}
+        \acro_property_if_set:nnF {#1} {#3-#4}
           {
-            \bool_lazy_and:nnT
-              { \use:c {l__acro_##1_bool} }
-              { \use:c { c_ \prop_item:cn {l__acro_#2_##1_form_prop} {#1} _bool } }
-              { \prop_get:cncF {l__acro_#2_##1_prop} {#1} {l__acro_#2_tl} {} }
+            \__acro_property_set:nne {#1} {#3-#4}
+              { \acro_attribute_get:nn {#2:endings} {#4} }
           }
       }
   }
 
 % #1: id
-% #2: short|alt|…
-\cs_new_protected:Npn \acro_endings:nn #1#2
+\cs_new_protected:Npn \acro_set_endings:n #1
   {
-    \group_begin:
-      \str_if_eq:nnTF {#2} {single}
-        {
-          \keys_set:nn {acro}
-            { long-format= \l__acro_single_format_tl }
-          \__acro_endings:nn {#1} {long}
-        }
-        { \__acro_endings:nn {#1} {#2} }
-    \group_end:
+    \__acro_set_endings:nn {#1} {short}
+    \__acro_set_endings:nn {#1} {long}
+  }
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{tools}{tools for treating different aspects}
+
+% ----------------------------------------------------------------------------
+\bool_new:N \l__acro_label_bool
+\tl_new:N \l_acro_label_prefix_tl
+
+\keys_define:nn {acro}
+  {
+    labels       .bool_set:N = \l__acro_label_bool ,
+    labels       .initial:n  = false ,
+    label-prefix .tl_set:N   = \l_acro_label_prefix_tl ,
+    label-prefix .initial:n  = ac:
   }
 
-\cs_new_protected:Npn \__acro_endings:nn #1#2
+% --------------------------------------------------------------------------
+% check for first usage:
+\bool_new:N \l__acro_first_bool
+
+\cs_new_protected:Npn \acro_first:
+  { \bool_set_true:N \l__acro_first_bool }
+
+\prg_new_conditional:Npnn \acro_if_first:n #1 {p,T,F,TF}
   {
-    \acro_for_endings_do:n
+    \bool_if:NTF \l__acro_first_bool
+      { \prg_return_true: }
       {
-        \__acro_set_ending_for:nnn {##1} {#1} {#2}
-        \bool_if:cT {l__acro_##1_bool}
-          { \__acro_ending_format:nn {#2} { \tl_use:c {l__acro_#2_##1_tl} } }
+        \acro_boolean_property_if:nnTF {#1} {used}
+          { \prg_return_false: }
+          { \prg_return_true: }
       }
   }
+\prg_generate_conditional_variant:Nnn \acro_if_first:n {e,V} {T,F,TF}
+
+% --------------------------------------------------------------------------
+% check for single usage:
+\int_new:N \l__acro_minimal_usage_int
 
-% #1: long|short|alt
-% #2: string
-\cs_new_protected:Npn \__acro_ending_format:nn #1#2
+% #1: id
+\cs_new_protected:Npn \acro_step:n #1
+  { \int_gincr:c {g__acro_ \acro_case_insensitive:n {#1} _int} }
+\cs_generate_variant:Nn \acro_step:n {e}
+
+% #1: id
+\prg_new_conditional:Npnn \acro_if_single:n #1 {p,T,F,TF}
   {
-    \bool_if:NTF \l__acro_include_endings_format_bool
+    \int_compare:nNnTF
       {
-        \str_case:nn {#1}
-          {
-            {long}
-            {
-              \bool_if:NTF \l__acro_custom_long_format_bool
-                { \l__acro_custom_long_format_tl }
-                {
-                  \bool_if:NTF \l__acro_first_instance_bool
-                    { \l__acro_first_long_format_tl }
-                    { \l__acro_long_format_tl }
-                }
-            }
-            {short}
-            {
-              \bool_if:NTF \l__acro_custom_short_format_bool
-                { \l__acro_custom_short_format_tl }
-                { \l__acro_short_format_tl }
-            }
-            {alt}
-            {
-              \bool_if:NTF \l__acro_custom_alt_format_bool
-                { \l__acro_custom_alt_format_tl }
-                { \l__acro_alt_format_tl }
-            }
-            {foreign}
-            {
-              \bool_if:NTF \l__acro_custom_foreign_format_bool
-                { \l__acro_custom_foreign_format_tl }
-                { \l__acro_foreign_format_tl }
-            }
-          }
+        \bool_if:NTF \l__acro_usage_local_bool
+          { \acro_barrier_usage:n {#1} }
+          { \acro_property_get:nn {#1} {usage} }
       }
-      { \use:n }
-      {#2}
+      > \l__acro_minimal_usage_int
+      { \prg_return_false: }
+      { \prg_return_true: }
   }
-  
-\prg_new_conditional:Npnn \acro_if_ending_exist:n #1 {p,T,F,TF}
+\prg_generate_conditional_variant:Nnn \acro_if_single:n {e,V} {p,TF}
+
+\bool_new:N \l__acro_use_only_first_bool
+\tl_new:N \l__acro_single_tl
+
+\keys_define:nn {acro}
   {
-    \seq_if_in:NnTF \l__acro_endings_seq {#1}
-      { \prg_return_true: }
-      { \prg_return_false: }
+    single         .code:n    =
+      \str_case:nnF {#1}
+        {
+          {} { \int_set:Nn \l__acro_minimal_usage_int {1} }
+          {true} { \int_set:Nn \l__acro_minimal_usage_int {1} }
+          {false} { \int_set:Nn \l__acro_minimal_usage_int {0} }
+        }
+        { \int_set:Nn \l__acro_minimal_usage_int {#1} } ,
+    minimal-usage  .meta:n    = { single = #1 } ,
+    single         .initial:n = 0 ,
+    single-style   .tl_set:N   = \l__acro_single_tl ,
+    single-style   .initial:n  = long ,
+    use-only-first .bool_set:N = \l__acro_use_only_first_bool ,
+    use-only-first .initial:n  = false
   }
 
-% #1: ending
-% #2: short|alt|…
-\prg_new_conditional:Npnn \acro_if_ending_form_exist:nn #1#2 {p,T,F,TF}
+% --------------------------------------------------------------------------
+% uppercasing the first letter:
+\bool_new:N \l__acro_upper_bool
+\bool_new:N \l__acro_upper_short_bool
+\bool_new:N \l__acro_upper_list_bool
+
+\cs_new:Npn \__acro_upper_case:n #1 {}
+\cs_new:Npn \__acro_list_upper_case:n #1 {}
+
+\cs_new_protected:Npn \acro_soft_upper:
   {
-    \cs_if_exist:cTF {l__acro_#2_#1_prop}
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \bool_if:NF \l__acro_upper_short_bool
+      { \bool_set_false:N \l__acro_upper_bool }
   }
-  
-% #1: name
-% #2: default short
-% #3: default long
-\cs_new_protected:Npn \acro_provide_ending:nnn #1#2#3
-  {
-    \acro_if_ending_exist:nTF {#1}
-      {
-        \acro_harmless_message:nn {ending-exists} {#1}
-        % short variables
-        \acro_set_ending_variables:nnn {short} {#1} {#2}
-        % alt variables
-        \acro_set_ending_variables:nnn {alt} {#1} {#2}
-        % long variables
-        \acro_set_ending_variables:nnn {long} {#1} {#3}
-        % foreign variables % XXX
-        \acro_set_ending_variables:nnn {foreign} {#1} {#3}
-      }
-      {
-        % registering:
-        \bool_if:NT \g__acro_first_acronym_declared_bool
-          { \acro_serious_message:n {ending-before-acronyms} }
-        \seq_put_right:Nn \l__acro_endings_seq {#1}
-        \bool_new:c {l__acro_#1_bool}
-        % short variables
-        \acro_define_and_set_ending_variables:nnn {short} {#1} {#2}
-        % alt variables
-        \acro_define_and_set_ending_variables:nnn {alt} {#1} {#2}
-        % long variables
-        \acro_define_and_set_ending_variables:nnn {long} {#1} {#3}
-        % foreign variables % XXX
-        \acro_define_and_set_ending_variables:nnn {foreign} {#1} {#3}
-        % define setup command:
-        \tl_set:Nn \l__acro_tmpa_tl {#1}
-        \tl_replace_all:Nnn \l__acro_tmpa_tl {-} {_}
-        \cs_new_protected:cpn {acro_ \l__acro_tmpa_tl :}
-          { \bool_set_true:c {l__acro_#1_bool} }
-        % acronym properties:
-        % short-<ending>:
-        \acro_declare_property:nnn {short_#1} {short-#1}
-          {
-            \prop_put:cnn {l__acro_short_#1_form_prop} {##1} {false}
-            \prop_put:cnx {l__acro_pdfstring_short_#1_prop}
-              {##1} { \prop_item:Nn \l__acro_short_prop {##1} \exp_not:n {##2} }
-          }
-        % short-<ending>-form:
-        \acro_declare_property_generic:nnn {short_#1_form} {short-#1-form}
-          {
-            \__acro_property_check:nn {##1} {short-#1-form}
-            \prop_put:cnn {l__acro_short_#1_form_prop} {##1} {true}
-            \prop_put:cnn {l__acro_short_#1_prop} {##1} {##2}
-            \prop_put:cnn {l__acro_pdfstring_short_#1_prop} {##1} {##2}
-          }
-        % alt-<ending>:
-        \acro_declare_property:nnn {alt_#1} {alt-#1}
-          {
-            \prop_put:cnn {l__acro_alt_#1_form_prop} {##1} {false}
-            \prop_put:cnx {l__acro_pdfstring_alt_#1_prop}
-              {##1} { \prop_item:Nn \l__acro_alt_prop {##1} \exp_not:n {##2} }
-          }
-        % alt-<ending>-form:
-        \acro_declare_property_generic:nnn {alt_#1_form} {alt-#1-form}
-          {
-            \__acro_property_check:nn {##1} {alt-#1-form}
-            \prop_put:cnn {l__acro_alt_#1_form_prop} {##1} {true}
-            \prop_put:cnn {l__acro_alt_#1_prop} {##1} {##2}
-            \prop_put:cnn {l__acro_pdfstring_alt_#1_prop} {##1} {##2}
-          }
-        % long-<ending>:
-        \acro_declare_property:nnn {long_#1} {long-#1}
-          { \prop_put:cnn {l__acro_long_#1_form_prop} {##1} {false} }
-        % long-<ending>-form:
-        \acro_declare_property_generic:nnn {long_#1_form} {long-#1-form}
-          {
-            \__acro_property_check:nn {##1} {long-#1-form}
-            \prop_put:cnn {l__acro_long_#1_form_prop} {##1} {true}
-            \prop_put:cnn {l__acro_long_#1_prop} {##1} {##2}
-          }
-        % foreign-<ending>: % XXX
-        \acro_declare_property:nnn {foreign_#1} {foreign-#1}
-          { \prop_put:cnn {l__acro_foreign_#1_form_prop} {##1} {false} }
-        % foreign-<ending>-form: % XXX
-        \acro_declare_property_generic:nnn {foreign_#1_form} {foreign-#1-form}
-          {
-            \__acro_property_check:nn {##1} {foreign-#1-form}
-            \prop_put:cnn {l__acro_foreign_#1_form_prop} {##1} {true}
-            \prop_put:cnn {l__acro_foreign_#1_prop} {##1} {##2}
-          }
-        % options:
-        %   short-<ending>-ending
-        %   alt-<ending>-ending
-        %   long-<ending>-ending
-        %   foreign-<ending>-ending % XXX
-        %   <ending>-ending
-        \keys_define:nn {acro}
-          {
-            short-#1-ending .code:n =
-              \bool_if:NT \g__acro_first_acronym_declared_bool
-                { \acro_serious_message:n {ending-before-acronyms} }
-              \tl_set:cn {l__acro_default_short_#1_tl} {##1} ,
-            alt-#1-ending   .code:n =
-              \bool_if:NT \g__acro_first_acronym_declared_bool
-                { \acro_serious_message:n {ending-before-acronyms} }
-              \tl_set:cn {l__acro_default_alt_#1_tl} {##1} ,
-            long-#1-ending  .code:n =
-              \bool_if:NT \g__acro_first_acronym_declared_bool
-                { \acro_serious_message:n {ending-before-acronyms} }
-                \tl_set:cn {l__acro_default_long_#1_tl} {##1} ,
-            foreign-#1-ending .code:n =
-              \bool_if:NT \g__acro_first_acronym_declared_bool
-                { \acro_serious_message:n {ending-before-acronyms} }
-              \tl_set:cn {l__acro_default_foreign_#1_tl} {##1} ,
-            #1-ending       .code:n   =
-              \bool_if:NT \g__acro_first_acronym_declared_bool
-                { \acro_serious_message:n {ending-before-acronyms} }
-              \__acro_read_ending_settings:nww {#1} ##1// \acro_stop:
-          }
-        % pdfstrings:
-        % TODO: add long forms:
-        \prop_new:c {l__acro_pdfstring_short_#1_prop}
-        \cs_new:cpn {acro_pdf_string_short_#1:n} ##1
-          {
-            \acro_if_star_gobble:nTF {##1}
-              { \use:e { \prop_item:cn {l__acro_pdfstring_short_#1_prop} } }
-              { \use:e {\prop_item:cn {l__acro_pdfstring_short_#1_prop} {##1} } }
-          }
-        \cs_new:cpn {acpdfstring#1} { \use:c {acro_pdf_string_short_#1:n} }
-        \prop_new:c {l__acro_pdfstring_alt_#1_prop}
-        \cs_new:cpn {acro_pdf_string_alt_#1:n} ##1
-          {
-            \acro_if_star_gobble:nTF {##1}
-              { \prop_item:cn {l__acro_pdfstring_alt_#1_prop} }
-              { \prop_item:cn {l__acro_pdfstring_alt_#1_prop} {##1} }
-          }
-        \cs_new:cpn {acpdfstringalt#1} { \use:c {acro_pdf_string_alt_#1:n} }
-      }
+
+\cs_new_protected:Npn \acro_upper:
+  {
+    \bool_if:NT \l__acro_article_bool
+      { \bool_set_false:N \l__acro_article_bool }
+    \bool_set_true:N \l__acro_upper_bool
+  }
+
+\cs_new:Npn \__acro_upper:n #1
+  {
+    \bool_if:NTF \l__acro_upper_bool
+      { \__acro_upper_case:n {#1} }
+      {#1}
   }
+\cs_generate_variant:Nn \__acro_upper:n {e}
 
-% #1: short|alt|long
-% #2: ending name
-% #3: default ending
-\cs_new_protected:Npn \acro_define_and_set_ending_variables:nnn #1#2#3
+\keys_define:nn {acro/uppercase}
   {
-    \acro_define_ending_variables:nn {#1} {#2}
-    \acro_set_ending_variables:nnn {#1} {#2} {#3}
+    cmd   .cs_set:Np  = \__acro_upper_case:n ,
+    cmd   .value_required:n = true ,
+    first .meta:n     = { cmd = \text_titlecase_first:n } ,
+    first .value_forbidden:n = true ,
+    all   .meta:n     = { cmd = \text_uppercase:n } ,
+    all   .value_forbidden:n = true ,
+    none  .meta:n     = { cmd = \text_lowercase:n } ,
+    none  .value_forbidden:n = true ,
+    title .meta:n     = { first } ,
+    title .value_forbidden:n = true ,
+    short .bool_set:N = \l__acro_upper_short_bool ,
+    short .initial:n  = true ,
+    list  .bool_set:N = \l__acro_upper_list_bool ,
+    list  .initial:n  = false
   }
 
-% #1: short|alt|long
-% #2: ending name
-\cs_new_protected:Npn \acro_define_ending_variables:nn #1#2
+\keys_define:nn {acro/list/uppercase}
   {
-    \prop_new:c {l__acro_#1_#2_prop}
-    \prop_new:c {l__acro_#1_#2_form_prop}
-    \tl_new:c   {l__acro_#1_#2_tl}
-    \tl_new:c   {l__acro_default_#1_#2_tl}
+    cmd   .cs_set:Np  = \__acro_list_upper_case:n ,
+    cmd   .value_required:n = true ,
+    first .meta:n     = { cmd = \text_titlecase_first:n } ,
+    first .value_forbidden:n = true ,
+    all   .meta:n     = { cmd = \text_uppercase:n } ,
+    all   .value_forbidden:n = true ,
+    none  .meta:n     = { cmd = \text_lowercase:n } ,
+    none  .value_forbidden:n = true ,
+    title .meta:n     = { first } ,
+    title .value_forbidden:n = true ,
   }
 
-% #1: short|alt|long
-% #2: ending name
-% #3: default ending
-\cs_new_protected:Npn \acro_set_ending_variables:nnn #1#2#3
-  { \tl_set:cn  {l__acro_default_#1_#2_tl} {#3} }
+\keys_set:nn {acro} { list/uppercase/first , uppercase/first }
 
-% #1: ending name
-% #2: short (and long if #4 is blank)
-% #3: long
-\cs_new_protected:Npn \__acro_read_ending_settings:nww #1#2/#3/#4 \acro_stop:
+% --------------------------------------------------------------------------
+% citing:
+\bool_new:N \l__acro_cite_bool
+\bool_new:N \l__acro_cite_always_bool
+\bool_new:N \l__acro_cite_group_bool
+\bool_new:N \g__acro_cited_bool
+
+\tl_new:N \l__acro_cite_pre_tl
+\tl_new:N \l__acro_cite_between_tl
+
+% #1: id
+\cs_new_protected:Npn \__acro_cite:n #1
   {
-    \acro_set_ending_variables:nnn {short} {#1} {#2}
-    \acro_set_ending_variables:nnn {alt} {#1} {#2}
-    \tl_if_blank:nTF {#4}
+    \use:e
       {
-        \acro_set_ending_variables:nnn {long} {#1} {#3}
-        \acro_set_ending_variables:nnn {foreign} {#1} {#3}
-      }
-      {
-        \acro_set_ending_variables:nnn {long} {#1} {#2}
-        \acro_set_ending_variables:nnn {foreign} {#1} {#2}
+        \__acro_cite:w
+        \acro_property_get:nn {#1} {cite}
       }
+      [\q_no_value]
+      [\q_no_value]
+      \scan_stop:
+    \acro_stop:
   }
+\cs_generate_variant:Nn \__acro_cite:n {e}
 
-% --------------------------------------------------------------------------
-% enable us to know if the acronym is used only once and provide a different
-% style for that:
-\prg_new_protected_conditional:Npnn \acro_is_used:n #1 { T,F,TF }
+% #1: boolean, true if starred
+% #2: id
+\prg_new_conditional:Npnn \acro_cite_if:nn #1#2 {T,F,TF}
   {
-    \acro_record_barrier:n {#1}
-    \bool_lazy_and:nnTF
-      { \bool_if_p:c {g__acro_#1_used_bool} }
+    \bool_lazy_all:nTF
       {
-        \bool_lazy_or_p:nn
-          {
-            \bool_lazy_and_p:nn
-              { \bool_if_p:c {g__acro_#1_first_use_bool} }
-              { \g__acro_mark_first_as_used_bool }
-          }
-          { !\g__acro_mark_first_as_used_bool }
+        { \l__acro_cite_bool }
+        { \l__acro_use_bool }
+        { !#1 }
       }
       {
-        \bool_if:NTF \l__acro_mark_as_used_bool
-          {
-            \__acro_aux_file:Nxxxx \acro@used@twice
-              {#1}
-              { \thepage }
-              { \arabic {page} }
-              { \arabic {abspage} }
-          }
-          { \__acro_aux_file:Nxxxx \acro@used@twice {#1} {} {} {} }
-        \prg_return_true:
+        \bool_lazy_or:nnTF
+          { \l__acro_cite_always_bool }
+          { \acro_if_first_p:n {#2} }
+          { \prg_return_true: }
+          { \prg_return_false: }
       }
+      { \prg_return_false: }
+  }
+\prg_generate_conditional_variant:Nnn \acro_cite_if:nn {ne} {T}
+
+% #1: cite key
+\cs_new_protected:Npn \acro_cite:n #1
+  {
+    \acro_property_if_set:nnT {#1} {cite}
       {
-        \bool_if:NTF \l__acro_mark_as_used_bool
-          {
-            \__acro_aux_file:Nxxxx \acro@used@once
-              {#1}
-              { \thepage }
-              { \arabic {page} }
-              { \arabic {abspage} }
-            \bool_lazy_and:nnT
-              { !\bool_if_p:c {g__acro_#1_label_bool} }
-              { \l__acro_place_label_bool }
-              {
-                \bool_gset_true:c { g__acro_#1_label_bool }
-                \label{\l__acro_label_prefix_tl #1}
-              }
-            \bool_gset_true:c { g__acro_#1_used_bool }
-          }
-          {}
-          % I can't remember why I want an empty first use case for starred
-          % acronyms…
-          % { \__acro_aux_file:Nxxxx \acro@used@once {#1} {} {} {} }
-        \prg_return_false:
+        \acro_property_get:nn {#1} {before-citation}
+        \l__acro_cite_pre_tl
+        \__acro_cite:n {#1}
+        \bool_gset_true:N \g__acro_cited_bool
       }
   }
+\cs_generate_variant:Nn \acro_cite:n {e}
 
-\cs_new:Npn \acro_is_used:n #1
-  { \acro_is_used:nTF {#1} { } { } }
+\cs_new_protected:Npn \__acro_cite:w #1[#2]#3[#4]#5#6 \acro_stop:
+  {
+    % no options: #1: key, #6 is blank
+    % 1 option:   #3: key, #2: option, #4: \q_no_value
+    % 2 options:  #5: property, #2: first option, #4: second option
+    \tl_if_blank:nTF {#6}
+      { \__acro_cite_cmd:w {#1} }
+      {
+        \quark_if_no_value:nTF {#4}
+          { \__acro_cite_cmd:w [{#2}] {#3}}
+          { \__acro_cite_cmd:w [{#2}] [{#4}] {#5} }
+      }
+  }
 
-\cs_new_protected:Npn \__acro_aux_file:Nnnnn #1#2#3#4#5
-  { \iow_shipout:Nn \@auxout { #1 {#2} {#3} {#4} {#5} } }
-\cs_generate_variant:Nn \__acro_aux_file:Nnnnn {Nxxxx}
-  
-\cs_new_protected:Npn \__acro_aux_file_now:n #1
-  { \iow_now:Nn \@auxout {#1} }
-\cs_generate_variant:Nn \__acro_aux_file_now:n {x}
+\cs_new_protected:Npn \__acro_cite_cmd:w {}
+\cs_new_protected:Npn \__acro_cite_group_cmd:w {}
+
+\keys_define:nn {acro/cite}
+  {
+    cmd           .cs_set:Np  = \__acro_cite_cmd:w ,
+    cmd           .initial:n  = \cite ,
+    cmd           .value_required:n = true ,
+    group         .code:n     =
+      \str_case:nnTF {#1}
+        { {true} {} {false} {} }
+        { \use:c {bool_set_#1:N} \l__acro_cite_group_bool }
+        { \msg_error:nnn {kernel} {boolean-values-only} {group} } ,
+    group         .initial:n  = false ,
+    display       .choice: ,
+    display/all   .code:n     =
+      \bool_set_true:N \l__acro_cite_bool
+      \bool_set_true:N \l__acro_cite_always_bool ,
+    display/first .code:n     =
+      \bool_set_true:N \l__acro_cite_bool
+      \bool_set_false:N \l__acro_cite_always_bool ,
+    display/none  .code:n     = \bool_set_false:N \l__acro_cite_bool ,
+    display       .initial:n  = first ,
+    pre           .tl_set:N   = \l__acro_cite_pre_tl ,
+    pre           .initial:n  = \nobreakspace ,
+    group / pre   .tl_set:N   = \l__acro_cite_between_tl ,
+    group / pre   .initial:n  = {,~} ,
+    group / cmd   .cs_set:Np  = \__acro_cite_group_cmd:w ,
+    group / cmd   .initial:n  = \cite
+  }
 
 % --------------------------------------------------------------------------
-% the commands for the auxiliary file:
-\cs_new_protected:Npn \acro@used@once #1#2#3#4
+% indexing
+\bool_new:N \l__acro_index_bool
+\tl_new:N \l_acro_index_disable_tl
+
+\cs_new_protected:Npn   \__acro_index:n {}
+\cs_generate_variant:Nn \__acro_index:n {e}
+
+% #1: id
+\cs_new_protected:Npn \acro_index:n #1
   {
-    \cs_gset_nopar:cpn {acro@#1@once} {#1}
-    \bool_gset_true:c {g__acro_#1_in_list_bool}
-    \tl_if_empty:nF {#2#3#4}
+    \bool_lazy_and:nnT
+      { \l__acro_index_bool }
+      { !\acro_boolean_property_if_p:nn {#1} {no-index} }
       {
-        % \bool_gset_true:c { g__acro_#1_used_bool }
-        \seq_gput_right:cn {g__acro_#1_pages_seq} { {#2}{#3}{#4} }
+        \group_begin:
+          \acro_trailing_map:n
+            { \bool_set_false:c {l__acro_trailing_##1_bool} }
+          \l_acro_index_disable_tl
+          \acro_property_if_set:nnT {#1} {index-cmd}
+            {
+              \exp_args:NNe
+              \cs_set:Npn \__acro_index:n
+                { \acro_property_get:nn {#1} {index-cmd} }
+            }
+          \acro_property_if_set:nnTF {#1} {index}
+            { \__acro_index:e { \acro_property_get:nn {#1} {index} } }
+            {
+              \__acro_index:e
+                {
+                  \acro_property_get:nn {#1} {index-sort} @
+                  \acro_format:nnn
+                    {#1}
+                    {short}
+                    { \acro_property_get:nn {#1} {short} }
+                }
+            }
+        \group_end:
       }
   }
-\cs_new_protected:Npn \acro@used@twice #1#2#3#4
+
+\keys_define:nn {acro/index}
   {
-    \cs_gset_nopar:cpn {acro@#1@twice} {#1}
-    \tl_if_empty:nF {#2#3#4}
-      { \seq_gput_right:cn {g__acro_#1_pages_seq} { {#2}{#3}{#4} } }
+    use     .bool_set:N = \l__acro_index_bool ,
+    use     .initial:n  = false ,
+    cmd     .cs_set:Np  = \__acro_index:n ,
+    cmd     .initial:n  = \index ,
+    cmd     .value_required:n  = true ,
+    disable .code:n     = \tl_put_right:Nn \l_acro_index_disable_tl {#1} ,
+    disable .value_required:n  = true ,
+    clear   .code:n     = \tl_clear:N \l_acro_index_disable_tl ,
+    clear   .value_forbidden:n = true
   }
 
-\cs_new_protected:Npn \acro@pages #1#2
-  { \tl_gset:cn {g__acro_#1_recorded_pages_tl} {#2} }
+\keys_set:nn {acro/index} { disable = \def\@{} }
 
-\cs_new_protected:Npn \acro@rerun@check
+% --------------------------------------------------------------------------
+% looking for trailing tokens and define action
+\bool_new:N \l__acro_trailing_tokens_bool
+\tl_new:N \l__acro_trailing_tokens_tl
+\tl_new:N \g__acro_trailing_tokens_tl
+\acro_attribute_new:n {trailing:token}
+\acro_attribute_new:n {trailing:action}
+
+\cs_new_protected:Npn \acro_trailing_action_new:n #1
+  { \bool_new:c {l__acro_trailing_#1_bool} }
+
+\cs_new_protected:Npn \acro_trailing_action_activate:n #1
+  { \bool_set_true:c {l__acro_trailing_#1_bool} }
+
+\cs_new_protected:Npn \acro_trailing_action_deactivate:n #1
+  { \bool_set_false:c {l__acro_trailing_#1_bool} }
+
+% register a new token but don't activate its action:
+% #1: token
+% #2: action
+\cs_new_protected:Npn \acro_trailing_token_register:Nn #1#2
   {
-    \bool_if:NT \g__acro_rerun_bool
-      {
-        \@latex@warning@no@line
-          {Acronyms~ may~ have~ changed.~ Please~ rerun~ LaTeX}
-      }
+    \tl_gput_right:Nn \g__acro_trailing_tokens_tl {{#2}}
+    \acro_attribute_set:nnn {trailing:token} {#2} {#1}
+    \acro_attribute_set:nnn {trailing:action} {#1}
+      { \acro_trailing_action_activate:n {#2} }
+    \acro_trailing_action_new:n {#2}
   }
 
-\AtEndDocument
+% maps over actions
+\cs_new_protected:Npn \acro_trailing_map:n #1
+  { \tl_map_inline:Nn \g__acro_trailing_tokens_tl {#1} }
+
+% activate a token:
+% #1: action
+\cs_new_protected:Npn \acro_trailing_token_activate:n #1
   {
-    \bool_gset_false:N \g__acro_rerun_bool
-    \cs_gset_protected:Npn \acro@used@once #1#2#3#4
+    \tl_set:Ne \l__acro_tmpa_tl { \acro_attribute_get:nn {trailing:token} {#1} }
+    \tl_if_blank:VF \l__acro_tmpa_tl
       {
-        \tl_set:Nn \l__acro_tmpa_tl {#1}
-        \tl_if_eq:cNF {acro@#1@once} \l__acro_tmpa_tl
-          { \bool_gset_true:N \g__acro_rerun_bool }
+        \tl_remove_all:NV \l__acro_trailing_tokens_tl \l__acro_tmpa_tl
+        \tl_put_right:NV \l__acro_trailing_tokens_tl \l__acro_tmpa_tl
       }
-    \cs_gset_protected:Npn \acro@used@twice #1#2#3#4
+  }
+
+% deactivate a token:
+% #1: action
+\cs_new_protected:Npn \acro_trailing_token_deactivate:n #1
+  {
+    \tl_set:Ne \l__acro_tmpa_tl { \acro_attribute_get:nn {trailing:token} {#1} }
+    \tl_if_blank:VF \l__acro_tmpa_tl
+      { \tl_remove_once:NV \l__acro_trailing_tokens_tl \l__acro_tmpa_tl }
+  }
+
+% #1: action
+\prg_new_conditional:Npnn \acro_trailing_if_token:n #1 {p,T,F,TF}
+  {
+    \bool_if:cTF {l__acro_trailing_#1_bool}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+
+% #1: csv list of actions
+\prg_new_conditional:Npnn \acro_trailing_if_tokens:n #1 {T,F,TF}
+  {
+    \clist_map_function:nN {#1} \__acro_trailing_if_tokens:n
+    \use_ii:nn
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+
+% #1: action
+\cs_new:Npn \__acro_trailing_if_tokens:n #1
+  {
+    \bool_if:cT {l__acro_trailing_#1_bool}
+      { \clist_map_break:n { \use_ii:nnn  } }
+  }
+
+\cs_new_protected:Npn \__acro_trailing_check:N #1
+  {
+    \tl_map_inline:Nn \l__acro_trailing_tokens_tl
       {
-        \tl_set:Nn \l__acro_tmpa_tl {#1}
-        \tl_if_eq:cNF {acro@#1@twice} \l__acro_tmpa_tl
-          { \bool_gset_true:N \g__acro_rerun_bool }
+        \token_if_eq_meaning:NNT #1 ##1
+          { \acro_attribute_get:nn {trailing:action} {##1} }
       }
-    \acro_for_all_acronyms_do:n
+  }
+
+\cs_new_protected:Npn \acro_begin:
+  {
+    \group_begin:
+    \__acro_check_after_end:w
+  }
+
+\cs_new_protected:Npn \__acro_check_after_end:w #1 \acro_end:
+  {
+    \cs_set:Npn \__acro_execute:
       {
-        \seq_if_empty:cF {g__acro_#1_pages_seq}
-          {
-            \__acro_aux_file_now:x
-              {
-                \acro@pages {#1}
-                  { \seq_use:cn {g__acro_#1_pages_seq} {|} } ^^J
-                \acro@barriers {#1}
-                  { \seq_use:cn {g__acro_#1_barriers_seq} {,} }
-              }
-          }
-        \acro_check_barriers:n {#1}
+        \__acro_trailing_check:N \l_peek_token
+        #1
+        \acro_end: % this will end the group opened by \acro_begin:
       }
-    \__acro_aux_file_now:n { \acro@rerun@check }
+    \peek_after:Nw \__acro_execute:
   }
 
-% if `acro' is deactivated prevent unnecessary errors from aux file:
-\if@filesw
-\AtBeginDocument
+\bool_new:N \g__acro_gobble_trail_bool
+
+\cs_new_protected:Npn \acro_end:
   {
-    \__acro_aux_file_now:n
+    \bool_if:NT \g__acro_gobble_trail_bool
       {
-        \providecommand \acro@used@once [4] {} ^^J
-        \providecommand \acro@used@twice [4] {} ^^J
-        \providecommand \acro@pages [2] {} ^^J
-        \providecommand \acro@rerun@check {} ^^J
-        \providecommand \acro@print@list {} ^^J
-        \providecommand \acro@barriers [2] {}
+        \bool_gset_false:N \g__acro_gobble_trail_bool
+        \use_i:nn
       }
+    \group_end:
   }
-\fi
 
-% --------------------------------------------------------------------------
-% #1: short|alt|long
-% #2: string to be typeset
-\cs_new_protected:Npn \__acro_typeset:nn #1#2
+% register some tokens to be checked for:
+\acro_trailing_token_register:Nn . {dot}
+\acro_trailing_token_register:Nn , {comma}
+\acro_trailing_token_register:Nn - {dash}
+\acro_trailing_token_register:Nn \babelhyphen {babel-hyphen}
+
+\tl_new:N \l__acro_fnpct_check_tl
+
+\cs_new_protected:Npn \acro_footnote:n #1
   {
-    \mode_if_horizontal:F { \leavevmode }
-    \group_begin:
-      \use:x
-        {
-          \bool_if:cTF {l__acro_custom_#1_format_bool}
-            { \exp_not:v {l__acro_custom_#1_format_tl} }
-            { \exp_not:v {l__acro_#1_format_tl} }
-            {#2}
-        }
-    \group_end:
+    \tl_set:Ne \l__acro_fnpct_check_tl { \l__acro_fnpct_check_tl }
+    \exp_last_unbraced:Nno
+    \footnote {#1}
+    \l__acro_fnpct_check_tl
   }
 
-% typeset the short form:
-% #1: ID
-% #2: short form
-\cs_new_protected:Npn \acro_write_short:nn #1#2
+% options for activating actions:
+\keys_define:nn {acro/trailing}
   {
-    \__acro_make_link:nn {#1}
+    activate    .code:n    =
+      \clist_map_inline:nn {#1} { \acro_trailing_token_activate:n {##1} } ,
+    activate    .initial:n = {dot,comma} ,
+    deactivate  .code:n    =
+      \clist_map_inline:nn {#1} { \acro_trailing_token_deactivate:n {##1} } ,
+    register    .code:n    = \acro_trailing_token_register:Nn #1 ,
+    fnpct-check .tl_set:N  = \l__acro_fnpct_check_tl ,
+    fnpct-check .initial:n =
+      \aciftrailing {dot}   { . \acgobbletrail } {}
+      \aciftrailing {comma} { , \acgobbletrail } {}
+  }
+
+% some user macros:
+\cs_new:Npn \acro_dot:
+  { \acro_trailing_if_token:nF {dot} {.\@} }
+
+\cs_new:Npn \acro_space:
+  { \acro_trailing_if_tokens:nF {dash,babel-hyphen} { \c_space_tl } }
+
+% ----------------------------------------------------------------------------
+% sorting the list:
+% the following code is an adaption of expl3 code used for \str_if_eq:NN(TF)
+\sys_if_engine_luatex:TF
+  {
+    \cs_new_protected:Npn \__acro_strcmp:nn #1#2
       {
-        \__acro_typeset:nn {short}
+        \lua_now:e
           {
-            \bool_if:NTF \l__acro_first_upper_bool
-              { \exp_not:N \__acro_first_upper_case:n { \exp_not:n {#2} } }
-              { \exp_not:n {#2} }
+            l3kernel.strcmp
+              (
+                " \__acro_escape_x:n {#1} " ,
+                " \__acro_escape_x:n {#2} "
+              )
           }
       }
+    \cs_new:Npn \__acro_escape_x:n #1
+      {
+        \lua_escape:e
+          { \tex_detokenize:D \use:e { {#1} } }
+      }
   }
-\cs_generate_variant:Nn \acro_write_short:nn {nV,nv}
+  { \cs_new_eq:NN \__acro_strcmp:nn \tex_strcmp:D }
 
-% typeset the alternative form:
-% #1: ID
-% #2: alt form
-\cs_new_protected:Npn \acro_write_alt:nn #1#2
+\cs_new_protected:Npn \acro_list_sort:
   {
-    \__acro_make_link:nn {#1}
+    \seq_sort:Nn \g__acro_list_seq
       {
-        \__acro_typeset:nn {alt}
+        \int_compare:nNnTF
           {
-            \bool_lazy_and:nnTF
-              { \l__acro_first_upper_bool }
-              { \l__acro_upper_short_bool }
-              { \exp_not:N \__acro_first_upper_case:n { \exp_not:n {#2} } }
-              { \exp_not:n {#2} }
-          }
+            \__acro_strcmp:nn
+              { \str_fold_case:e { \acro_property_get:nn {##1} {sort} } }
+              { \str_fold_case:e { \acro_property_get:nn {##2} {sort} } }
+          } = {-1}
+          { \sort_return_same: }
+          { \sort_return_swapped: }
       }
   }
-\cs_generate_variant:Nn \acro_write_alt:nn {nV,nv}
 
-% typeset a long form:
-%   TODO: rethink the formatting mechanism
-%   right now a custom format gets applied additionally to the global one
-%   although before it
-% #1: format
-% #2: long form
-\cs_new_protected:Npn \acro_write_long:nn #1#2
+% --------------------------------------------------------------------------
+% barriers:
+\int_new:N \g_acro_barrier_int
+\int_new:N \g_acro_barrier_total_int
+\bool_new:N \l__acro_barriers_bool
+\bool_new:N \l__acro_barriers_reset_bool
+\bool_new:N \l__acro_usage_local_bool
+
+\msg_new:nnn {acro} {barriers}
   {
-    \__acro_typeset:nn {long}
-      {
-        \exp_not:n {#1}
-        {
-          \bool_if:NTF \l__acro_first_upper_bool
-            { \exp_not:N \__acro_first_upper_case:n { \exp_not:n {#2} } }
-            { \exp_not:n {#2} }
-        }
-      }
+    You~ seem~ to~ be~ using~ barriers~ but~ haven't~ set~ `barriers/use~ =~
+    true',~ yet!
   }
-\cs_generate_variant:Nn \acro_write_long:nn {VV,Vo,Vf,V,v,vv}
 
-\prg_new_conditional:Npnn \acro_if_foreign:n #1 {T,F,TF}
+\__acro_auxlist_field_new:cpn {total-barriers} #1
+  { \int_gset:Nn \g_acro_barrier_total_int {#1} }
+
+\acro_at_begin_document:n
+  { \int_gset:Nn \g_acro_barrier_int {1} }
+
+\acro_at_end_document:n
   {
-    \bool_lazy_and:nnTF
-      { \l__acro_foreign_bool }
-      { \prop_if_in_p:Nn \l__acro_foreign_prop {#1} }
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \acro_auxlist_to_aux:nn
+      {total-barriers}
+      { { \int_use:N \g_acro_barrier_int } }
   }
 
-\cs_new_protected:Npn \acro_foreign_language:nn #1#2 {}
-\AtBeginDocument{
-  \cs_if_exist:NTF \foreignlanguage
-    {
-      \cs_set_protected:Npn \acro_foreign_language:nn #1#2
-        {
-          \tl_if_blank:nTF {#1}
-            {#2}
-            { \foreignlanguage {#1} {#2} }
-        }
-    }
-    {
-      \cs_set_protected:Npn \acro_foreign_language:nn #1#2
-        { \use_ii:nn {#1} {#2} }
-    }
-}
-\cs_generate_variant:Nn \acro_foreign_language:nn {VV}
+\cs_new_protected:Npn \acro_barrier:
+  {
+    \int_gincr:N \g_acro_barrier_int
+    \bool_if:NT \l__acro_barriers_reset_bool
+      { \acro_reset_all: }
+    \bool_if:NF \l__acro_barriers_bool
+      { \msg_warning:nnn {acro} {barriers} }
+  }
 
-\cs_new_protected:Npn \acro_write_foreign:n #1
+% #1: id
+\cs_new_protected:Npn \acro_record_barrier:n #1
   {
-    \acro_if_foreign:nT {#1}
+    \bool_if:NT \l__acro_barriers_bool
       {
-        \acro_property_get:nnT {#1} {foreign}
+        \int_compare:nNnTF
+          { \intarray_count:c {g__acro_#1_barriers_intarray} } > 0
           {
-            \group_begin:
-              \__acro_endings:nn {#1} {foreign}
-              \tl_use:N \l__acro_foreign_format_tl
+            \intarray_gset:cnn {g__acro_#1_barriers_intarray}
+              { \int_use:N \g_acro_barrier_int }
               {
-                \acro_foreign_language:VV
-                  \l__acro_foreign_lang_tl
-                  \l__acro_foreign_tl
+                \intarray_item:cn {g__acro_#1_barriers_intarray}
+                  { \int_use:N \g_acro_barrier_int }
+                +1
               }
-            \group_end:
           }
+          { \acro_rerun:n {barriers} }
       }
   }
 
-\cs_new:Npn \acroenparen #1 { (#1) }
-
-\cs_new_protected:Npn \acro_get_foreign:n #1
+% #1: id
+\cs_new:Npn \acro_barrier_usage:n #1
   {
-    \acro_property_get:nnT {#1} {foreign}
+    \clist_if_empty:eTF { \acro_property_get:nn {#1} {barriers} }
+      {0}
       {
-        \tl_use:N \l__acro_foreign_sep_tl
-        \group_begin:
-          \tl_use:N \l__acro_foreign_list_format_tl
-          {
-            \acro_foreign_language:VV
-              \l__acro_foreign_lang_tl
-              \l__acro_foreign_tl
-          }
-        \group_end:
+        \clist_item:en
+          { \acro_property_get:nn {#1} {barriers} }
+          { \g_acro_barrier_int }
       }
   }
 
-% --------------------------------------------------------------------------
 % #1: id
-% #2: short|alt
-\cs_set_protected:Npn \acro_write_compact:nn #1#2
+\cs_new_protected:Npn \acro_set_barriers:n #1
   {
-    \acro_get_ending_form:nn {#1} {#2}
-    \acro_acc_supp:nn
-      {#1}
+    \bool_if:NT \l__acro_barriers_bool
       {
-        \acro_write_tooltip:nnV
-          {#1}
+        \int_compare:nNnTF
+          { \intarray_count:c {g__acro_#1_barriers_intarray} } = 0
+          { \acro_rerun:n {barriers} }
           {
-            \use:c {acro_write_#2:nv} {#1} {l__acro_#2_tl}
-            \acro_endings:nn {#1} {#2}
+            \int_zero:N \l__acro_tmpa_int
+            \int_do_while:nNnn
+              \l__acro_tmpa_int < { \intarray_count:c {g__acro_#1_barriers_intarray} }
+              {
+                \int_incr:N \l__acro_tmpa_int
+                \seq_gput_right:ce {g__acro_#1_barriers_seq}
+                  {
+                    \intarray_item:cn {g__acro_#1_barriers_intarray}
+                      { \l__acro_tmpa_int }
+                  }
+              }
+            \acro_property_set:nnx {#1} {barriers}
+              { \seq_use:cn {g__acro_#1_barriers_seq} {,} }
           }
-          \l__acro_long_tl
       }
   }
 
-% TODO: get rid of argument #3?
-% #1: ID
-% #2: long|first-long|list-long|extra
-% #3: long form
-\cs_new_protected:Npn \acro_write_expanded:nnn #1#2#3
+\keys_define:nn {acro/barriers}
   {
-    \tl_set:Nn \l__acro_tmpa_tl {#2}
-    \tl_replace_all:Nnn \l__acro_tmpa_tl {-} {_}
-    \acro_write_long:vn {l__acro_ \l__acro_tmpa_tl _format_tl} {#3}
-    \acro_endings:nn {#1} {long}
-    \tl_if_in:nnT {#2} {long}
-      { \l__acro_long_post_tl }
+    use    .bool_set:N = \l__acro_barriers_bool ,
+    use    .initial:n  = false ,
+    reset  .bool_set:N = \l__acro_barriers_reset_bool ,
+    reset  .initial:n  = false ,
+    single .bool_set:N = \l__acro_usage_local_bool ,
+    single .initial:n  = false
   }
-\cs_generate_variant:Nn \acro_write_expanded:nnn {nnV}
 
-% #1: ID
-% #2: long|first-long|list-long|extra
-\cs_new_protected:Npn \acro_write_expanded:nn #1#2
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{commands}{frameworks for user commands}
+
+% --------------------------------------------------------------------------
+% case insensitivity of the ID:
+\bool_new:N \g__acro_case_sensitive_bool
+
+\cs_new:Npn \acro_case_insensitive:n #1
   {
-    \tl_set:Nn \l__acro_tmpa_tl {#2}
-    \tl_replace_all:Nnn \l__acro_tmpa_tl {-} {_}
-    \acro_write_long:vv
-      {l__acro_ \l__acro_tmpa_tl _format_tl}
-      {l__acro_ \l__acro_tmpa_tl _tl}
-    \acro_endings:nn {#1} {long}
-    \tl_if_in:nnT {#2} {long}
-      { \l__acro_long_post_tl }
+    \bool_if:NTF \g__acro_case_sensitive_bool
+      { \tl_to_str:n {#1} }
+      { \str_lowercase:n {#1} }
   }
 
+\cs_new_protected:Npn \acro_protected_case_insensitive:n #1
+  { \acro_case_insensitive:n {#1} }
+
+\cs_new:Npn \acro_case_insensitive:Nn #1#2
+  { \exp_args:Ne #1 { \acro_case_insensitive:n {#2} } }
+
+\keys_define:nn {acro}
+  {
+    case-sensitive .bool_set:N = \g__acro_case_sensitive_bool ,
+    case-sensitive .initial:n  = true ,
+  }
+
+% ----------------------------------------------------------------------------
+% typeset endings and ending forms:
+\bool_new:N \l__acro_include_endings_bool
+
 % #1: id
-\cs_new_protected:Npn \acro_after:n #1
+% #2: property
+% #3: ending
+\cs_new:Npn \__acro_get_ending:nnn #1#2#3
   {
-    \acro_cite_if:Nn \l__acro_citation_all_bool {#1}
-    \acro_index_if:Nn \l__acro_addto_index_bool {#1}
-    \acro_property_get:nnT {#1} {post}
-      { \tl_use:N \l__acro_post_tl }
+    \use:c {acro_if_#3:T}
+      { \acro_property_get:nn {#1} {#2-#3} }
   }
 
-\cs_new_protected:Npn \acro_check_single:n #1
+% #1: id
+% #2: property
+\cs_new:Npn \__acro_ending:nn #1#2
   {
-    \acro_if_is_single:nT {#1}
-      { \cs_set_eq:NN \acro_hyper_link:nn \use_ii:nn }
+    \tl_map_tokens:Nn \l__acro_endings_tl
+      { \__acro_get_ending:nnn {#1} {#2} }
   }
 
-% --------------------------------------------------------------------------
 % #1: id
-\cs_new_protected:Npn \acro_before:n #1
+% #2: property
+% #3: ending
+\cs_new:Npn \__acro_get_ending_form:nnn #1#2#3
   {
-    \acro_get:n {#1}
-    \acro_is_used:n {#1}
-    \acro_check_single:n {#1}
+    \acro_property_if_set:nnT {#1} {#2-#3-form}
+      {
+        \use:c {acro_if_#3:T}
+          {
+            \acro_property_get:nn {#1} {#2-#3-form}
+            \tl_map_break:n { \use_ii:nnn }
+          }
+      }
   }
 
-% the standard internals:
 % #1: id
-\cs_new_protected:Npn \acro_short:n #1
+% #2: property
+\cs_new:Npn \acro_ending_form:nnTF #1#2#3#4
   {
-    \acro_before:n {#1}
-    \acro_write_indefinite:nn {#1} {short}
-    \acro_write_compact:nn {#1} {short}
-    \acro_after:n {#1}
+    \tl_map_tokens:Nn \l__acro_endings_tl
+      { \__acro_get_ending_form:nnn {#1} {#2} }
+    \use_ii:nn {#3} {#4}
   }
 
-% get alternative entry:
 % #1: id
-\cs_new_protected:Npn \acro_alt:n #1
+% #2: property
+\cs_new:Npn \acro_ending_form:nnT #1#2#3
+  { \acro_ending_form:nnTF {#1} {#2} {#3} {} }
+
+% #1: id
+% #2: property
+\cs_new:Npn \acro_ending_form:nnF #1#2#3
+  { \acro_ending_form:nnTF {#1} {#2} {} {#3} }
+
+% #1: id
+% #2: property
+\cs_new:Npn \acro_ending_form:nn #1#2
+  { \acro_ending_form:nnTF {#1} {#2} {} {} }
+
+% #1: id
+% #2: property
+% #3: ending
+\cs_new:Npn \__acro_check_ending_form:nnn #1#2#3
   {
-    \acro_before:n {#1}
-    \acro_alt_error:n {#1}
-    \acro_write_indefinite:nn {#1} {alt}
-    \acro_write_compact:nn {#1} {alt}
-    \acro_after:n {#1}
+    \acro_property_if_set:nnT {#1} {#2-#3-form}
+      { \use:c {acro_if_#3:T} { \tl_map_break:n { \use_ii:nnn } } }
   }
 
-% get long entry:
 % #1: id
-\cs_new_protected:Npn \acro_long:n #1
+% #2: property
+\cs_new:Npn \acro_if_ending_form:nnTF #1#2#3#4
   {
-    \acro_before:n {#1}
-    \acro_write_indefinite:nn {#1} {long}
-    \acro_write_expanded:nn {#1} {long}
-    \acro_after:n {#1}
+    \tl_map_tokens:Nn \l__acro_endings_tl
+      { \__acro_check_ending_form:nnn {#1} {#2} }
+    \use_ii:nn {#3} {#4}
   }
 
-% get foreign entry:
 % #1: id
-\cs_new_protected:Npn \acro_foreign:n #1
+% #2: property
+\cs_new:Npn \acro_if_ending_form:nnT #1#2#3
+  { \acro_if_ending_form:nnTF {#1} {#2} {#3} {} }
+
+% #1: id
+% #2: property
+\cs_new:Npn \acro_if_ending_form:nnF #1#2#3
+  { \acro_if_ending_form:nnTF {#1} {#2} {} {#3} }
+
+% --------------------------------------------------------------------------
+% typeset acronyms:
+% #1: id
+% #2: property
+\cs_new:Npn \__acro_article:nn #1#2
   {
-    \acro_get:n {#1}
-    \tl_if_blank:VF \l__acro_foreign_tl
+    \bool_if:NT \l__acro_article_bool
       {
-        \acro_is_used:n {#1}
-        \acro_check_single:n {#1}
-        \acro_write_long:VV \l__acro_foreign_format_tl \l__acro_foreign_tl
-        \acro_after:n {#1}
+        \tl_map_tokens:Nn \g__acro_articles_tl
+          { \__acro_article:nnn {#1} {#2} }
       }
   }
 
-% get extra entry:
 % #1: id
-\cs_new_protected:Npn \acro_extra:n #1
+% #2: property
+% #3: article
+\cs_new:Npn \__acro_article:nnn #1#2#3
   {
-    \acro_get:n {#1}
-    \tl_if_blank:VF \l__acro_extra_tl
+    \bool_if:cT {l__acro_article_#3_bool}
       {
-        \acro_is_used:n {#1}
-        \acro_check_single:n {#1}
-        \acro_write_long:VV \l__acro_extra_format_tl \l__acro_extra_tl
-        \acro_after:n {#1}
+        \tl_map_break:n
+          { \acro_property_get:nn {#1} {#2-#3} \exp_stop_f: }
       }
   }
 
-% output like the first time:
 % #1: id
-\cs_new_protected:Npn \acro_first:n #1
+% #2: property
+\cs_new_protected:Npn \__acro_write:nn #1#2
   {
-    \bool_gset_true:c {g__acro_#1_first_use_bool}
-    \acro_before:n {#1}
-    \acro_first_instance:nV {#1} \l__acro_long_tl
+    \acro_property_if_exist:nTF {#2-acc}
+      {
+        \__acro_accsupp:ee
+          { \__acro_write_acronym:nn {#1} {#2-acc} }
+          { \__acro_write_acronym:nn {#1} {#2} }
+      }
+      { \__acro_write_acronym:nn {#1} {#2} }
   }
 
-% output like the first time with own long version:
 % #1: id
-% #2: instead of long entry
-\cs_new_protected:Npn \acro_first_like:nn #1#2
+% #2: property
+\cs_new:Npn \__acro_write_acronym:nn #1#2
   {
-    \bool_gset_true:c {g__acro_#1_first_use_bool}
-    \acro_before:n {#1}
-    \acro_first_instance:nn {#1} {#2}
+    \bool_lazy_and:nnTF
+      { \acro_property_if_eq_p:nn {#2} {long} }
+      { \acro_if_first_p:n {#1} }
+      { \acro_format:nnn {#1} {first-#2} }
+      { \acro_format:nnn {#1} {#2} }
+      {
+        \__acro_upper:n
+          {
+            \__acro_article:nn {#1} {#2}
+            \acro_if_ending_form:nnTF {#1} {#2}
+              { \acro_ending_form:nn {#1} {#2} }
+              { \acro_property_get:nn {#1} {#2} }
+          }
+      }
+  }
+
+% #1: id
+% #2: property
+\cs_new_protected:Npn \acro_write:nn #1#2
+  {
+    \group_begin:
+      \acro_if_short:nT {#2} { \acro_soft_upper: }
+      \__acro_make_link:nnn {#1} {#2}
+        {
+          \acro_locale:nnn {#1} {#2}
+            {
+              \__acro_write:nn {#1} {#2}
+              \bool_if:NT \l__acro_include_endings_bool
+                {
+                  \acro_if_ending_form:nnF {#1} {#2}
+                    { \__acro_ending:nn {#1} {#2} }
+                }
+            }
+        }
+    \group_end:
+    \acro_if_ending_form:nnF {#1} {#2}
+      {
+        \bool_if:NF \l__acro_include_endings_bool
+          { \__acro_ending:nn {#1} {#2} }
+      }
+    \acro_property_if_eq:nnT {#2} {long}
+      { \acro_property_get:nn {#1} {long-post} }
+    \bool_set_false:N \l__acro_upper_bool
+    \bool_set_false:N \l__acro_article_bool
+  }
+\cs_generate_variant:Nn \acro_write:nn {e}
+
+\keys_define:nn {acro}
+  {
+    include-endings .bool_set:N = \l__acro_include_endings_bool ,
+    include-endings .initial:n  = true
   }
 
-% ----------------------------------------------------------------------------
-% citations:
-\cs_new:Npn \__acro_citation_cmd:w { \cite }
-\cs_new:Npn \__acro_group_citation_cmd:w { \cite }
 
-% #1 pre
-% #2 post
-% #3 key
-\cs_new:Npn \__acro_cite:nnn #1#2#3
+% --------------------------------------------------------------------------
+% #1: boolean
+% #2: id
+\cs_new_protected:Npn \acro_finalize:nn #1#2
   {
-    \quark_if_no_value:nTF {#1}
-      { \__acro_citation_cmd:w {#3} }
+    \bool_if:NF \g__acro_cited_bool
+      { \acro_cite_if:nnT {#1} {#2} { \acro_cite:n {#2} } }
+    \bool_gset_false:N \g__acro_cited_bool
+    \acro_property_if_set:nnT {#1} {post}
+      { \acro_property_get:nn {#2} {post} }
+    \bool_lazy_all:nT
+      {
+        { \l__acro_label_bool }
+        { \l__acro_use_bool }
+        { !#1 }
+      }
+      {
+        \acro_if_first:nT {#2}
+          {
+            \acro_property_if_set:nnF {#2} {label}
+              {
+                \acro_property_set:nnn {#2} {label} {#2}
+                \label { \l_acro_label_prefix_tl #2 }
+              }
+          }
+      }
+    \bool_lazy_and:nnT
+      { \l__acro_use_bool }
+      { !#1 }
       {
-        \quark_if_no_value:nTF {#2}
-          { \__acro_citation_cmd:w [#1] {#3} }
-          { \__acro_citation_cmd:w [#1] [#2] {#3} }
+        \acro_use:n {#2}
+        \acro_record_page:n {#2}
+        \acro_record_barrier:n {#2}
+        \acro_index:n {#2}
       }
   }
-\cs_generate_variant:Nn \__acro_cite:nnn {VVV}
+\cs_generate_variant:Nn \acro_finalize:nn {ne}
 
-\cs_new_protected:Npn \acro_cite:n #1
+% --------------------------------------------------------------------------
+% define acronym typesetting commands:
+\bool_new:N \l__acro_star_bool
+\tl_new:N \l__acro_options_tl
+
+\cs_new:Npn \__acro_remove_bs:N #1
+  { \exp_after:wN \use_none:n \token_to_str:N #1 }
+
+\tl_new:N \l__acro_begin_command_hook_tl
+\tl_new:N \l__acro_end_command_hook_tl
+
+% #1: csname
+% #2: xparse csname
+% #3: action
+\cs_set_protected:Npn \acro_new_definition_command:NNn #1#2#3
   {
-    \acro_property_get:nnT {#1} {before-citation}
-      { \acro_no_break: \l__acro_before_citation_tl  }
-    \prop_get:NnNT \l__acro_citation_prop {#1} \l__acro_tmpa_tl
+    % internal command for \NewAcroCommand
+    % ##1: csname
+    % ##2: arg spec
+    % ##3: code with arg numbers n=n+2
+    \cs_new_protected:cpn {acro_command_#3:Nnn} ##1##2##3
       {
-        \prop_get:NnN \l__acro_citation_pre_prop {#1} \l__acro_tmpb_tl
-        \prop_get:NnN \l__acro_citation_post_prop {#1} \l__acro_tmpc_tl
-        \acro_no_break:
-        \tl_use:N \l__acro_citation_connect_tl
-        \__acro_cite:VVV
-          \l__acro_tmpb_tl
-          \l__acro_tmpc_tl
-          \l__acro_tmpa_tl
+        \exp_args:Nc \DeclareDocumentCommand
+          { base \__acro_remove_bs:N ##1  } {##2}
+          {
+            \acro_begin:
+              \l__acro_begin_command_hook_tl
+              \cs_set:Npn \nospace { \exp:w \exp_end_continue_f:w }
+              \acro_check_definition:n {####1}
+              \bool_set_true:N \l__acro_use_bool
+              \keys_set:nV {acro} \l__acro_options_tl
+              \tl_set:Ne \AcronymID { \acro_case_insensitive:n {####1} }
+              \tl_set:Ne \l_acro_id_tl { \acro_case_insensitive:n {####1} }
+              ##3
+              \acro_finalize:ne
+                { \l__acro_star_bool }
+                { \acro_case_insensitive:n {####1} }
+              \l__acro_end_command_hook_tl
+            \acro_end:
+          }
+        \use:x
+          {
+            \exp_not:n { #2 ##1 {so} }
+              {
+                \exp_not:n
+                  {
+                    \mode_leave_vertical:
+                    \bool_set_false:N \l__acro_star_bool
+                    \tl_clear:N \l__acro_options_tl
+                    \IfBooleanT {####1} { \bool_set_true:N \l__acro_star_bool }
+                    \IfNoValueF {####2} { \tl_set:Nn \l__acro_options_tl {####2} }
+                   }
+                \exp_not:c { base \__acro_remove_bs:N ##1 }
+              }
+          }
       }
-    \acro_property_get:nnT {#1} {after-citation}
-      { \acro_no_break: \l__acro_after_citation_tl  }
+    % define \NewAcroCommand
+    \NewDocumentCommand #1 {mm+m}
+      { \use:c {acro_command_#3:Nnn} ##1 {##2} {##3} }
+  }
+
+\acro_new_definition_command:NNn
+  \NewAcroCommand
+  \NewDocumentCommand
+  {new}
+
+\acro_new_definition_command:NNn
+  \RenewAcroCommand
+  \RenewDocumentCommand
+  {renew}
+
+\acro_new_definition_command:NNn
+  \DeclareAcroCommand
+  \DeclareDocumentCommand
+  {declare}
+
+\acro_new_definition_command:NNn
+  \ProvideAcroCommand
+  \ProvideDocumentCommand
+  {provide}
+
+\keys_define:nn {acro/commands}
+  {
+    begin .code:n =
+      \tl_put_right:Nn \l__acro_begin_command_hook_tl {#1} ,
+    end   .code:n =
+      \tl_put_right:Nn \l__acro_end_command_hook_tl {#1} ,
+    clear .choice: ,
+    clear / begin .code:n =
+      \tl_clear:N \l__acro_begin_command_hook_tl ,
+    clear / end   .code:n =
+      \tl_clear:N \l__acro_end_command_hook_tl ,
+    clear / all   .code:n =
+      \tl_clear:N \l__acro_begin_command_hook_tl
+      \tl_clear:N \l__acro_end_command_hook_tl
   }
 
-\cs_new_protected:Npn \acro_group_cite:n #1
+% --------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{templates}{templates for typesetting exercises}
+
+\msg_new:nnn {acro} {unknown-template}
   {
-    \group_begin:
-      \cs_set_eq:NN \__acro_citation_cmd:w \__acro_group_citation_cmd:w
-      \tl_set_eq:NN
-        \l__acro_citation_connect_tl
-        \l__acro_between_group_connect_citation_tl
-      \acro_cite_if:Nn \l__acro_citation_first_bool {#1}
-    \group_end:
+    The~ template~ `#1'~ (template~ type~ `#2')~ \msg_line_context: \
+    does~ not~ seem~ to~ be~ defined.
   }
 
-\cs_new_protected:Npn \acro_cite_if:Nn #1#2
-  { \bool_if:NT #1 { \acro_cite:n {#2} } }
+\msg_new:nnn {acro} {template-type-exists}
+  { The~ template~ type~ `#1'~ already~ exists~ \msg_line_context: }
+
+\msg_new:nnn {acro} {package-needed}
+  {
+    The~ template~ `#1'~ needs~ the~ package~ `#2'~ loaded~
+    \msg_line_context:
+  }
 
 % ----------------------------------------------------------------------------
-% indexing:
-\cs_new_protected:Npn \acro_index_if:Nn #1#2
+\seq_new:N \l__acro_template_types_seq
+
+% #1: template type
+\cs_new_protected:Npn \acro_template_type_new:n #1
   {
-    \bool_lazy_and:nnT {#1} { \l__acro_mark_as_used_bool }
+    \seq_if_in:NnTF \l__acro_template_types_seq {#1}
+      { \msg_error:nnn {acro} {template-type-exists} {#1} }
       {
-        \prop_get:NnN \l__acro_index_cmd_prop  {#2} \l__acro_tmpa_tl
-        \prop_get:NnN \l__acro_index_sort_prop {#2} \l__acro_tmpb_tl
-        \prop_get:NnN \l__acro_index_prop      {#2} \l__acro_tmpc_tl
-        \__acro_index:VnVV
-          \l__acro_tmpa_tl
-          {#2}
-          \l__acro_tmpb_tl
-          \l__acro_tmpc_tl
+        \seq_put_right:Nn \l__acro_template_types_seq {#1}
+        \acro_attribute_new:n {template::#1}
       }
   }
 
-\cs_new:Npn \__acro_index_cmd:n { \index }
+% #1: template type
+% #2: template name
+% #3: code
+\cs_new_protected:Npn \__acro_template_add:nnn #1#2#3
+  {
+    \tl_new:c {l__acro_template_#1_#2_setup_tl}
+    \acro_attribute_set:nnn {template::#1} {#2} {#3}
+  }
+
+% #1: template type
+% #2: template name
+% #3: code
+\cs_new_protected:Npn \__acro_template_change:nnn #1#2#3
+  {
+    \acro_template_if_exist:nnTF {#1} {#2}
+      { \acro_attribute_set:nnn {template::#1} {#2} {#3} }
+      { \msg_error:nnnn {acro} {unknown-template} {#2} {#1} }
+  }
 
-% #1: cmd
-% #2: key
-% #3: sort
-% #4: replace
-\cs_new_protected:Npn \__acro_index:nnnn #1#2#3#4
+% #1: template type
+% #2: template name
+\prg_new_conditional:Npnn \acro_template_if_exist:nn #1#2 {T,F,TF}
   {
-    \prop_get:NnNF \l__acro_short_prop  {#2} \l__acro_index_short_tl {}
-    \prop_get:NnNF \l__acro_format_prop {#2} \l__acro_index_format_tl {}
-    \quark_if_no_value:VTF \l__acro_index_format_tl
-      { \tl_set:Nn \l__acro_tmpa_tl { \l__acro_short_format_tl \l__acro_index_short_tl } }
-      { \tl_set:Nn \l__acro_tmpa_tl { \l__acro_index_format_tl \l__acro_index_short_tl } }
-    \quark_if_no_value:nF {#1}
-      { \cs_set:Npn \__acro_index_cmd:n {#1} }
-    \quark_if_no_value:nTF {#4}
+    \acro_attribute_if_set:nnTF {template::#1} {#2}
+      { \prg_return_true: }
+      { \prg_return_false: }
+  }
+
+% #1: parameter number
+% #2: template type
+% #3: template name
+\cs_new_protected:Npn \__acro_template_get:nnn #1#2#3
+  {
+    \use:x
       {
-        \quark_if_no_value:nTF {#3}
-          { \__acro_index_cmd:n { #2 @ { \l__acro_tmpa_tl } } }
-          { \__acro_index_cmd:n { #3 @ { \l__acro_tmpa_tl } } }
+         \cs_set:cn { __acro_tmp: \prg_replicate:nn {#1} {n} }
+          { \acro_attribute_get:nn {template::#2} {#3} }
       }
-      { \__acro_index_cmd:n {#4} }
+    \use:c { __acro_tmp: \prg_replicate:nn {#1} {n} }
   }
-\cs_generate_variant:Nn \__acro_index:nnnn {VnVV}
 
-% ----------------------------------------------------------------------------
-% accessability support
-\cs_new_eq:NN \acro_acc_supp:nn \use_ii:nn
+% using templates:
+% setup up the next usage of `template name':
+% #1: template type
+% #2: template name
+% #3: setup code
+\cs_new_protected:Npn \acro_template_setup:nnn #1#2#3
+  { \tl_set:cn {l__acro_template_#1_#2_setup_tl} {#3} }
+\cs_generate_variant:Nn \acro_template_setup:nnn {nnV,nVn}
+
+% #1: template type
+% #2: template name
+\cs_new_protected:Npn \__acro_template_setup:nn #1#2
+  { \tl_use:c {l__acro_template_#1_#2_setup_tl} }
+
+% #1: template type
+% #2: template name
+\cs_new_protected:Npn \__acro_clear_template_setup:nn #1#2
+  { \tl_clear:c {l__acro_template_#1_#2_setup_tl} }
+
+% #1: template type
+% #2: template name
+\cs_new_protected:Npn \__acro_template_start:nn #1#2
+  {
+    \group_begin:
+      \__acro_template_setup:nn {#1} {#2}
+      \tl_clear_new:N \TemplateType
+      \tl_set:Nn \TemplateType {#1}
+      \tl_clear_new:N \TemplateName
+      \tl_set:Nn \TemplateName {#2}
+  }
+
+% #1: template type
+% #2: template name
+\cs_new_protected:Npn \__acro_template_stop:nn #1#2
+  { \group_end: \__acro_clear_template_setup:nn {#1} {#2} }
+
+% typesetting the first appearance of acronym: pseude template `first'
 
-\cs_new_protected:Npn \acro_get_acc_supp:nn #1#2
+% #1: parameter number
+% #2: template type
+% #3: template name
+\cs_new_protected:Npn \acro_template_use:nnn #1#2#3
   {
-    \prop_get:NnNF \l__acro_acc_supp_prop {#1} \l__acro_acc_supp_tl
-      { \prop_get:NnNF \l__acro_short_prop {#1} \l__acro_acc_supp_tl {} }
-    \acro_for_endings_do:n
+    \bool_set_false:N \l__acro_tmpa_bool
+    \bool_if:NT \l__acro_use_only_first_bool
       {
-        \bool_if:cT {l__acro_##1_bool}
+        \bool_if:NT \l__acro_use_bool
           {
-            \tl_put_right:Nv
-              \l__acro_acc_supp_tl
-              {l__acro_short_##1_tl}
+            \bool_set_true:N \l__acro_tmpa_bool
+            \bool_set_false:N \l__acro_use_bool
           }
       }
-    \acro_do_acc_supp:VVn
-      \l__acro_acc_supp_tl
-      \l__acro_acc_supp_options_tl
-      {#2}
+    \str_case:nnF {#3}
+      {
+        {first} {
+          \bool_if:NT \l__acro_tmpa_bool
+            { \bool_set_true:N \l__acro_use_bool }
+          \bool_lazy_and:nnTF
+            { !\l__acro_first_bool }
+            { \acro_if_single_p:V \l_acro_id_tl }
+            {
+              \acro_property_if_set:VnTF \l_acro_id_tl {single-style}
+                {
+                  \tl_set:Ne \l__acro_tmpa_tl
+                    { \acro_property_get:Vn \l_acro_id_tl {single-style} }
+                }
+                { \tl_set_eq:NN \l__acro_tmpa_tl \l__acro_single_tl }
+            }
+            {
+              \acro_if_first:VTF \l_acro_id_tl
+                {
+                  \acro_property_if_set:VnTF \l_acro_id_tl {first-style}
+                    {
+                      \tl_set:Ne \l__acro_tmpa_tl
+                        { \acro_property_get:Vn \l_acro_id_tl {first-style} }
+                    }
+                    { \tl_set_eq:NN \l__acro_tmpa_tl \l__acro_first_style_tl }
+                }
+                { \tl_set:Nn \l__acro_tmpa_tl {short} }
+            }
+        }
+        {single} {
+          \acro_property_if_set:VnTF \l_acro_id_tl {single-style}
+            {
+              \tl_set:Ne \l__acro_tmpa_tl
+                { \acro_property_get:Vn \l_acro_id_tl {single-style} }
+            }
+            { \tl_set_eq:NN \l__acro_tmpa_tl \l__acro_single_tl }
+        }
+      }
+      { \tl_set:Nn \l__acro_tmpa_tl {#3} }
+    \str_if_eq:VnT \l__acro_tmpa_tl {first}
+      {
+        \acro_property_if_set:VnTF \l_acro_id_tl {first-style}
+          {
+            \tl_set:Ne \l__acro_tmpa_tl
+              { \acro_property_get:Vn \l_acro_id_tl {first-style} }
+          }
+          { \tl_set_eq:NN \l__acro_tmpa_tl \l__acro_first_style_tl }
+      }
+    \__acro_template_use:nnV {#1} {#2} \l__acro_tmpa_tl
   }
+\cs_generate_variant:Nn \acro_template_use:nnn {nnV}
 
-\cs_new:Npn \acro_do_acc_supp:nnn #1#2#3
+\cs_new_protected:Npn \__acro_template_use:nnn #1#2#3
   {
-    \BeginAccSupp { ActualText = #1 , #2 }
-      #3
-    \EndAccSupp { }
+    \acro_template_if_exist:nnTF {#2} {#3}
+      { \__acro_template_get:nnn {#1} {#2} {#3} }
+      {
+        \msg_warning:nnnn {acro} {unknown-template} {#3} {#2}
+        \__acro_template_get:nnn {#1} {#2} {first}
+      }
   }
-\cs_generate_variant:Nn \acro_do_acc_supp:nnn {VV}
+\cs_generate_variant:Nn \__acro_template_use:nnn {nnx,nnV}
 
-\AtEndPreamble
+% ----------------------------------------------------------------------------
+% acronym templates:
+\acro_template_type_new:n {acronym}
+
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_acronym_template_new:nn #1#2
   {
-    \bool_if:NT \l__acro_acc_supp_bool
+    \__acro_template_add:nnn {acronym} {#1}
       {
-        \RequirePackage {accsupp}
-        \cs_set_eq:NN \acro_acc_supp:nn \acro_get_acc_supp:nn
+        \__acro_template_start:nn {acronym} {#1}
+        #2
+        \__acro_template_stop:nn {acronym} {#1}
       }
-    \bool_if:NT \l__acro_tooltip_bool
+  }
+
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_acronym_template_renew:nn #1#2
+  {
+    \__acro_template_change:nnn {acronym} {#1}
       {
-        \RequirePackage {pdfcomment}
-        \cs_if_eq:NNT \__acro_tooltip_cmd:nn \use_i:nn
-          { \cs_set:Npn \__acro_tooltip_cmd:nn { \pdftooltip } }
+        \__acro_template_start:nn {acronym} {#1}
+        #2
+        \__acro_template_stop:nn {acronym} {#1}
       }
   }
 
-% --------------------------------------------------------------------------
-% tooltips for acronyms
+% ----------------------------------------------------------------------------
+% heading templates:
+\acro_template_type_new:n {heading}
 
-% #1: id
-% #2: printed text
-% #3: tool tip text
-\cs_new_protected:Npn \acro_write_tooltip:nnn #1#2#3
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_heading_template_new:nn #1#2
   {
-    \acro_property_get:nnTF {#1} {tooltip}
-      { \__acro_check_tooltip:nV {#2} \l__acro_tooltip_tl }
-      { \__acro_check_tooltip:nn {#2} {#3} }
+    \__acro_template_add:nnn {heading} {#1}
+      {
+        \__acro_template_start:nn {heading} {#1}
+        #2
+        \__acro_template_stop:nn {heading} {#1}
+      }
   }
-\cs_generate_variant:Nn \acro_write_tooltip:nnn {nnV}
 
-% #1: printed text
-% #2: tool tip text
-\cs_new_protected:Npn \__acro_check_tooltip:nn #1#2
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_heading_template_renew:nn #1#2
   {
-    \bool_if:NTF \l__acro_tooltip_inside_bool
-      {#1}
+    \__acro_template_change:nnn {heading} {#1}
       {
-        \bool_set_true:N \l__acro_tooltip_inside_bool
-        \__acro_tooltip_cmd:nn {#1} {#2}
+        \__acro_template_start:nn {heading} {#1}
+        #2
+        \__acro_template_stop:nn {heading} {#1}
       }
   }
-\cs_generate_variant:Nn \__acro_check_tooltip:nn { nV }
 
-% use whatever command you like for creating tooltips here:
-% #1: printed text
-% #2: tool tip text
-\cs_new_eq:NN \__acro_tooltip_cmd:nn \use_i:nn
-  
-% --------------------------------------------------------------------------
-% indefinite articles:
+% ----------------------------------------------------------------------------
+% list templates:
+\acro_template_type_new:n {list}
 
-% #1: ID
-% #2: short|long|alt
-\cs_new_protected:Npn \acro_write_indefinite:nn #1#2
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_list_template_new:nn #1#2
   {
-    \bool_if:NT \l__acro_indefinite_bool
-      { \prop_item:cn {l__acro_#2_indefinite_prop} {#1} ~ }
-    \bool_if:NT \l__acro_upper_indefinite_bool
-      { %  \bool_set_true:N \l__acro_first_upper_bool
-         \__acro_first_upper_case:x
-           { \prop_item:cn {l__acro_#2_indefinite_prop} {#1} } ~
+    \__acro_template_add:nnn {list} {#1}
+      {
+        \__acro_template_start:nn {list} {#1}
+        \tl_clear_new:N \AcronymTable
+        #2
+        \__acro_template_stop:nn {list} {#1}
       }
   }
 
-% --------------------------------------------------------------------------
-% experimental sorting feature:
-
-% the following code is an adaption of expl3 code used for \str_if_eq:NN(TF)
-\sys_if_engine_luatex:TF
+% #1: template name
+% #2: code
+\cs_new_protected:Npn \acro_list_template_renew:nn #1#2
   {
-    \tl_set:Nn \l__acro_tmpa_tl
+    \__acro_template_change:nnn {list} {#1}
       {
-        acro ~ = ~ acro ~ or ~ { ~ } ~
-        function ~ acro.strcmp ~ (A, B) ~
-          if ~ A ~ == ~ B ~ then ~
-            tex.write ("0") ~
-          elseif ~ A ~ < ~ B ~ then ~
-            tex.write ("-1") ~
-          else ~
-            tex.write ("1") ~
-          end ~
-        end
+        \__acro_template_start:nn {list} {#1}
+        \tl_clear_new:N \AcronymTable
+        #2
+        \__acro_template_stop:nn {list} {#1}
       }
-    \lua_now:e { \l__acro_tmpa_tl }
-    \cs_new_protected:Npn \acro_strcmp:nn #1#2
+  }
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{list}{the list of acronyms}
+% --------------------------------------------------------------------------
+% list of acronyms:
+\bool_new:N \l__acro_list_display_all_bool
+\bool_new:N \l__acro_list_bool
+\bool_new:N \l__acro_list_local_bool
+
+\seq_new:N \g__acro_list_seq
+
+\tl_new:N \l__acro_list_tl
+
+\clist_new:N \l__acro_tag_include_clist
+\clist_new:N \l__acro_tag_exclude_clist
+
+\cs_new_protected:Npn \acro_list_choose_set:
+  {
+    \bool_if:NTF \l__acro_list_display_all_bool
+      { \seq_gset_eq:NN \g__acro_list_seq \g__acro_acronyms_seq }
       {
-        \lua_now:e
+        \seq_gclear:N \g__acro_list_seq
+        \seq_map_inline:Nn \g__acro_acronyms_seq
           {
-            acro.strcmp
-              (
-                " \__acro_escape_x:n {#1} " ,
-                " \__acro_escape_x:n {#2} "
-              )
+            \acro_if_single:nF {##1}
+              { \seq_gput_right:Nn \g__acro_list_seq {##1} }
           }
       }
-    \cs_new:Npn \__acro_escape_x:n #1
+  }
+
+% --------------------------------------------------------------------------
+% #1: filtered sequence
+% #2: sequence
+\cs_new_protected:Npn \__acro_list_filter:NN #1#2
+  {
+    \seq_clear:N #2
+    \seq_clear:N \l__acro_tmpc_seq
+    \bool_if:NF \l__acro_list_local_bool
+      { \bool_set_true:N \l__acro_tmpb_bool }
+    \seq_map_inline:Nn #1
       {
-        \lua_escape:e
-          { \__kernel_tl_to_str:w \use:e { {#1} } }
+        \__acro_check_tags:Nn \l__acro_tmpa_bool {##1}
+        \bool_lazy_and:nnT
+          { \l__acro_list_local_bool }
+          {
+            \int_compare_p:nNn
+            { \intarray_count:c {g__acro_##1_barriers_intarray} } > 0
+          }
+          {
+            \bool_set_false:N \l__acro_tmpb_bool
+            \int_compare:nNnT
+              { \acro_barrier_usage:n {##1} } > 0
+              { \bool_set_true:N \l__acro_tmpb_bool }
+          }
+        \bool_lazy_and:nnT { \l__acro_tmpa_bool } { \l__acro_tmpb_bool }
+          { \seq_put_right:Nn #2 {##1} }
       }
   }
-  { \cs_new_eq:NN \acro_strcmp:nn \tex_strcmp:D }
 
-\AtBeginDocument
-  {
-    \bool_if:NT \l__acro_sort_bool
-      {
-        \cs_new_protected:Npn \acro_sort_prop:NN #1#2
+% #1: boolean
+% #2: id
+\cs_new_protected:Npn \__acro_check_tags:Nn #1#2
+  {
+    \bool_set_false:N #1
+    % get tags for acronym:
+    \clist_set:Ne \l__acro_tmpa_clist
+      { \acro_property_get:nn {#2} {tag} }
+    \clist_if_empty:NTF \l__acro_tmpa_clist
+      {% acronym does not have (a) tag(s)
+        \clist_if_empty:NT \l__acro_tag_include_clist
+          { \bool_set_true:N #1 }
+      }
+      {% acronym has (a) tag(s)
+        \clist_if_empty:NTF \l__acro_tag_include_clist
+          { \bool_set_true:N #1 }
           {
-            \seq_clear:N  \l__acro_tmpa_seq
-            \prop_clear:N \l__acro_tmpa_prop
-            \prop_clear:N \l__acro_tmpb_prop
-            \prop_map_inline:Nn #2
-              {
-                \seq_put_right:Nn \l__acro_tmpa_seq {##2}
-                \prop_put:Nnn \l__acro_tmpa_prop {##1} {##2}
-              }
-            \seq_sort:Nn \l__acro_tmpa_seq
+            \clist_map_inline:Nn \l__acro_tmpa_clist
               {
-                \int_compare:nTF
-                  {
-                    \acro_strcmp:nn
-                      { \str_fold_case:n {##1} }
-                      { \str_fold_case:n {##2} }
-                        = -1
+                \clist_if_in:NnT \l__acro_tag_include_clist {##1}
+                  {% acronym is included
+                    \bool_set_true:N #1
+                    \clist_map_break:
                   }
-                  { \sort_return_same: }
-                  { \sort_return_swapped: }
               }
-            \seq_map_inline:Nn \l__acro_tmpa_seq
+          }
+        \bool_if:NT #1
+          {% we only need to check if acronym is included:
+            \clist_if_empty:NF \l__acro_tag_exclude_clist
               {
-                \prop_map_inline:Nn \l__acro_tmpa_prop
+                \clist_map_inline:Nn \l__acro_tmpa_clist
                   {
-                    \str_if_eq:nnT {##1} {####2}
-                      {
-                        \prop_get:NnN #1 {####1} \l__acro_tmpa_tl
-                        \prop_put:NnV \l__acro_tmpb_prop {####1}
-                          \l__acro_tmpa_tl
+                    \clist_if_in:NnT \l__acro_tag_exclude_clist {##1}
+                      {% acronym is excluded
+                        \bool_set_false:N #1
+                        \clist_map_break:
                       }
                   }
               }
-            \prop_set_eq:NN #1 \l__acro_tmpb_prop
           }
       }
   }
 
 % --------------------------------------------------------------------------
-% regarding list printing:
-% this command ensures that a rerun warning is given when \printacronyms
-% is set the first time. This mechanism doesn't make very much sense,
-% should be replaced by a different and more efficient one
-%
-\cs_new_protected:Npn \acro@print@list
-  { \cs_if_exist:NF \acro@printed@list { \cs_new:Npn \acro@printed@list { printed } } }
+\prg_new_protected_conditional:Npnn \acro_acronyms_map:n #1 {T,F,TF}
+  {
+    \__acro_list_filter:NN \g__acro_list_seq \l__acro_tmpa_seq
+    \seq_if_empty:NTF \l__acro_tmpa_seq
+      { \prg_return_false: }
+      {
+        \seq_map_inline:Nn \l__acro_tmpa_seq {#1}
+        \prg_return_true:
+      }
+  }
+
+\cs_new_protected:Npn \acro_list:
+  {
+    \group_begin:
+      \bool_set_true:N \l__acro_list_bool
+      \acro_list_choose_set:
+      \cs_set_eq:NN \__acro_upper_case:n \__acro_list_upper_case:n
+      \bool_if:NT \l__acro_sort_bool { \acro_list_sort: }
+      \acro_template_use:nnV {0} {list} \l__acro_list_tl
+    \group_end:
+  }
 
 % --------------------------------------------------------------------------
-% trailing tokens and what to do when present
+\tl_new:N \l__acro_heading_tl
+\tl_new:N \l__acro_preamble_tl
 
-\cs_new_protected:Npn \acro_new_trailing_token:n #1
-  { \bool_new:c {l__acro_trailing_#1_bool} }
-\cs_new_protected:Npn \acro_activate_trailing_action:n #1
-  { \bool_set_true:c {l__acro_trailing_#1_bool} }
-\cs_new_protected:Npn \acro_deactivate_trailing_action:n #1
-  { \bool_set_false:c {l__acro_trailing_#1_bool} }
+\cs_new_protected:Npn \acro_heading:
+  { \acro_template_use:nnV {0} {heading} \l__acro_heading_tl }
 
-% register a new token but don't activate its action:
-% #1: token
-% #2: name
-\cs_new_protected:Npn \acro_register_trailing_token:Nn #1#2
-  {
-    \prop_put:Nnn \l__acro_trailing_tokens_prop {#2} {#1}
-    \prop_put:Nnn \l__acro_trailing_actions_prop {#1}
-      { \acro_activate_trailing_action:n {#2} }
-    \acro_new_trailing_token:n {#2}
-  }
+\cs_new_protected:Npn \acro_preamble:
+  { \tl_use:N \l__acro_preamble_tl }
 
-\cs_new_protected:Npn \acro_for_all_trailing_tokens_do:n #1
-  { \prop_map_inline:Nn \l__acro_trailing_tokens_prop {#1} }
+\tl_new:N \l__acro_list_name_tl
 
-% activate a token:
-\cs_new_protected:Npn \acro_activate_trailing_token:n #1
+% --------------------------------------------------------------------------
+\keys_define:nn {acro/list}
   {
-    \prop_get:NnN \l__acro_trailing_tokens_prop {#1} \l__acro_tmpa_tl
-    \tl_put_right:NV \l__acro_trailing_tokens_tl \l__acro_tmpa_tl
+    template     .tl_set:N    = \l__acro_list_tl ,
+    template     .initial:n   = description ,
+    sort         .bool_set:N  = \l__acro_sort_bool ,
+    sort         .initial:n   = true ,
+    display      .choice: ,
+    display/all  .code:n      = \bool_set_true:N \l__acro_list_display_all_bool ,
+    display/used .code:n      = \bool_set_false:N \l__acro_list_display_all_bool ,
+    display      .initial:n   = used ,
+    include      .clist_set:N = \l__acro_tag_include_clist ,
+    exclude      .clist_set:N = \l__acro_tag_exclude_clist ,
+    local        .bool_set:N  = \l__acro_list_local_bool ,
+    heading      .tl_set:N  = \l__acro_heading_tl ,
+    preamble     .tl_set:N  = \l__acro_preamble_tl ,
+    preamble     .initial:n = ,
+    name         .tl_set:N  = \l__acro_list_name_tl ,
+    name         .initial:n = \acro_translate:n {list-name}
   }
 
-% deactivate a token:
-\cs_new_protected:Npn \acro_deactivate_trailing_token:n #1
+\acro_if_komascript:TF
   {
-    \prop_get:NnN \l__acro_trailing_tokens_prop {#1} \l__acro_tmpa_tl
-    \tl_remove_all:NV \l__acro_trailing_tokens_tl \l__acro_tmpa_tl
+    \cs_if_exist:NTF \chapter
+      { \keys_set:nn {acro/list}{ heading = addchap } }
+      { \keys_set:nn {acro/list}{ heading = addsec } }
   }
-
-% #1: name
-\prg_new_conditional:Npnn \acro_if_trailing_token:n #1 {p,T,F,TF}
   {
-    \bool_if:cTF {l__acro_trailing_#1_bool}
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \cs_if_exist:NTF \chapter
+      { \keys_set:nn {acro/list}{ heading = chapter* } }
+      { \keys_set:nn {acro/list}{ heading = section* } }
   }
 
-% #1: csv list of names
-\prg_new_protected_conditional:Npnn \acro_if_trailing_tokens:n #1 {T,F,TF}
+% --------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{pages}{recording and printing of pages}
+% ----------------------------------------------------------------------------
+% record page numbers:
+\RequirePackage {zref-abspage}
+
+\msg_new:nnn {acro} {label}
+  { The~ list~ template~ `#1'~ needs~ the~ option~ `labels'~ activated. }
+
+\msg_new:nnn {acro} {threshold}
+  { The~ sequentes~ threshold~ needs~ to~ be~ at~ least~ 3. }
+
+\group_begin:
+\char_set_catcode_other:N \@
+
+% #1: id
+\cs_new_protected:Npn \acro_record_page:n #1
   {
-    \bool_set_false:N \l__acro_trailing_tokens_bool
-    \clist_map_inline:nn {#1}
+    \seq_if_in:ceF {g__acro_#1_pages_seq}
+      { \arabic{abspage} @ \int_use:N \g_acro_barrier_int @ \thepage }
       {
-        \bool_if:cT {l__acro_trailing_##1_bool}
-          {
-            \bool_set_true:N \l__acro_trailing_tokens_bool
-            \clist_map_break:
-          }
+        \seq_gput_right:ce {g__acro_#1_pages_seq}
+          { \arabic{abspage} @ \int_use:N \g_acro_barrier_int @ \thepage }
       }
-    \bool_if:NTF \l__acro_trailing_tokens_bool
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \seq_gremove_duplicates:c {g__acro_#1_pages_seq}
+    \acro_at_end_document:n
+      {
+        \acro_property_set:nnx {#1} {pages}
+          { \seq_use:cn {g__acro_#1_pages_seq} {|} }
+      }
+  }
+
+\cs_new:Npn \__acro_page_name:w #1@#2@#3 \q_stop
+  {
+    \acro_package_if_loaded:nTF {hyperref}
+      { \exp_not:N \hyperpage { \exp_not:n {#3} } }
+      { \exp_not:n {#3} }
   }
 
-\cs_new_protected:Npn \aciftrailing { \acro_if_trailing_tokens:nTF }
+\cs_new:Npn \__acro_absolute_page:w  #1@#2@#3 \q_stop {#1}
 
-\cs_new_protected:Npn \__acro_check_trail:N #1
+\cs_new:Npn \__acro_barrier:w  #1@#2@#3 \q_stop {#2}
+
+\group_end:
+
+\RequirePackage {zref-totpages}
+
+\acro_at_begin_document:n
+  { \intarray_new:Nn \g__acro_pages_intarray { \ztotpages } }
+
+% #1: id
+% #2: one page
+% #3: more than one page
+\cs_new_protected:Npn \acro_print_pages:nnn #1#2#3
   {
-    \tl_map_inline:Nn \l__acro_trailing_tokens_tl
+    \acro_if_pages:nT {#1}
       {
-        \token_if_eq_meaning:NNT #1 ##1
-          { \prop_item:Nn \l__acro_trailing_actions_prop {##1} }
+        \bool_if:NTF \l__acro_pages_all_bool
+          {
+            \bool_if:NTF \l__acro_pages_name_display_bool
+              { \acro_print_page_ranges:nnn {#1} {#2} {#3} }
+              { \acro_print_page_ranges:nnn {#1} {} {} }
+          }
+          {
+            \bool_if:NT \l__acro_pages_name_display_bool {#2}
+            \pageref { \l_acro_label_prefix_tl #1 }
+          }
       }
   }
+\cs_generate_variant:Nn \acro_print_pages:nnn {e}
 
-% options for activating actions:
-\keys_define:nn {acro}
-  {
-    activate-trailing-tokens   .code:n =
-      \clist_map_inline:nn {#1} { \acro_activate_trailing_token:n {##1} } ,
-    deactivate-trailing-tokens .code:n =
-      \clist_map_inline:nn {#1} { \acro_deactivate_trailing_token:n {##1} }
-  }
-  
-% ---------------------------------------------------------------------------
-% reset outputs, they'll behave like the first time again (!not like the _only_
-% time!):
-\cs_new_protected:Npn \acro_reset:n #1
-  {
-    \bool_gset_false:c { g__acro_#1_used_bool }
-    \bool_gset_false:c { g__acro_#1_first_use_bool }
+% #1: id
+% #2: one page
+% #3: more than one page
+\cs_set_protected:Npn \acro_print_page_ranges:nnn #1#2#3
+  {
+    \seq_set_split:Nnx \l__acro_tmpa_seq {|}
+      { \acro_property_get:nn {#1} {pages} }
+    \intarray_gzero:N \g__acro_pages_intarray
+    \seq_map_inline:Nn \l__acro_tmpa_seq
+      {
+        \intarray_gset:Nnn \g__acro_pages_intarray
+          { \__acro_absolute_page:w ##1 \q_stop + 1 }
+          {
+            \bool_if:NTF \l__acro_list_local_bool
+              {
+                \int_compare:nNnTF
+                  { \__acro_barrier:w ##1 \q_stop }
+                  =
+                  \g_acro_barrier_int
+                  {1}
+                  {0}
+              }
+              {1}
+          }
+      }
+    \bool_if:NT \l__acro_list_local_bool
+      {
+        \seq_clear:N \l__acro_tmpb_seq
+        \seq_map_inline:Nn \l__acro_tmpa_seq
+          {
+            \int_compare:nNnT
+              { \__acro_barrier:w ##1 \q_stop }
+              =
+              \g_acro_barrier_int
+              { \seq_put_right:Nn \l__acro_tmpb_seq {##1} }
+          }
+        \seq_set_eq:NN \l__acro_tmpa_seq \l__acro_tmpb_seq
+      }
+    \seq_clear:N \l__acro_tmpb_seq
+    \int_zero:N \l__acro_tmpb_int
+    \seq_map_inline:Nn \l__acro_tmpa_seq
+      {
+        % the current page
+        \int_set:Nn \l__acro_tmpa_int
+          { \__acro_absolute_page:w ##1 \q_stop + 1 }
+        \int_compare:nNnTF \l__acro_tmpa_int = 1
+          { % first page, start range
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              { \__acro_page_name:w ##1 \q_stop }
+            \int_incr:N \l__acro_tmpb_int
+          }
+          { % not first page
+            \int_compare:nNnTF
+              {
+                \intarray_item:Nn \g__acro_pages_intarray
+                  { \l__acro_tmpa_int - 1 }
+              }
+              = 0
+              { % start range
+                \int_zero:N \l__acro_tmpb_int
+                \seq_put_right:Ne \l__acro_tmpb_seq
+                  { \__acro_page_name:w ##1 \q_stop }
+                \int_incr:N \l__acro_tmpb_int
+              }
+              { % continue range
+                \int_compare:nNnTF
+                  \l__acro_tmpa_int = { \intarray_count:N \g__acro_pages_intarray }
+                  { % last page, range ended
+                    \__acro_finish_range:Nnn \l__acro_tmpb_seq
+                      { \l__acro_tmpb_int }
+                      {##1}
+                    \int_zero:N \l__acro_tmpb_int
+                  }
+                  { % not last page
+                    \int_compare:nNnTF
+                      {
+                        \intarray_item:Nn \g__acro_pages_intarray
+                          { \l__acro_tmpa_int + 1 }
+                      }
+                      = 0
+                      { % range ended
+                        \__acro_finish_range:Nnn \l__acro_tmpb_seq
+                          { \l__acro_tmpb_int }
+                          {##1}
+                        \int_zero:N \l__acro_tmpb_int
+                      }
+                      {% continue range
+                        \int_incr:N \l__acro_tmpb_int
+                      }
+                  }
+              }
+          }
+      }
+    \seq_use:Nn \l__acro_tmpb_seq { \l__acro_pages_sep_tl }
   }
 
-\cs_new_protected:Npn \acro_mark_as_used:n #1
+% #1: sequence
+% #2: range length
+% #3: page property entry
+\cs_new_protected:Npn \__acro_finish_range:Nnn #1#2#3
   {
-    \bool_gset_true:c { g__acro_#1_used_bool }
-    \bool_gset_true:c { g__acro_#1_first_use_bool }
-    \bool_gset_true:c { g__acro_#1_in_list_bool }
-    \if@filesw
-      \__acro_aux_file_now:n { \acro@used@once {#1} {} {} {} }
-      \__acro_aux_file_now:n { \acro@used@twice {#1} {} {} {} }
-    \fi
+    \seq_pop_right:NN #1 \l__acro_tmpa_tl
+    \int_compare:nNnTF {#2} > 1
+      {
+        \bool_lazy_and:nnTF
+          { \l__acro_seq_use_bool }
+          { \int_compare_p:nNn {#2} < \l__acro_pages_seq_threshold_int }
+          {
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              {
+                \exp_not:V \l__acro_tmpa_tl
+                \exp_not:V \l__acro_pages_seq_pre_tl
+                \acro_translate:n {sequentes}
+              }
+          }
+          {
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              {
+                \exp_not:V \l__acro_tmpa_tl
+                --
+                \__acro_page_name:w #3 \q_stop
+              }
+          }
+      }
+      {
+        \bool_if:NTF \l__acro_seq_use_bool
+          {
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              {
+                \exp_not:V \l__acro_tmpa_tl
+                \exp_not:V \l__acro_pages_seq_pre_tl
+                \acro_translate:n {sequens}
+              }
+          }
+          {
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              { \exp_not:V \l__acro_tmpa_tl }
+            \seq_put_right:Ne \l__acro_tmpb_seq
+              {  \__acro_page_name:w #3 \q_stop }
+          }
+      }
   }
 
-\cs_new_protected:Npn \acro_reset_all:
-  { \acro_for_all_acronyms_do:n { \acro_reset:n {##1} } }
+\bool_new:N \l__acro_pages_all_bool
+\bool_new:N \l__acro_pages_display_bool
+\bool_new:N \l__acro_seq_use_bool
 
-% make sure that no acronym is used at the beginning of the document, see
-% issue #81 for reasons why this may be necessary:
-\AfterEndPreamble { \acro_reset_all: }
-  
-\cs_new_protected:Npn \acro_mark_all_as_used:
-  { \acro_for_all_acronyms_do:n { \acro_mark_as_used:n {##1} } }
-
-\prg_new_conditional:Npnn \acro_if_acronym_used:n #1 { p,T,F,TF }
+% #1: id
+\prg_new_conditional:Npnn \acro_if_pages:n #1 {p,T,F,TF}
   {
     \bool_lazy_and:nnTF
-      { \bool_if_p:c {g__acro_#1_used_bool} }
-      { !\acro_if_is_single_p:n {#1} }
+      { \l__acro_pages_display_bool }
+      {
+        \bool_lazy_and_p:nn
+          { \acro_attribute_if_set_p:nn {pages} {#1} }
+          { !\acro_if_single_p:n {#1} }
+      }
       { \prg_return_true: }
       { \prg_return_false: }
   }
+\prg_generate_conditional_variant:Nnn \acro_if_pages:n {e} {p,T,F,TF}
 
-% --------------------------------------------------------------------------
-% acronym barriers: allow local lists of only those acronyms used between two
-% barriers
-
-\keys_define:nn {acro}
+\acro_at_begin_document:n
   {
-    use-barriers      .bool_gset:N = \g__acro_use_barriers_bool ,
-    use-barriers      .initial:n   = false ,
-    reset-at-barriers .bool_gset:N = \g__acro_reset_at_barrier_bool ,
-    reset-at-barriers .initial:n   = false
+    \bool_lazy_and:nnT
+      { \l__acro_pages_display_bool }
+      { !\l__acro_pages_all_bool }
+      { \bool_set_true:N \l__acro_label_bool }
+  }
+
+% #1: style name
+\cs_new_protected:Npn \acro_no_page_ranges:n #1
+  {
+    \bool_if:NF \l__acro_label_bool
+      { \msg_warning:nnn {acro} {label} {#1} }
+    \bool_set_false:N \l__acro_pages_all_bool
+  }
+\cs_generate_variant:Nn \acro_no_page_ranges:n {e}
+
+\tl_new:N \l__acro_pages_fill_tl
+\tl_new:N \l__acro_pages_sep_tl
+\tl_new:N \l__acro_pages_seq_pre_tl
+
+\int_new:N \l__acro_pages_seq_threshold_int
+
+\keys_define:nn {acro/pages}
+  {
+    display .choice: ,
+    display / all   .code:n =
+     \bool_set_true:N \l__acro_pages_display_bool
+     \bool_set_true:N \l__acro_pages_all_bool ,
+    display / first .code:n =
+      \bool_set_true:N \l__acro_pages_display_bool
+      \bool_set_false:N \l__acro_pages_all_bool ,
+    display / none  .code:n =
+      \bool_set_false:N \l__acro_pages_display_bool ,
+    seq / use       .bool_set:N = \l__acro_seq_use_bool ,
+    seq / use       .initial:n  = true ,
+    seq / pre       .tl_set:N   = \l__acro_pages_seq_pre_tl ,
+    seq / pre       .initial:n  = \, ,
+    seq / threshold .code:n     =
+      \int_compare:nNnTF {#1} < 3
+        { \msg_error:nn {acro} {threshold} }
+        { \int_set:Nn \l__acro_pages_seq_threshold_int {#1} } ,
+    seq / threshold .initial:n = 3 ,
+    fill            .tl_set:N   = \l__acro_pages_fill_tl ,
+    fill            .initial:n  = \dotfill ,
+    sep             .tl_set:N   = \l__acro_pages_sep_tl ,
+    sep             .initial:n  = {,~} ,
+    name            .bool_set:N = \l__acro_pages_name_display_bool ,
+    name            .initial:n  = false
   }
 
-\cs_new_protected:Npn \acro_barrier:
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{locale}{language support}
+
+\RequirePackage{translations}
+
+% --------------------------------------------------------------------------
+\msg_new:nnn {acro} {language-not-defined}
   {
-    \int_gincr:N \g__acro_barrier_int
-    \bool_if:NT \g__acro_reset_at_barrier_bool
-      { \acro_reset_all: }
+    You~ chose~ the~ language~ `#1'~ which~ is~ not~ defined~ by~ acro.~
+    `english'~ is~ used~ instead.~ If~ you~ just~ mistyped~ try~ again!~
+    Otherwise~ contact~ the~ author~ and~ he'll~ probably~ add~ your~ language.
   }
 
-\cs_new_protected:Npn \acro_check_barriers:n #1
+\msg_new:nnn {acro} {translation-value}
+  { You~ need~ to~ give~ a~ value~ to~ `#1'~ \msg_line_context: }
+
+% --------------------------------------------------------------------------
+\bool_new:N \l__acro_show_locale_bool
+\bool_new:N \l__acro_list_show_locale_bool
+\tl_new:N \l__acro_locale_format_tl
+
+% #1: id
+% #2: property
+\prg_new_conditional:Npnn \acro_if_locale:nn #1#2 {p,T,F,TF}
   {
-    \bool_if:NT \g__acro_use_barriers_bool
+    \str_if_eq:nnTF {#2} {foreign}
       {
-        \tl_set:Nx \l__acro_tmpa_tl
-          { \seq_use:cn {g__acro_#1_barriers_seq} {} }
-        \tl_set:Nx \l__acro_tmpb_tl
-          { \seq_use:cn {g__acro_#1_recorded_barriers_seq} {} }
-        \tl_if_eq:NNF \l__acro_tmpa_tl \l__acro_tmpb_tl
-          {
-            \@latex@warning@no@line
-              {Rerun~to~get~barriers~of~acronym~#1~right}
-          }
+        \bool_lazy_or:nnTF
+          { \acro_property_if_set_p:nn {#1} {foreign-babel} }
+          { \acro_property_if_set_p:nn {#1} {foreign-locale} }
+          { \prg_return_true: }
+          { \prg_return_false: }
       }
+      { \prg_return_false: }
   }
 
-\cs_new_protected:Npn \acro_record_barrier:n #1
+% #1: id
+% #2: property
+% #3: text
+\cs_new_protected:Npn \acro_locale:nnn #1#2#3
   {
-    \bool_if:NT \g__acro_use_barriers_bool
+    \acro_if_locale:nnTF {#1} {#2}
       {
-        \seq_if_in:cxF {g__acro_#1_barriers_seq}
-          { \int_use:N \g__acro_barrier_int }
+        \__acro_foreign_language:en
+          { \str_lowercase:e { \acro_property_get:nn {#1} {foreign-babel} } }
           {
-            \seq_gput_right:cx  {g__acro_#1_barriers_seq}
-              { \int_use:N \g__acro_barrier_int }
+            \bool_lazy_or:nnT
+              { \l__acro_show_locale_bool }
+              {
+                \bool_lazy_and_p:nn
+                  { \l__acro_list_bool }
+                  { \l__acro_list_show_locale_bool }
+              }
+              {
+                {
+                  \l__acro_locale_format_tl
+                    {
+                      \acro_property_if_set:nnTF {#1} {foreign-locale}
+                        { \acro_property_get:nn {#1} {foreign-locale} }
+                        {
+                           \baselanguage
+                             { \acro_property_get:nn {#1} {foreign-babel} }
+                        }
+                    }
+                }
+                :~
+              }
+            #3
           }
       }
+      {#3}
   }
 
-% #1: id
-% #2: barrier number
-\prg_new_protected_conditional:Npnn \acro_if_in_barrier:nn #1#2 {T,F,TF}
+\cs_new_protected:Npn \__acro_foreign_language:nn #1#2
   {
-    \seq_if_in:cnTF {g__acro_#1_recorded_barriers_seq} {#2}
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \bool_lazy_or:nnTF
+      { \acro_package_if_loaded_p:n {babel} }
+      { \acro_package_if_loaded_p:n {polyglossia} }
+      { \foreignlanguage {#1} {#2} }
+      {#2}
+  }
+\cs_generate_variant:Nn \__acro_foreign_language:nn {e}
+
+\keys_define:nn {acro/locale}
+  {
+    display .bool_set:N = \l__acro_show_locale_bool ,
+    display .initial:n  = false ,
+    format  .tl_set:N   = \l__acro_locale_format_tl ,
+    format  .initial:n  = \em \text_titlecase_first:n
   }
-\cs_generate_variant:Nn \acro_if_in_barrier:nnTF {nx}
 
-\cs_new_protected:Npn \acro@barriers #1#2
-  { \seq_gset_split:cnn {g__acro_#1_recorded_barriers_seq} {,} {#2} }
+\keys_define:nn {acro/list/locale}
+  {
+    display .bool_set:N = \l__acro_list_show_locale_bool ,
+    display .initial:n  = false
+  }
 
 % --------------------------------------------------------------------------
-% the user commands -- preparation:
-\cs_new_protected:Npn \acro_begin:
+
+\bool_new:N      \l__acro_language_auto_bool
+\bool_set_true:N \l__acro_language_auto_bool
+% this token list will hold the chosen language for acro; since the
+% language is either chosen automatically or by option it is only available at
+% begin document
+\tl_new:N  \l_acro_language_tl
+\tl_set:Nn \l_acro_language_tl {english}
+\tl_new:N  \l__acro_current_language_tl
+
+% ----------------------------------------------------------------------------
+\tl_const:Nn \c__acro_keyword_prefix_tl {acro-keyword-}
+\prop_new:N \g_acro_translations_prop
+
+% translate the key #1
+\cs_new:Npn \acro_translate:n #1
   {
-    \group_begin:
-    \__acro_check_after_end:w
+    \bool_if:NTF \l__acro_language_auto_bool
+      { \GetTranslation { \c__acro_keyword_prefix_tl #1 } }
+      {
+        \GetTranslationFor
+          { \l_acro_language_tl }
+          { \c__acro_keyword_prefix_tl #1 }
+      }
   }
 
-\cs_new_protected:Npn \__acro_check_after_end:w #1 \acro_end:
+\acro_at_begin_document:n
   {
-    \cs_set:Npn \__acro_execute:
+    \bool_if:NTF \l__acro_language_auto_bool
       {
-        \__acro_check_trail:N \l_peek_token
-        #1
-        \acro_end: % this will end the group opened by \acro_begin:
+        \tl_set:Nx \l_acro_language_tl
+          { \@trnslt@language{\@trnslt@current@language} }
       }
-    \peek_after:Nw \__acro_execute:
+      {
+        \tl_set_eq:NN
+          \l_acro_language_tl
+          \l__acro_current_language_tl
+      }
+  }
+
+% ----------------------------------------------------------------------------
+% #1: language
+% #2: keyword
+% #3: translation
+\cs_new_protected:Npn \acro_declare_translation:nnn #1#2#3
+  {
+    \declaretranslation
+      {#1}
+      { \c__acro_keyword_prefix_tl #2 }
+      {#3}
+    \prop_gput:Nnn \g_acro_translations_prop {#2(#1)} {#3}
   }
+\cs_generate_variant:Nn \acro_declare_translation:nnn {V,VnV}
 
-\cs_new_protected:Npn \acro_end: { \group_end: }
+% #1: key
+% #2: csv list: { <lang1> = <translation1> , <lang2> = <translation2> }
+\cs_new_protected:Npn \acro_declare_translations:nn #1#2
+  {
+    \cs_set:Npn \__acro_declare_translation_aux:n ##1
+      { \msg_error:nnn {acro} {translation-value} {##1} }
+    \cs_set:Npn \__acro_declare_translation_aux:nn ##1##2
+      { \acro_declare_translation:nnn {##1} {#1} {##2} }
+    \keyval_parse:NNn
+      \__acro_declare_translation_aux:n
+      \__acro_declare_translation_aux:nn
+      {#2}
+  }
 
-\cs_new_protected:Npn \acro_reset_specials:
+% #1: language
+% #2: csv list: { <key1> = <translation1> , <key2> = <translation2> }
+\cs_new_protected:Npn \acro_add_translations:nn #1#2
   {
-    \bool_set_false:N \l__acro_indefinite_bool
-    \bool_set_false:N \l__acro_first_upper_bool
-    \bool_set_false:N \l__acro_upper_indefinite_bool
-    \acro_for_endings_do:n { \bool_set_false:c {l__acro_##1_bool} }
+    \cs_set:Npn \__acro_declare_translation_aux:n ##1
+      { \msg_error:nnn {acro} {translation-value} {##1} }
+    \cs_set:Npn \__acro_declare_translation_aux:nn ##1##2
+      { \acro_declare_translation:nnn {#1} {##1} {##2} }
+    \keyval_parse:NNn
+      \__acro_declare_translation_aux:n
+      \__acro_declare_translation_aux:nn
+      {#2}
   }
 
-% #1: ID
-% #2: true|false
-\cs_new_protected:Npn \acro_check_acronym:nn #1#2
+% within the loop:
+% #1: keyword
+% #2: language
+% #3: translation
+\cs_new_protected:Npn \__acro_for_all_translations_do:n #1
   {
-    \acro_defined:n {#1}
-    \acro_use_acronym:n {#2}
+    \cs_set:Npn \__acro_parse_translate_list_entry:nnn ##1##2##3 {#1}
+    \prop_map_inline:Nn \g_acro_translations_prop
+      { \__acro_parse_translate_list_entry:www ##1 \q_mark ##2 \q_stop }
   }
 
-% #1: boolean
-% #2: ID
-\cs_new_protected:Npn \acro_check_and_mark_if:nn #1#2
+% the purpose of the following is to easy documentation:
+\cs_new:Npn \__acro_parse_translate_list_entry:nnn #1#2#3 {}
+
+\cs_new_protected:Npn \__acro_parse_translate_list_entry:www #1(#2)\q_mark#3\q_stop
+  { \__acro_parse_translate_list_entry:nnn {#1} {#2} {#3} }
+
+% ----------------------------------------------------------------------------
+
+\keys_define:nn {acro}
   {
-    \bool_lazy_or:nnTF {#1} { !\l__acro_use_acronyms_bool }
-      { \acro_check_acronym:nn {#2} {false} }
-      { \acro_check_acronym:nn {#2} {true} }
+    language .value_required:n = true ,
+    language .code:n =
+      \str_case:nnF {#1} 
+        { {auto} { \bool_set_true:N \l__acro_language_auto_bool } }
+        {
+          \bool_set_false:N \l__acro_language_auto_bool
+          \tl_set:Nn \l__acro_current_language_tl {#1}
+        } ,
+    language .initial:n = auto
   }
 
-\cs_new_protected:Npn \acro_switch_off:
-  { \bool_set_false:N \l__acro_use_acronyms_bool }
+% --------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{pdfsupport}{support for bookmarks and accessibility}
 
-\cs_new_protected:Npn \acro_switch_on:
-  { \bool_set_true:N \l__acro_use_acronyms_bool }
+\msg_new:nnn {acro} {pdf-template-exists}
+  { The~ pdfstring~ template~ `#1'~ already~ exists~ \msg_line_context: }
+
+\msg_new:nnn {acro} {pdf-template-undefined}
+  { The~ pdfstring~ template~ `#1'~ is~ not~ defined~ \msg_line_context: }
+
+\msg_new:nnn {acro} {local-links}
+  {
+    You~ are~ using~ the~ option~ `make-links'~ in~ combination~ with~ local~
+    acronym~ lists.~ Please~ make~ sure~ to~ also~ set \\
+    \ \ \ \ barriers/single~ =~ true \\
+    for~ referencing~ only~ existing~ and~ unique~ links.
+  }
+
+% --------------------------------------------------------------------------
+% hyper linking
+\bool_new:N \l__acro_hyperref_use_bool
+
+\cs_new_eq:NN \__acro_hyper_target:nn \use_ii:nn
+\cs_new_eq:NN \__acro_hyper_link:nn   \use_ii:nn
+
+\cs_generate_variant:Nn \__acro_hyper_target:nn {e}
+\cs_generate_variant:Nn \__acro_hyper_link:nn {e}
+
+% \acro_property_declare:nnnnn
+%   { \c_false_bool } % not unique
+%   { \c_true_bool }  % boolean
+%   { \c_false_bool } % not mandatory
+%   { \c_false_bool } % dynamic
+%   {target-set}
 
-% commands for (re)defining \ac-like macros:
-\cs_new_protected:Npn \acro_define_new_acro_command:NN #1#2
+\cs_new_protected:Npn \__acro_activate_hyperref_support:
   {
-    % #1: csname
-    % #2: definition where `#1' refers to the ID
-    \cs_new_protected:Npn #1 ##1##2
+    \bool_lazy_and:nnT
+      { \acro_package_if_loaded_p:n {hyperref} }
+      { \l__acro_hyperref_use_bool }
       {
-        \cs_set:Npn \__acro_tmp:n ####1 {##2}
-        \cs_new_protected:cpx
-          {acro_ \__acro_remove_backslash:N ##1 :nnn} ####1####2####3
-          {
-            \acro_begin:
-              \acro_reset_specials:
-              \exp_not:N \tl_if_blank:nF {####2} { \keys_set:nn {acro} {####2} }
-              \acro_check_and_mark_if:nn {####1} {####3}
-              \__acro_tmp:n {####3}
-            \acro_end:
-          }
-        #2 ##1 {sO{}m}
+        \sys_if_engine_xetex:TF
           {
-            \acro_case_insensitive_command:cnnn
-              {acro_ \__acro_remove_backslash:N ##1 :nnn}
-              {####1}
-              {####2}
-              {####3}
+            \cs_set:Npn \__acro_hyper_link:nn ##1##2
+              { \hyperlink {##1} { \XeTeXLinkBox {##2} } }
           }
+          { \cs_set_eq:NN \__acro_hyper_link:nn \hyperlink }
+        \cs_set:Npn \__acro_hyper_target:nn ##1##2
+          { \raisebox {3ex} [0pt] { \hypertarget {##1} { } } ##2 }
       }
   }
-\cs_generate_variant:Nn \acro_define_new_acro_command:NN {cc}
-\cs_generate_variant:Nn \acro_check_and_mark_if:nn {nx}
 
-% commands for (re)defining \acflike-like macros:
-\cs_new_protected:Npn \acro_define_new_acro_pseudo_command:NN #1#2
+% #1: id
+% #2: property
+% #3: text
+\cs_new_protected:Npn \__acro_make_link:nnn #1#2#3
   {
-    % #1: csname
-    % #2: definition where `#1' refers to the ID and `#2' to the pseudo long form
-    \cs_new_protected:Npn #1 ##1##2
+    \acro_if_short:nTF {#2}
       {
-        \cs_set:Npn \__acro_tmp:nn ####1####2 {##2}
-        \cs_new_protected:cpx
-          {acro_ \__acro_remove_backslash:N ##1 :nnn} ####1####2####3
+        \bool_lazy_all:nTF
           {
-            \acro_begin:
-              \acro_reset_specials:
-              \acro_check_and_mark_if:nn {####1} {####3}
-              \__acro_tmp:nn {####3} {####2}
-            \acro_end:
+            { \acro_package_if_loaded_p:n {hyperref} }
+            { \l__acro_hyperref_use_bool }
+            { !\acro_if_single_p:n {#1} }
           }
-        #2 ##1 {smm}
           {
-            \acro_case_insensitive_command:cnnn
-              {acro_ \__acro_remove_backslash:N ##1 :nnn}
-              {####1}
-              {####3}
-              {####2}
+            \bool_if:NTF \l__acro_list_bool
+              {
+                \__acro_hyper_target:en
+                  {
+                    acro : #1
+                    \bool_lazy_and:nnT
+                      { \l__acro_list_local_bool }
+                      { \l__acro_usage_local_bool }
+                      { : \int_use:N \g_acro_barrier_int }
+                  }
+                  {#3}
+              }
+              {
+                \__acro_hyper_link:en
+                  {
+                    acro : #1
+                    \bool_if:NT \l__acro_usage_local_bool
+                      { : \int_use:N \g_acro_barrier_int }
+                  }
+                  { \phantom {#3} }
+                \__acro_color_link:n { \hbox_overlap_left:n {#3} }
+              }
           }
+          {#3}
       }
+      {#3}
   }
-\cs_generate_variant:Nn \acro_define_new_acro_pseudo_command:NN {cc}
 
-\clist_map_inline:nn {New,Renew,Declare,Provide}
+\acro_at_begin_document:n
   {
-    \acro_define_new_acro_command:cc
-      {#1AcroCommand}
-      {#1DocumentCommand}
-    \acro_define_new_acro_pseudo_command:cc
-      {#1PseudoAcroCommand}
-      {#1DocumentCommand}
-  }
-
-% --------------------------------------------------------------------------
-% user commands -- facilities
-\cs_new_protected:Npn \acro_first_upper:
-  {
-    \bool_if:NTF \l__acro_indefinite_bool
+    \bool_if:nT
       {
-        \bool_set_false:N \l__acro_indefinite_bool
-        \bool_set_true:N \l__acro_upper_indefinite_bool
+        \l__acro_hyperref_use_bool &&
+        \l__acro_barriers_bool &&
+        ! \l__acro_usage_local_bool
       }
-      { \bool_set_true:N \l__acro_first_upper_bool }
+      { \msg_warning:nn {acro} {local-links} }
   }
 
-\cs_new_protected:Npn \acro_indefinite:
+% #1: text
+\cs_new:Npn \__acro_color_link:n #1
   {
-    \bool_if:NTF \l__acro_first_upper_bool
+    \bool_lazy_and:nnTF
+      { \cs_if_exist_p:N \hypersetup }
       {
-        \bool_set_true:N \l__acro_upper_indefinite_bool
-        \bool_set_false:N \l__acro_first_upper_bool
+        \bool_lazy_or_p:nn
+          { \legacy_if_p:n {Hy@colorlinks} }
+          { \legacy_if_p:n {Hy@ocgcolorlinks} }
       }
-      { \bool_set_true:N \l__acro_indefinite_bool }
+      { \textcolor { \@linkcolor } {#1} }
+      {#1}
   }
 
-\cs_new_protected:Npn \acro_cite:
+\acro_at_begin_document:n
   {
-    \bool_set_true:N \l__acro_citation_all_bool
-    \bool_set_true:N \l__acro_citation_first_bool
+    \__acro_activate_hyperref_support:
+    \cs_if_exist:NF \textcolor { \cs_new_eq:NN \textcolor \use_ii:nn }
   }
 
-\cs_new_protected:Npn \acro_no_cite:
+\keys_define:nn {acro}
   {
-    \bool_set_false:N \l__acro_citation_all_bool
-    \bool_set_false:N \l__acro_citation_first_bool
+    make-links .bool_set:N = \l__acro_hyperref_use_bool ,
+    make-links .initial:n  = false
   }
 
-\cs_new_protected:Npn \acro_index:
-  { \bool_set_true:N \l__acro_addto_index_bool }
+% --------------------------------------------------------------------------
+% accessibility support
+\bool_new:N \l__acro_accsupp_bool
+\tl_new:N \l__acro_accsupp_options_tl
+\tl_new:N \l__acro_accsupp_method_tl
 
-% similar macros \acro_<ending>: are defined by \acro_provide_ending:nnn
+% #1: copied text
+% #2: printed text
+\cs_new_protected:Npn \__acro_accsupp:nn #1#2
+  {
+    \bool_if:NTF \l__acro_accsupp_bool
+      {
+        \__acro_do_accsupp:Vnn
+          \l__acro_acc_supp_options_tl
+          {#1}
+          {#2}
+      }
+      {#2}
+  }
+\cs_generate_variant:Nn \__acro_accsupp:nn {ee}
 
-% ---------------------------------------------------------------------------
-% process options:
-\ProcessKeysPackageOptions {acro}
+% #1: options
+% #2: copied text
+% #3: printed text
+\cs_new_protected:Npn \__acro_do_accsupp:nnn #1#2#3
+  {
+    \BeginAccSupp { method = \l__acro_accsupp_method_tl ,  ActualText = {#2} , #1 }
+      #3
+    \EndAccSupp { }
+  }
+\cs_generate_variant:Nn \__acro_do_accsupp:nnn {V}
 
-% ---------------------------------------------------------------------------
-% PDF bookmark support
-\cs_new:Npn \acpdfstring
-  { \acro_pdf_string_short:n }
+\acro_at_begin_document:n
+  {
+    \bool_lazy_all:nT
+      {
+        { \acro_package_if_loaded_p:n {accsupp} }
+        { \acro_package_if_loaded_p:n {hyperref} }
+        { \l__acro_use_accsupp_bool }
+      }
+      { \bool_set_true:N \l__acro_accsupp_bool }
+  }
 
-\cs_new:Npn \acpdfstringalt
-  { \acro_pdf_string_alt:n }
+\keys_define:nn {acro/accsupp}
+  {
+    use      .code:n     =
+      \str_case:nnTF {#1}
+        { {true} {} {false} {} }
+        { \use:c {bool_set_#1:N} \l__acro_use_accsupp_bool }
+        { \msg_error:nnn {kernel} {boolean-values-only} {group} } ,
+    use     .initial:n  = true ,
+    options .tl_set:N   = \l__acro_acc_supp_options_tl ,
+    options .initial:n  = ,
+    method  .tl_set:N   = \l__acro_accsupp_method_tl ,
+    method  .initial:n  = pdfstringdef
+  }
 
-\cs_new:Npn \acpdfstringlong
-  { \acro_pdf_string_long:n }
+% --------------------------------------------------------------------------
+% pdf comments a.k.a. tooltips
+\bool_new:N \l__acro_pdfcomment_use_bool
 
-\cs_new:Npn \acpdfstringfirst #1
-  { \acpdfstringlong {#1} ~ ( \acpdfstring {#1} ) }
+% #1: id
+% #2: property
+% #3: text
+\cs_new_protected:Npn \__acro_pdf_comment:nnn #1#2#3
+  {
+    \bool_lazy_all:nTF
+      {
+        { \l__acro_pdfcomment_use_bool }
+        { \acro_property_if_set_p:nn {#1} {pdfcomment} }
+        { \acro_if_short_p:n {#2} }
+      }
+      {
+        \__acro_pdf_comment_cmd:nn
+          {#3}
+          { \acro_property_get:nn {#1} {pdfcomment} }
+      }
+      {#3}
+  }
 
-% TODO: place this somewhere where endings are defined:
-\cs_new:Npn \acpdfstringlongplural
-  { \acro_pdf_string_long_plural:n }
+\keys_define:nn {acro/pdfcomments}
+  {
+    use .bool_set:N = \l__acro_pdfcomment_use_bool ,
+    use .initial:n = false ,
+    cmd .cs_set:Np = \__acro_pdf_comment_cmd:nn #1#2 ,
+    cmd .initial:n = \pdftooltip {#1} {#2}
+  }
 
+% --------------------------------------------------------------------------
+% expandable templates for use in pdfstrings
 \prg_new_conditional:Npnn \acro_if_star_gobble:n #1 {TF}
   {
     \if_meaning:w *#1
@@ -3500,625 +4251,1201 @@
     \fi:
   }
 
-\cs_new:Npn \acro_expandable_short:n #1
-  { \use:e { \prop_item:Nn \l__acro_short_prop {#1} } }
-  
-\cs_new:Npn \acro_expandable_alt:n #1
-  { \use:e { \prop_item:Nn \l__acro_alt_prop {#1} } }
+% #1: name
+% #2: code
+\cs_new_protected:Npn \acro_pdfstring_template_new:nn #1#2
+  {
+    \cs_if_exist:cTF {____acro:pdfstring:template:#1}
+      { \msg_error:nnn {acro} {pdf-template-exists} {#1} }
+      { \cs_new:cpn {____acro:pdfstring:template:#1} ##1 {#2} }
+  }
 
-\cs_new:Npn \acro_expandable_long:n #1
-  { \use:e { \prop_item:Nn \l__acro_long_prop {#1} } }
+% #1: name
+% #2: code
+\cs_new_protected:Npn \acro_pdfstring_template_set:nn #1#2
+  {
+    \cs_if_exist:cTF {____acro:pdfstring:template:#1}
+      { \cs_set:cpn {____acro:pdfstring:template:#1} ##1 {#2} }
+      { \cs_new:cpn {____acro:pdfstring:template:#1} ##1 {#2} }
+  }
 
-\cs_new:Npn \acro_expandable_long_plural:n #1
+% #1: name
+% #2: name to be let to
+\cs_new_protected:Npn \acro_pdfstring_template_let:nn #1#2
   {
-    \bool_if:cTF
-      { c_ \prop_item:Nn \l__acro_long_plural_form_prop {#1} _bool }
-      { \use:e { \prop_item:Nn \l__acro_long_plural_prop {#1} } }
+    \cs_if_exist:cTF {____acro:pdfstring:template:#2}
       {
-        \use:e {
-          \prop_item:Nn \l__acro_long_prop {#1}
-          \prop_item:Nn \l__acro_long_plural_prop {#1}
-        }
+        \cs_set_eq:cc
+          {____acro:pdfstring:template:#1}
+          {____acro:pdfstring:template:#2}
+      }
+      { \msg_error:nnn {acro} {pdf-template-undefined} {#2} }
+  }
+
+% #1: name
+% #2: id
+\cs_new:Npn \acro_pdfstring_template:nn #1#2
+  {
+     \cs_if_exist:cTF {____acro:pdfstring:template:#1}
+       { \use:c {____acro:pdfstring:template:#1} {#2} }
+       { \msg_expandable_error:nnn {acro} {pdf-template-undefined} {#1} }
+  }
+
+% #1: cs
+% #2: template
+\cs_new_protected:Npn \acro_set_pdf_cs:Nn #1#2
+  {
+    \cs_set:Npn #1 ##1
+      {
+        \acro_if_star_gobble:nTF {##1}
+          { \acro_pdfstring_template:nn {#2} }
+          { \acro_pdfstring_template:nn {#2} {##1} }
+      }
+  }
+
+% #1: id
+% #2: property
+\cs_new:Npn \__acro_pdfstring_plural:nn #1#2
+  {
+    \acro_property_get_if_set:nnF {#1} {#2-plural-form}
+      {
+        \str_if_eq:nnTF {#2} {short}
+          { \acro_property_get:nn {#1} {pdfstring} }
+          { \acro_property_get:nn {#1} {#2} }
+        \acro_property_get:nn {#1} {#2-plural}
       }
   }
 
-\cs_new:Npn \acro_pdf_string_short:n #1
+% #1: id
+% #2: property
+\cs_new:Npn \__acro_pdfstring_indefinite:nn #1#2
   {
-    \acro_if_star_gobble:nTF {#1}
-      { \acro_expandable_short:n }
-      { \acro_expandable_short:n {#1} }
+    \acro_property_get_if_set:nnT {#1} {#2-indefinite}
+      { \c_space_tl }
   }
 
-\cs_new:Npn \acro_pdf_string_alt:n #1
+% #1: text
+\cs_new:Npn \__acro_pdfstring_upper:n #1
+  { \text_titlecase_first:e {#1} }
+
+\cs_generate_variant:Nn \text_titlecase_first:n {e}
+
+% --------------------------------------------------------------------------
+% long-short
+\acro_pdfstring_template_new:nn {long-short}
   {
-    \acro_if_star_gobble:nTF {#1}
-      { \acro_expandable_alt:n }
-      { \acro_expandable_alt:n {#1} }
+    \acro_property_get:nn {#1} {long}
+    \acro_space:
+    ( \acro_property_get:nn {#1} {pdfstring} )
   }
 
-\cs_new:Npn \acro_pdf_string_long:n #1
+% indef-long-short
+\acro_pdfstring_template_new:nn {indef-long-short}
   {
-    \acro_if_star_gobble:nTF {#1}
-      { \acro_expandable_long:n }
-      { \acro_expandable_long:n {#1} }
+    \__acro_pdfstring_indefinite:nn {#1} {long}
+    \acro_property_get:nn {#1} {long}
+    \acro_space:
+    ( \acro_property_get:nn {#1} {pdfstring} )
   }
 
-% TODO: place this somewhere where endings are defined:
-\cs_new:Npn \acro_pdf_string_long_plural:n #1
+% Long-short
+\acro_pdfstring_template_new:nn {Long-short}
   {
-    \acro_if_star_gobble:nTF {#1}
-      { \acro_expandable_long_plural:n }
-      { \acro_expandable_long_plural:n {#1} }
+    \__acro_pdfstring_upper:n
+      { \acro_property_get:nn {#1} {long} }
+    \acro_space:
+    ( \acro_property_get:nn {#1} {pdfstring} )
   }
 
-\AtBeginDocument
+% Indef-long-short
+\acro_pdfstring_template_new:nn {Indef-long-short}
   {
-    \@ifpackageloaded {hyperref}
+    \__acro_pdfstring_upper:n
       {
-        \bool_set_true:N \l__acro_hyperref_loaded_bool
-        \pdfstringdefDisableCommands
-          {
-            \cs_set_eq:NN \ac   \acpdfstring
-            \cs_set_eq:NN \Ac   \acpdfstring
-            \cs_set_eq:NN \acs  \acpdfstring
-            \cs_set_eq:NN \acl  \acpdfstringlong
-            \cs_set_eq:NN \Acl  \acpdfstringlong
-            \cs_set_eq:NN \acf  \acpdfstringfirst
-            \cs_set_eq:NN \Acf  \acpdfstringfirst
-            \cs_set_eq:NN \aca  \acpdfstringalt
-            \cs_set_eq:NN \acp  \acpdfstringplural
-            \cs_set_eq:NN \Acp  \acpdfstringplural
-            \cs_set_eq:NN \acsp \acpdfstringplural
-            \cs_set_eq:NN \aclp \acpdfstringlongplural
-            \cs_set_eq:NN \Aclp \acpdfstringlongplural
-            \cs_set_eq:NN \acfp \acpdfstringplural
-            \cs_set_eq:NN \Acfp \acpdfstringplural
-            \cs_set_eq:NN \acap \acpdfstringaltplural
-          }
-        \cs_set_protected:Npn \acro_hyper_page:n #1 { \hyperpage {#1} }
-      } {}
+        \__acro_pdfstring_indefinite:nn {#1} {long}
+        \acro_property_get:nn {#1} {long}
+      }
+    \acro_space:
+    ( \acro_property_get:nn {#1} {pdfstring} )
   }
 
-% --------------------------------------------------------------------------
-% key and order checking
-\msg_new:nnn {acro} {no-id}
+% long-short-plural
+\acro_pdfstring_template_new:nn {long-short-plural}
   {
-    Something~ has~ gone~ wrong,~ you've~ probably~ forgotten~ to~ set~ the~
-    acronym~ ID.
+    \__acro_pdfstring_plural:nn {#1} {long}
+    \acro_space:
+    ( \__acro_pdfstring_plural:nn {#1} {short} )
   }
 
-\msg_new:nnn {acro} {before-short}
+% Long-short-plural
+\acro_pdfstring_template_new:nn {Long-short-plural}
   {
-    You've~ set~ the~ property~ `#2'~ before~ the~ `short'~ property~ for~
-    acronym~ `#1'~ but~ it~ needs~ to~ be~ set~ after~ it.
+    \__acro_pdfstring_upper:n
+      { \__acro_pdfstring_plural:nn {#1} {long} }
+    \acro_space:
+    ( \__acro_pdfstring_plural:nn {#1} {short} )
   }
 
-\msg_new:nnn {acro} {missing}
-  { The~ `#2'~ property~ for~ acronym~ `#1'~ is~ missing. }
+% --------------------------------------------------------------------------
+% short-long
+\acro_pdfstring_template_new:nn {short-long}
+  {
+    \acro_property_get:nn {#1} {pdfstring}
+    \acro_space:
+    ( \acro_property_get:nn {#1} {long} )
+  }
 
-\msg_new:nnn {acro} {doubled-property}
+% indef-short-long
+\acro_pdfstring_template_new:nn {indef-short-long}
   {
-    It~ seems~ to~ me~ you~ have~ used~ the~ `#2'~ property~ twice~ in~ the~
-    declaration~ of~ acronym~ `#1'.~ If~ you~ haven't~ there's~
-    something~ different~ wrong~ and~ I'm~ lost.~ You~'re~ on~ your~ own~
-    then.
+    \__acro_pdfstring_indefinite:nn {#1} {short}
+    \acro_property_get:nn {#1} {pdfstring}
+    \acro_space:
+    ( \acro_property_get:nn {#1} {long} )
   }
 
-% #1: acronym
-% #2: property
-\cs_new_protected:Npn \__acro_property_check:nn #1#2
+% Short-long
+\acro_pdfstring_template_new:nn {Short-long}
   {
-    \str_if_empty:NT \l__acro_current_id_str
-      { \acro_serious_message:n {no-id} }
-    \str_if_eq:nnF {#2} {short}
-      {
-        \acro_property_if_set:nnF {#1} {short}
-          {
-            \keys_set:nn {acro/declare-acronym} { short = {#1} }
-            \acro_harmless_message:nn {substitute-short} {#1}
-          }
-      }
-    \acro_property_mark_set:nn {#1} {#2}
+    \__acro_pdfstring_upper:n
+      { \acro_property_get:nn {#1} {pdfstring} }
+    \acro_space:
+    ( \acro_property_get:nn {#1} {long} )
   }
 
-\cs_new_protected:Npn \__acro_first_property_check:nn #1#2
+% Indef-short-long
+\acro_pdfstring_template_new:nn {Indef-short-long}
   {
-    \cs_if_exist:cTF {l__acro_#1_short_set_bool}
+    \__acro_pdfstring_upper:n
       {
-         \acro_property_if_set:nnT {#1} {short}
-           { \acro_serious_message:nnn {doubled-property} {#1} {#2} }
+        \__acro_pdfstring_indefinite:nn {#1} {short}
+        \acro_property_get:nn {#1} {pdfstring}
       }
-      { \bool_new:c {l__acro_#1_short_set_bool} }
-    \acro_property_mark_set:nn {#1} {short}
+    \acro_space:
+    ( \acro_property_get:nn {#1} {long} )
   }
 
-% #1: ID
-% #2: property
-\prg_new_conditional:Npnn \acro_property_if_set:nn #1#2 {T,F,TF}
+% short-long-plural
+\acro_pdfstring_template_new:nn {short-long-plural}
   {
-    \bool_if:cTF {l__acro_#1_#2_set_bool}
-      { \prg_return_true: }
-      { \prg_return_false: }
+    \__acro_pdfstring_plural:nn {#1} {short}
+    \acro_space:
+    ( \__acro_pdfstring_plural:nn {#1} {long} )
   }
 
-% #1: ID
-% #2: property
-\cs_new_protected:Npn \acro_property_mark_set:nn #1#2
-  { \bool_set_true:c { l__acro_#1_#2_set_bool } }  
-\cs_generate_variant:Nn \acro_property_mark_set:nn {V}
+% Short-long-plural
+\acro_pdfstring_template_new:nn {Short-long-plural}
+  {
+    \__acro_pdfstring_upper:n
+      { \__acro_pdfstring_plural:nn {#1} {short} }
+    \acro_space:
+    ( \__acro_pdfstring_plural:nn {#1} {long} )
+  }
 
 % --------------------------------------------------------------------------
-% the internal property selection functions for \DeclareAcronym:
+% short
+\acro_pdfstring_template_new:nn {short}
+  { \acro_property_get:nn {#1} {pdfstring} }
 
-\cs_new_protected:Npn \acro_for_properties_do:n
-  { \prop_map_inline:Nn \g__acro_properties_prop }
+% indef-short
+\acro_pdfstring_template_new:nn {indef-short}
+  {
+    \__acro_pdfstring_indefinite:nn {#1} {short}
+    \acro_property_get:nn {#1} {pdfstring}
+  }
 
-% #1: name in associated cs
-% #2: property name
-% #3: action
-\cs_new_protected:Npn \acro_declare_property_generic:nnn #1#2#3
+% Short
+\acro_pdfstring_template_new:nn {Short}
   {
-    \prop_clear_new:c {l__acro_#1_prop}
-    \tl_clear_new:c {l__acro_#1_tl}
-    \cs_new_protected:cpn   {__acro_declare_#1:nn} ##1##2 {#3}
-    \cs_generate_variant:cn {__acro_declare_#1:nn} {V}
-    \keys_define:nn {acro/declare-acronym}
-      {
-        #2 .code:n =
-          \use:c {__acro_declare_#1:Vn} \l__acro_current_id_str {##1}
-          \acro_property_mark_set:Vn \l__acro_current_id_str {#2}
-      }
-    \prop_gput:Nnn \g__acro_properties_prop {#2} {#1}
+    \__acro_pdfstring_upper:n
+      { \acro_property_get:nn {#1} {pdfstring} }
   }
 
-% #1: name in associated cs
-% #2: property name
-% #3: action
-\cs_new_protected:Npn \acro_declare_property:nnn #1#2#3
+% Indef-short
+\acro_pdfstring_template_new:nn {Indef-short}
   {
-    \acro_declare_property_generic:nnn {#1} {#2}
+    \__acro_pdfstring_upper:n
       {
-        \__acro_property_check:nn {##1} {#2}
-        \prop_put:cnn {l__acro_#1_prop} {##1} {##2}
-        #3
+        \__acro_pdfstring_indefinite:nn {#1} {short}
+        \acro_property_get:nn {#1} {pdfstring}
       }
   }
 
-% #1: name in associated cs
-% #2: property name
-\cs_new_protected:Npn \acro_declare_property:nn #1#2
-  { \acro_declare_property:nnn {#1} {#2} {} }
-\cs_generate_variant:Nn \acro_declare_property:nn {V}
+% short-plural
+\acro_pdfstring_template_new:nn {short-plural}
+  { \__acro_pdfstring_plural:nn {#1} {short} }
 
-\cs_new_protected:Npn \acro_declare_property_simple:n #1
+% Short-plural
+\acro_pdfstring_template_new:nn {Short-plural}
   {
-    \tl_set:Nn \l__acro_tmpa_tl {#1}
-    \tl_replace_all:Nnn \l__acro_tmpa_tl {-} {_}
-    \acro_declare_property:Vn \l__acro_tmpa_tl {#1}
+    \__acro_pdfstring_upper:n
+      { \__acro_pdfstring_plural:nn {#1} {short} }
   }
 
-% #1: new alias property
-% #2: old property
-\cs_new_protected:Npn \acro_declare_property_alias:nn #1#2
+% --------------------------------------------------------------------------
+% alt
+\acro_pdfstring_template_new:nn {alt}
   {
-    \keys_define:nn {acro/declare-acronym}
-      { #1 .meta:n = { #2 = {##1} } }
+    \acro_property_get_if_set:nnF {#1} {alt}
+      { \acro_pdfstring_template:nn {#1} {short} }
   }
 
-% --------------------------------------------------------------------------
-% declare the properties for \DeclareAcronym:
-% short:
-\acro_declare_property_generic:nnn {short} {short}
-  {
-    \__acro_first_property_check:nn {#1} {short}
-    \prop_put:Nnn \l__acro_short_prop      {#1} {#2}
-    \prop_put:Nnn \l__acro_sort_prop       {#1} {#1}
-    \prop_put:Nnn \l__acro_index_sort_prop {#1} {#1}
-    \prop_put:Nnn \l__acro_alt_prop        {#1} {#2}
-    \prop_put:Nnn \l__acro_pdfstring_short_prop {#1} {#2}
-    \prop_put:Nnn \l__acro_pdfstring_alt_prop {#1} {#2}
-    \acro_for_endings_do:n
-      {
-        \prop_put:cnv {l__acro_short_##1_prop}
-          {#1} {l__acro_default_short_##1_tl}
-        \prop_put:cnx {l__acro_pdfstring_short_##1_prop}
-          {#1} { \exp_not:n {#2} \exp_not:v {l__acro_default_short_##1_tl} }
-        \prop_put:cnn {l__acro_short_##1_form_prop} {#1} {false}
-        \prop_put:cnv {l__acro_alt_##1_prop}
-          {#1} {l__acro_default_alt_##1_tl}
-        \prop_put:cnx {l__acro_pdfstring_alt_##1_prop}
-          {#1} { \exp_not:n {#2} \exp_not:v {l__acro_default_short_##1_tl} }
-        \prop_put:cnn {l__acro_alt_##1_form_prop} {#1} {false}
-      }
-    \prop_put:NnV \l__acro_short_indefinite_prop
-      {#1} \l__acro_default_indefinite_tl
-    \prop_put:NnV \l__acro_alt_indefinite_prop
-      {#1} \l__acro_default_indefinite_tl
-  }
-
-% long:
-\acro_declare_property:nnn {long} {long}
-  {
-    \prop_put:NnV \l__acro_long_indefinite_prop
-      {#1}
-      \l__acro_default_indefinite_tl
-    \acro_for_endings_do:n
+% indef-alt
+\acro_pdfstring_template_new:nn {indef-alt}
+  {
+    \acro_property_if_set:nnTF {#1} {alt}
       {
-        \prop_put:cnn {l__acro_long_##1_form_prop} {#1} {false}
-        \acro_property_if_set:nnF {#1} {long-##1}
-          { \prop_put:cnv {l__acro_long_##1_prop} {#1} {l__acro_default_long_##1_tl} }
-        \prop_put:cnn {l__acro_foreign_##1_form_prop} {#1} {false}
-        \acro_property_if_set:nnF {#1} {foreign-##1}
-          { \prop_put:cnv {l__acro_foreign_##1_prop} {#1} {l__acro_default_foreign_##1_tl} }
+        \__acro_pdfstring_indefinite:nn {#1} {alt}
+        \acro_property_get:nn {#1} {alt}
       }
+      { \acro_pdfstring_template:nn {#1} {indef-short} }
   }
 
-\acro_declare_property_simple:n {first-style}
-
-% list:
-\acro_declare_property_simple:n {list}
-
-% defines `short-plural', `long-plural' and `long-plural-form' as well as the
-% options `plural-ending', `short-plural-ending' and `long-plural-ending':
-% \ProvideAcroEnding {plural} {s} {s}
-
-% short indefinite article:
-\acro_declare_property_simple:n {short-indefinite}
+% Alt
+\acro_pdfstring_template_new:nn {Alt}
+  {
+    \acro_property_if_set:nnTF {#1} {alt}
+      {
+        \__acro_pdfstring_upper:n
+          { \acro_property_get:nn {#1} {alt} }
+      }
+      { \acro_pdfstring_template:nn {#1} {Short} }
+  }
 
-% long indefinite article:
-\acro_declare_property_simple:n {long-indefinite}
+% Indef-alt
+\acro_pdfstring_template_new:nn {Indef-alt}
+  {
+    \acro_property_if_set:nnTF {#1} {alt}
+      {
+        \__acro_pdfstring_upper:n
+          { \__acro_pdfstring_indefinite:nn {#1} {alt} }
+        \acro_property_get:nn {#1} {alt}
+      }
+      { \acro_pdfstring_template:nn {#1} {Indef-short} }
+  }
 
-% pre long:
-\acro_declare_property_simple:n {long-pre}
+% alt-plural
+\acro_pdfstring_template_new:nn {alt-plural}
+  {
+    \acro_property_if_set:nnTF {#1} {alt}
+      { \__acro_pdfstring_plural:nn {#1} {alt} }
+      { \acro_pdfstring_template:nn {#1} {short-plural} }
+  }
 
-% post long:
-\acro_declare_property_simple:n {long-post}
+% Alt-plural
+\acro_pdfstring_template_new:nn {Alt-plural}
+  {
+    \acro_property_if_set:nnTF {#1} {alt}
+      {
+        \__acro_pdfstring_upper:n
+          { \__acro_pdfstring_plural:nn {#1} {alt} }
+      }
+      { \acro_pdfstring_template:nn {#1} {Short-plural} }
+  }
 
-% post:
-\acro_declare_property_simple:n {post}
+% --------------------------------------------------------------------------
+% long
+\acro_pdfstring_template_new:nn {long}
+  { \acro_property_get:nn {#1} {long} }
 
-% sort:
-\acro_declare_property:nnn {sort} {sort}
+% indef-long
+\acro_pdfstring_template_new:nn {indef-long}
   {
-    \acro_property_if_set:nnF {#1} {index-sort}
-      { \prop_put:Nnn \l__acro_index_sort_prop {#1} {#2} }
+    \__acro_pdfstring_indefinite:nn {#1} {long}
+    \acro_property_get:nn {#1} {long}
   }
 
-% alternative:
-\acro_declare_property:nnn {alt} {alt}
+% Long
+\acro_pdfstring_template_new:nn {Long}
   {
-    \prop_put:Nnn \l__acro_pdfstring_alt_prop {#1} {#2}
-    \prop_put:NnV \l__acro_alt_indefinite_prop
-      {#1} \l__acro_default_indefinite_tl
+    \__acro_pdfstring_upper:n
+      { \acro_property_get:nn {#1} {long} }
   }
 
-\cs_set_protected:Npn \acro_alt_error:n #1
+% Indef-long
+\acro_pdfstring_template_new:nn {Indef-long}
   {
-    \acro_property_if_set:nnF {#1} {alt} 
-      { \acro_harmless_message:nn {no-alternative} {#1} }
+    \__acro_pdfstring_upper:n
+      {
+        \__acro_pdfstring_indefinite:nn {#1} {long}
+        \acro_property_get:nn {#1} {long}
+      }
   }
 
-% alt. indefinite article:
-\acro_declare_property_simple:n {alt-indefinite}
+% long-plural
+\acro_pdfstring_template_new:nn {long-plural}
+  { \__acro_pdfstring_plural:nn {#1} {long} }
 
-% foreign:
-\acro_declare_property_simple:n {foreign}
+% Long-plural
+\acro_pdfstring_template_new:nn {Long-plural}
+  {
+    \__acro_pdfstring_upper:n
+      { \__acro_pdfstring_plural:nn {#1} {long} }
+  }
 
-% foreign-lang:
-\acro_declare_property_simple:n {foreign-lang}
+% --------------------------------------------------------------------------
+% first
+\acro_pdfstring_template_let:nn {first} {short}
 
-% format:
-\acro_declare_property_simple:n {format}
+% indef-first
+\acro_pdfstring_template_let:nn {indef-first} {indef-short}
 
-% short format:
-\acro_declare_property_alias:nn {short-format} {format}
+% First
+\acro_pdfstring_template_let:nn {First} {Short}
 
-% alt format:
-\acro_declare_property_simple:n {alt-format}
+% indef-first
+\acro_pdfstring_template_let:nn {Indef-first} {Indef-short}
 
-% long format:
-\acro_declare_property_simple:n {long-format}
+% first-plural
+\acro_pdfstring_template_let:nn {first-plural} {short-plural}
 
-% first long format:
-\acro_declare_property_simple:n {first-long-format}
+% First-plural
+\acro_pdfstring_template_let:nn {First-plural} {Short-plural}
 
-% pdfstring -- currently needs to be done `by hand':
-\cs_new_protected:Npn \__acro_declare_pdfstring:nw #1#2/#3/#4 \acro_stop:
+% --------------------------------------------------------------------------
+
+\acro_at_begin_document:n
   {
-    \__acro_property_check:nn {#1} {pdfstring}
-    \prop_put:Nnx \l__acro_pdfstring_short_prop {#1} {#2}
-    \acro_for_endings_do:n
+    \acro_package_if_loaded:nT {hyperref}
       {
-        \tl_if_blank:nTF {#4}
-          {
-            \prop_put:cnx {l__acro_pdfstring_short_##1_prop}
-              {#1} { \exp_not:n {#2} \exp_not:v {l__acro_default_short_##1_tl} }
-          }
+        \pdfstringdefDisableCommands
           {
-            \prop_put:cnn {l__acro_pdfstring_short_##1_prop}
-              {#1} {#2#3}
+            \acro_set_pdf_cs:Nn \ac {first}
+            \acro_set_pdf_cs:Nn \iac {indef-first}
+            \acro_set_pdf_cs:Nn \Ac {First}
+            \acro_set_pdf_cs:Nn \Iac {Indef-first}
+            \acro_set_pdf_cs:Nn \acs {short}
+            \acro_set_pdf_cs:Nn \iacs {indef-short}
+            \acro_set_pdf_cs:Nn \Acs {Short}
+            \acro_set_pdf_cs:Nn \Iacs {Indef-short}
+            \acro_set_pdf_cs:Nn \acl {long}
+            \acro_set_pdf_cs:Nn \iacl {indef-long}
+            \acro_set_pdf_cs:Nn \Acl {Long}
+            \acro_set_pdf_cs:Nn \Iacl {Indef-long}
+            \acro_set_pdf_cs:Nn \aca {alt}
+            \acro_set_pdf_cs:Nn \iaca {indef-alt}
+            \acro_set_pdf_cs:Nn \Aca {Alt}
+            \acro_set_pdf_cs:Nn \Iaca {Indef-alt}
+
+            \acro_set_pdf_cs:Nn \acp {first-plural}
+            \acro_set_pdf_cs:Nn \Acp {First-plural}
+            \acro_set_pdf_cs:Nn \acsp {short-plural}
+            \acro_set_pdf_cs:Nn \Acsp {Short-plural}
+            \acro_set_pdf_cs:Nn \aclp {long-plural}
+            \acro_set_pdf_cs:Nn \Aclp {Long-plural}
+            \acro_set_pdf_cs:Nn \acap {alt-plural}
+            \acro_set_pdf_cs:Nn \Acap {Alt-plural}
+            \cs_set_eq:NN \acro_format:nnn \use_iii:nnn
+            \cs_set:Npn \@ {}
           }
-      }
+        \cs_set_protected:Npn \acro_hyper_page:n #1 { \hyperpage {#1} }
+      } {}
   }
-\cs_generate_variant:Nn \__acro_declare_pdfstring:nw {V}
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+\AcroModule{definitions}{definitions of user commands}
+
+% --------------------------------------------------------------------------
+% commands for typesetting acronyms:
+\NewAcroCommand \ac {m}
+  { \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \acp {m}
+  { \acroplural \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \iac {m}
+  { \acroindefinite \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Ac {m}
+  { \acroupper \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Acp {m}
+  { \acroplural \acroupper \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Iac {m}
+  { \acroupper \acroindefinite \UseAcroTemplate {first} {#1} }
+
+\NewAcroCommand \acs {m}
+  { \UseAcroTemplate {short} {#1} }
+\NewAcroCommand \acsp {m}
+  { \acroplural \UseAcroTemplate {short} {#1} }
+\NewAcroCommand \iacs {m}
+  { \acroindefinite \UseAcroTemplate {short} {#1} }
+\NewAcroCommand \Acs {m}
+  { \acroupper \UseAcroTemplate {short} {#1} }
+\NewAcroCommand \Acsp {m}
+  { \acroplural \acroupper \UseAcroTemplate {short} {#1} }
+\NewAcroCommand \Iacs {m}
+  { \acroupper \acroindefinite \UseAcroTemplate {short} {#1} }
   
-\keys_define:nn {acro/declare-acronym}
+\NewAcroCommand \acl {m}
+  { \UseAcroTemplate {long} {#1} }
+\NewAcroCommand \aclp {m}
+  { \acroplural \UseAcroTemplate {long} {#1} }
+\NewAcroCommand \iacl {m}
+  { \acroindefinite \UseAcroTemplate {long} {#1} }
+\NewAcroCommand \Acl {m}
+  { \acroupper \UseAcroTemplate {long} {#1} }
+\NewAcroCommand \Aclp {m}
+  { \acroplural \acroupper \UseAcroTemplate {long} {#1} }
+\NewAcroCommand \Iacl {m}
+  { \acroupper \acroindefinite \UseAcroTemplate {long} {#1} }
+
+\NewAcroCommand \aca {m}
+  { \UseAcroTemplate {alt} {#1} }
+\NewAcroCommand \acap {m}
+  { \acroplural \UseAcroTemplate {alt} {#1} }
+\NewAcroCommand \iaca {m}
+  { \acroindefinite \UseAcroTemplate {alt} {#1} }
+\NewAcroCommand \Aca {m}
+  { \acroupper \UseAcroTemplate {alt} {#1} }
+\NewAcroCommand \Acap {m}
+  { \acroplural \acroupper \UseAcroTemplate {alt} {#1} }
+\NewAcroCommand \Iaca {m}
+  { \acroupper \acroindefinite \UseAcroTemplate {alt} {#1} }
+
+\NewAcroCommand \acf {m}
+  { \acrofull \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \acfp {m}
+  { \acrofull \acroplural \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \iacf {m}
+  { \acrofull \acroindefinite \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Acf {m}
+  { \acrofull \acroupper \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Acfp {m}
+  { \acrofull \acroplural \acroupper \UseAcroTemplate {first} {#1} }
+\NewAcroCommand \Iacf {m}
+  { \acrofull \acroupper \acroindefinite \UseAcroTemplate {first} {#1} }
+
+\NewAcroCommand \acshow {m}
+  { \acrodonotuse \UseAcroTemplate {show} {#1} }
+
+% --------------------------------------------------------------------------
+\DeclareAcroEnding {plural} {s} {s}
+
+\DeclareAcroArticle {indefinite} {a}
+
+\ProvideExpandableDocumentCommand \nospace {} {}
+
+% --------------------------------------------------------------------------
+% acronym templates:
+\NewAcroTemplate {long-short}
   {
-    pdfstring    .code:n =
-      \__acro_declare_pdfstring:Vw \l__acro_current_id_str #1 // \acro_stop:
+    \acroiffirstTF
+      {
+        \acrowrite {long}
+        \acspace
+          (
+            \acroifT {foreign} { \acrowrite {foreign} ,~ }
+            \acrowrite {short}
+            \acroifT {alt} { ~ \acrotranslate {or} ~ \acrowrite {alt} }
+            \acrogroupcite
+          )
+      }
+      { \acrowrite {short} }
   }
 
-\cs_new_protected:Npn \__acro_declare_pdfstring_alt:nw #1#2/#3/#4 \acro_stop:
+\NewAcroTemplate {short-long}
   {
-    \__acro_property_check:nn {#1} {pdfstring-alt}
-    \prop_put:Nnn \l__acro_pdfstring_alt_prop {#1} {#2}
-    \acro_for_endings_do:n
+    \acrowrite {short}
+    \acroiffirstT
       {
-        \tl_if_empty:nTF {#3}
-          {
-            \prop_put:cnx {l__acro_pdfstring_alt_##1_prop}
-              {#1} { \exp_not:n {#2} \exp_not:v {l__acro_default_alt_##1_tl} }
-          }
-          { \prop_put:cnn {l__acro_pdfstring_alt_##1_prop} {#1} {#2#3} }
+        \space
+          (
+            \acroifT {alt} { \acrotranslate {or} ~ \acrowrite {alt} ~ }
+            \acroifT {foreign} { \acrowrite {foreign} :~ }
+            \acrowrite {long}
+            \acrogroupcite
+          )
       }
   }
-\cs_generate_variant:Nn \__acro_declare_pdfstring_alt:nw {V}
   
-\keys_define:nn {acro/declare-acronym}
+\NewAcroTemplate {footnote}
   {
-    pdfstring-alt .code:n =
-      \__acro_declare_pdfstring_alt:Vw \l__acro_current_id_str #1 // \acro_stop:
+    \acrowrite {short}
+    \acroiffirstT
+      {
+        \acfootnote
+          {
+            \acroifT {alt} { \acrotranslate {or} ~ \acrowrite {alt} :~ }
+            \acroifT {foreign} { \acrowrite {foreign} ,~ }
+            \acrowrite {long}
+            \acrogroupcite
+          }
+      }
   }
-  
-% class:
-\acro_declare_property_simple:n {class}
 
-% extra information:
-\acro_declare_property_simple:n {extra}
+\NewAcroTemplate {long}
+  { \acrowrite {long} }
 
-% single appearances:
-\acro_declare_property_simple:n {single}
+\NewAcroTemplate {short}
+  { \acrowrite {short} }
 
-% single format:
-\acro_declare_property_simple:n {single-format}
+\NewAcroTemplate {alt}
+  {
+    \acroifTF {alt}
+      { \acrowrite {alt} }
+      { \acrowrite {short} }
+  }
 
-% acc supp:
-\acro_declare_property:nn {acc_supp} {accsupp}
+\NewAcroTemplate {show}
+  {
+    \iow_term:n {}
+    \iow_term:x
+      {
+        The~ acronym~ `\AcronymID'~ has~ the~ properties~ (without~ outer~
+        braces):
+      }
+    \iow_term:n {}
+    \AcroPropertiesMap { \acroshow {##1} }
+    \iow_term:n {}
+  }
 
-% tooltip:
-\acro_declare_property_simple:n {tooltip}
+% --------------------------------------------------------------------------
+% heading templates:
+\NewAcroTemplate[heading] {none} { }
 
-% before-citation:
-\acro_declare_property_simple:n {before-citation}
+\NewAcroTemplate[heading] {section}
+  { \section { \acrolistname } }
 
-% after-citation:
-\acro_declare_property_simple:n {after-citation}
+\NewAcroTemplate[heading] {section*}
+  { \section* { \acrolistname } }
 
-% citation -- this needs a bit more work:
-\cs_new_protected:Npn \__acro_declare_citation:nw #1#2[#3]#4[#5]#6#7 \acro_stop:
+\acro_if_komascript:T
   {
-    % no options: #1: ID, #2: property, #7 is blank
-    % 1 option:   #1: ID, #4: property, #3: option, #5: \q_no_value
-    % 2 options:  #1: ID: #6: property, #3: first option, #5: second option
-    \tl_if_blank:nTF {#7}
+    \NewAcroTemplate[heading] {addsec}
+      { \addsec { \acrolistname } }
+  }
+  
+\cs_if_exist:NT \chapter
+  {
+    \NewAcroTemplate[heading] {chapter}
+      { \chapter { \acrolistname } }
+    \NewAcroTemplate[heading] {chapter*}
+      { \chapter* { \acrolistname } }
+    \acro_if_komascript:T
       {
-        \__acro_declare_citation_aux:nnnn {#1}
-          { \q_no_value }
-          { \q_no_value }
-          {#2}
+        \NewAcroTemplate[heading] {addchap}
+        { \addchap { \acrolistname } }
       }
+  }
+
+% --------------------------------------------------------------------------
+% list templates:
+\NewAcroTemplate[list] {description}
+  {
+    \acroheading
+    \acropreamble
+    \begin {description}
+      \acronymsmapF
+        {
+          \item [ \acrowrite {short} \acroifT {alt} { / \acrowrite {alt} } ]
+            \acrowrite {list}
+            \acroifanyT {foreign,extra} {~(}
+            \acroifT {foreign}
+              {
+                \acrowrite {foreign}
+                \acroifT {extra} {,~}
+              }
+            \acroifT {extra}
+              { \acrowrite {extra} }
+            \acroifanyT {foreign,extra} {)}
+            \acropagefill
+            \acropages
+              { \acrotranslate {page} \nobreakspace }
+              { \acrotranslate {pages} \nobreakspace }
+        }
+        { \item \AcroRerun }
+    \end {description}
+  }
+
+\NewAcroTemplate[list] {tabular}
+  {
+    \AcroNeedPackage {array}
+    \acronymsmapF
       {
-        \quark_if_no_value:nTF {#5}
+        \AcroAddRow
           {
-            \__acro_declare_citation_aux:nnnx {#1}
-              { \q_no_value }
-              {#3}
-              { \tl_head:n {#4} }
+            \acrowrite {short}
+            \acroifT {alt} { / \acrowrite {alt} }
+            &
+            \acrowrite {list}
+            \acroifanyT {foreign,extra} {~(}
+            \acroifT {foreign}
+              {
+                \acrowrite {foreign}
+                \acroifT {extra} {,~}
+              }
+            \acroifT {extra}
+              { \acrowrite {extra} }
+            \acroifanyT {foreign,extra} {)}
+            \acropagefill
+            \acropages
+              { \acrotranslate {page} \nobreakspace }
+              { \acrotranslate {pages} \nobreakspace }
+            \tabularnewline
           }
-          { \__acro_declare_citation_aux:nnnn {#1} {#3} {#5} {#6} }
       }
+      { \AcroRerun }
+    \acroheading
+    \acropreamble
+    \par \noindent
+    \begin {tabular} {>{\bfseries}lp{.7\linewidth}}
+      \AcronymTable
+    \end {tabular}
   }
-\cs_generate_variant:Nn \__acro_declare_citation:nw {V}
 
-\keys_define:nn {acro/declare-acronym}
+\NewAcroTemplate[list] {longtable}
   {
-    cite .code:n =
-      \__acro_declare_citation:Vw
-        \l__acro_current_id_str #1 [\q_no_value][\q_no_value] \scan_stop: \acro_stop:
+    \AcroNeedPackage {array}
+    \AcroNeedPackage {longtable}
+    \acronymsmapF
+      {
+        \AcroAddRow
+          {
+            \acrowrite {short}
+            \acroifT {alt} { / \acrowrite {alt} }
+            &
+            \acrowrite {list}
+            \acroifanyT {foreign,extra} {~(}
+            \acroifT {foreign}
+              {
+                \acrowrite {foreign}
+                \acroifT {extra} {,~}
+              }
+            \acroifT {extra}
+              { \acrowrite {extra} }
+            \acroifanyT {foreign,extra} {)}
+            \acropagefill
+            \acropages
+              { \acrotranslate {page} \nobreakspace }
+              { \acrotranslate {pages} \nobreakspace }
+            \tabularnewline
+          }
+      }
+      { \AcroRerun }  
+    \acroheading
+    \acropreamble
+    \par \noindent
+    \begin {longtabu} {>{\bfseries}lp{.7\linewidth}}
+      \AcronymTable
+    \end {longtabu}
   }
-\prop_gput:Nnn \g__acro_properties_prop {cite} {cite}
-  
-% #1: ID
-% #2: pre
-% #3: post
-% #4: citation key
-\cs_new_protected:Npn \__acro_declare_citation_aux:nnnn #1#2#3#4
-  {
-    \__acro_property_check:nn {#1} {cite}
-    \prop_put:Nnn \l__acro_citation_prop {#1} {#4}
-    \quark_if_no_value:nF {#2}
-      { \prop_put:Nnn \l__acro_citation_pre_prop {#1} {#2} }
-    \quark_if_no_value:nF {#3}
-      { \prop_put:Nnn \l__acro_citation_post_prop {#1} {#3} }
-  }
-\cs_generate_variant:Nn \__acro_declare_citation_aux:nnnn {nnnx}
   
-% TODO:
-% add index entries, by default \index{<sort>@<short>}
-% index: overwrite default <sort>@<short> entry completely
-% index-sort: overwrite the <sort> part of <sort>@<short> entry
-
-% need to take care of custom index cmd, at least
-%  - \index{}
-%  - \index[]{}
-% question is, though, if it should be the same one for all acronyms?
-% I go for yes but would also add a `post' property that allows to add arbitrary
-% TeX code after an acronym is typeset
-
-% index:
-\acro_declare_property_simple:n {index}
-
-% index-sort:
-\acro_declare_property_simple:n {index-sort}
-
-% index-cmd:
-\acro_declare_property_simple:n {index-cmd}
+\NewAcroTemplate[list] {longtabu}
+  {
+    \AcroNeedPackage {array}
+    \AcroNeedPackage {longtable}
+    \AcroNeedPackage {tabu}
+    \acronymsmapF
+      {
+        \AcroAddRow
+          {
+            \acrowrite {short}
+            \acroifT {alt} { / \acrowrite {alt} }
+            &
+            \acrowrite {list}
+            \acroifanyT {foreign,extra} {~(}
+            \acroifT {foreign}
+              {
+                \acrowrite {foreign}
+                \acroifT {extra} {,~}
+              }
+            \acroifT {extra}
+              { \acrowrite {extra} }
+            \acroifanyT {foreign,extra} {)}
+            \acropagefill
+            \acropages
+              { \acrotranslate {page} \nobreakspace }
+              { \acrotranslate {pages} \nobreakspace }
+            \tabularnewline
+          }
+      }
+      { \AcroRerun }
+    \acroheading
+    \acropreamble
+    \par \noindent
+    \begin {longtabu} {>{\bfseries}lX[l]}
+      \AcronymTable
+    \end {longtabu}
+  }
+
+\NewAcroTemplate [list] {lof}
+  {
+    \acroheading
+    \acropreamble
+    \acronopagerange
+    \let\l@acro\l@figure
+    \acronymsmapF
+      {
+        \contentsline {acro}
+          {
+            \numberline
+              { \acrowrite {short} \acroifT {alt} { / \acrowrite {alt} } }
+              {
+                \acrowrite {list}
+                \acroifT {foreign}
+                  { \acrowrite {foreign} \acroifT {extra} {,~} }
+                \acroifT {extra} { \acrowrite {extra} }
+                \acroifanyT {foreign,extra} {)}
+              }
+          }
+          { \acropages {} {} }
+          {}
+      }
+      { \AcroRerun }
+  }
 
-% --------------------------------------------------------------------------
-% acronym macros:
-\cs_new_protected:Npn \__acro_define_acronym_macro:n #1
+\NewAcroTemplate [list] {toc}
   {
-    \bool_if:NT \l__acro_create_macros_bool
+    \acroheading
+    \acropreamble
+    \acronopagerange
+    \acronymsmapF
       {
-        \cs_if_exist:cTF {#1}
+        \contentsline { \acroifchapterTF {chapter} {section} }
+          { \acrowrite {short} \acroifT {alt} { / \acrowrite {alt} } }
+          {}{}
+        \contentsline { \acroifchapterF {sub} section }
           {
-            \bool_if:NTF \l__acro_strict_bool
-              { \cs_set:cpn {#1} { \ac {#1} \acro_xspace: } }
-              { \acro_serious_message:nn {macro} {#1} }
+            \acrowrite {list}
+            \acroifT {foreign}
+              { \acrowrite {foreign} \acroifT {extra} {,~} }
+            \acroifT {extra} { \acrowrite {extra} }
+            \acroifanyT {foreign,extra} {) }
           }
-          { \cs_new:cpn {#1} { \ac {#1} \acro_xspace: } }
+          { \acropages {} {} }
+          {}
       }
+      { \AcroRerun }
   }
 
 % --------------------------------------------------------------------------
-% internal acronym declaring function:
-\cs_new_protected:Npn \acro_declare_acronym:nn #1#2
-  { \acro_case_insensitive:Nnn \__acro_declare_acronym:nn {#1} {#2} }
+% translations:
+% list name
+\DeclareAcroTranslation {list-name}
+  {
+    Fallback   = Acronyms ,
+    English    = Acronyms ,
+    French     = Acronymes ,
+    German     = Abk\"urzungen ,
+    Italian    = Acronimi ,
+    Portuguese = Acr\'onimos ,
+    Spanish    = Siglas ,
+    Catalan    = Sigles
+  }
+
+% page name
+\DeclareAcroTranslation {page}
+  {
+    Fallback   = p\abbrdot ,
+    English    = p\abbrdot ,
+    French     = p\abbrdot ,
+    German     = S\abbrdot ,
+    Italian    = p\abbrdot ,
+    Portuguese = p\abbrdot ,
+    Spanish    = p\'ag\abbrdot ,
+    Catalan    = p\`ag\abbrdot
+  }
+
+% pages name
+\DeclareAcroTranslation {pages}
+  {
+    Fallback   = pp\abbrdot ,
+    English    = pp\abbrdot ,
+    French     = pp\abbrdot ,
+    German     = S\abbrdot ,
+    Italian    = pp\abbrdot ,
+    Portuguese = pp\abbrdot ,
+    Spanish    = p\'ags\abbrdot ,
+    Catalan    = p\`ag\abbrdot
+  }
+
+% following page
+\DeclareAcroTranslation {sequens}
+  {
+    Fallback   = f\abbrdot ,
+    English    = f\abbrdot ,
+    French     = sq\abbrdot ,
+    German     = f\abbrdot ,
+    Italian    = s\abbrdot ,
+    Portuguese = s\abbrdot ,
+    Spanish    = s\abbrdot ,
+    Catalan    = seq\abbrdot
+  }
+
+% following pages
+\DeclareAcroTranslation {sequentes}
+  {
+    Fallback   = ff\abbrdot ,
+    English    = ff\abbrdot ,
+    French     = sqq\abbrdot ,
+    German     = ff\abbrdot ,
+    Italian    = ss\abbrdot ,
+    Portuguese = ss\abbrdot ,
+    Spanish    = ss\abbrdot ,
+    Catalan    = et seq\abbrdot
+  }
+
+% also
+\DeclareAcroTranslation {also}
+  {
+    Fallback   = also ,
+    English    = also ,
+    French     = aussi ,
+    German     = auch ,
+    Italian    = anche ,
+    Portuguese = tamb\'{e}m ,
+    Spanish    = tambien ,
+    Catalan    = tamb\'{e}
+  }
+
+% or
+\DeclareAcroTranslation {or}
+  {
+    Fallback   = or ,
+    English    = or ,
+    French     = ou ,
+    German     = oder ,
+    Italian    = o ,
+    Portuguese = ou ,
+    Spanish    = o ,
+    Catalan    = o
+  }
+
+% and
+\DeclareAcroTranslation {and}
+  {
+    Fallback   = and ,
+    English    = and ,
+    French     = et ,
+    German     = und ,
+    Italian    = e ,
+    Portuguese = e ,
+    Spanish    = y ,
+    Catalan    = i
+  }
+
+% --------------------------------------------------------------------------  
+\AcroModuleEnd
+\AcroModule{upgrade}{ease upgrading from version 2}
 
-\cs_new_protected:Npn \__acro_declare_acronym:nn #1#2
+% ----------------------------------------------------------------------------
+\msg_new:nnn {acro} {deprecated}
   {
-    \seq_gput_right:Nn \g__acro_declared_acronyms_seq {#1}
-    \bool_gset_true:N \g__acro_first_acronym_declared_bool
-    \str_set:Nn \l__acro_current_id_str {#1}
-    \acro_for_properties_do:n
-      { \bool_new:c {l__acro_ \l__acro_current_id_str _##1_set_bool} }
-    \keys_set:nn {acro/declare-acronym} {#2}
-    \bool_new:c {g__acro_#1_first_use_bool}
-    \bool_new:c {g__acro_#1_used_bool}
-    \bool_new:c {g__acro_#1_label_bool}
-    \bool_new:c {g__acro_#1_in_list_bool}
-    \seq_new:c  {g__acro_#1_barriers_seq}
-    \seq_new:c  {g__acro_#1_recorded_barriers_seq}
-    \bool_if:NF \l__acro_print_only_used_bool
-      { \bool_gset_true:c {g__acro_#1_in_list_bool} }
-    \__acro_create_page_records:n {#1}
-    \__acro_define_acronym_macro:n {#1}
-    \str_clear:N \l__acro_current_id_str
-    \acro_property_if_set:nnF {#1} {short}
-      { \acro_serious_message:nnn {missing} {#1} {short} }
-    \acro_property_if_set:nnF {#1} {long}
-      { \acro_serious_message:nnn {missing} {#1} {long} }
-    \__acro_log_acronym:n {#1}
+    On~ line~ \msg_line_number: : \\
+    The~ #1~ `#2'~ is~ deprecated.~ Use~ #1~ `#3'~ instead .
   }
 
-  
-% --------------------------------------------------------------------------
-% print the list:
-% #1: list of classes
-% #2: list of excluded classes
-\keys_define:nn {acro/print-acronyms}
+\msg_new:nnn {acro} {deprecated-function}
+  { The~ command~ #1~ is~ deprecated.~ Use~ #2 instead . }
+
+\msg_new:nnn {acro} {removed-function}
+  { The~ command~ #1~ has~ been~ removed. }
+
+\msg_new:nnn {acro} {removed}
   {
-    include-classes   .tl_set:N   = \l__acro_included_classes_tl ,
-    exclude-classes   .tl_set:N   = \l__acro_excluded_classes_tl ,
-    name              .tl_set:N   = \l__acro_list_name_tl ,
-    heading           .code:n     = \__acro_set_list_heading:n {#1} ,
-    sort              .bool_set:N = \l__acro_sort_bool ,
-    local-to-barriers .bool_set:N = \l__acro_use_barrier_bool
+    On~ line~ \msg_line_number: : \\
+    The~ #1~ `#2'~ has~ been~ removed~ from~ acro. \\
+    If~ you~ need~ it~ back~ please~ open~ an~ issue~ on~ \\
+    https://github.com/cgnieder/acro/issues
+    \tl_if_blank:nF {#3} { \\ #3 }
   }
 
-\cs_new_protected:Npn \acro_print_acronyms:n #1
+% ----------------------------------------------------------------------------
+% #1: type
+% #2: old
+% #3: new
+\cs_new_protected:Npn \__acro_deprecation_warning:nnn #1#2#3
+  { \msg_warning:nnnnn {acro} {deprecated} {#1} {#2} {#3} }
+\cs_generate_variant:Nn \__acro_deprecation_warning:nnn {nne,nV}
+
+\acro_attribute_new:n {deprecated}
+\acro_attribute_new:n {removed}
+
+\prg_new_conditional:Npnn \acro_if_deprecated:n #1 {p,T,F,TF}
   {
-    \group_begin:
-      % this is a cheap trick to prevent the \@noitemerr
-      % if one forgot to delete either the aux file or
-      % remove \printacronyms -- but it's local:
-      \cs_set:Npn \@noitemerr {}
-      \tl_clear:N \l__acro_included_classes_tl
-      \tl_clear:N \l__acro_excluded_classes_tl
-      \tl_if_blank:nF {#1}
-        { \keys_set:nn {acro/print-acronyms} {#1} }
-      \__acro_aux_file_now:n { \acro@print@list }
-      \bool_if:NT \l__acro_sort_bool
-        { \acro_sort_prop:NN \l__acro_short_prop \l__acro_sort_prop }
-      \acro_title_instance:VV
-        \l__acro_list_heading_cmd_tl
-        \l__acro_list_name_tl
-      \cs_if_exist:NTF \acro@printed@list
-        {
-          \acro_list_instance:VVV
-            \l__acro_list_instance_tl
-            \l__acro_included_classes_tl
-            \l__acro_excluded_classes_tl
-        }
-        { \@latex@warning@no@line {Rerun~to~get~acronym~list~right} }
-    \group_end:
+    \acro_attribute_if_set:nnTF {deprecated} {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-% --------------------------------------------------------------------------
-% language support
-\RequirePackage {translations}
-
-\cs_new_protected:Npn \__acro_declare_translation:www #1 \q_mark #2=#3 \q_stop
-  {
-    \tl_set:Nx \l__acro_tmpa_tl { \tl_trim_spaces:n {#1} }
-    \tl_set:Nx \l__acro_tmpb_tl { \tl_trim_spaces:n {#2} }
-    \tl_if_in:nnT {#3} {=}
-      {} % TODO: misplaced equal sign
-    \tl_set:Nx \l__acro_tmpc_tl { \tl_trim_spaces:n {#3} }
-    \__acro_declare_translation:VVV
-      \l__acro_tmpb_tl
-      \l__acro_tmpa_tl
-      \l__acro_tmpc_tl
+\prg_new_conditional:Npnn \acro_if_removed:n #1 {p,T,F,TF}
+  {
+    \acro_attribute_if_set:nnTF {removed} {#1}
+      { \prg_return_true: }
+      { \prg_return_false: }
   }
 
-% #1: key
-% #2: lang
-% #3: translation
-\cs_new_protected:Npn \__acro_declare_translation:nnn #1#2#3
-  { \DeclareTranslation {#1} {#2} {#3} }
-\cs_generate_variant:Nn \__acro_declare_translation:nnn {VVV}
+% #1: old
+% #2: new
+\cs_new_protected:Npn \acro_deprecate:nn #1#2
+  { \acro_attribute_set:nnn {deprecated} {#1} {#2} }
 
-% #1: key
-% #2: csv list: { <lang1> = <translation1> , <lang2> = <translation2> }
-\cs_new_protected:Npn \acro_declare_translation:nn #1#2
+% #1: old
+\cs_new_protected:Npn \acro_remove:n #1
+  { \acro_attribute_set:nnn {removed} {#1} {} }
+
+% #1: type
+% #2: old
+\cs_new_protected:Npn \acro_deprecation_warning:nn #1#2
   {
-    \clist_map_inline:nn {#2}
+    \__acro_deprecation_warning:nne
+      {#1}
+      {#2}
+      { \acro_attribute_get:nn {deprecated} {#2} }
+  }
+
+% #1: type
+% #2: old
+% #3: additional text
+\cs_new_protected:Npn \acro_removal_warning:nnn #1#2#3
+  { \msg_warning:nnnnn {acro} {removed} {#1} {#2} {#3} }
+\cs_generate_variant:Nn \acro_removal_warning:nnn {nV}
+
+% #1: type
+% #2: old
+\cs_new_protected:Npn \acro_removal_warning:nn #1#2
+  { \msg_warning:nnnn {acro} {removed} {#1} {#2} }
+\cs_generate_variant:Nn \acro_removal_warning:nn {nV}
+
+% ----------------------------------------------------------------------------
+% #1: id
+% #2: property
+% #3: value
+\cs_set_protected:Npn \__acro_property_set:nnn #1#2#3
+  {
+    \acro_if_deprecated:nT {#2}
       {
-        \tl_if_blank:nF {##1}
-          { \__acro_declare_translation:www #1 \q_mark ##1 \q_stop }
+        \acro_deprecation_warning:nn {property} {#2}
+        \__acro_property_remove_from_auxlist:ne {#1}
+          { \acro_attribute_get:nn {deprecated} {#2} }
+        \__acro_auxlist_add:en
+          { \acro_attribute_get:nn {deprecated} {#2} }
+          {#1=={#3}}
+        \acro_attribute_set:enn
+          { \acro_attribute_get:nn {deprecated} {#2} }
+          {#1} {#3}
+      }
+    \acro_if_removed:nT {#2}
+      { \acro_removal_warning:nn {property} {#2} }
+    \bool_lazy_and:nnT
+      { ! \acro_if_deprecated_p:n {#2} }
+      { ! \acro_if_removed_p:n {#2} }
+      {
+        \__acro_property_remove_from_auxlist:nn {#1} {#2}
+        \__acro_auxlist_add:nn {#2} {#1=={#3}}
+        \acro_attribute_set:nnn {#2} {#1} {#3}
       }
   }
 
-% tokenlists using the translations:
-\tl_set:Nn \l__acro_list_name_tl  { \GetTranslation {acronym-list-name} }
-\tl_set:Nn \l__acro_page_name_tl  { \GetTranslation {acronym-page-name}\@\, }
-\tl_set:Nn \l__acro_pages_name_tl { \GetTranslation {acronym-pages-name}\@\, }
-\tl_set:Nn \l__acro_next_page_tl  { \,\GetTranslation {acronym-next-page}\@ }
-\tl_set:Nn \l__acro_next_pages_tl { \,\GetTranslation {acronym-next-pages}\@ }
+\cs_generate_variant:Nn \acro_attribute_set:nnn {e}
+\cs_generate_variant:Nn \__acro_auxlist_add:nn {e}
+\cs_generate_variant:Nn \__acro_property_remove_from_auxlist:nn {ne}
 
-% --------------------------------------------------------------------------
-% definition file:
-\tl_const:Nn \c_acro_definition_file_name_tl      {acro.definitions}
-\tl_const:Nn \c_acro_definition_file_extension_tl {tex}
+% #1: old
+% #2: new
+\cs_new_protected:Npn \acro_deprecated_property:nn #1#2
+  {
+    \acro_deprecate:nn {#1} {#2}
+    \acro_property_declare:nnnnn
+      { \c_false_bool }
+      { \c_false_bool }
+      { \c_false_bool }
+      { \c_false_bool }
+      {#1}
+  }
 
-\file_if_exist:nTF
-  { \c_acro_definition_file_name_tl .\c_acro_definition_file_extension_tl }
+% #1: old
+\cs_new_protected:Npn \acro_removed_property:n #1
   {
-    \@onefilewithoptions
-      {\c_acro_definition_file_name_tl} [] []
-      \c_acro_definition_file_extension_tl
+    \acro_remove:n {#1}
+    \acro_property_declare:nnnnn
+      { \c_false_bool }
+      { \c_false_bool }
+      { \c_false_bool }
+      { \c_false_bool }
+      {#1}
   }
-  { \acro_serious_message:n {definitions-missing} }
 
-% --------------------------------------------------------------------------
-% allow for a configuration file:
+% ----------------------------------------------------------------------------
+% #1: old
+% #2: new
+\cs_new_protected:Npn \acro_deprecate_function:NN #1#2
+  {
+    \cs_set_protected:Npn #1
+      {
+        \msg_error:nnnn {acro} {deprecated-function} {#1} {#2}
+        #2
+      }
+  }
 
-\file_if_exist:nT
-  { \l_acro_config_file_name_tl . \l_acro_config_file_extension_tl }
+% #1: old
+\cs_new_protected:Npn \acro_remove_function:N #1
   {
-    \@onefilewithoptions
-      {\l_acro_config_file_name_tl} [] []
-      \l_acro_config_file_extension_tl
+    \cs_set_protected:Npn #1
+      { \msg_error:nnn {acro} {removed-function} {#1} }
   }
 
+% ----------------------------------------------------------------------------
+% #1: new
+% #2: value
+\cs_new_protected:Npn \acro_deprecate_option:nn #1#2
+  {
+    \__acro_deprecation_warning:nVn {option} \l_keys_key_str {#1}
+    \keys_set:nn {acro} { #1 = #2 }
+  }
+
+% #1: additional text
+\cs_new_protected:Npn \acro_remove_option:n #1
+  { \acro_removal_warning:nVn {option} \l_keys_key_str {#1} }
+
+\cs_new_protected:Npn \acro_remove_option:
+  { \acro_removal_warning:nV {option} \l_keys_key_str }
+
+% ----------------------------------------------------------------------------
+% old properties:
+\acro_deprecated_property:nn {accsupp} {short-acc}
+\acro_deprecated_property:nn {tooltip} {pdfcomment}
+\acro_deprecated_property:nn {class} {tag}
+\acro_deprecated_property:nn {foreign-lang} {foreign-babel}
+
+\acro_removed_property:n {long-pre}
+\acro_removed_property:n {after-citation}
+\acro_removed_property:n {index-cmd}
+
+% ----------------------------------------------------------------------------
+% old functions
+\acro_remove_function:N \acflike
+\acro_remove_function:N \acfplike
+\acro_remove_function:N \acsingle
+\acro_remove_function:N \Acsingle
+\acro_remove_function:N \acpsingle
+\acro_remove_function:N \Acpsingle
+
+\acro_remove_function:N \acpdfstring
+\acro_remove_function:N \acpdfstringplural
+\acro_remove_function:N \AcroRegisterTrailing
+
+\acro_deprecate_function:NN \acifused \acroifusedTF
+\acro_deprecate_function:NN \aciffirst \acroiffirstTF
+\acro_deprecate_function:NN \ProvideAcroEnding \DeclareAcroEnding
+
+\acro_remove_function:N \DeclareAcroListStyle
+\acro_remove_function:N \DeclareAcroListHeading
+\acro_remove_function:N \DeclareAcroFirstStyle
+\acro_remove_function:N \DeclareAcroExtraStyle
+\acro_remove_function:N \DeclareAcroPageStyle
+\acro_remove_function:N \AcroRegisterTrailing
+
+% ----------------------------------------------------------------------------
+% old options:
+\keys_define:nn {acro}
+  {
+    %%% package:
+    log .code:n =
+      \acro_remove_option:n
+        { You~ can~ use~ \acshow ~ to~ inspect~ an~ acronym~ instead . } ,
+    messages .code:n = \acro_remove_option: ,
+    macros .code:n = \acro_remove_option: ,
+    xspace .code:n = \acro_remove_option: ,
+    strict .code:n = \acro_remove_option: ,
+    %%% behaviour:
+    hyperref .code:n =
+      \acro_deprecate_option:nn {make-links} {true} ,
+    label .code:n =
+      \acro_deprecate_option:nn {labels} {true} ,
+    only-used .code:n =
+      \acro_deprecate_option:nn {list/display} {used} ,
+    mark-as-used .code:n =
+      \acro_deprecate_option:nn {use-only-first} {true} ,
+    sort .code:n =
+      \acro_deprecate_option:nn {list/sort} {true} ,
+    display-foreign .code:n = \acro_remove_option: ,
+    cite .code:n =
+      \acro_deprecate_option:nn {cite/display} {#1} ,
+    cite-cmd .code:n =
+      \acro_deprecate_option:nn {cite/cmd} {#1} ,
+    group-citation .code:n =
+      \acro_deprecate_option:nn {cite/group} {true} ,
+    cite-connect .code:n =
+      \acro_deprecate_option:nn {cite/pre} {#1} ,
+    group-cite-connect .code:n =
+      \acro_deprecate_option:nn {cite/group/pre} {#1} ,
+    group-cite-cmd .code:n =
+      \acro_remove_option:n {Maybe~ the~ option~ `cite/cmd'~ helps.} ,
+    index .code:n =
+      \acro_deprecate_option:nn {index/use} {true} ,
+    index-cmd .code:n =
+      \acro_deprecate_option:nn {index/cmd} {#1} ,
+    short-format .code:n =
+      \acro_deprecate_option:nn {format/short} {#1} ,
+    long-format .code:n =
+      \acro_deprecate_option:nn {format/long} {#1} ,
+    foreign-format .code:n =
+      \acro_deprecate_option:nn {format/foreign} {#1} ,
+    extra-format .code:n =
+      \acro_deprecate_option:nn {format/extra} {#1} ,
+    single-format .code:n = \acro_remove_option: ,
+    single-form   .code:n =
+      \acro_deprecate_option:nn {single-style} {#1} ,
+    first-long-format .code:n =
+      \acro_deprecate_option:nn {format/first-long} {#1} ,
+    list-short-format .code:n = \acro_remove_option: ,
+    list-long-format .code:n =
+      \acro_deprecate_option:nn {format/list} {#1} ,
+    list-foreign-format .code:n = \acro_remove_option: ,
+    override-list-format .code:n = \acro_remove_option: ,
+    format-include-endings .code:n =
+      \acro_deprecate_option:nn {include-endings} {true} ,
+    extra-style .code:n = \acro_remove_option: ,
+    page-style.code:n = \acro_remove_option: ,
+    pages .code:n =
+      \acro_deprecate_option:nn {pages/display} {#1} ,
+    page-name .code:n = \acro_remove_option: ,
+    pages-name .code:n = \acro_remove_option: ,
+    following-page .code:n =
+      \acro_deprecate_option:nn {pages/seq} {true} ,
+    following-pages .code:n =
+      \acro_deprecate_option:nn {pages/seq} {true} ,
+    next-page .code:n = \acro_remove_option: ,
+    next-pages .code:n = \acro_remove_option: ,
+    uc-cmd .code:n =
+      \acro_deprecate_option:nn {uppercase/cmd} {#1} ,
+    uppercase-short .code:n =
+      \acro_deprecate_option:nn {uppercase/short} {#1} ,
+    tooltip .code:n =
+      \acro_deprecate_option:nn {pdfcomments/use} {#1} ,
+    tooltip-cmd .code:n =
+      \acro_deprecate_option:nn {pdfcomments/cmd} {#1} ,
+    use-barriers .code:n = \acro_remove_option: ,
+    reset-at-barriers .code:n =
+      \acro_deprecate_option:nn {barriers/reset} {#1} ,
+    activate-trailing-tokens .code:n =
+      \acro_deprecate_option:nn {trailing/activate} {#1} ,
+    deactivate-trailing-tokens .code:n =
+      \acro_deprecate_option:nn {trailing/deactivate} {#1} ,
+    %%% list options:
+    list-style .code:n =
+      \acro_deprecate_option:nn {list/template} {#1} ,
+    list-heading .code:n =
+      \acro_deprecate_option:nn {list/heading} {#1} ,
+    list-name .code:n =
+      \acro_deprecate_option:nn {list/name} {#1} ,
+    list-caps .code:n = \acro_remove_option: ,
+    print-acronyms/include-classes .code:n =
+      \acro_deprecate_option:nn {list/include} {#1} ,
+    print-acronyms/exclude-classes .code:n =
+      \acro_deprecate_option:nn {list/exclude} {#1} ,
+    print-acronyms/name .code:n =
+      \acro_deprecate_option:nn {list/name} {#1} ,
+    print-acronyms/heading .code:n =
+      \acro_deprecate_option:nn {list/heading} {#1} ,
+    print-acronyms/sort .code:n =
+      \acro_deprecate_option:nn {list/sort} {true} ,
+    print-acronyms/local-to-barriers .code:n =
+      \acro_deprecate_option:nn {list/local} {true}
+  }
+
+% ----------------------------------------------------------------------------
+\AcroModuleEnd
+% finish package:
+\AtEndDocument { \acro_close_aux: \acro_do_rerun: }
+%----------------------------------------------------------------------------
 \file_input_stop: