l3experimental 3287

git-svn-id: svn://tug.org/texlive/trunk@25308 c570f23f-e606-0410-a88d-b1316a301751

7 files changed, 2057 insertions, 1283 deletions

diff --git a/Master/texmf-dist/tex/latex/l3experimental/l3dt/l3dt.sty b/Master/texmf-dist/tex/latex/l3experimental/l3dt/l3dt.sty
new file mode 100644
index 00000000000..5346944521c
--- /dev/null
+++ b/Master/texmf-dist/tex/latex/l3experimental/l3dt/l3dt.sty
@@ -0,0 +1,459 @@
+%%
+%% This is file `l3dt.sty',
+%% generated with the docstrip utility.
+%%
+%% The original source files were:
+%%
+%% l3dt.dtx  (with options: `package')
+%% 
+%% EXPERIMENTAL CODE
+%% 
+%% Do not distribute this file without also distributing the
+%% source files specified above.
+%% 
+%% Do not distribute a modified version of this file.
+%% 
+%% File l3dt.dtx Copyright (C) 2011,2012 The LaTeX3 Project
+%%
+%% It may be distributed and/or modified under the conditions of the
+%% LaTeX Project Public License (LPPL), either version 1.3c of this
+%% license or (at your option) any later version.  The latest version
+%% of this license is in the file
+%%
+%%    http://www.latex-project.org/lppl.txt
+%%
+%% This file is part of the "l3experimental bundle" (The Work in LPPL)
+%% and all files in that bundle must be distributed together.
+%%
+%% The released version of this bundle is available from CTAN.
+%%
+%% -----------------------------------------------------------------------
+%%
+%% The development version of the bundle can be found at
+%%
+%%    http://www.latex-project.org/svnroot/experimental/trunk/
+%%
+%% for those people who are interested.
+%%
+%%%%%%%%%%%
+%% NOTE: %%
+%%%%%%%%%%%
+%%
+%%   Snapshots taken from the repository represent work in progress and may
+%%   not work or may contain conflicting material!  We therefore ask
+%%   people _not_ to put them into distributions, archives, etc. without
+%%   prior consultation with the LaTeX Project Team.
+%%
+%% -----------------------------------------------------------------------
+%%
+\RequirePackage{expl3}
+\GetIdInfo$Id: l3dt.dtx 3251 2012-01-28 09:42:44Z joseph $
+  {L3 Experimental data tables}
+\ProvidesExplPackage
+  {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
+\package_check_loaded_expl:
+\quark_new:N \q_dt
+\quark_new:N \q_dt_row
+\quark_new:N \q_dt_header
+\tl_const:Nn \c_empty_dt
+  {
+    { 0 }
+    \q_dt
+    \q_nil
+    \q_dt_header
+    \q_dt_row
+  }
+\cs_new_protected:Npn \dt_new:N #1 { \cs_new_eq:NN  #1  \c_empty_dt }
+\cs_new_protected:Npn \dt_clear:N #1  { \cs_set_eq:NN   #1  \c_empty_dt }
+\cs_new_protected:Npn \dt_gclear:N #1 { \cs_gset_eq:NN  #1  \c_empty_dt }
+\cs_new_protected:Npn \dt_clear_new:N #1
+  { \cs_if_exist:NTF #1 { \dt_clear:N #1 } { \dt_new:N #1 } }
+\cs_new_protected:Npn \dt_gclear_new:N #1
+  { \cs_if_exist:NTF #1 { \dt_gclear:N #1 } { \dt_new:N #1 } }
+\cs_new_eq:NN \dt_set_eq:NN  \tl_set_eq:NN
+\cs_new_eq:NN \dt_gset_eq:NN \tl_gset_eq:NN
+\dt_new:N \l_tmpa_dt
+\dt_new:N \l_tmpb_dt
+\dt_new:N \g_tmpa_dt
+\dt_new:N \g_tmpb_dt
+\cs_new_protected:Npn \dt_split_aux:nnnn #1#2#3#4 { #3 #2 }
+\cs_new_protected:Npn \dt_split_aux:w { }
+\cs_new:Npn \dt_split_header:NT #1#2
+  { \exp_after:wN \dt_split_header_aux:wn #1 \q_stop {#2} }
+\cs_new:Npn \dt_split_header_aux:wn #1 \q_nil \q_dt_header #2 \q_stop #3
+  { #3 {#1} { \q_dt_header #2 } }
+\cs_new_protected:Npn \dt_split_key:nnTF #1#2
+  { \exp_args:No \dt_split_key_aux:nnTF { \tl_to_str:n {#2} } {#1} }
+\cs_new_protected:Npn \dt_split_key_aux:nnTF #1#2
+  {
+    \cs_set_protected:Npn \dt_split_aux:w
+      ##1 \q_dt #1 \q_dt ##2##3##4 \q_mark ##5 \q_stop
+      { \dt_split_aux:nnnn ##3 { { ##1 \q_dt } {##2} {##4} } }
+    \dt_split_aux:w #2 \q_mark
+      \q_dt #1 \q_dt { } { ? \use_ii:nn { } } \q_mark \q_stop
+  }
+\cs_new_protected:Npn \dt_split_key_list:NnTF #1#2
+  { \exp_args:NNo \dt_split_key_list_aux:NnTF #1 { \tl_to_str:n {#2} } }
+\cs_new_protected:Npn \dt_split_key_list_aux:NnTF #1#2
+  {
+    \cs_set_protected:Npn \dt_split_aux:w
+      ##1##2 \q_dt #2 \q_dt ##3##4 \q_dt_header ##5 \q_mark ##6 \q_stop
+      {
+        \dt_split_aux:nnnn ##3
+          { { {##1} ##2 \q_dt } { ##3##4 \q_dt_header ##5 } }
+      }
+    \exp_after:wN \dt_split_aux:w #1 \q_mark
+      \q_dt #2 \q_dt { ? \use_ii:nn { } } \q_dt_header \q_mark \q_stop
+  }
+\cs_new_protected:Npn \dt_split_row:NnTF #1#2
+  { \dt_split_row_aux:NfTF #1 { \int_eval:n {#2} } }
+\cs_new_protected:Npn \dt_split_row_aux:NnTF #1#2
+  {
+    \cs_set_protected:Npn \dt_split_aux:w
+      ##1 \q_dt_row #2 \q_dt ##2##3 \q_dt_row ##4 \q_mark ##5 \q_stop
+      {
+        \dt_split_aux:nnnn ##2
+          { { ##1 \q_dt_row } { #2 \q_dt ##2##3 } {##4} }
+      }
+    \exp_after:wN \dt_split_aux:w #1 \q_mark
+      \q_dt_row #2 \q_dt { ? \use_ii:nn { } } \q_dt_row \q_mark \q_stop
+  }
+\cs_generate_variant:Nn \dt_split_row_aux:NnTF { Nf }
+\cs_new_protected_nopar:Npn \dt_add_key:Nn { \dt_add_key_aux:NNn \tl_set:Nx }
+\cs_new_protected_nopar:Npn \dt_gadd_key:Nn { \dt_add_key_aux:NNn \tl_gset:Nx }
+\cs_new_protected:Npn \dt_add_key_aux:NNn #1#2#3
+  {
+    \dt_split_key_list:NnTF #2 {#3}
+      { \use_none:nn }
+      {
+        \dt_split_header:NT #2
+          { \dt_add_key_aux:NNnnn #1 #2 {#3} }
+      }
+  }
+\cs_new_protected:Npn \dt_add_key_aux:NNnnn #1#2#3#4#5
+  {
+    #1 #2
+      {
+        \exp_not:n {#4}
+        \tl_to_str:n {#3}
+        \exp_not:n { \q_dt \q_nil #5 }
+      }
+  }
+\cs_new_protected_nopar:Npn \dt_add_row:N { \dt_add_row_aux:NN \tl_set:Nx }
+\cs_new_protected_nopar:Npn \dt_gadd_row:N { \dt_add_row_aux:NN \tl_gset:Nx }
+\cs_new_protected:Npn \dt_add_row_aux:NN #1#2
+  { \exp_args:NNf \dt_add_row_aux:NnN #1 { \dt_rows:N #2 } #2 }
+\cs_new_protected:Npn \dt_add_row_aux:NnN #1#2#3
+  {
+    #1 #3
+      {
+        { \int_eval:n { #2 + \c_one } }
+        \exp_after:wN \dt_add_row_aux:nw #3 \q_stop
+        #2
+        \exp_not:n { \q_dt \q_nil \q_dt_row }
+      }
+  }
+\cs_new:Npn \dt_add_row_aux:nw #1#2 \q_stop { \exp_not:n {#2} }
+\cs_new_protected:Npn \dt_put:Nnn #1
+  { \dt_put:Nnnn #1 { \dt_rows:N #1 - \c_one } }
+\cs_new_protected:Npn \dt_gput:Nnn #1
+  { \dt_gput:Nnnn #1 { \dt_rows:N #1 - \c_one } }
+\cs_new_protected_nopar:Npn \dt_put:Nnnn
+  { \dt_put_aux:NNNnnn \dt_add_key:Nn \tl_set:Nx }
+\cs_new_protected_nopar:Npn \dt_gput:Nnnn
+  { \dt_put_aux:NNNnnn \dt_gadd_key:Nn \tl_gset:Nx }
+\cs_new_protected:Npn \dt_put_aux:NNNnnn #1#2#3#4#5#6
+  {
+    #1 #3 {#5}
+    \dt_split_row:NnTF #3 {#4}
+      { \dt_put_aux:NNnnnnn #2 #3 {#5} {#6} }
+      {
+        \msg_kernel_error:nnxxx { dt } { unknown-row }
+          { \token_to_str:N #3 } { \int_eval:n {#4} } { \dt_rows:N #3 }
+      }
+  }
+\cs_new_protected:Npn \dt_put_aux:NNnnnnn #1#2#3#4#5#6#7
+  {
+    \dt_split_key:nnTF {#6} {#3}
+      { \dt_put_update:NNnnnnnnn #1 #2 {#3} {#4} {#5} {#7} }
+      { \dt_put_add_to_row:NNnnnnn #1 #2 {#3} {#4} {#5} {#6} {#7} }
+  }
+\cs_new_protected:Npn \dt_put_update:NNnnnnnnn #1#2#3#4#5#6#7#8#9
+  {
+    #1 #2
+      {
+        \exp_not:n { #5 #7 }
+        \tl_to_str:n {#3}
+        \exp_not:n { \q_dt {#4} \q_dt #9 \q_dt_row #6 }
+      }
+  }
+\cs_new_protected:Npn \dt_put_add_to_row:NNnnnnn #1#2#3#4#5#6#7
+  {
+    #1 #2
+      {
+        \exp_not:n {#5}
+        \exp_not:o { \dt_put_add_row_aux:w #6 }
+        \tl_to_str:n {#3}
+        \exp_not:n { \q_dt {#4} \q_dt \q_nil \q_dt_row #7 }
+      }
+  }
+\cs_new:Npn \dt_put_add_row_aux:w #1 \q_nil {#1}
+\cs_new:Npn \dt_keys:N #1
+  { \dt_split_header:NT #1 { \dt_keys_aux:nn } }
+\cs_new:Npn \dt_keys_aux:nn #1#2
+  {
+    \int_eval:n
+      {
+        0
+        \exp_after:wN \dt_keys_aux:wN \use_none:nn #1 \q_recursion_tail \q_dt
+          \prg_break_point:n { }
+      }
+  }
+\cs_new:Npn \dt_keys_aux:wN #1 \q_dt
+  {
+    \if_meaning:w \q_recursion_tail #1
+      \exp_after:wN \prg_map_break:
+    \fi:
+    +1
+    \dt_keys_aux:wN
+  }
+\cs_new:Npn \dt_rows:N #1
+  { \exp_after:wN \use_i_delimit_by_q_stop:nw #1 \q_stop }
+\cs_new_protected:Npn \dt_del:Nn #1 { \dt_del:Nnn #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new_protected:Npn \dt_gdel:Nn #1 { \dt_gdel:Nnn #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new_protected_nopar:Npn \dt_del:Nnn { \dt_del_aux:NNnn \tl_set:Nn }
+\cs_new_protected_nopar:Npn \dt_gdel:Nnn { \dt_del_aux:NNnn \tl_gset:Nn }
+\cs_new_protected:Npn \dt_del_aux:NNnn #1#2#3#4
+  {
+    \dt_split_row:NnTF #2 {#3}
+      { \dt_del_aux:NNnnnn #1 #2 {#4} }
+      { }
+  }
+\cs_new_protected:Npn \dt_del_aux:NNnnnn #1#2#3#4#5#6
+  {
+    \dt_split_key:nnTF {#5} {#3}
+      { \dt_del_aux:NNnnnnn #1 #2 {#4} {#6} }
+      { }
+  }
+\cs_new_protected:Npn \dt_del_aux:NNnnnnn #1#2#3#4#5#6#7
+  { #1 #2 { #3 #5 #7 #4 } }
+\cs_new_protected_nopar:Npn \dt_remove_key:Nn
+  { \dt_remove_key_aux:NNn \tl_set:Nx }
+\cs_new_protected_nopar:Npn \dt_gremove_key:Nn
+  { \dt_remove_key_aux:NNn \tl_gset:Nx }
+\cs_new_protected:Npn \dt_remove_key_aux:NNn #1#2#3
+  {
+    \dt_split_key_list:NnTF #2 {#3}
+      { \exp_args:No \dt_remove_key_aux:nNNnn { \tl_to_str:n {#3} } #1 #2 }
+      { }
+  }
+\cs_new_protected:Npn \dt_remove_key_aux:nNNnn #1#2#3#4#5
+  {
+    \cs_set:Npn \dt_remove_key_aux:w ##1 \q_dt #1 \q_dt ##2 ##3
+      {
+        \exp_not:n {##1}
+        \if_meaning:w \q_recursion_tail ##3
+          \exp_after:wN \prg_map_break:
+        \fi:
+        \dt_remove_key_aux:w ##3
+      }
+    #2 #3
+      {
+        \exp_not:n {#4}
+        \dt_remove_key_aux:w #5 \q_dt #1 \q_dt { } \q_recursion_tail
+          \prg_break_point:n { }
+      }
+  }
+\cs_new:Npn \dt_remove_key_aux:w { }
+\cs_new_protected_nopar:Npn \dt_remove_row:Nn
+  { \dt_remove_row_aux:NNn \tl_set:Nx }
+\cs_new_protected_nopar:Npn \dt_gremove_row:Nn
+  { \dt_remove_row_aux:NNn \tl_gset:Nx }
+\cs_new_protected:Npn \dt_remove_row_aux:NNn #1#2#3
+  {
+    \dt_split_row:NnTF #2 {#3}
+      { \dt_remove_row_aux:NNnnn #1 #2 }
+      { }
+  }
+\cs_new_protected:Npn \dt_remove_row_aux:NNnnn #1#2#3#4#5
+  {
+    #1 #2
+      {
+        { \int_eval:n { \dt_rows:N #2 - \c_one } }
+        \dt_remove_row_aux:nw #3 \q_stop
+        \dt_remove_row_loop:nw #5 \q_recursion_tail \q_dt_row
+          \prg_break_point:n { }
+      }
+  }
+\cs_new_eq:NN \dt_remove_row_aux:nw \dt_add_row_aux:nw
+\cs_new:Npn \dt_remove_row_loop:nw #1#2 \q_dt_row
+  {
+    \if_meaning:w \q_recursion_tail #1
+      \exp_after:wN \prg_map_break:
+    \fi:
+    \int_eval:n { #1 - \c_one }
+    \exp_not:n { #2 \q_dt_row }
+    \dt_remove_row_loop:nw
+  }
+\cs_new_protected:Npn \dt_get:NnnN #1#2#3#4
+  {
+    \dt_split_row:NnTF #1 {#2}
+      { \dt_get_aux:nNnnn {#3} #4 }
+      { \tl_set:Nn #4 { \q_no_value } }
+  }
+\cs_new_protected:Npn \dt_get_aux:nNnnn #1#2#3#4#5
+  {
+    \dt_split_key:nnTF {#4} {#1}
+      { \dt_get_aux:Nnnn #2 }
+      { \tl_set:Nn #2 { \q_no_value } }
+  }
+\cs_new_protected:Npn \dt_get_aux:Nnnn #1#2#3#4 { \tl_set:Nn #1 {#3} }
+\prg_new_protected_conditional:Npnn \dt_get:NnnN #1#2#3#4 { T , F , TF }
+  {
+    \dt_split_row:NnTF #1 {#2}
+      { \dt_get_aux_true:nNnnn {#3} #4 }
+      { \prg_return_false: }
+  }
+\cs_new_protected:Npn \dt_get_aux_true:nNnnn #1#2#3#4#5
+  {
+    \dt_split_key:nnTF {#4} {#1}
+      { \dt_get_aux_true:Nnnn #2 }
+      { \prg_return_false: }
+  }
+\cs_new_protected:Npn \dt_get_aux_true:Nnnn #1#2#3#4
+  {
+    \tl_set:Nn #1 {#3}
+    \prg_return_true:
+  }
+\cs_new_protected:Npn \dt_get:NnN #1 { \dt_get:NnnN #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new_protected:Npn \dt_get:NnNT  #1 { \dt_get:NnnNF  #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new_protected:Npn \dt_get:NnNF  #1 { \dt_get:NnnNF  #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new_protected:Npn \dt_get:NnNTF #1 { \dt_get:NnnNTF #1
+  { \dt_rows:N #1 - \c_one } }
+\int_new:N \g_dt_map_level_int
+\cs_new_protected:Npn \dt_map_variables:Nnn #1#2#3
+  {
+    \int_gincr:N \g_dt_map_level_int
+    \seq_gclear_new:c { g_dt_map_ \int_use:N \g_dt_map_level_int _seq }
+    \keyval_parse:NNn \use_none:n \dt_map_variables_key:nn {#2}
+    \dt_split_header:NT #1 { \dt_map_variables_aux:nnn {#3} }
+  }
+\cs_new_protected:Npn \dt_map_variables_key:nn #1#2
+  {
+    \seq_gput_right:cn { g_dt_map_ \int_use:N \g_dt_map_level_int _seq }
+      { {#1} #2 }
+  }
+\cs_new_protected:Npn \dt_map_variables_aux:nnn #1#2#3
+  { \dt_map_variables_aux:nNNw {#1} #3 \q_stop }
+\cs_new_protected:Npn \dt_map_variables_aux:nNNw
+  #1 \q_dt_header \q_dt_row #2 \q_stop
+  {
+    \int_zero_new:c { l_dt_map_ \int_use:N \g_dt_map_level_int _row_int }
+    \dt_map_variables_aux:nnw {#1} #2 { } \q_recursion_tail \q_dt_row
+      \prg_break_point:n { \int_gdecr:N \g_dt_map_level_int }
+  }
+\cs_new_protected:Npn \dt_map_variables_aux:nnw #1#2#3#4 \q_dt_row
+  {
+    \if_meaning:w \q_recursion_tail #3
+      \exp_after:wN \dt_map_break:
+    \fi:
+    \seq_map_inline:cn { g_dt_map_ \int_use:N \g_dt_map_level_int _seq }
+      { \dt_get_aux:nNnnn ##1 { } {#3#4} { } }
+    #1
+    \int_incr:c { l_dt_map_ \int_use:N \g_dt_map_level_int _row_int }
+    \dt_map_variables_aux:nnw {#1}
+  }
+\cs_new_eq:NN \dt_map_break:  \prg_map_break:
+\cs_new_eq:NN \dt_map_break:n \prg_map_break:n
+\prg_new_conditional:Npnn \dt_if_empty:N #1 { T , F , TF , p }
+  {
+    \if_meaning:w #1 \c_empty_dt
+      \prg_return_true:
+    \else:
+      \prg_return_false:
+    \fi:
+  }
+\prg_new_conditional:Npnn \dt_if_in:Nn #1#2 { p , T , F , TF }
+  { \dt_split_header:NT #1 { \dt_if_in_aux:nnn {#2} } }
+\cs_new:Npn \dt_if_in_aux:nnn #1#2#3
+  {
+    \exp_last_unbraced:Nno \dt_if_in_aux:nwN {#1} { \use_none:nn #2 }
+      \q_recursion_tail \q_dt
+      \prg_break_point:n { }
+  }
+\cs_new:Npn \dt_if_in_aux:nwN #1#2 \q_dt
+  {
+    \if_meaning:w \q_recursion_tail #2
+      \exp_after:wN \prg_map_break:n
+    \else:
+      \exp_after:wN \use_none:n
+    \fi:
+      { \prg_return_false: }
+    \str_if_eq:nnTF {#1} {#2}
+      { \prg_map_break:n { \prg_return_true: } }
+      { \dt_if_in_aux:nwN {#1} }
+  }
+\prg_new_conditional:Npnn \dt_if_in_row:Nnn #1#2#3 { p , T , F , TF }
+  {
+    \exp_last_unbraced:Nno \dt_if_in_row_aux:nw {#2} #1
+      \q_recursion_tail \q_nil
+      \prg_break_point:n { }
+      { \tl_to_str:n {#3} }
+  }
+\cs_new:Npn \dt_if_in_row_aux:nw #1#2 \q_dt_row #3#4 \q_nil
+  {
+    \if_meaning:w \q_recursion_tail #3
+      \exp_after:wN \prg_map_break:n
+    \else:
+      \exp_after:wN \use_none:n
+    \fi:
+      {
+        \use_i:nn
+        \prg_return_false:
+      }
+    \int_compare:nNnTF {#1} = {#3}
+      { \prg_map_break:n { \exp_args:Nno \dt_if_in_row_aux:nn {#4} } }
+      { \dt_if_in_row_aux:nw {#1} }
+  }
+\cs_new:Npn \dt_if_in_row_aux:nn #1#2
+  {
+    \dt_if_in_row_aux:nwn {#2} #1 {#2} \q_dt { } \q_recursion_tail
+      \prg_break_point:n { }
+  }
+\cs_new:Npn \dt_if_in_row_aux:nwn #1 \q_dt #2 \q_dt #3
+  {
+    \str_if_eq:xxTF {#1} {#2}
+      { \dt_if_in_row_aux:N }
+      { \dt_if_in_row_aux:nwn {#1} }
+  }
+\cs_new:Npn \dt_if_in_row_aux:N #1
+  {
+    \if_meaning:w \q_dt #1
+      \prg_return_true:
+    \else:
+      \prg_return_false:
+    \fi:
+    \prg_map_break:
+  }
+\cs_new:Npn \dt_if_in_row_p:Nn #1 { \dt_if_in_row_p:Nnn #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new:Npn \dt_if_in_row:NnT  #1 { \dt_if_in_row:NnnT  #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new:Npn \dt_if_in_row:NnF  #1 { \dt_if_in_row:NnnF  #1
+  { \dt_rows:N #1 - \c_one } }
+\cs_new:Npn \dt_if_in_row:NnTF #1 { \dt_if_in_row:NnnTF #1
+  { \dt_rows:N #1 - \c_one } }
+\msg_kernel_new:nnnn { dt } { unknown-row }
+  { Data~table~#1~does~not~contain~a~row~'#2'. }
+  {
+    Data~table~#1~contains~#3~rows.~These~must~be~accessed~by~number:~row~
+    #2~is~not~present~in~the~table.
+  }
+%% 
+%%
+%% End of file `l3dt.sty'.
diff --git a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3flag.sty b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3flag.sty
index 2bb94e7c62a..b56100853ab 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3flag.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3flag.sty
@@ -50,48 +50,56 @@
   {L3 Experimental Flags}
 \ProvidesExplPackage
   {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
-\tl_new:N \g_flag_list_tl
-\cs_new_protected:Npn \flag_new:N #1
+\cs_new_protected:Npn \flag_new:n #1
   {
-    \cs_new_eq:NN #1 \c_undefined:D
-    \tl_if_in:NnTF \g_flag_list_tl {#1}
-      {
-        \msg_kernel_error:nnx
-          { flag } { already-defined }
-          { \token_to_str:N #1 }
-      }
-      { \tl_gput_right:Nn \g_flag_list_tl {#1} }
+    \cs_new:cpn { flag_trap_#1:w } ##1 ;
+      { \exp_after:wN \use_none:n \cs:w l_#1_##1_flag \cs_end: }
   }
-\cs_generate_variant:Nn \flag_new:N { c }
-\prg_new_conditional:Npnn \flag_test:N #1 { p , T , F , TF }
+\cs_new_protected:Npn \flag_clear:n #1
+  { \flag_clear_aux:ww 0 ; #1 \q_stop }
+\cs_new_protected:Npn \flag_clear_aux:ww #1 ; #2 \q_stop
   {
-    \if_cs_exist:N #1
-      \prg_return_true:
+    \if_cs_exist:w l_#2_#1_flag \cs_end:
     \else:
-      \prg_return_false:
+      \exp_after:wN \use_none_delimit_by_q_stop:w
     \fi:
+    \cs_set_eq:cN { l_#2_#1_flag } \c_undefined:D
+    \exp_after:wN \flag_clear_aux:ww
+    \int_use:N \int_eval:w \c_one + #1 ;
+    #2 \q_stop
+  }
+\cs_new_protected:Npn \flag_clear_new:n #1
+  { \flag_if_exist:nTF {#1} { \flag_clear:n } { \flag_new:n } {#1} }
+\cs_new_protected:Npn \flag_set_trap:nn #1#2
+  { \cs_set:cpn { flag_trap_#1:w } ##1 ; {#2} }
+\prg_new_conditional:Npnn \flag_if_exist:n #1 { p , T , F , TF }
+  {
+    \cs_if_exist:cTF { flag_trap_#1:w }
+      { \prg_return_true: } { \prg_return_false: }
   }
-\prg_new_conditional:Npnn \flag_test:c #1 { p , T , F , TF }
+\prg_new_conditional:Npnn \flag_if_raised:n #1 { p , T , F , TF }
   {
-    \if_cs_exist:w #1 \cs_end:
+    \if_cs_exist:w l_#1_0_flag \cs_end:
       \prg_return_true:
     \else:
       \prg_return_false:
     \fi:
   }
-\cs_new:Npn \flag_raise:N #1
-  { \exp_after:wN \use_none:n \cs:w \cs_to_str:N #1 \cs_end: }
-\cs_new:Npn \flag_raise:c #1
-  { \exp_after:wN \use_none:n \cs:w #1 \cs_end: }
-\cs_new_protected:Npn \flag_lower:N #1
-  { \cs_set_eq:NN #1 \c_undefined:D }
-\cs_generate_variant:Nn \flag_lower:N { c }
-\msg_kernel_new:nnnn { flag } { already-defined }
-  { The~control~sequence~#1~is~already~declared~as~a~flag. }
+\cs_new:Npn \flag_height:n #1 { \flag_height_loop:ww 0; #1 \q_stop }
+\cs_new:Npn \flag_height_loop:ww #1 ; #2 \q_stop
+  {
+    \if_cs_exist:w l_#2_#1_flag \cs_end:
+      \exp_after:wN \flag_height_loop:ww \int_use:N \int_eval:w \c_one +
+    \else:
+      \exp_after:wN \flag_height_end:ww
+    \fi:
+    #1 ; #2 \q_stop
+  }
+\cs_new:Npn \flag_height_end:ww #1 ; #2 \q_stop { #1 }
+\cs_new:Npn \flag_raise:n #1
   {
-    LaTeX~was~asked~to~define~the~flag~#1,~but~it~has~already~
-    been~defined~as~a~flag.~The~flag~module~is~mostly~meant~
-    for~kernel~use,~and~booleans~should~be~preferred.
+    \cs:w flag_trap_#1:w \exp_after:wN \cs_end:
+    \int_value:w \flag_height:n {#1} ;
   }
 %% 
 %%
diff --git a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3regex.sty b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3regex.sty
index 8d1f45803f9..f88c8fa4e15 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3regex.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3regex.sty
@@ -46,19 +46,63 @@
 %%
 %% -----------------------------------------------------------------------
 \RequirePackage{expl3}
-\GetIdInfo$Id: l3regex.dtx 3200 2012-01-16 03:50:54Z bruno $
+\GetIdInfo$Id: l3regex.dtx 3259 2012-01-29 20:50:48Z bruno $
   {L3 Experimental Regular Expressions}
 \ProvidesExplPackage
   {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
 \RequirePackage{l3str, l3tl-analysis, l3flag}
 \cs_new:Npn \regex_tmp:w { }
-\tl_new:N   \l_regex_tmpa_tl
-\tl_new:N   \l_regex_tmpb_tl
-\tl_new:N   \l_regex_tmpc_tl
-\int_new:N  \l_regex_tmpa_int
-\int_new:N  \l_regex_tmpb_int
-\flag_new:N \l_regex_group_begin_flag
-\flag_new:N \l_regex_group_end_flag
+\tl_new:N   \l_regex_internal_a_tl
+\tl_new:N   \l_regex_internal_b_tl
+\int_new:N  \l_regex_internal_a_int
+\int_new:N  \l_regex_internal_b_int
+\int_new:N  \l_regex_internal_c_int
+\tl_new:N   \g_regex_internal_tl
+\tl_const:Nn \c_regex_d_tl
+  { \regex_item_range:nn \c_forty_eight { 57 } } % 0--9
+\tl_const:Nn \c_regex_h_tl
+  {
+    \regex_item_equal:n \c_thirty_two % space
+    \regex_item_equal:n \c_nine       % tab
+  }
+\tl_const:Nn \c_regex_s_tl
+  {
+    \regex_item_equal:n \c_thirty_two % space
+    \regex_item_equal:n \c_nine       % tab
+    \regex_item_equal:n \c_ten        % lf
+    \regex_item_equal:n \c_twelve     % ff
+    \regex_item_equal:n \c_thirteen   % cr
+  }
+\tl_const:Nn \c_regex_v_tl
+  { \regex_item_range:nn \c_ten \c_thirteen } % lf, vtab, ff, cr
+\tl_const:Nn \c_regex_w_tl
+  {
+    \regex_item_range:nn \c_ninety_seven { 122 } % a--z
+    \regex_item_range:nn \c_sixty_five   {  90 } % A--Z
+    \regex_item_range:nn \c_forty_eight  {  57 } % 0--9
+    \regex_item_equal:n  { 95 } % _
+  }
+\tl_const:Nn \c_regex_D_tl
+  { \c_regex_d_tl \regex_break_point:TF { } \regex_break_true:w }
+\tl_const:Nn \c_regex_H_tl
+  { \c_regex_h_tl \regex_break_point:TF { } \regex_break_true:w }
+\tl_const:Nn \c_regex_S_tl
+  { \c_regex_s_tl \regex_break_point:TF { } \regex_break_true:w }
+\tl_const:Nn \c_regex_V_tl
+  { \c_regex_v_tl \regex_break_point:TF { } \regex_break_true:w }
+\tl_const:Nn \c_regex_W_tl
+  { \c_regex_w_tl \regex_break_point:TF { } \regex_break_true:w }
+\tl_const:Nn \c_regex_N_tl
+  {
+    \regex_item_equal:n \c_ten
+    \regex_break_point:TF { } { \regex_break_true:w }
+  }
+\tl_const:cn { c_regex_._tl }
+  {
+    \if_num:w \l_regex_current_char_int > - \c_two
+      \exp_after:wN \regex_break_true:w
+    \fi:
+  }
 \int_new:N \l_regex_build_mode_int
 \int_new:N  \l_regex_max_state_int
 \int_new:N  \l_regex_left_state_int
@@ -87,105 +131,56 @@
 \int_const:Nn \c_regex_catcode_A_int { "4000000 }
 \int_const:Nn \c_regex_catcodes_all_int { "5515155 }
 \bool_new:N \l_regex_catcodes_bool
-\tl_new:N \l_regex_tmpa_regex_tl
-\bool_new:N \l_regex_class_bool
-\tl_new:N   \l_regex_class_tl
-\bool_new:N \l_regex_class_saved_bool
-\tl_new:N   \l_regex_class_saved_tl
-\tl_const:Nn \c_regex_d_tl
-  {
-    \regex_item_range:nn { \c_forty_eight } { 57 } % 0--9
-  }
-\tl_const:Nn \c_regex_D_tl
-  {
-    \regex_item_geq:n { \c_fifty_eight } % > `9
-    \regex_item_range:nn { \c_zero } { 47 } % 0
-  }
-\tl_const:Nn \c_regex_h_tl
-  {
-    \regex_item_equal:n { \c_thirty_two } % space
-    \regex_item_equal:n { \c_nine } % tab
-  }
-\tl_const:Nn \c_regex_H_tl
-  {
-    \regex_item_geq:n { 33 } % > space
-    \regex_item_range:nn { \c_ten } { 31 } % tab < ... < space
-    \regex_item_range:nn { \c_zero } { \c_eight } % < tab
-  }
-\tl_const:Nn \c_regex_s_tl
-  {
-    \regex_item_equal:n  { \c_thirty_two } % space
-    \regex_item_range:nn { \c_nine } { \c_ten } % tab, lf
-    \regex_item_range:nn { \c_twelve } { \c_thirteen } % ff, cr
-  }
-\tl_const:Nn \c_regex_S_tl
-  {
-    \regex_item_geq:n    { 33 } % > space
-    \regex_item_range:nn { \c_fourteen } { 31 } % tab < ... < space
-    \regex_item_range:nn { \c_zero } { \c_eight } % < tab
-    \regex_item_equal:n  { \c_eleven } % vtab
-  }
-\tl_const:Nn \c_regex_v_tl
-  {
-    \regex_item_range:nn { \c_ten } { \c_thirteen } % lf, vtab, ff, cr
-  }
-\tl_const:Nn \c_regex_V_tl
-  {
-    \regex_item_geq:n    { \c_fourteen } % >cr
-    \regex_item_range:nn { \c_zero } { \c_nine } % < lf
-  }
-\tl_const:Nn \c_regex_w_tl
-  {
-    \regex_item_range:nn { \c_ninety_seven } { 122 } % a--z
-    \regex_item_range:nn { \c_sixty_five } { 90 } % A--Z
-    \regex_item_range:nn { \c_forty_eight } { 57 } % 0--9
-    \regex_item_equal:n  { 95 } % _
-  }
-\tl_const:Nn \c_regex_W_tl
-  {
-    \regex_item_range:nn { \c_zero } { 47 } % <`0
-    \regex_item_range:nn { \c_fifty_eight } { 64 } % (`9+1)--(`A-1)
-    \regex_item_range:nn { \c_ninety_one } { 94 } % (`Z+1)--(`_-1)
-    \regex_item_equal:n  { 96 } % `
-    \regex_item_geq:n    { \c_one_hundred_twenty_three } % z
-  }
-\tl_const:Nn \c_regex_N_tl
-  {
-    \regex_item_geq:n { \c_eleven } % > lf
-    \regex_item_range:nn { \c_zero } { \c_nine } % < lf
-  }
+\bool_new:N \l_regex_tests_bool
+\tl_new:N   \l_regex_tests_tl
+\bool_new:N \l_regex_tests_saved_bool
+\tl_new:N   \l_regex_tests_saved_tl
+\int_new:N  \l_regex_catcodes_saved_int
+\int_new:N \l_regex_min_index_int
+\int_new:N \l_regex_max_index_int
 \int_new:N \l_regex_nesting_int
-\int_new:N \l_regex_min_step_int
-\int_new:N \l_regex_max_step_int
-\int_new:N \l_regex_current_step_int
-\int_new:N \l_regex_start_step_int
-\int_new:N \l_regex_success_step_int
-\int_new:N \l_regex_unique_id_int
+\int_new:N \l_regex_current_index_int
+\int_new:N \l_regex_start_index_int
+\int_new:N \l_regex_success_index_int
 \int_new:N \l_regex_current_char_int
 \int_new:N \l_regex_current_catcode_int
-\tl_new:N \l_regex_current_token_tl
+\tl_new:N  \l_regex_current_token_tl
 \int_new:N \l_regex_last_char_int
 \int_new:N \l_regex_case_changed_char_int
 \bool_new:N \l_regex_caseless_bool
 \int_new:N \l_regex_current_state_int
 \prop_new:N \l_regex_current_submatches_prop
 \prop_new:N \l_regex_success_submatches_prop
-\int_new:N \l_regex_max_index_int
+\int_new:N \l_regex_step_int
+\int_new:N \l_regex_max_active_int
 \tl_new:N \l_regex_every_match_tl
+\bool_new:N \l_regex_fresh_thread_bool
+\bool_new:N \l_regex_success_empty_bool
+\cs_new_eq:NN \regex_if_two_empty_matches:F \use:n
 \bool_new:N \g_regex_success_bool
 \bool_new:N \l_regex_saved_success_bool
 \bool_new:N \l_regex_success_match_bool
-\cs_new_protected:Npn \regex_last_match_empty_no:F #1 {#1}
-\cs_new_protected:Npn \regex_last_match_empty_yes:F
-  { \int_compare:nNnF \l_regex_start_step_int = \l_regex_current_step_int }
-\cs_new_eq:NN \regex_last_match_empty:F \regex_last_match_empty_no:F
-\bool_new:N \l_regex_success_empty_bool
-\bool_new:N \l_regex_fresh_thread_bool
-\int_new:N \l_regex_replacement_int
+\tl_const:Nn \c_regex_no_match_regex
+  {
+    \regex_nfa:Nw \c_regex_no_match_regex
+      \l_regex_max_state_int = \c_one
+      \l_regex_capturing_group_int = \c_zero
+      \tex_toks:D \c_zero { \s_stop }
+    \s_stop
+  }
+\cs_new_protected:Npn \regex_new:N #1
+  {
+    \chk_if_free_cs:N #1
+    \cs_gset_eq:NN #1 \c_regex_no_match_regex
+  }
+\regex_new:N \l_regex_internal_regex
 \int_new:N \l_regex_replacement_csnames_int
+\int_new:N \l_regex_replacement_int
 \int_new:N \l_regex_submatch_int
 \int_new:N \l_regex_submatch_start_int
 \int_new:N \l_regex_match_count_int
+\flag_new:n { regex_begin }
+\flag_new:n { regex_end }
 \cs_new_protected:Npn \regex_toks_put_left:Nx #1#2
   {
     \cs_set_nopar:Npx \regex_tmp:w \s_stop { \s_stop #2 }
@@ -198,11 +193,22 @@
     \tex_toks:D #1 \exp_after:wN
       { \tex_the:D \tex_toks:D \exp_after:wN #1 \regex_tmp:w }
   }
-\cs_new:Npn \regex_query_substr:nn #1#2
+\cs_new:Npn \regex_toks_range:nn #1#2
+  {
+    \exp_after:wN \regex_toks_range:ww
+    \int_use:N \int_eval:w #1 \exp_after:wN ;
+    \int_use:N \int_eval:w #2 ;
+    \prg_break_point:n { }
+  }
+\cs_new:Npn \regex_toks_range:ww #1 ; #2 ;
   {
-    \if_num:w \int_eval:w #1 < \int_eval:w #2 \int_eval_end:
-      \str_aux_toks_range:nn {#1} {#2}
+    \if_num:w #1 < #2 \exp_stop_f:
+    \else:
+      \exp_after:wN \prg_map_break:
     \fi:
+    \tex_the:D \tex_toks:D #1 \exp_stop_f:
+    \exp_after:wN \regex_toks_range:ww
+      \int_use:N \int_eval:w #1 + \c_one ; #2 ;
   }
 \cs_new:Npn \regex_query_submatch:nn #1#2
   {
@@ -213,41 +219,63 @@
   }
 \cs_new:Npn \regex_query_submatch:w #1 ;
   {
-    \regex_query_substr:nn
+    \regex_toks_range:nn
       { \tex_skip:D #1 }
       { \etex_gluestretch:D \tex_skip:D #1 }
   }
 \cs_new_protected:Npn \regex_seq_pop_int:NN #1#2
   {
-    \seq_pop:NN #1 \l_regex_tmpa_tl
-    \int_set:Nn #2 \l_regex_tmpa_tl
+    \seq_pop:NN #1 \l_regex_internal_a_tl
+    \int_set:Nn #2 \l_regex_internal_a_tl
   }
 \cs_new_protected:Npn \regex_seq_get_int:NN #1#2
   {
-    \seq_get:NN #1 \l_regex_tmpa_tl
-    \int_set:Nn #2 \l_regex_tmpa_tl
+    \seq_get:NN #1 \l_regex_internal_a_tl
+    \int_set:Nn #2 \l_regex_internal_a_tl
   }
 \cs_new_protected:Npn \regex_seq_push_int:NN #1#2
   { \seq_push:No #1 { \int_use:N #2 } }
 \cs_new_protected:Npn \regex_seq_pop_use:N #1
   {
-    \seq_pop:NN #1 \l_regex_tmpa_tl
-    \l_regex_tmpa_tl
+    \seq_pop:NN #1 \l_regex_internal_a_tl
+    \l_regex_internal_a_tl
   }
 \cs_new_protected:Npn \regex_seq_get_use:N #1
   {
-    \seq_get:NN #1 \l_regex_tmpa_tl
-    \l_regex_tmpa_tl
+    \seq_get:NN #1 \l_regex_internal_a_tl
+    \l_regex_internal_a_tl
   }
-\cs_new_protected:Npn \regex_break_true:w
-   #1 \regex_break_point:TF #2 #3 {#2}
-\cs_new_protected:Npn \regex_break_point:TF #1 #2 { #2 }
-\cs_new_protected_nopar:Npn \regex_item_dot:
+\cs_new_protected:Npn \regex_get_digits:nw #1
   {
-    \if_num:w \l_regex_current_char_int > - \c_two
-      \exp_after:wN \regex_break_true:w
+    \tex_afterassignment:D \regex_tmp:w
+    \cs_set_nopar:Npx \regex_tmp:w
+      {
+        \exp_not:n {#1}
+        { \if_false: } } \fi:
+        \regex_get_digits_aux:NN
+  }
+\cs_new:Npn \regex_get_digits_aux:NN #1#2
+  {
+    \if_meaning:w \regex_build_raw:N #1
+      \if_num:w 9 < 1 \exp_not:N #2 \exp_stop_f:
+        #2
+      \else:
+        \regex_get_digits_end:w #1 #2
+      \fi:
+    \else:
+      \regex_get_digits_end:w #1 #2
     \fi:
+    \regex_get_digits_aux:NN
+  }
+\cs_new:Npn \regex_get_digits_end:w #1 \fi: #2 \regex_get_digits_aux:NN
+  {
+    \fi: #2
+    \if_false: { { \fi: } }
+    #1
   }
+\cs_new_protected:Npn \regex_break_true:w
+   #1 \regex_break_point:TF #2 #3 {#2}
+\cs_new_protected:Npn \regex_break_point:TF #1 #2 { #2 }
 \cs_new_protected:Npn \regex_item_caseful_equal:n #1
   {
     \if_num:w #1 = \l_regex_current_char_int
@@ -316,16 +344,19 @@
     \cs_set:Npn \regex_item_range:nn { \regex_item_caseful_range:nn }
     \cs_set:Npn \regex_item_geq:n    { \regex_item_caseful_geq:n }
   }
+\cs_new_protected:Npn \regex_item_catcode_aux:
+  {
+    "
+    \if_case:w \l_regex_current_catcode_int
+         1       \or: 4       \or: 10      \or: 40
+    \or: 100     \or:         \or: 1000    \or: 4000
+    \or: 10000   \or:         \or: 100000  \or: 400000
+    \or: 1000000 \or: 4000000 \else: 1*\c_zero
+    \fi:
+  }
 \cs_new_protected:Npn \regex_item_catcode:nT #1
   {
-    \if_int_odd:w \int_eval:w #1 / "
-        \if_case:w \l_regex_current_catcode_int
-             1       \or: 4       \or: 10      \or: 40
-        \or: 100     \or:         \or: 1000    \or: 4000
-        \or: 10000   \or:         \or: 100000  \or: 400000
-        \or: 1000000 \or: 4000000 \else: 1*\c_zero
-        \fi:
-      \int_eval_end:
+    \if_int_odd:w \int_eval:w #1 / \regex_item_catcode_aux: \int_eval_end:
       \exp_after:wN \use:n
     \else:
       \exp_after:wN \use_none:n
@@ -335,9 +366,9 @@
   {
     \int_compare:nNnT \l_regex_current_catcode_int = \c_zero
       {
-        \tl_set:Nn \l_regex_tmpa_regex_tl {#1}
+        \tl_set:Nn \l_regex_internal_regex {#1}
         \bool_set_eq:NN \l_regex_saved_success_bool \g_regex_success_bool
-        \exp_args:NNx \regex_match:NnTF \l_regex_tmpa_regex_tl
+        \exp_args:NNx \regex_match:NnTF \l_regex_internal_regex
           {
             \exp_after:wN \exp_after:wN
             \exp_after:wN \cs_to_str:N \l_regex_current_token_tl
@@ -349,43 +380,140 @@
           { \bool_gset_eq:NN \g_regex_success_bool \l_regex_saved_success_bool }
       }
   }
-\cs_new_protected:Npn \regex_get_digits:nw #1
+\cs_new_protected:Npn \regex_escape_use:nnnn #1#2#3#4
   {
-    \tex_afterassignment:D \regex_tmp:w
-    \cs_set_nopar:Npx \regex_tmp:w
+    \group_begin:
+      \cs_set_nopar:Npn \regex_escape_unescaped:N ##1 { #1 }
+      \cs_set_nopar:Npn \regex_escape_escaped:N ##1 { #2 }
+      \cs_set_nopar:Npn \regex_escape_raw:N ##1 { #3 }
+      \int_set:Nn \tex_escapechar:D { 92 }
+      \str_gset_other:Nn \g_regex_internal_tl {#4}
+      \int_zero:N \l_regex_internal_a_int
+      \tl_set:Nx \l_regex_internal_a_tl
+        {
+          \exp_after:wN \regex_escape_loop:N \g_regex_internal_tl
+          { break } \prg_break_point:n { }
+        }
+      \use:x
+        {
+          \group_end:
+          \regex_toks_range:nn \c_zero \l_regex_internal_a_int
+          \exp_not:o \l_regex_internal_a_tl
+        }
+  }
+\cs_new:Npn \regex_escape_loop:N #1
+  {
+    \cs_if_exist_use:cF { regex_escape_\token_to_str:N #1:w }
+      { \regex_escape_unescaped:N #1 }
+    \regex_escape_loop:N
+  }
+\cs_new_nopar:cpn { regex_escape_ \c_backslash_str :w }
+    \regex_escape_loop:N #1
+  {
+    \cs_if_exist_use:cF { regex_escape_/\token_to_str:N #1:w }
+      { \regex_escape_escaped:N #1 }
+    \regex_escape_loop:N
+  }
+\cs_new_eq:NN \regex_escape_unescaped:N ?
+\cs_new_eq:NN \regex_escape_escaped:N   ?
+\cs_new_eq:NN \regex_escape_raw:N       ?
+\cs_new_eq:NN \regex_escape_break:w \prg_map_break:
+\cs_new_nopar:cpn { regex_escape_/break:w }
+  {
+    \if_false: { \fi: }
+    \msg_kernel_error:nn { regex } { trailing-backslash }
+    \exp_after:wN \use_none:n \exp_after:wN { \if_false: } \fi:
+  }
+\cs_new_nopar:cpn { regex_escape_~:w } { }
+\cs_new_nopar:cpx { regex_escape_/a:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^G }
+\cs_new_nopar:cpx { regex_escape_/t:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^I }
+\cs_new_nopar:cpx { regex_escape_/n:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^J }
+\cs_new_nopar:cpx { regex_escape_/f:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^L }
+\cs_new_nopar:cpx { regex_escape_/r:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^M }
+\cs_new_nopar:cpx { regex_escape_/e:w }
+  { \exp_not:N \regex_escape_raw:N \iow_char:N \^^[ }
+\cs_new_nopar:cpn { regex_escape_/x:w } \regex_escape_loop:N
+  {
+    \if_false: { \fi: }
+    \tex_toks:D \l_regex_internal_a_int
+      \exp_after:wN { \l_regex_internal_a_tl }
+    \int_incr:N \l_regex_internal_a_int
+    \int_zero:N \l_regex_current_char_int
+    \regex_escape_x_test:N
+  }
+\cs_new_protected:Npx \regex_escape_x_test:N #1
+  {
+    \exp_not:N \token_if_eq_charcode:NNTF \c_space_token #1
+      { \exp_not:N \regex_escape_x_test:N }
       {
-        \exp_not:n {#1}
-        { \if_false: } } \fi:
-        \regex_get_digits_aux:NN
+        \l_regex_current_char_int = "0
+          \exp_not:N \token_if_eq_charcode:NNTF \c_lbrace_str #1
+            { \exp_not:N \regex_escape_x_braced_loop:N }
+            { \exp_not:N \regex_escape_x_unbraced_i:N #1 }
+      }
   }
-\cs_new:Npn \regex_get_digits_aux:NN #1#2
+\cs_new:Npn \regex_escape_x_unbraced_i:N #1
   {
-    \if_meaning:w \regex_build_raw:N #1
-      \if_charcode:w \c_space_token \exp_not:N #2
-      \else:
-        \if_num:w 9 < 1 \exp_not:N #2 \exp_stop_f:
-          #2
-        \else:
-          \regex_get_digits_end:w #1 #2
-        \fi:
-      \fi:
-    \else:
-      \regex_get_digits_end:w #1 #2
-    \fi:
-    \regex_get_digits_aux:NN
+    \str_aux_hexadecimal_use:NTF #1
+      { \regex_escape_x_unbraced_ii:N }
+      { \exp_stop_f: \regex_escape_x_end: #1 }
   }
-\cs_new:Npn \regex_get_digits_end:w #1 \fi: #2 \regex_get_digits_aux:NN
+\cs_new:Npn \regex_escape_x_unbraced_ii:N #1
   {
-    \fi: #2
-    \if_false: { { \fi: } }
-    #1
+    \token_if_eq_charcode:NNTF \c_space_token #1
+      { \regex_escape_x_unbraced_ii:N }
+      {
+        \str_aux_hexadecimal_use:NTF #1
+          { \exp_stop_f: \regex_escape_x_end: }
+          { \exp_stop_f: \regex_escape_x_end: #1 }
+      }
+  }
+\cs_new:Npn \regex_escape_x_braced_loop:N #1
+  {
+    \token_if_eq_charcode:NNTF \c_space_token #1
+      { \regex_escape_x_braced_loop:N }
+      {
+        \str_aux_hexadecimal_use:NTF #1
+          { \regex_escape_x_braced_loop:N }
+          { \exp_stop_f: \regex_escape_x_braced_end:N #1 }
+      }
   }
-\prg_new_conditional:Npnn \regex_token_if_other_digit:N #1 { TF }
+\cs_new_protected:Npx \regex_escape_x_braced_end:N #1
   {
-    \if_num:w \c_nine < 1 \exp_not:N #1 \exp_stop_f:
-      \prg_return_true: \else: \prg_return_false: \fi:
+    \exp_not:N \token_if_eq_charcode:NNTF \c_rbrace_str #1
+      { \exp_not:N \regex_escape_x_end: }
+      {
+        \msg_kernel_error:nnx { regex } { x-missing-rbrace }
+          { \int_use:N \l_regex_current_char_int }
+        \exp_not:N \regex_escape_x_end: #1
+      }
   }
-\prg_new_conditional:Npnn \regex_aux_char_if_special:N #1 { TF }
+\group_begin:
+  \char_set_catcode_other:N \^^@
+  \cs_new_protected_nopar:Npn \regex_escape_x_end:
+    {
+      \if_num:w \l_regex_current_char_int > \c_max_char_int
+        \msg_kernel_error:nnx { regex } { x-overflow }
+          { \int_use:N \l_regex_current_char_int }
+        \exp_after:wN \use:n
+      \else:
+        \tex_lccode:D \c_zero \l_regex_current_char_int
+        \exp_after:wN \tl_to_lowercase:n
+      \fi:
+        {
+          \tl_set:Nx \l_regex_internal_a_tl
+            { \if_false: } \fi:
+            \regex_escape_raw:N ^^@
+            \regex_escape_loop:N
+        }
+    }
+\group_end:
+\prg_new_conditional:Npnn \regex_char_if_special:N #1 { TF }
   {
     \if_num:w `#1 < \c_ninety_one
       \if_num:w `#1 < \c_fifty_eight
@@ -407,7 +535,7 @@
       \fi:
     \fi:
   }
-\prg_new_conditional:Npnn \regex_aux_char_if_alphanumeric:N #1 { TF }
+\prg_new_conditional:Npnn \regex_char_if_alphanumeric:N #1 { TF }
   {
     \if_num:w `#1 < \c_ninety_one
       \if_num:w `#1 < \c_fifty_eight
@@ -434,6 +562,18 @@
       \exp_after:wN \use_ii:nn
     \fi:
   }
+\cs_new_nopar:Npn \regex_build_if_assertions_forbidden:TF
+  {
+    \if_int_odd:w \l_regex_build_mode_int
+      \exp_after:wN \use_i:nn
+    \else:
+      \if_int_compare:w \l_regex_build_mode_int > \c_zero
+        \exp_after:wN \exp_after:wN \exp_after:wN \use_i:nn
+      \else:
+        \exp_after:wN \exp_after:wN \exp_after:wN \use_ii:nn
+      \fi:
+    \fi:
+  }
 \cs_new_protected_nopar:Npn \regex_build_new_state:
   {
     \tex_toks:D \l_regex_max_state_int { \s_stop }
@@ -456,61 +596,35 @@
         #3 { \int_eval:n { #4 - \l_regex_left_state_int } }
       }
   }
-\cs_new_protected:Npn \regex_build:n #1
-  {
-    \int_set_eq:NN \l_regex_build_mode_int \c_zero
-    \regex_build:w
-    \regex_build_new_state:
-    \regex_toks_put_right:Nx \l_regex_left_state_int
-      { \regex_action_start_wildcard: }
-    \regex_build_open_aux:
-      \str_escape_use:NNNn
-        \regex_build_i_unescaped:N
-        \regex_build_i_escaped:N
-        \regex_build_i_raw:N
-        { #1 }
-      \prg_do_nothing: \prg_do_nothing:
-      \prg_do_nothing: \prg_do_nothing:
-    \regex_build_end:
-  }
-\cs_new:Npn \regex_build_i_unescaped:N #1
-  {
-    \regex_aux_char_if_special:NTF #1
-      { \exp_not:N \regex_build_special:N #1 }
-      { \exp_not:N \regex_build_raw:N #1 }
-  }
-\cs_new:Npn \regex_build_i_escaped:N #1
-  {
-    \regex_aux_char_if_alphanumeric:NTF #1
-      { \exp_not:N \regex_build_escaped:N #1 }
-      { \exp_not:N \regex_build_raw:N #1 }
-  }
-\cs_new:Npn \regex_build_i_raw:N #1
-  { \exp_not:N \regex_build_raw:N #1 }
-\cs_new_protected:Npn \regex_build_special:N #1
-  {
-    \cs_if_exist_use:cF { regex_build_#1: }
-      { \regex_build_raw:N #1 }
-  }
-\cs_new_protected:Npn \regex_build_escaped:N #1
-  {
-    \cs_if_exist_use:cF { regex_build_/#1: }
-      { \regex_build_raw:N #1 }
-  }
 \cs_new_protected_nopar:Npn \regex_build:w
   {
     \int_set_eq:NN \l_regex_catcodes_default_int \c_regex_catcodes_all_int
-    \int_set_eq:NN \l_regex_capturing_group_int  \c_zero
+    \int_set_eq:NN \l_regex_catcodes_int \l_regex_catcodes_default_int
+    \int_set_eq:NN \l_regex_capturing_group_int \c_zero
+    \tl_clear:N \l_regex_tests_tl
+    \bool_set_true:N \l_regex_tests_bool
     \int_zero:N \l_regex_max_state_int
     \regex_build_new_state:
-    \tl_clear:N \l_regex_class_tl
-    \bool_set_true:N \l_regex_class_bool
-    \int_set_eq:NN \l_regex_catcodes_int \l_regex_catcodes_default_int
   }
 \cs_new_protected_nopar:Npn \regex_build_end:
   {
-    \regex_seq_push_int:NN \l_regex_capturing_group_seq \c_zero
-    \regex_build_close_aux: \regex_build_group_:
+    \regex_build_exit_class:
+    \regex_build_exit_groups:
+    \regex_toks_put_right:Nx \l_regex_right_state_int
+      { \regex_action_success: }
+    \int_incr:N \l_regex_capturing_group_int
+  }
+\cs_new_protected_nopar:Npn \regex_build_exit_class:
+  {
+    \regex_build_if_in_class:TF
+      {
+        \msg_kernel_error:nn { regex } { missing-rbrack }
+        \use:c { regex_build_]: }
+      }
+      { }
+  }
+\cs_new_protected_nopar:Npn \regex_build_exit_groups:
+  {
     \seq_if_empty:NF \l_regex_capturing_group_seq
       {
         \msg_kernel_error:nnx { regex } { missing-rparen }
@@ -519,23 +633,61 @@
           { \seq_length:N \l_regex_capturing_group_seq }
           { \regex_build_close_aux: \regex_build_group_: }
       }
-    \regex_toks_put_right:Nx \l_regex_right_state_int
-      { \regex_action_success: }
-    \int_incr:N \l_regex_capturing_group_int
+  }
+\cs_new_protected:Npn \regex_build:n #1
+  {
+    \regex_build:w
+      \int_set_eq:NN \l_regex_build_mode_int \c_zero
+      \regex_build_new_state:
+      \regex_toks_put_right:Nx \l_regex_left_state_int
+        { \regex_action_start_wildcard: }
+      \regex_build_open_aux:
+        \regex_escape_use:nnnn
+          {
+            \regex_char_if_special:NTF ##1
+              \regex_build_special:N \regex_build_raw:N ##1
+          }
+          {
+            \regex_char_if_alphanumeric:NTF ##1
+              \regex_build_escaped:N \regex_build_raw:N ##1
+          }
+          { \regex_build_raw:N ##1 }
+          { #1 }
+        \prg_do_nothing: \prg_do_nothing:
+        \prg_do_nothing: \prg_do_nothing:
+      \int_compare:nNnT \l_regex_build_mode_int < \c_zero
+        {
+          \msg_kernel_error:nn { regex } { c-missing-rbrace }
+          \exp_after:wN \regex_build_special:N \c_rbrace_str
+        }
+      \seq_put_right:Nn \l_regex_capturing_group_seq {0}
+      \regex_build_close_aux: \regex_build_group_:
+    \regex_build_end:
+  }
+\cs_new_protected:Npn \regex_build_special:N #1
+  {
+    \cs_if_exist_use:cF { regex_build_#1: }
+      { \regex_build_raw:N #1 }
+  }
+\cs_new_protected:Npn \regex_build_escaped:N #1
+  {
+    \cs_if_exist_use:cF { regex_build_/#1: }
+      { \regex_build_raw:N #1 }
   }
 \cs_new_protected:Npn \regex_build_one:n #1
   { \regex_build_one:x { \exp_not:n {#1} } }
 \cs_new_protected:Npn \regex_build_one:x #1
   {
-    \tl_put_right:Nx \l_regex_class_tl
+    \tl_put_right:Nx \l_regex_tests_tl
       {
-        \if_num:w \l_regex_catcodes_int = \c_regex_catcodes_all_int
-          \exp_after:wN \use:n
-        \else:
+        \if_num:w \l_regex_catcodes_int < \c_regex_catcodes_all_int
           \regex_item_catcode:nT { \int_use:N \l_regex_catcodes_int }
+        \else:
+          \exp_after:wN \use:n
         \fi:
         {#1}
       }
+    \int_set_eq:NN \l_regex_catcodes_int \l_regex_catcodes_default_int
     \if_num:w \l_regex_build_mode_int = \c_two
       \l_regex_build_mode_int = \c_zero
     \else:
@@ -547,28 +699,21 @@
       \exp_after:wN \regex_build_one_quantifier:
     \fi:
   }
-\cs_new:Npn \regex_build_tmp_class:n #1
+\cs_new:Npn \regex_tests_action_cost:n #1
   {
-    \exp_not:o \l_regex_class_tl
-    \bool_if:NTF \l_regex_class_bool
+    \exp_not:o \l_regex_tests_tl
+    \bool_if:NTF \l_regex_tests_bool
       { \regex_break_point:TF { \regex_action_cost:n {#1} } { } }
       { \regex_break_point:TF { } { \regex_action_cost:n {#1} } }
   }
-\cs_new_protected:Npn \regex_class_put:N #1
-  {
-    \tl_put_right:Nx \l_regex_class_tl
-      { \regex_item_equal:n { \int_value:w `#1 ~ } }
-  }
-\cs_new_protected:Npn \regex_class_put:NN #1#2
-  {
-    \tl_put_right:Nx \l_regex_class_tl
-      { \regex_item_range:nn { \int_value:w `#1 ~ } { \int_value:w `#2 ~ } }
-  }
-\cs_new_protected:Npn \regex_build_raw_alphanum_is_error:N #1
+\cs_new_protected:Npn \regex_build_raw_error:N #1
   {
-    \regex_aux_char_if_alphanumeric:NTF #1
-      { \msg_kernel_error:nnx { regex } { class-bad-escape } { #1 } }
-      { \regex_build_raw:N #1 }
+    \if_int_odd:w \l_regex_build_mode_int
+      \msg_kernel_error:nnx { regex } { class-bad-escape } {#1}
+    \else:
+      \msg_kernel_error:nnx { regex } { catcode-bad-escape } {#1}
+    \fi:
+    \regex_build_raw:N #1
   }
 \cs_new_protected:Npn \regex_build_raw:N #1#2#3
   {
@@ -586,39 +731,45 @@
     \token_if_eq_meaning:NNTF #2 \regex_build_escaped:N % [
       { \use_i:nn } { \str_if_eq:nnTF { #2#3 } { \regex_build_special:N ] } }
       {
-        \msg_kernel_warning:nnx { regex } { end-range-missing } % [
-          { #1 - \if_meaning:w #3 ] \else: \c_backslash_str \fi: #3 }
-        \regex_class_put:N #1
-        \regex_class_put:N -
+        \msg_kernel_warning:nnxx { regex } { range-missing-end } % [
+          {#1} { \token_if_eq_charcode:NNF #3 ] { \c_backslash_str } #3 }
+        \tl_put_right:Nx \l_regex_tests_tl
+          {
+            \regex_item_equal:n { \int_value:w `#1 ~ }
+            \regex_item_equal:n { \int_value:w `- ~ }
+          }
         #2#3
       }
       {
         \if_num:w `#1 > `#3 \exp_stop_f:
-          \msg_kernel_error:nnxx { regex } { backwards-range } {#1} {#3}
+          \msg_kernel_error:nnxx { regex } { range-backwards } {#1} {#3}
         \else:
-          \if_num:w `#1 = `#3 \exp_stop_f:
-            \regex_class_put:N #3
-          \else:
-            \regex_class_put:NN #1#3
-          \fi:
+          \tl_put_right:Nx \l_regex_tests_tl
+            {
+              \if_num:w `#1 = `#3 \exp_stop_f:
+                \regex_item_equal:n
+              \else:
+                \regex_item_range:nn { \int_value:w `#1 ~ }
+              \fi:
+              { \int_value:w `#3 ~ }
+            }
         \fi:
       }
   }
-\cs_new_protected_nopar:cpn { regex_build_.: }
+\cs_new_protected_nopar:cpx { regex_build_.: }
   {
-    \regex_build_if_in_class:TF
+    \exp_not:N \regex_build_if_in_class:TF
       { \regex_build_raw:N . }
-      { \regex_build_one:x \regex_item_dot: }
+      { \regex_build_one:n \exp_not:c { c_regex_._tl } }
   }
 \tl_map_inline:nn { dDhHsSvVwWN }
   {
     \cs_new_protected_nopar:cpx { regex_build_/#1: }
       { \regex_build_one:n \exp_not:c { c_regex_#1_tl } }
   }
-\cs_new_protected:Npn \regex_build_simple_assertion:Nn #1#2
+\cs_new_protected:Npn \regex_build_simple_assertion:nn #1#2
   {
-    \regex_build_if_in_class:TF
-      { \regex_build_raw_alphanum_is_error:N #1 }
+    \regex_build_if_assertions_forbidden:TF {#1}
       {
         \regex_build_new_state:
         \regex_toks_put_right:Nx \l_regex_left_state_int
@@ -632,47 +783,50 @@
                   }
               }
           }
-        %^^A \regex_assertion_quantifier:
+        %^^A todo: add \regex_assertion_quantifier:
       }
   }
 \cs_new_protected_nopar:cpn { regex_build_^: }
   {
-    \regex_build_simple_assertion:Nn ^
-      { \int_compare:nNnT \l_regex_min_step_int = \l_regex_current_step_int }
+    \regex_build_simple_assertion:nn { \regex_build_raw:N ^ }
+      { \int_compare:nNnT \l_regex_min_index_int = \l_regex_current_index_int }
   }
 \cs_new_protected_nopar:cpn { regex_build_/A: }
   {
-    \regex_build_simple_assertion:Nn A
-      { \int_compare:nNnT \l_regex_min_step_int = \l_regex_current_step_int }
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N A }
+      { \int_compare:nNnT \l_regex_min_index_int = \l_regex_current_index_int }
   }
 \cs_new_protected_nopar:cpn { regex_build_/G: }
   {
-    \regex_build_simple_assertion:Nn G
-      { \int_compare:nNnT \l_regex_start_step_int = \l_regex_current_step_int }
-  }
-\cs_new_protected_nopar:cpn { regex_build_$: } % $
-  {
-    \regex_build_simple_assertion:Nn $ % $
-      { \int_compare:nNnT \l_regex_current_char_int < \c_minus_one }
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N G }
+      { \int_compare:nNnT \l_regex_start_index_int = \l_regex_current_index_int }
   }
+\group_begin:
+  \char_set_catcode_other:N \$
+  \cs_new_protected_nopar:cpn { regex_build_$: } % $
+    {
+      \regex_build_simple_assertion:nn { \regex_build_raw:N $ } % $
+        { \int_compare:nNnT \l_regex_current_char_int < \c_minus_one }
+    }
+\group_end:
 \cs_new_protected_nopar:cpn { regex_build_/Z: }
   {
-    \regex_build_simple_assertion:Nn Z
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N Z }
       { \int_compare:nNnT \l_regex_current_char_int < \c_minus_one }
   }
 \cs_new_protected_nopar:cpn { regex_build_/z: }
   {
-    \regex_build_simple_assertion:Nn z
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N z }
       { \int_compare:nNnT \l_regex_current_char_int < \c_minus_one }
   }
 \cs_new_protected_nopar:cpn { regex_build_/b: }
   {
-    \regex_build_simple_assertion:Nn b
-      { \regex_if_word_boundary:TF \use:n \use_none:n }
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N b }
+      { \regex_if_word_boundary:T }
   }
 \cs_new_protected_nopar:cpn { regex_build_/B: }
   {
-    \regex_build_simple_assertion:Nn B
+    \regex_build_simple_assertion:nn { \regex_build_raw_error:N B }
       { \regex_if_word_boundary:TF { } }
   }
 \cs_new_protected_nopar:Npn \regex_if_word_boundary:TF
@@ -685,6 +839,8 @@
         { \group_end: \c_regex_w_tl }
     \regex_break_point:TF
   }
+\cs_new_protected_nopar:Npn \regex_if_word_boundary:T
+  { \regex_if_word_boundary:TF \use:n \use_none:n }
 \cs_new_protected_nopar:cpn { regex_build_[: }
   {
     \regex_build_if_in_class:TF
@@ -696,21 +852,22 @@
     \regex_build_if_in_class:TF
       {
         \if_num:w \l_regex_build_mode_int > \c_sixteen
-          \tl_set:Nx \l_regex_class_tl
+          \tl_set:Nx \l_regex_tests_tl
             {
-              \exp_not:o \l_regex_class_saved_tl
-              \if_num:w \l_regex_catcodes_int < \c_regex_catcodes_all_int
-                \regex_item_catcode:nT { \int_use:N \l_regex_catcodes_int }
+              \exp_not:o \l_regex_tests_saved_tl
+              \if_num:w \l_regex_catcodes_saved_int < \c_regex_catcodes_all_int
+                \regex_item_catcode:nT
+                  { \int_use:N \l_regex_catcodes_saved_int }
               \else:
                 \exp_after:wN \use:n
               \fi:
                 {
-                  \exp_not:o \l_regex_class_tl
-                  \bool_if:NF \l_regex_class_bool
-                    { \regex_break_point:TF { } { \regex_break_true:w } }
+                  \exp_not:o \l_regex_tests_tl
+                  \bool_if:NF \l_regex_tests_bool
+                    { \regex_break_point:TF { } \regex_break_true:w }
                 }
             }
-          \bool_set_eq:NN \l_regex_class_bool \l_regex_class_saved_bool
+          \bool_set_eq:NN \l_regex_tests_bool \l_regex_tests_saved_bool
         \fi:
         \tex_advance:D \l_regex_build_mode_int - \c_fifteen
         \tex_divide:D \l_regex_build_mode_int \c_thirteen
@@ -724,14 +881,16 @@
   {
     \l_regex_build_mode_int = \int_value:w \l_regex_build_mode_int 3 ~ %
     \if_num:w \l_regex_build_mode_int > \c_sixteen
-      \tl_set_eq:NN \l_regex_class_saved_tl \l_regex_class_tl
-      \bool_set_eq:NN \l_regex_class_saved_bool \l_regex_class_bool
+      \tl_set_eq:NN   \l_regex_tests_saved_tl     \l_regex_tests_tl
+      \bool_set_eq:NN \l_regex_tests_saved_bool   \l_regex_tests_bool
+      \int_set_eq:NN  \l_regex_catcodes_saved_int \l_regex_catcodes_int
+      \int_set_eq:NN  \l_regex_catcodes_int       \c_regex_catcodes_all_int
     \fi:
     \token_if_eq_meaning:NNTF #1 \regex_build_special:N
       {
         \token_if_eq_charcode:NNTF #2 ^
           {
-            \bool_set_false:N \l_regex_class_bool % [
+            \bool_set_false:N \l_regex_tests_bool % [
             \str_if_eq:nnTF {#3#4} { \regex_build_special:N ] }
               { \regex_build_raw:N }
           }
@@ -766,8 +925,7 @@
       }
       { \cs_if_exist_use:cF { regex_build_c_#3: } }
           {
-            \msg_kernel_error:nnxx { regex } { c-command }
-              { regular~expression } { #3 }
+            \msg_kernel_error:nnx { regex } { c-missing-category } {#3}
             #2 #3
           }
   }
@@ -808,8 +966,7 @@
           { \regex_build_c_lbrack_end: }
       }
           {
-            \msg_kernel_error:nnxx { regex } { c-command }
-              { regular-expression } { #2 }
+            \msg_kernel_error:nnx { regex } { c-missing-rbrack } {#2}
             \regex_build_c_lbrack_end:
           }
   }
@@ -830,18 +987,21 @@
     \fi:
   }
 \cs_new_protected:cpn { regex_build_ \c_rbrace_str : }
-  { %^^A incorrect recovery for \c{...(...[...} with missing ) or ].
+  {
     \int_compare:nNnTF \l_regex_build_mode_int < \c_zero
       {
-        \use:c { regex_build_/Z: }
-        \regex_toks_put_right:Nx \l_regex_right_state_int
-          { \regex_action_success: }
-        \int_incr:N \l_regex_capturing_group_int
+        \regex_build_exit_class:
+        \regex_build_exit_groups:
+        \regex_build_escaped:N Z
+        \regex_build_end:
         \use:x
           {
             \group_end:
               \regex_build_one:n
-                { \regex_item_cs:n { \regex_set_aux:N ? } }
+                {
+                  \regex_item_cs:n
+                    { \regex_set_aux:N \l_regex_internal_regex }
+                }
           }
       }
       { \exp_after:wN \regex_build_raw:N \c_rbrace_str }
@@ -913,7 +1073,7 @@
         \tl_if_empty:nTF {#2}
           { \regex_build_quantifier_aux:nnNN { {#1} } { n* } }
           { \regex_build_quantifier_aux:nnNN { {#1} {#2} } { nn } }
-      } %^^A todo: catch the case m>n
+      }
       {
         \regex_build_quantifier_end:nn { } { }
         \use:x
@@ -928,82 +1088,101 @@
 \cs_new_protected:Npn \regex_build_quantifier_end:nn #1#2
   {
     \use:c { regex_build_ \l_regex_one_or_group_tl _ #1 : } #2
-    \tl_clear:N \l_regex_class_tl
-    \bool_set_true:N \l_regex_class_bool
-    \int_set_eq:NN \l_regex_catcodes_int \l_regex_catcodes_default_int
+    \tl_clear:N \l_regex_tests_tl
+    \bool_set_true:N \l_regex_tests_bool
   }
 \cs_new_protected_nopar:Npn \regex_build_one_quantifier:
   {
     \tl_set:Nx \l_regex_one_or_group_tl { one }
     \regex_build_quantifier:w
   }
-\cs_new_protected_nopar:Npn \regex_build_one_:
-  {
-    \regex_build_transition:NN
-      \regex_build_tmp_class:n \l_regex_right_state_int
-  }
-\cs_new_protected_nopar:cpn { regex_build_one_?: }
-  {
-    \regex_build_transitions:NNNN
-      \regex_build_tmp_class:n \l_regex_right_state_int
-      \regex_action_free:n     \l_regex_right_state_int
-  }
-\cs_new_protected_nopar:cpn { regex_build_one_??: }
-  {
-    \regex_build_transitions:NNNN
-      \regex_action_free:n     \l_regex_right_state_int
-      \regex_build_tmp_class:n \l_regex_right_state_int
-  }
-\cs_new_protected_nopar:cpn { regex_build_one_*: }
-  {
-    \regex_build_transitions:NNNN
-      \regex_build_tmp_class:n \l_regex_left_state_int
-      \regex_action_free:n     \l_regex_right_state_int
-  }
-\cs_new_protected_nopar:cpn { regex_build_one_*?: }
+\cs_new_protected:Npn \regex_build_one_n: #1
   {
-    \regex_build_transitions:NNNN
-      \regex_action_free:n     \l_regex_right_state_int
-      \regex_build_tmp_class:n \l_regex_left_state_int
+    \prg_replicate:nn {#1}
+      {
+        \regex_build_transition:NN
+          \regex_tests_action_cost:n \l_regex_right_state_int
+      }
   }
-\cs_new_protected_nopar:cpn { regex_build_one_+: }
+\cs_new_eq:cN { regex_build_one_n?: } \regex_build_one_n:
+\cs_new_protected_nopar:Npn \regex_build_one_:
+  { \regex_build_one_n: \c_one }
+\cs_new_protected:cpn { regex_build_one_n*: } #1
   {
-    \regex_build_one_:
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_tmpa_int
-      \regex_action_free:n \l_regex_right_state_int
+    \int_compare:nNnTF {#1} = \c_zero
+      {
+        \regex_build_transitions:NNNN
+          \regex_tests_action_cost:n \l_regex_left_state_int
+          \regex_action_free:n       \l_regex_right_state_int
+      }
+      {
+        \regex_build_one_n: {#1}
+        \int_set_eq:NN \l_regex_internal_a_int \l_regex_left_state_int
+        \regex_build_transitions:NNNN
+          \regex_action_free:n \l_regex_internal_a_int
+          \regex_action_free:n \l_regex_right_state_int
+      }
   }
-\cs_new_protected_nopar:cpn { regex_build_one_+?: }
+\cs_new_protected:cpn { regex_build_one_n*?: } #1
   {
-    \regex_build_one_:
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_right_state_int
-      \regex_action_free:n \l_regex_tmpa_int
+    \int_compare:nNnTF {#1} = \c_zero
+      {
+        \regex_build_transitions:NNNN
+          \regex_action_free:n       \l_regex_right_state_int
+          \regex_tests_action_cost:n \l_regex_left_state_int
+      }
+      {
+        \regex_build_one_n: {#1}
+        \int_set_eq:NN \l_regex_internal_a_int \l_regex_left_state_int
+        \regex_build_transitions:NNNN
+          \regex_action_free:n \l_regex_right_state_int
+          \regex_action_free:n \l_regex_internal_a_int
+      }
   }
-\cs_new_protected:Npn \regex_build_one_n: #1
-  { \prg_replicate:nn {#1} { \regex_build_one_: } }
-\cs_new_eq:cN { regex_build_one_n?: } \regex_build_one_n:
-\cs_new_protected:cpx { regex_build_one_n*: } #1
-  {
-    \exp_not:N \prg_replicate:nn {#1} { \exp_not:N \regex_build_one_: }
-    \exp_not:c { regex_build_one_*: }
+\cs_new_protected_nopar:cpx { regex_build_one_*: }
+  { \exp_not:c { regex_build_one_n*: } \c_zero }
+\cs_new_protected_nopar:cpx { regex_build_one_*?: }
+  { \exp_not:c { regex_build_one_n*?: } \c_zero }
+\cs_new_protected_nopar:cpx { regex_build_one_+: }
+  { \exp_not:c { regex_build_one_n*: } \c_one }
+\cs_new_protected_nopar:cpx { regex_build_one_+?: }
+  { \exp_not:c { regex_build_one_n*?: } \c_one }
+\cs_new_protected_nopar:Npn \regex_build_one_nn:
+  {
+    \regex_build_one_nn_aux:nnnn { }
+      {
+        \regex_build_transitions:NNNN
+          \regex_tests_action_cost:n \l_regex_right_state_int
+          \regex_action_free:n       \l_regex_internal_a_int
+      }
   }
-\cs_new_protected:cpx { regex_build_one_n*?: } #1
+\cs_new_protected_nopar:cpn { regex_build_one_nn?: }
   {
-    \exp_not:N \prg_replicate:nn {#1} { \exp_not:N \regex_build_one_: }
-    \exp_not:c { regex_build_one_*?: }
+    \regex_build_one_nn_aux:nnnn {?}
+      {
+        \regex_build_transitions:NNNN
+          \regex_action_free:n       \l_regex_internal_a_int
+          \regex_tests_action_cost:n \l_regex_right_state_int
+      }
   }
-\cs_new_protected:Npn \regex_build_one_nn_aux:Nnn #1#2#3
+\cs_new_protected:Npn \regex_build_one_nn_aux:nnnn #1#2#3#4
   {
-    \prg_replicate:nn {#2} { \regex_build_one_: }
-    \prg_replicate:nn {#3-#2} {#1}
+    \regex_build_one_n: {#3}
+    \int_compare:nNnTF {#3} > {#4}
+      {
+        \msg_kernel_error:nnxxx
+          { regex } { quantifier-backwards } {#3} {#4} {#1}
+      }
+      {
+        \int_set:Nn \l_regex_internal_a_int
+          { \l_regex_right_state_int + #4 - #3 }
+        \prg_replicate:nn { #4 - #3 } { #2 }
+      }
   }
-\cs_new_protected_nopar:Npx \regex_build_one_nn:
-  { \regex_build_one_nn_aux:Nnn \exp_not:c { regex_build_one_?: } }
-\cs_new_protected_nopar:cpx { regex_build_one_nn?: }
-  { \regex_build_one_nn_aux:Nnn \exp_not:c { regex_build_one_??: } }
+\cs_new_protected_nopar:cpn { regex_build_one_?: }
+  { \regex_build_one_nn: \c_zero \c_one }
+\cs_new_protected_nopar:cpx { regex_build_one_??: }
+  { \exp_not:c { regex_build_one_nn?: } \c_zero \c_one }
 \cs_new_protected:cpn { regex_build_(: } #1#2
   {
     \regex_build_if_in_class:TF
@@ -1060,7 +1239,7 @@
     \regex_seq_pop_int:NN \l_regex_left_state_seq  \l_regex_left_state_int
     \regex_seq_pop_int:NN \l_regex_right_state_seq \l_regex_right_state_int
     \regex_seq_pop_use:N \l_regex_end_group_seq
-    \seq_pop:NN \l_regex_end_alternation_seq \l_regex_tmpa_tl
+    \seq_pop:NN \l_regex_end_alternation_seq \l_regex_internal_a_tl
   }
 \cs_new_protected_nopar:Npn \regex_build_begin_alternation:
   {
@@ -1093,7 +1272,7 @@
   {
     \cs_if_exist_use:cF { regex_build_special_group_\token_to_str:N #2 : }
       {
-        \msg_kernel_error:nnx { regex } { unsupported }
+        \msg_kernel_error:nnx { regex } { special-group-unknown }
           { (? \token_to_str:N #2 } %)
         \regex_build_special:N ( % )
         \regex_build_raw:N ?
@@ -1149,7 +1328,7 @@
     \token_if_eq_meaning:NNTF \regex_build_raw:N #2
       {
         \cs_if_exist_use:cF { regex_build_option_#1#3: }
-          { \msg_error:nnx { regex } { unknown-option } { #3 } }
+          { \msg_kernel_error:nnx { regex } { unknown-option } { #3 } }
         \regex_build_options:NNN #1
       }
       {
@@ -1158,7 +1337,7 @@
             { ) } { }
             { - } { \regex_build_options:NNN - }
           }
-          { \msg_error:nnx { regex } { invalid-in-option } { #3 } }
+          { \msg_kernel_error:nnx { regex } { invalid-in-option } { #3 } }
       }
   }
 \cs_new_protected_nopar:cpn { regex_build_option_+i: }
@@ -1176,53 +1355,52 @@
   }
 \cs_new_protected:Npn \regex_build_group_submatches:NN #1#2
   {
-    \seq_pop:NN \l_regex_capturing_group_seq \l_regex_tmpa_tl
-    \int_compare:nNnF { \l_regex_tmpa_tl } < \c_zero
+    \seq_pop:NN \l_regex_capturing_group_seq \l_regex_internal_a_tl
+    \int_compare:nNnF { \l_regex_internal_a_tl } < \c_zero
       {
         \regex_toks_put_left:Nx #1
-          { \regex_action_submatch:n { \l_regex_tmpa_tl < } }
+          { \regex_action_submatch:n { \l_regex_internal_a_tl < } }
         \regex_toks_put_left:Nx #2
-          { \regex_action_submatch:n { \l_regex_tmpa_tl > } }
+          { \regex_action_submatch:n { \l_regex_internal_a_tl > } }
       }
   }
-\cs_new_protected_nopar:Npn \regex_build_group_:
-  {
-    \regex_build_group_submatches:NN
-      \l_regex_left_state_int \l_regex_right_state_int
-    \regex_build_transition:NN
-      \regex_action_free:n \l_regex_right_state_int
-  }
-\cs_new_protected:Npn \regex_build_group_shift:N #1
+\cs_new_protected_nopar:Npn \regex_build_group_qs_aux:
   {
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
+    \int_set_eq:NN \l_regex_internal_a_int \l_regex_left_state_int
     \regex_build_new_state:
-    \tex_toks:D \l_regex_right_state_int = \tex_toks:D \l_regex_tmpa_int
+    \tex_toks:D \l_regex_right_state_int = \tex_toks:D \l_regex_internal_a_int
     \regex_toks_put_left:Nx \l_regex_right_state_int
       {
-        \int_set:Nn \l_regex_current_state_int
-          { \int_use:N \l_regex_tmpa_int } % ^^A here we lie!
+        \int_sub:Nn \l_regex_current_state_int
+          {
+            \int_eval:n % ^^A here we lie!
+              { \l_regex_right_state_int - \l_regex_internal_a_int }
+          }
       }
-    \cs_set:Npx \regex_tmp:w
+    \use:x
       {
-        \tex_toks:D \l_regex_tmpa_int
+        \tex_toks:D \l_regex_internal_a_int
           {
             \s_stop
-            #1 { \int_eval:n { \l_regex_right_state_int - \l_regex_tmpa_int } }
+            \regex_action_free:n
+              {
+                \int_eval:n
+                  { \l_regex_right_state_int - \l_regex_internal_a_int }
+              }
           }
       }
-    \regex_tmp:w
     \regex_build_group_submatches:NN
       \l_regex_right_state_int \l_regex_left_state_int
   }
 \cs_new_protected:Npn \regex_build_group_qs_aux:NN #1#2
   {
-    \regex_build_group_shift:N \regex_action_free:n
+    \regex_build_group_qs_aux:
     \int_set_eq:NN \l_regex_right_state_int \l_regex_left_state_int
     \regex_build_transition:NN \regex_action_free:n #1
-    #2 \l_regex_tmpa_int
+    #2 \l_regex_internal_a_int
       {
         \regex_action_free:n
-          { \int_eval:n { \l_regex_right_state_int - \l_regex_tmpa_int } }
+          { \int_eval:n { \l_regex_right_state_int - \l_regex_internal_a_int } }
       }
   }
 \cs_new_protected_nopar:cpn { regex_build_group_?: }
@@ -1235,99 +1413,241 @@
     \regex_build_group_qs_aux:NN
       \l_regex_right_state_int \regex_toks_put_left:Nx
   }
-\cs_new_protected_nopar:cpn { regex_build_group_*: }
+\cs_new_protected:Npn \regex_build_group_transition_right_max:
   {
-    \regex_build_group_qs_aux:NN
-      \l_regex_tmpa_int \regex_toks_put_right:Nx
+    \regex_toks_put_right:Nx \l_regex_right_state_int
+      {
+        \regex_action_free:n
+          { \int_eval:n { \l_regex_max_state_int - \l_regex_right_state_int } }
+      }
   }
-\cs_new_protected_nopar:cpn { regex_build_group_*?: }
+\cs_new_protected:Npn \regex_build_group_n_aux:n #1
   {
-    \regex_build_group_qs_aux:NN
-      \l_regex_tmpa_int \regex_toks_put_left:Nx
+    \int_set_eq:NN \l_regex_internal_a_int \l_regex_left_state_int
+    \int_set_eq:NN \l_regex_internal_b_int \l_regex_max_state_int
+    \int_add:Nn \l_regex_right_state_int
+      { ( #1 - 1 ) * ( \l_regex_max_state_int - \l_regex_left_state_int ) }
+    \int_set:Nn \l_regex_max_state_int
+      {
+        \l_regex_left_state_int
+        + (#1) * ( \l_regex_max_state_int - \l_regex_left_state_int )
+      }
+    \int_while_do:nNnn \l_regex_internal_b_int < \l_regex_max_state_int
+      {
+        \tex_toks:D \l_regex_internal_b_int
+          = \tex_toks:D \l_regex_internal_a_int
+        \int_incr:N \l_regex_internal_a_int
+        \int_incr:N \l_regex_internal_b_int
+      }
+  }
+\cs_new_protected:Npn \regex_build_group_n: #1
+  {
+    \regex_build_group_transition_right_max:
+    \regex_build_group_n_aux:n {#1}
+    \regex_build_new_state:
+    \int_compare:nNnF {#1} = \c_zero
+      {
+        \regex_build_group_submatches:NN
+          \l_regex_internal_a_int \l_regex_left_state_int
+      }
   }
-\cs_new_protected_nopar:cpn { regex_build_group_+: }
+\cs_new_eq:cN { regex_build_group_n?: } \regex_build_group_n:
+\cs_new_protected_nopar:Npn \regex_build_group_:
+  { \regex_build_group_n: \c_one }
+\cs_new_protected_nopar:cpn { regex_build_group_n*: }
   {
-    \regex_build_group_submatches:NN
-      \l_regex_left_state_int \l_regex_right_state_int
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_tmpa_int
-      \regex_action_free:n \l_regex_right_state_int
+    \regex_build_group_n_star_aux:NNn
+      \regex_toks_put_right:Nx \regex_toks_put_left:Nx
   }
-\cs_new_protected_nopar:cpn { regex_build_group_+?: }
+\cs_new_protected_nopar:cpn { regex_build_group_n*?: }
   {
-    \regex_build_group_submatches:NN
-      \l_regex_left_state_int \l_regex_right_state_int
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_right_state_int
-      \regex_action_free:n \l_regex_tmpa_int
+    \regex_build_group_n_star_aux:NNn
+      \regex_toks_put_left:Nx \regex_toks_put_right:Nx
   }
-\cs_new_protected:Npn \regex_build_group_n_aux:n #1
+\cs_new_protected:Npn \regex_build_group_n_star_aux:NNn #1#2#3
   {
-    \regex_toks_put_right:Nx \l_regex_right_state_int
+    \int_compare:nNnTF {#3} = \c_zero
+      { \regex_build_group_qs_aux:NN \l_regex_internal_a_int #1 }
       {
-        \regex_action_free:n
+        \regex_build_group_transition_right_max:
+        \regex_build_group_n_aux:n {#3}
+        \regex_build_new_state:
+        #2 \l_regex_left_state_int
           {
-            \int_eval:n %^^A todo: document why that value.
-              { \l_regex_max_state_int - \c_one - \l_regex_left_state_int }
+            \regex_action_free:n
+              {
+                \int_eval:n
+                  { \l_regex_internal_a_int - \l_regex_left_state_int }
+              }
           }
+        \regex_build_group_submatches:NN
+          \l_regex_internal_a_int \l_regex_left_state_int
       }
-    \int_set_eq:NN \l_regex_tmpa_int \l_regex_left_state_int
-    \int_set_eq:NN \l_regex_tmpb_int \l_regex_max_state_int
-    \int_set:Nn \l_regex_max_state_int
+  }
+\cs_new_protected_nopar:cpx { regex_build_group_*: }
+  { \exp_not:c { regex_build_group_n*: } \c_zero }
+\cs_new_protected_nopar:cpx { regex_build_group_*?: }
+  { \exp_not:c { regex_build_group_n*?: } \c_zero }
+\cs_new_protected_nopar:cpx { regex_build_group_+: }
+  { \exp_not:c { regex_build_group_n*: } \c_one }
+\cs_new_protected_nopar:cpx { regex_build_group_+?: }
+  { \exp_not:c { regex_build_group_n*?: } \c_one }
+\cs_new_protected_nopar:Npn \regex_build_group_nn:
+  {
+    \regex_build_group_nn_aux:nnnn { }
+      \regex_build_group_transition_right_max:
+  }
+\cs_new_protected_nopar:cpn { regex_build_group_nn?: }
+  {
+    \regex_build_group_nn_aux:nnnn { }
       {
-        \l_regex_left_state_int
-        + #1 * ( \l_regex_max_state_int - \l_regex_left_state_int )
+        \use:x
+          {
+            \tex_toks:D \l_regex_right_state_int
+              {
+                \exp_after:wN \regex_build_group_nn_aux_ii:w
+                \tex_the:D \tex_toks:D \l_regex_right_state_int
+              }
+          }
       }
-    \int_while_do:nNnn \l_regex_tmpb_int < \l_regex_max_state_int
+  }
+\cs_new_protected:Npn \regex_build_group_nn_aux:nnnn #1#2#3#4
+  {
+    \int_compare:nNnTF {#3} > {#4}
       {
-        \tex_toks:D \l_regex_tmpb_int = \tex_toks:D \l_regex_tmpa_int
-        \int_incr:N \l_regex_tmpa_int
-        \int_incr:N \l_regex_tmpb_int
+        \msg_kernel_error:nnxxx
+          { regex } { quantifier-backwards } {#3} {#4} {#1}
+      }
+      {
+        \int_compare:nNnTF {#3} = \c_zero
+          {
+            \regex_build_group_qs_aux:
+            \int_set_eq:NN \l_regex_right_state_int \l_regex_left_state_int
+            \int_set_eq:NN \l_regex_left_state_int  \l_regex_internal_a_int
+            \regex_build_group_transition_right_max:
+            \regex_build_group_n_aux:n { #4 - #3 }
+            \int_set_eq:NN \l_regex_internal_c_int \l_regex_right_state_int
+            \int_set_eq:NN \l_regex_right_state_int \l_regex_left_state_int
+            \prg_replicate:nn { #4 - #3 }
+              {
+                #2
+                \int_add:Nn \l_regex_right_state_int
+                  { \l_regex_internal_b_int - \l_regex_internal_a_int }
+              }
+            \int_set_eq:NN \l_regex_right_state_int \l_regex_internal_c_int
+            \int_set_eq:NN \l_regex_left_state_int \l_regex_internal_a_int
+            \regex_build_new_state:
+          }
+          {
+            \regex_build_group_transition_right_max:
+            \regex_build_group_n_aux:n {#3}
+            \int_set_eq:NN \l_regex_left_state_int \l_regex_internal_a_int
+            \regex_build_group_submatches:NN
+              \l_regex_left_state_int \l_regex_right_state_int
+            \regex_build_group_n_aux:n { #4 - #3 + \c_one }
+            \int_sub:Nn \l_regex_right_state_int
+              { \l_regex_internal_a_int - \l_regex_left_state_int }
+            \prg_replicate:nn { #4 - #3 }
+              {
+                #2
+                \int_add:Nn \l_regex_right_state_int
+                  { \l_regex_internal_b_int - \l_regex_internal_a_int }
+              }
+            \int_set_eq:NN \l_regex_left_state_int \l_regex_internal_a_int
+            \regex_build_new_state:
+          }
       }
   }
-\cs_new_protected:Npn \regex_build_group_n: #1
-  { % ^^A todo: catch case #1 <= 0.
-    \regex_build_group_n_aux:n {#1}
-    \regex_build_transition:NN
-      \regex_action_free:n \l_regex_right_state_int
-    \regex_build_group_submatches:NN
-      \l_regex_tmpa_int \l_regex_left_state_int
+\cs_new_protected:Npn \regex_build_group_nn_aux_ii:w #1 \regex_action_free:n
+  {
+    #1
+    \regex_action_free:n
+      {
+        \int_eval:n
+          { \l_regex_max_state_int - \l_regex_right_state_int }
+      }
+    \regex_action_free:n
   }
-\cs_new_eq:cN { regex_build_group_n?: } \regex_build_group_n:
-\cs_new_protected:cpn { regex_build_group_n*: } #1
-  { % ^^A todo: catch case #1 <= 0.
-    \regex_build_group_n_aux:n {#1}
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_tmpa_int
-      \regex_action_free:n \l_regex_right_state_int
-    \regex_build_group_submatches:NN
-      \l_regex_tmpa_int \l_regex_left_state_int
+\cs_new_protected:cpn { regex_build_/u: } #1#2
+  {
+    \regex_build_if_assertions_forbidden:TF
+      { \regex_build_raw_error:N u #1#2 }
+      {
+        \str_if_eq:xxTF {#1#2} { \regex_build_special:N \c_lbrace_str }
+          {
+            \tl_set:Nx \l_regex_internal_a_tl { \if_false: } \fi:
+            \regex_build_u_loop:NN
+          }
+          {
+            \msg_kernel_error:nn { regex } { u-missing-lbrace }
+            #1#2
+          }
+      }
   }
-\cs_new_protected:cpn { regex_build_group_n*?: } #1
-  { % ^^A todo: catch case #1 <= 0.
-    \regex_build_group_n_aux:n {#1}
-    \regex_build_transitions:NNNN
-      \regex_action_free:n \l_regex_right_state_int
-      \regex_action_free:n \l_regex_tmpa_int
-    \regex_build_group_submatches:NN
-      \l_regex_tmpa_int \l_regex_left_state_int
+\cs_new:Npn \regex_build_u_loop:NN #1#2
+  {
+    \token_if_eq_meaning:NNTF #1 \regex_build_raw:N
+      { #2 \regex_build_u_loop:NN }
+      {
+        \token_if_eq_meaning:NNTF #1 \regex_build_special:N
+          {
+            \exp_after:wN \token_if_eq_charcode:NNTF \c_rbrace_str #2
+              { \if_false: { \fi: } \regex_build_u_end: }
+              { #2 \regex_build_u_loop:NN }
+          }
+          {
+            \if_false: { \fi: }
+            \msg_kernel_error:nnx { regex } { u-missing-rbrace } {#2}
+            \regex_build_u_end:
+            #1#2
+          }
+      }
+  }
+\cs_new_protected:Npn \regex_build_u_end:
+  {
+    \tl_set:Nv \l_regex_internal_a_tl \l_regex_internal_a_tl
+    \if_num:w \l_regex_build_mode_int = \c_zero
+      \regex_build_u_not_cs:
+    \else:
+      \regex_build_u_in_cs:
+    \fi:
+    \tl_clear:N \l_regex_tests_tl
   }
-\cs_new_protected:Npn \regex_build_group_nn: #1#2
-  { % ^^A Not Implemented Yet!
-    \msg_expandable_error:n { Quantifier~{m,n}~not~implemented~yet }
-    \use:c { regex_build_group_n*: } {#1}
+\cs_new_protected:Npn \regex_build_u_in_cs:
+  {
+    \exp_args:NNo \str_gset_other:Nn \g_regex_internal_tl
+      { \l_regex_internal_a_tl }
+    \tl_map_inline:Nn \g_regex_internal_tl
+      {
+        \tl_set:Nx \l_regex_tests_tl { \regex_item_equal:n { `##1 } }
+        \regex_build_one_:
+      }
   }
-\cs_new_protected:cpn { regex_build_group_nn?: } #1#2
-  { % ^^A Not Implemented Yet!
-    \msg_expandable_error:n { Quantifier~{m,n}~not~implemented~yet }
-    \use:c { regex_build_group_n*?: } {#1}
+\cs_new_protected:Npn \regex_build_u_not_cs:
+  {
+    \exp_args:No \tl_analysis_map_inline:nn { \l_regex_internal_a_tl }
+      {
+        \tl_set:Nx \l_regex_tests_tl
+          {
+            \exp_not:N \int_compare:nNnT
+              \l_regex_current_catcode_int = { \int_value:w "##2 }
+              {
+                \int_compare:nNnTF { "##2 } = \c_zero
+                  {
+                    \exp_not:n
+                      { \str_if_eq:xxT { \l_regex_current_token_tl } {##1} }
+                      { \regex_break_true:w }
+                  }
+                  { \regex_item_equal:n {##3} }
+              }
+          }
+        \regex_build_one_:
+      }
   }
 \cs_new_protected:Npn \regex_store_state:n #1
   {
-    \int_incr:N \l_regex_max_index_int
-    \tex_skip:D \l_regex_max_index_int #1 sp \scan_stop:
+    \int_incr:N \l_regex_max_active_int
+    \tex_skip:D \l_regex_max_active_int #1 sp \scan_stop:
     \regex_store_submatches:n {#1}
   }
 \cs_new_protected_nopar:Npn \regex_state_use_with_submatches:
@@ -1336,10 +1656,9 @@
   { \regex_state_use_aux:n { \exp_after:wN \use_none_delimit_by_s_stop:w } }
 \cs_new_protected:Npn \regex_state_use_aux:n #1
   {
-    \if_num:w \tex_dimen:D \l_regex_current_state_int
-        < \l_regex_unique_id_int
+    \if_num:w \tex_dimen:D \l_regex_current_state_int < \l_regex_step_int
       \tex_dimen:D \l_regex_current_state_int
-        = \l_regex_unique_id_int sp \scan_stop:
+        = \l_regex_step_int sp \scan_stop:
       #1 \tex_the:D \tex_toks:D \exp_after:wN \l_regex_current_state_int
     \fi:
     \scan_stop:
@@ -1374,68 +1693,55 @@
   {
     \exp_after:wN \c_zero
     \exp_after:wN \regex_state_submatches:nn \exp_after:wN
-      {
-        \int_value:w \int_eval:w
-          \l_regex_unique_id_int + \c_one
-        \exp_after:wN
-      }
+      { \int_value:w \int_eval:w \l_regex_step_int + \c_one \exp_after:wN }
       \exp_after:wN { \l_regex_current_submatches_prop }
     \regex_state_submatches:nn {#1} {#2}
     \s_stop
   }
 \cs_new_protected:Npn \regex_state_submatches:nn #1#2
   {
-    \if_num:w #1 = \l_regex_unique_id_int
+    \if_num:w #1 = \l_regex_step_int
       \tl_set:Nn \l_regex_current_submatches_prop { #2 }
     \fi:
   }
 \cs_new_protected:Npn \regex_match:n #1
   {
-    \tl_set_analysis:Nn \l_regex_tmpa_tl {#1}
-
     \int_zero:N \l_regex_nesting_int
-    \int_set_eq:NN \l_regex_current_step_int \l_regex_max_state_int
+    \int_set_eq:NN \l_regex_current_index_int \l_regex_max_state_int
     \regex_query_set:nnn { } { -1 } { -2 }
-    \int_set_eq:NN \l_regex_min_step_int \l_regex_current_step_int
-    \exp_after:wN \regex_query_set_loop:ww
-      \l_regex_tmpa_tl
-      \s_tl { ? \prg_map_break: } \s_tl
-    \prg_break_point:n { }
-    \int_set_eq:NN \l_regex_max_step_int \l_regex_current_step_int
+    \int_set_eq:NN \l_regex_min_index_int \l_regex_current_index_int
+    \tl_analysis_map_inline:nn {#1}
+      {
+        \regex_query_set:nnn {##1} {"##2} {##3}
+        \if_case:w "##2 \exp_stop_f:
+        \or: \int_incr:N \l_regex_nesting_int
+        \or: \int_decr:N \l_regex_nesting_int
+        \fi:
+      }
+    \int_set_eq:NN \l_regex_max_index_int \l_regex_current_index_int
     \regex_query_set:nnn { } { -1 } { -2 }
-
     \regex_match_initial_setup:
     \regex_match_once:
   }
-\cs_new:Npn \regex_query_set_loop:ww #1 \s_tl #2#3 \s_tl
-  {
-    \use_none:n #2
-    \regex_query_set:nnn {#1} {"#2} {#3}
-    \if_case:w "#2 \exp_stop_f:
-    \or: \int_incr:N \l_regex_nesting_int
-    \or: \int_decr:N \l_regex_nesting_int
-    \fi:
-    \regex_query_set_loop:ww
-  }
 \cs_new_protected:Npn \regex_query_set:nnn #1#2#3
   {
-    \tex_muskip:D \l_regex_current_step_int
+    \tex_muskip:D \l_regex_current_index_int
       = \etex_gluetomu:D
         #3 sp
         plus #2 sp
         minus \l_regex_nesting_int sp
       \scan_stop:
-    \tex_toks:D \l_regex_current_step_int {#1}
-    \int_incr:N \l_regex_current_step_int
+    \tex_toks:D \l_regex_current_index_int {#1}
+    \int_incr:N \l_regex_current_index_int
   }
 \cs_new_protected_nopar:Npn \regex_query_get:
   {
     \tl_set:Nx \l_regex_current_token_tl
-      { \tex_the:D \tex_toks:D \l_regex_current_step_int }
+      { \tex_the:D \tex_toks:D \l_regex_current_index_int }
     \l_regex_current_char_int
-      = \etex_mutoglue:D \tex_muskip:D \l_regex_current_step_int
+      = \etex_mutoglue:D \tex_muskip:D \l_regex_current_index_int
     \l_regex_current_catcode_int = \etex_gluestretch:D
-      \etex_mutoglue:D \tex_muskip:D \l_regex_current_step_int
+      \etex_mutoglue:D \tex_muskip:D \l_regex_current_index_int
   }
 \cs_new_protected_nopar:Npn \regex_match_once:
   {
@@ -1451,13 +1757,14 @@
   }
 \cs_new_protected_nopar:Npn \regex_match_initial_setup:
   {
-    \prg_stepwise_inline:nnnn {0} {1} { \l_regex_max_state_int - \c_one }
-      { \tex_dimen:D ##1 \c_minus_one sp \scan_stop: }
-    \int_set_eq:NN \l_regex_unique_id_int  \c_minus_one
-    \int_set:Nn \l_regex_start_step_int
-      { \l_regex_min_step_int - \c_one }
-    \int_set_eq:NN \l_regex_current_step_int \l_regex_min_step_int
-    \int_set_eq:NN \l_regex_success_step_int \l_regex_min_step_int
+    \int_set_eq:NN \l_regex_step_int \c_minus_one
+    \prg_stepwise_inline:nnnn
+      \c_zero \c_one { \l_regex_max_state_int - \c_one }
+      { \tex_dimen:D ##1 \l_regex_step_int sp \scan_stop: }
+    \int_set:Nn \l_regex_start_index_int
+      { \l_regex_min_index_int - \c_one }
+    \int_set_eq:NN \l_regex_current_index_int \l_regex_min_index_int
+    \int_set_eq:NN \l_regex_success_index_int \l_regex_min_index_int
     \int_set_eq:NN \l_regex_submatch_int \l_regex_max_state_int
     \bool_set_false:N \l_regex_success_empty_bool
     \bool_gset_false:N \g_regex_success_bool
@@ -1466,49 +1773,48 @@
   {
     \prop_clear:N \l_regex_current_submatches_prop
     \bool_if:NTF \l_regex_success_empty_bool
-      { \cs_set_eq:NN \regex_last_match_empty:F \regex_last_match_empty_yes:F }
-      { \cs_set_eq:NN \regex_last_match_empty:F \regex_last_match_empty_no:F }
-    \int_set_eq:NN \l_regex_start_step_int \l_regex_success_step_int
-    \int_set:Nn \l_regex_current_step_int
-      { \l_regex_start_step_int - \c_one }
+      { \cs_set_eq:NN \regex_if_two_empty_matches:F \regex_if_match_empty:F }
+      { \cs_set_eq:NN \regex_if_two_empty_matches:F \use:n }
+    \int_set_eq:NN \l_regex_start_index_int \l_regex_success_index_int
+    \int_set:Nn \l_regex_current_index_int
+      { \l_regex_start_index_int - \c_one }
     \bool_set_false:N \l_regex_success_match_bool
-    \int_zero:N \l_regex_max_index_int
+    \int_zero:N \l_regex_max_active_int
     \regex_store_state:n {0} %^^A _state_int!
   }
 \cs_new_protected_nopar:Npn \regex_match_loop:
   {
-    \int_incr:N \l_regex_current_step_int
-    \int_incr:N \l_regex_unique_id_int
+    \int_incr:N \l_regex_current_index_int
+    \int_incr:N \l_regex_step_int
     \bool_set_false:N \l_regex_fresh_thread_bool
     \int_set_eq:NN \l_regex_last_char_int \l_regex_current_char_int
     \regex_query_get:
     \regex_match_loop_case_hook:
-    \cs_set_nopar:Npx \regex_tmp:w
+    \use:x
       {
-        \int_zero:N \l_regex_max_index_int
-        \regex_match_one_index:w 1 ; \prg_break_point:n { }
+        \int_zero:N \l_regex_max_active_int
+        \regex_match_one_active:w 1 ; \prg_break_point:n { }
         \exp_not:N \prg_break_point:n { }
       }
-    \regex_tmp:w
     \if_num:w \l_regex_current_char_int < \c_minus_one
       \exp_after:wN \prg_map_break:
     \fi:
-    \if_num:w \l_regex_max_index_int = \c_zero
+    \if_num:w \l_regex_max_active_int = \c_zero
       \exp_after:wN \prg_map_break:
     \fi:
     \regex_match_loop:
   }
-\cs_new:Npn \regex_match_one_index:w #1;
+\cs_new:Npn \regex_match_one_active:w #1;
   {
-    \if_num:w #1 > \l_regex_max_index_int
+    \if_num:w #1 > \l_regex_max_active_int
       \exp_after:wN \prg_map_break:
     \fi:
-    \regex_match_one_index_aux:n
+    \regex_match_one_active_aux:n
       { \int_value:w \tex_skip:D #1 }
-    \exp_after:wN \regex_match_one_index:w
+    \exp_after:wN \regex_match_one_active:w
     \int_use:N \int_eval:w #1 + \c_one ;
   }
-\cs_new_protected:Npn \regex_match_one_index_aux:n #1
+\cs_new_protected:Npn \regex_match_one_active_aux:n #1
   {
     \int_set:Nn \l_regex_current_state_int {#1}
     \prop_clear:N \l_regex_current_submatches_prop
@@ -1546,12 +1852,12 @@
   }
 \cs_new_protected_nopar:Npn \regex_action_success:
   {
-    \regex_last_match_empty:F
+    \regex_if_two_empty_matches:F
       {
         \bool_set_true:N \l_regex_success_match_bool
         \bool_set_eq:NN \l_regex_success_empty_bool
           \l_regex_fresh_thread_bool
-        \int_set_eq:NN \l_regex_success_step_int \l_regex_current_step_int
+        \int_set_eq:NN \l_regex_success_index_int \l_regex_current_index_int
         \prop_set_eq:NN \l_regex_success_submatches_prop
           \l_regex_current_submatches_prop
         \prg_map_break:
@@ -1559,7 +1865,7 @@
   }
 \cs_new_protected:Npn \regex_action_free:n #1
   {
-    \cs_set_nopar:Npx \regex_tmp:w
+    \use:x
       {
         \int_add:Nn \l_regex_current_state_int {#1}
         \regex_state_use:
@@ -1568,13 +1874,16 @@
         \tl_set:Nn \exp_not:N \l_regex_current_submatches_prop
           { \exp_not:o \l_regex_current_submatches_prop }
       }
-    \regex_tmp:w
   }
 \cs_new_protected:Npn \regex_action_submatch:n #1
   {
     \prop_put:Nno \l_regex_current_submatches_prop {#1}
-      { \int_use:N \l_regex_current_step_int }
+      { \int_use:N \l_regex_current_index_int }
   }
+\cs_new:Npn \regex_if_match_empty:T
+  { \int_compare:nNnT \l_regex_start_index_int = \l_regex_current_index_int }
+\cs_new:Npn \regex_if_match_empty:F
+  { \int_compare:nNnF \l_regex_start_index_int = \l_regex_current_index_int }
 \cs_new_protected:Npn \regex_submatch_nesting_aux:n #1
   {
     + \etex_glueshrink:D \etex_mutoglue:D \etex_muexpr:D
@@ -1589,10 +1898,10 @@
     \int_zero:N \l_regex_replacement_int
     \int_zero:N \l_regex_nesting_int
     \tl_clear:N \l_regex_nesting_tl
-    \str_escape_use:NNNn
-      \regex_replacement_unescaped:N
-      \regex_replacement_escaped:N
-      \regex_replacement_raw:N
+    \regex_escape_use:nnnn
+      { \regex_replacement_unescaped:N ##1 }
+      { \regex_replacement_escaped:N ##1 }
+      { \regex_replacement_raw:N ##1 }
       {#1}
     \prg_do_nothing: \prg_do_nothing:
     \cs_set:Npx \regex_nesting:n ##1
@@ -1604,9 +1913,9 @@
     \use:x
       {
         \exp_not:n { \cs_set:Npn \regex_replacement_tl:n ##1 }
-          { \str_aux_toks_range:nn \c_zero \l_regex_replacement_int }
+          { \regex_toks_range:nn \c_zero \l_regex_replacement_int }
       }
-      % ^^A rename! Careful with \cP\#.
+      % ^^A rename!
   }
 \cs_new_protected:Npn \regex_replacement_raw:N #1
   { \regex_replacement_put:n {#1} }
@@ -1629,19 +1938,14 @@
   }
 \cs_new_protected:Npn \regex_replacement_escaped:N #1
   {
-    \if_charcode:w c #1
-      \exp_after:wN \regex_replacement_c:w
-    \else:
-      \if_charcode:w g #1
-        \exp_after:wN \exp_after:wN \exp_after:wN \regex_replacement_g:w
-      \else:
+    \cs_if_exist_use:cF { regex_replacement_#1:w }
+      {
         \if_num:w \c_one < 1#1 \exp_stop_f:
           \regex_replacement_put_submatch:n {#1}
         \else:
           \regex_replacement_put:n #1
         \fi:
-      \fi:
-    \fi:
+      }
   }
 \cs_new_protected:Npn \regex_replacement_put_submatch:n #1
   {
@@ -1668,7 +1972,7 @@
       { \exp_not:n { #1#2 } }
       { \regex_replacement_unescaped:N \c_lbrace_str }
       {
-        \int_zero:N \l_regex_tmpa_int
+        \int_zero:N \l_regex_internal_a_int
         \regex_replacement_g_digits:NN
       }
       { \regex_replacement_error:NNN g #1 #2 }
@@ -1678,13 +1982,13 @@
     \token_if_eq_meaning:NNTF #1 \regex_replacement_unescaped:N
       {
         \if_num:w \c_one < 1#2 \exp_stop_f:
-          \int_set:Nn \l_regex_tmpa_int { \c_ten * \l_regex_tmpa_int + #2 }
+          \int_set:Nn \l_regex_internal_a_int { \c_ten * \l_regex_internal_a_int + #2 }
           \exp_after:wN \use_i:nnn
           \exp_after:wN \regex_replacement_g_digits:NN
         \else:
           \if_charcode:w \c_rbrace_str #2
             \exp_args:No \regex_replacement_put_submatch:n
-              { \int_use:N \l_regex_tmpa_int }
+              { \int_use:N \l_regex_internal_a_int }
             \exp_after:wN \exp_after:wN \exp_after:wN \use_none:nn
           \else:
             \exp_after:wN \exp_after:wN
@@ -1696,6 +2000,16 @@
       { \regex_replacement_error:NNN g }
     #1 #2
   }
+\cs_new_protected:Npn \regex_replacement_u:w #1#2
+  {
+    \str_if_eq:xxTF { #1#2 } { \regex_replacement_unescaped:N \c_lbrace_str }
+      {
+        \int_incr:N \l_regex_replacement_csnames_int
+        \regex_replacement_put:n
+          { \exp_not:n { \exp_after:wN \exp_not:V \cs:w } }
+      }
+      { \regex_replacement_error:NNN u #1#2 }
+  }
 \cs_new_protected:Npn \regex_replacement_c:w #1#2
   {
     \token_if_eq_meaning:NNTF #1 \regex_replacement_unescaped:N
@@ -1711,8 +2025,6 @@
     \regex_replacement_put:n
       { \exp_not:n { \exp_after:wN \regex_replacement_exp_not:N \cs:w } }
   }
-\cs_new_eq:cc { regex_replacement_c_C:w }
-  { regex_replacement_c_ \c_lbrace_str :w }
 \cs_new:Npn \regex_replacement_exp_not:N #1 { \exp_not:n {#1} }
 \group_begin:
 
@@ -1790,11 +2102,11 @@
   {
     \group_begin:
       \regex_build:n {#3}
-      \cs_set_nopar:Npx \regex_tmp:w
-        { #1 \exp_not:N #2 { \regex_set_aux:N #2 } }
-      \exp_after:wN
-    \group_end:
-    \regex_tmp:w
+      \use:x
+        {
+          \group_end:
+          #1 \exp_not:N #2 { \regex_set_aux:N #2 }
+        }
   }
 \cs_new:Npn \regex_set_aux:N #1
   {
@@ -1811,7 +2123,7 @@
           \regex_match_loop_caseless_hook:
       }
     \prg_stepwise_function:nnnN
-      {0} {1} {\l_regex_max_state_int - \c_one }
+      \c_zero \c_one {\l_regex_max_state_int - \c_one }
       \regex_set_aux:n
     \s_stop
   }
@@ -1824,18 +2136,6 @@
   }
 \cs_new_protected_nopar:Npn \regex_use:N
   { \exp_last_unbraced:No \use_none:nn }
-\cs_new:Npn \regex_to_str:N #1
-  {
-    \exp_after:wN \regex_to_str_aux:Nw #1
-    \tex_toks:D \q_stop \prg_map_break: \tex_toks:D
-    \prg_break_point:n { }
-  }
-\cs_new:Npn \regex_to_str_aux:Nw #1#2\tex_toks:D
-  {
-    \use_none_delimit_by_q_stop:w #2 \q_stop
-    \tl_to_str:n {#1#2} \iow_newline:
-    \regex_to_str_aux:Nw \tex_toks:D
-  }
 \cs_new_protected_nopar:Npn \regex_aux_return:
   {
     \if_meaning:w \c_true_bool \g_regex_success_bool
@@ -1921,9 +2221,9 @@
 \cs_new_protected:Npn \regex_group_end_extract_seq:N #1
   {
       \cs_set_eq:NN \seq_item:n \scan_stop:
-      \flag_lower:N \l_regex_group_begin_flag
-      \flag_lower:N \l_regex_group_end_flag
-      \tl_set:Nx \l_regex_tmpa_tl
+      \flag_clear:n { regex_begin }
+      \flag_clear:n { regex_end }
+      \tl_set:Nx \l_regex_internal_a_tl
         {
           \prg_stepwise_function:nnnN
             \l_regex_max_state_int
@@ -1931,12 +2231,13 @@
             { \l_regex_submatch_int - \c_one }
             \regex_extract_seq_aux:n
         }
-      \flag_test:NF \l_regex_group_begin_flag
-        { \flag_test:NF \l_regex_group_end_flag { \use_none:nnn } }
-      \msg_kernel_error:nn { regex } { sequence-unbalanced }
-      \tl_set:Nx \l_regex_tmpa_tl { \l_regex_tmpa_tl }
+      \int_compare:nNnF
+        { \flag_height:n { regex_begin } + \flag_height:n { regex_end } }
+        = \c_zero
+        { \msg_kernel_error:nn { regex } { sequence-unbalanced } }
+      \tl_set:Nx \l_regex_internal_a_tl { \l_regex_internal_a_tl }
     \exp_args:NNNo \group_end:
-    \tl_set:Nn #1 \l_regex_tmpa_tl
+    \tl_set:Nn #1 \l_regex_internal_a_tl
   }
 \cs_new:Npn \regex_extract_seq_aux:n #1
   {
@@ -1947,14 +2248,14 @@
       }
   }
 \cs_new:Npn \regex_extract_seq_aux:ww #1; #2;
-  { %^^A todo: use flags
+  {
     \if_num:w #1 < \c_zero
-      \flag_raise:N \l_regex_group_end_flag
+      \flag_raise:n { regex_end }
       \prg_replicate:nn {-#1} { \exp_not:n { { \if_false: } \fi: } }
     \fi:
     \regex_query_submatch:w #2;
     \if_num:w #1 > \c_zero
-      \flag_raise:N \l_regex_group_begin_flag
+      \flag_raise:n { regex_begin }
       \prg_replicate:nn {#1} { \exp_not:n { \if_false: { \fi: } } }
     \fi:
   }
@@ -2016,20 +2317,20 @@
     \group_begin:
       \tl_set:Nn \l_regex_every_match_tl
         {
-          \if_num:w \l_regex_start_step_int < \l_regex_success_step_int
+          \if_num:w \l_regex_start_index_int < \l_regex_success_index_int
             \regex_extract:
             \tex_skip:D \l_regex_submatch_start_int
-              = \l_regex_start_step_int sp
+              = \l_regex_start_index_int sp
                 plus \tex_skip:D \l_regex_submatch_start_int \scan_stop:
           \fi:
           \regex_match_once:
         }
       #1 {#2} {#3}
       \tex_skip:D \l_regex_submatch_int
-        = \l_regex_start_step_int sp
-          plus \l_regex_current_step_int sp \scan_stop:
+        = \l_regex_start_index_int sp
+          plus \l_regex_current_index_int sp \scan_stop:
       \int_incr:N \l_regex_submatch_int
-      \if_num:w \l_regex_start_step_int = \l_regex_current_step_int
+      \if_num:w \l_regex_start_index_int = \l_regex_current_index_int
         \if_meaning:w \c_true_bool \l_regex_success_empty_bool
           \int_decr:N \l_regex_submatch_int
         \fi:
@@ -2044,34 +2345,34 @@
       \exp_args:Nno #1 {#2} #4
       \if_meaning:w \c_true_bool \g_regex_success_bool
         \regex_extract:
-        \int_set:Nn \l_regex_tmpa_int
+        \int_set:Nn \l_regex_internal_a_int
           { \regex_nesting:n { \l_regex_submatch_start_int } }
-        \if_num:w \l_regex_tmpa_int = \c_zero
+        \if_num:w \l_regex_internal_a_int = \c_zero
         \else:
           \msg_kernel_error:nnx { regex } { replace-unbalanced }
-            { \l_regex_tmpa_int }
+            { \l_regex_internal_a_int }
         \fi:
-        \tl_set:Nx \l_regex_tmpa_tl
+        \tl_set:Nx \l_regex_internal_a_tl
           {
-            \if_num:w \l_regex_tmpa_int < \c_zero
-              \prg_replicate:nn { - \l_regex_tmpa_int }
+            \if_num:w \l_regex_internal_a_int < \c_zero
+              \prg_replicate:nn { - \l_regex_internal_a_int }
                 { \exp_not:n { { \if_false: } \fi: } }
             \fi:
-            \regex_query_substr:nn
-              { \l_regex_min_step_int }
+            \regex_toks_range:nn
+              { \l_regex_min_index_int }
               { \tex_skip:D \l_regex_submatch_start_int }
             \regex_replacement_tl:n { \l_regex_submatch_start_int }
-            \regex_query_substr:nn
+            \regex_toks_range:nn
               { \etex_gluestretch:D \tex_skip:D \l_regex_submatch_start_int }
-              { \l_regex_max_step_int }
-            \if_num:w \l_regex_tmpa_int > \c_zero
-              \prg_replicate:nn { \l_regex_tmpa_int }
+              { \l_regex_max_index_int }
+            \if_num:w \l_regex_internal_a_int > \c_zero
+              \prg_replicate:nn { \l_regex_internal_a_int }
                 { \exp_not:n { \if_false: { \fi: } } }
             \fi:
           }
-        \tl_set:Nx \l_regex_tmpa_tl { \l_regex_tmpa_tl }
+        \tl_set:Nx \l_regex_internal_a_tl { \l_regex_internal_a_tl }
         \exp_args:NNNo \group_end:
-        \tl_set:Nn #4 \l_regex_tmpa_tl
+        \tl_set:Nn #4 \l_regex_internal_a_tl
       \else:
         \group_end:
       \fi:
@@ -2087,12 +2388,12 @@
           \regex_extract:
           \tex_skip:D \l_regex_submatch_start_int
             = \tex_the:D \tex_skip:D \l_regex_submatch_start_int
-              minus \l_regex_start_step_int sp \scan_stop:
+              minus \l_regex_start_index_int sp \scan_stop:
           \regex_match_once:
         }
       \regex_replacement:n {#3}
       \exp_args:Nno #1 {#2} #4
-      \int_set:Nn \l_regex_tmpa_int
+      \int_set:Nn \l_regex_internal_a_int
         {
           0
           \prg_stepwise_function:nnnN
@@ -2101,15 +2402,15 @@
             { \l_regex_submatch_int - \c_one }
             \regex_nesting:n
         }
-      \if_num:w \l_regex_tmpa_int = \c_zero
+      \if_num:w \l_regex_internal_a_int = \c_zero
       \else:
         \msg_kernel_error:nnx { regex } { replace-unbalanced }
-          { \l_regex_tmpa_int }
+          { \l_regex_internal_a_int }
       \fi:
-      \tl_set:Nx \l_regex_tmpa_tl
+      \tl_set:Nx \l_regex_internal_a_tl
         {
-          \if_num:w \l_regex_tmpa_int < \c_zero
-            \prg_replicate:nn { - \l_regex_tmpa_int }
+          \if_num:w \l_regex_internal_a_int < \c_zero
+            \prg_replicate:nn { - \l_regex_internal_a_int }
               { \exp_not:n { { \if_false: } \fi: } }
           \fi:
           \prg_stepwise_function:nnnN
@@ -2117,30 +2418,144 @@
             \l_regex_capturing_group_int
             { \l_regex_submatch_int - \c_one }
             \regex_replace_all_aux:n
-          \regex_query_substr:nn
-            \l_regex_start_step_int \l_regex_max_step_int
-          \if_num:w \l_regex_tmpa_int > \c_zero
-            \prg_replicate:nn { \l_regex_tmpa_int }
+          \regex_toks_range:nn
+            \l_regex_start_index_int \l_regex_max_index_int
+          \if_num:w \l_regex_internal_a_int > \c_zero
+            \prg_replicate:nn { \l_regex_internal_a_int }
               { \exp_not:n { \if_false: { \fi: } } }
           \fi:
         }
-      \tl_set:Nx \l_regex_tmpa_tl { \l_regex_tmpa_tl }
+      \tl_set:Nx \l_regex_internal_a_tl { \l_regex_internal_a_tl }
     \exp_args:NNNo \group_end:
-    \tl_set:Nn #4 \l_regex_tmpa_tl
+    \tl_set:Nn #4 \l_regex_internal_a_tl
   }
 \cs_new:Npn \regex_replace_all_aux:n #1
   {
-    \regex_query_substr:nn
+    \regex_toks_range:nn
       { \etex_glueshrink:D \tex_skip:D #1 } { \tex_skip:D #1 }
     \regex_replacement_tl:n {#1}
   }
+\msg_kernel_new:nnnn { regex } { trailing-backslash }
+  { Trailing~escape~character~\iow_char:N\\. }
+  {
+    A~regular~expression~or~its~replacement~text~ends~with~
+    the~escape~character~\iow_char:N\\.~It~will~be~ignored.
+  }
+\msg_kernel_new:nnnn { regex } { x-missing-rbrace }
+  { Missing~closing~brace~in~\iow_char:N\\x~hexadecimal~sequence. }
+  {
+    You~wrote~something~like~
+    `\iow_char:N\\x\{\int_to_hexadecimal:n{#1}'.~
+    The~closing~brace~is~missing.
+  }
+\msg_kernel_new:nnnn { regex } { x-overflow }
+  { Character~code~'#1'~too~large~in~\iow_char:N\\x~hexadecimal~sequence. }
+  {
+    You~wrote~something~like~
+    `\iow_char:N\\x\{\int_to_hexadecimal:n{#1}\}'.~
+    The~character~code~'#1'~is~larger~than~\int_use:N \c_max_char_int.
+  }
+\msg_kernel_new:nnnn { regex } { missing-rbrack }
+  { Missing~right~bracket~inserted~in~regular~expression. }
+  {
+    LaTeX~was~given~a~regular~expression~where~a~character~class~
+    was~started~with~'[',~but~the~matching~']'~is~missing.
+  }
+\msg_kernel_new:nnnn { regex } { missing-rparen }
+  {
+    Missing~right~parenthes\int_compare:nTF{#1=1}{i}{e}s~
+    inserted~in~regular~expression.
+  }
+  {
+    LaTeX~was~given~a~regular~expression~with~\int_eval:n{#1}~
+    more~left~parenthes\int_compare:nTF{#1=1}{i}{e}s~than~right~
+    parenthes\int_compare:nTF{#1=1}{i}{e}s.
+  }
+\msg_kernel_new:nnnn { regex } { extra-rparen }
+  { Extra~right~parenthesis~ignored~in~regular~expression. }
+  {
+    LaTeX~came~across~a~closing~parenthesis~when~no~submatch~group~
+    was~open.~The~parenthesis~will~be~ignored.
+  }
+\msg_kernel_new:nnnn { regex } { class-bad-escape }
+  { Invalid~escape~\c_backslash_str #1~in~character~class. }
+  {
+    The~escape~sequence~\iow_char:N\\#1~may~not~appear~within~
+    a~character~class.~For~instance,~assertions~(which~match~zero~
+    characters)~would~not~make~sense~there.
+  }
+\msg_kernel_new:nnnn { regex } { catcode-bad-escape }
+  { Invalid~escape~\c_backslash_str #1~following~category~test. }
+  {
+    The~escape~sequence~\iow_char:N\\#1~may~not~appear~following~
+    a~category~test~such~as~\iow_char:N\\cL~or~
+    \iow_char:N\\c[\iow_char:N\^BE].
+  }
+\msg_kernel_new:nnnn { regex } { range-missing-end }
+  { Invalid~end-point~for~range~'#1-#2'~in~character~class. }
+  {
+    The~end-point~'#2'~of~the~range~'#1-#2'~may~not~serve~as~an~
+    end-point~for~a~range:~alphanumeric~characters~should~not~be~
+    escaped,~and~non-alphanumeric~characters~should~be~escaped.
+  }
+\msg_kernel_new:nnnn { regex } { range-backwards }
+  { Range~[#1-#2]~out~of~order~in~character~class. }
+  {
+    In~ranges~of~characters~[x-y]~appearing~in~character~classes,~
+    the~first~character~code~must~not~be~larger~than~the~second.~
+    Here,~#1~has~character~code~\int_eval:n {`#1},~while~#2~has~
+    character~code~\int_eval:n {`#2}.
+  }
+\msg_kernel_new:nnnn { regex } { c-bad-mode }
+  { Invalid~nested~\iow_char:N\\c~escape~in~regular~expression. }
+  {
+    The~\iow_char:N\\c~escape~cannot~be~used~within~
+    a~control~sequence~test~'\iow_char:N\\c{...}'.~
+    To~combine~several~category~tests,~use~'\iow_char:N\\c[...]'.
+  }
+\msg_kernel_new:nnnn { regex } { c-missing-rbrace }
+  { Missing~right~brace~inserted~for~\iow_char:N\\c~escape. }
+  {
+    LaTeX~was~given~a~regular~expression~where~a~
+    '\iow_char:N\\c\iow_char:N\{...'~construction~was~not~ended~
+    with~a~closing~brace~'\iow_char:N\}'.
+  }
+\msg_kernel_new:nnnn { regex } { c-missing-rbrack }
+  { Missing~right~bracket~inserted~for~\iow_char:N\\c~escape. }
+  {
+    A~construction~'\iow_char:N\\c[...'~appears~in~a~
+    regular~expression,~but~the~closing~']'~is~not~present.
+  }
+\msg_kernel_new:nnnn { regex } { c-missing-category }
+  { Invalid~character~'#1'~following~\iow_char\\c~escape. }
+  {
+    In~regular~expressions,~the~\iow_char:N\\c~escape~sequence~
+    may~only~be~followed~by~a~left~brace,~a~left~bracket,~or~a~
+    capital~letter~representing~a~character~category,~namely~
+    one~of~ABCDELMOPSTU.
+  }
+\msg_kernel_new:nnnn { regex } { u-missing-lbrace }
+  { Missing~left~brace~following~\iow_char:N\\u~escape. }
+  {
+    The~\iow_char:N\\u~escape~sequence~must~be~followed~by~
+    a~brace~group~with~the~name~of~the~variable~to~use.
+  }
+\msg_kernel_new:nnnn { regex } { u-missing-rbrace }
+  { Missing~right~brace~inserted~for~\iow_char:N\\u~escape. }
+  {
+    LaTeX~
+    \tl_if_empty:xTF {#2}
+      { reached~the~end~of~the~string~ }
+      { encountered~an~escaped~alphanumeric~character '\iow_char:N\\#2'~ }
+    when~parsing~the~argument~of~an~'\iow_char:N\\u\iow_char:N\{...\}'~escape.
+  }
 \msg_kernel_new:nnnn { regex } { sequence-unbalanced }
   {
     Missing~
-    \flag_test:NTF \l_regex_group_end_flag
+    \flag_if_raised:nTF { regex_end }
       {
         left~
-        \flag_test:NTF \l_regex_group_begin_flag
+        \flag_if_raised:nTF { regex_begin }
           { and~right~braces } { brace }
       }
       { right~brace }
@@ -2170,34 +2585,6 @@
       }
     \ inserted.
   }
-\msg_kernel_new:nnnn { regex } { missing-rparen }
-  { Missing~right~parenthesis~added~in~regular~expression. }
-  {
-    LaTeX~was~given~a~regular~expression~with~\int_eval:n{#1}~
-    more~left~parenthes\int_compare:nTF{#1=1}{i}{e}s~than~right~
-    parenthes\int_compare:nTF{#1=1}{i}{e}s.
-  }
-\msg_kernel_new:nnnn { regex } { extra-rparen }
-  { Extra~right~parenthesis~ignored~in~regular~expression. }
-  {
-    LaTeX~came~across~a~closing~parenthesis~when~no~submatch~group~
-    was~open.~The~parenthesis~will~be~ignored.
-  }
-\msg_kernel_new:nnnn { regex } { backwards-range }
-  { Range~[#1-#2]~out~of~order~in~character~class. }
-  {
-    In~ranges~of~characters~[x-y]~appearing~in~character~classes,~
-    the~first~character~code~must~not~be~larger~than~the~second.~
-    Here,~#1~has~character~code~\int_eval:n {`#1},~while~#2~has~
-    character~code~\int_eval:n {`#2}.
-  }
-\msg_kernel_new:nnnn { regex } { unsupported }
-  { Unsupported~construction~`#1'. }
-  {
-    The~construction~`#1'~is~not~supported~by~the~LaTeX~
-    regular~expression~module.~Perhaps~some~character~should~
-    have~been~escaped?
-  }
 \msg_kernel_new:nnnn { regex } { not-nfa }
   { This~is~not~a~regular~expression~variable. }
   {
@@ -2206,6 +2593,8 @@
     is~\\\\
     \ \ \ \ \token_to_str:N #1 = \token_to_meaning:N #1 .
   }
+\msg_kernel_new:nnn { regex } { nfa-misused }
+  { Automaton~#1 used~incorrectly. }
 \msg_kernel_new:nnnn { regex } { c-command }
   { Misused~\iow_char:N\\c~or\iow_char:N\\C~command~in~a~#1. }
   {
@@ -2232,8 +2621,6 @@
     submatches~are~represented~either~as~\iow_char:N \\g{dd..d},~
     or~\\d,~where~`d'~are~single~digits.~Here,~a~brace~is~missing.
   }
-\msg_kernel_new:nnn { regex } { nfa-misused }
-  { Automaton~#1 used~incorrectly. }
 %% 
 %%
 %% End of file `l3regex.sty'.
diff --git a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3str.sty b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3str.sty
index cc4d6716ed5..d9ef6271899 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3str.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3str.sty
@@ -46,31 +46,32 @@
 %%
 %% -----------------------------------------------------------------------
 \RequirePackage{expl3}
-\GetIdInfo$Id: l3str.dtx 3159 2012-01-09 00:51:58Z bruno $
+\GetIdInfo$Id: l3str.dtx 3257 2012-01-29 13:37:03Z bruno $
   {L3 Experimental Strings}
 \ProvidesExplPackage
   {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
-\RequirePackage{l3tl-analysis}
-\group_begin:
-  \cs_set_protected_nopar:Npn \str_tmp:w #1
-    {
-      \cs_new_protected:cpx { str_ #1 :Nn } ##1##2
-        { \exp_not:c { tl_ #1 :Nx } ##1 { \exp_not:N \tl_to_str:n {##2} } }
-      \exp_args:Nc \cs_generate_variant:Nn { str_ #1 :Nn } { Nx , cn , cx }
-    }
-  \str_tmp:w { set }
-  \str_tmp:w { gset }
-  \str_tmp:w { const }
-  \str_tmp:w { put_left }
-  \str_tmp:w { gput_left }
-  \str_tmp:w { put_right }
-  \str_tmp:w { gput_right }
-\group_end:
+\RequirePackage{l3tl-analysis,l3flag}
+\cs_if_exist:NF \use_ii_i:nn
+  { \cs_new:Npn \use_ii_i:nn #1#2 { #2 #1 } }
+\tl_map_inline:nn
+  {
+    { set }
+    { gset }
+    { const }
+    { put_left }
+    { gput_left }
+    { put_right }
+    { gput_right }
+  }
+  {
+    \cs_new_protected:cpx { str_ #1 :Nn } ##1##2
+      { \exp_not:c { tl_ #1 :Nx } ##1 { \exp_not:N \tl_to_str:n {##2} } }
+    \exp_args:Nc \cs_generate_variant:Nn { str_ #1 :Nn } { Nx , cn , cx }
+  }
 \cs_new_protected_nopar:Npn \str_tmp:w { }
-\tl_new:N \l_str_tmpa_tl
-\int_new:N \l_str_tmpa_int
+\tl_new:N \l_str_internal_tl
+\int_new:N \l_str_internal_int
 \tl_new:N \g_str_result_tl
-\int_new:N \l_str_char_int
 \int_const:Nn \c_forty_eight  { 48 }
 \int_const:Nn \c_fifty_eight  { 58 }
 \int_const:Nn \c_sixty_five   { 65 }
@@ -79,7 +80,7 @@
 \int_const:Nn \c_one_hundred_twenty_three { 123 }
 \int_const:Nn \c_one_hundred_twenty_seven { 127 }
 \int_const:Nn \c_max_char_int
-  { \pdftex_if_engine:TF { 255 } { 1114111 } }
+  { \pdftex_if_engine:TF { "FF } { "10FFFF } }
 \int_const:Nn \c_str_replacement_char_int { "FFFD }
 \tl_const:Nx \c_backslash_str { \cs_to_str:N \\ }
 \tl_const:Nx \c_lbrace_str    { \cs_to_str:N \{ }
@@ -87,18 +88,25 @@
 \tl_const:Nx \c_hash_str      { \cs_to_str:N \# }
 \tl_const:Nx \c_tilde_str     { \cs_to_str:N \~ }
 \tl_const:Nx \c_percent_str   { \cs_to_str:N \% }
-\prop_new:N \g_str_aliases_prop
-\prop_gput:Nnn \g_str_aliases_prop { latin1 } { iso88591 }
-\prop_gput:Nnn \g_str_aliases_prop { latin2 } { iso88592 }
-\prop_gput:Nnn \g_str_aliases_prop { latin3 } { iso88593 }
-\prop_gput:Nnn \g_str_aliases_prop { latin4 } { iso88594 }
-\prop_gput:Nnn \g_str_aliases_prop { latin5 } { iso88599 }
-\prop_gput:Nnn \g_str_aliases_prop { latin6 } { iso885910 }
-\prop_gput:Nnn \g_str_aliases_prop { latin7 } { iso885913 }
-\prop_gput:Nnn \g_str_aliases_prop { latin8 } { iso885914 }
-\prop_gput:Nnn \g_str_aliases_prop { latin9 } { iso885915 }
-\prop_gput:Nnn \g_str_aliases_prop { latin10 } { iso885916 }
-\prop_gput:Nnn \g_str_aliases_prop { hexadecimal } { hex }
+\prop_new:N \g_str_file_prop
+\prop_gput:Nnn \g_str_file_prop { latin1 } { iso88591 }
+\prop_gput:Nnn \g_str_file_prop { latin2 } { iso88592 }
+\prop_gput:Nnn \g_str_file_prop { latin3 } { iso88593 }
+\prop_gput:Nnn \g_str_file_prop { latin4 } { iso88594 }
+\prop_gput:Nnn \g_str_file_prop { latin5 } { iso88599 }
+\prop_gput:Nnn \g_str_file_prop { latin6 } { iso885910 }
+\prop_gput:Nnn \g_str_file_prop { latin7 } { iso885913 }
+\prop_gput:Nnn \g_str_file_prop { latin8 } { iso885914 }
+\prop_gput:Nnn \g_str_file_prop { latin9 } { iso885915 }
+\prop_gput:Nnn \g_str_file_prop { latin10 } { iso885916 }
+\prop_gput:Nnn \g_str_file_prop { utf16le } { utf16 }
+\prop_gput:Nnn \g_str_file_prop { utf16be } { utf16 }
+\prop_gput:Nnn \g_str_file_prop { utf32le } { utf32 }
+\prop_gput:Nnn \g_str_file_prop { utf32be } { utf32 }
+\prop_gput:Nnn \g_str_file_prop { hexadecimal } { hex }
+\bool_new:N \g_str_error_bool
+\flag_new:n { str_byte }
+\flag_new:n { str_error }
 \group_begin:
 \char_set_lccode:nn { `\* } { `\  }
 \char_set_lccode:nn { `\A } { `\A }
@@ -110,7 +118,7 @@
         \exp_after:wN \tl_to_other_str_loop:w \tl_to_str:n {#1} ~ %
         A ~ A ~ A ~ A ~ A ~ A ~ A ~ A ~ \q_mark \q_stop
       }
-    \cs_new_nopar:Npn \tl_to_other_str_loop:w
+    \cs_new:Npn \tl_to_other_str_loop:w
       #1 ~ #2 ~ #3 ~ #4 ~ #5 ~ #6 ~ #7 ~ #8 ~ #9 \q_stop
       {
         \if_meaning:w A #8
@@ -119,7 +127,7 @@
         \tl_to_other_str_loop:w
         #9 #1 * #2 * #3 * #4 * #5 * #6 * #7 * #8 * \q_stop
       }
-    \cs_new_nopar:Npn \tl_to_other_str_end:w \fi: #1 \q_mark #2 * A #3 \q_stop
+    \cs_new:Npn \tl_to_other_str_end:w \fi: #1 \q_mark #2 * A #3 \q_stop
       { \fi: #2 }
   }
 \group_begin:
@@ -133,10 +141,10 @@
         \tl_gset:Nx #1
           {
             \exp_after:wN \str_gset_other_loop:w \tl_to_str:n {#2} ~ %
-            A ~ A ~ A ~ A ~ A ~ A ~ A ~ A ~ A ~ \q_mark \q_stop
+            A ~ A ~ A ~ A ~ A ~ A ~ A ~ A ~ A ~ \q_stop
           }
       }
-    \cs_new_nopar:Npn \str_gset_other_loop:w
+    \cs_new:Npn \str_gset_other_loop:w
       #1 ~ #2 ~ #3 ~ #4 ~ #5 ~ #6 ~ #7 ~ #8 ~ #9 ~
       {
         \if_meaning:w A #9
@@ -145,32 +153,42 @@
         #1 * #2 * #3 * #4 * #5 * #6 * #7 * #8 * #9
         \str_gset_other_loop:w *
       }
-    \cs_new_nopar:Npn \str_gset_other_end:w \fi: #1 * A #2 \q_stop
+    \cs_new:Npn \str_gset_other_end:w \fi: #1 * A #2 \q_stop
       { \fi: #1 }
   }
-\cs_if_exist:NF \use_i:nnnnnnnn
-  { \cs_new:Npn \use_i:nnnnnnnn #1#2#3#4#5#6#7#8 {#1} }
-\cs_new:Npn \str_aux_toks_range:nn #1#2
+\cs_new:Npn \str_count_spaces:N
+  { \exp_args:No \str_count_spaces:n }
+\cs_new:Npn \str_count_spaces:n #1
   {
-    \exp_after:wN \str_aux_toks_range:ww
-    \int_use:N \int_eval:w #1 \exp_after:wN ;
-    \int_use:N \int_eval:w #2 ;
-    \prg_break_point:n { }
+    \int_eval:n
+      {
+        \exp_after:wN \str_count_spaces_loop:wwwwwwwww
+        \tl_to_str:n {#1} ~
+        X 7 ~ X 6 ~ X 5 ~ X 4 ~ X 3 ~ X 2 ~ X 1 ~ X 0 ~ X -1 ~
+        \q_stop
+      }
   }
-\cs_new:Npn \str_aux_toks_range:ww #1 ; #2 ;
+\cs_new:Npn \str_count_spaces_loop:wwwwwwwww #1~#2~#3~#4~#5~#6~#7~#8~#9~
   {
-    \if_num:w #1 = #2 \exp_stop_f:
-      \exp_after:wN \prg_map_break:
+    \if_meaning:w X #9
+      \exp_after:wN \use_none_delimit_by_q_stop:w
     \fi:
-    \tex_the:D \tex_toks:D #1 \exp_stop_f:
-    \exp_after:wN \str_aux_toks_range:ww
-      \int_use:N \int_eval:w #1 + \c_one ; #2 ;
+    \c_nine + \str_count_spaces_loop:wwwwwwwww
   }
 \cs_new_nopar:Npn \str_length:N { \exp_args:No \str_length:n }
 \cs_new:Npn \str_length:n #1
-  { \exp_args:Nf \str_length_unsafe:n { \tl_to_other_str:n {#1} } }
-\cs_new_nopar:Npn \str_length_unsafe:n #1
-  { \str_length_aux:n { \str_length_loop:NNNNNNNNN #1 } }
+  {
+    \str_length_aux:n
+      {
+        \str_count_spaces:n {#1}
+        + \exp_after:wN \str_length_loop:NNNNNNNNN \tl_to_str:n {#1}
+      }
+  }
+\cs_new:Npn \str_length_unsafe:n #1
+  {
+    \str_length_aux:n
+      { \str_length_loop:NNNNNNNNN #1 }
+  }
 \cs_new:Npn \str_length_ignore_spaces:n #1
   {
     \str_length_aux:n
@@ -189,7 +207,7 @@
   }
 \cs_set:Npn \str_length_loop:NNNNNNNNN #1#2#3#4#5#6#7#8#9
   {
-    \if_catcode:w X #9
+    \if_meaning:w X #9
       \exp_after:wN \use_none_delimit_by_q_stop:w
     \fi:
     \c_nine + \str_length_loop:NNNNNNNNN
@@ -201,12 +219,13 @@
     \tl_to_str:n {#1}
     { { } } ~ \q_stop
   }
-\cs_set_nopar:Npn \str_head_aux:w #1 ~ %
+\cs_set:Npn \str_head_aux:w #1 ~ %
   { \use_i_delimit_by_q_stop:nw #1 { ~ } }
 \cs_new:Npn \str_head_ignore_spaces:n #1
-  { \exp_after:wN \use_i_delimit_by_q_stop:nw \tl_to_str:n {#1} { } \q_stop }
-\cs_new_nopar:Npn \str_head_unsafe:n #1
-  { \use_i_delimit_by_q_stop:nw #1 { } \q_stop }
+  {
+    \exp_after:wN \use_i_delimit_by_q_stop:nw
+    \tl_to_str:n {#1} { } \q_stop
+  }
 \cs_new_nopar:Npn \str_tail:N { \exp_args:No \str_tail:n }
 \cs_set:Npn \str_tail:n #1
   {
@@ -214,107 +233,93 @@
     \reverse_if:N \if_charcode:w
         \scan_stop: \tl_to_str:n {#1} X X \q_stop
   }
-\cs_set_nopar:Npn \str_tail_aux:w #1 X #2 \q_stop { \fi: #1 }
+\cs_set:Npn \str_tail_aux:w #1 X #2 \q_stop { \fi: #1 }
 \cs_new:Npn \str_tail_ignore_spaces:n #1
   {
     \exp_after:wN \str_tail_aux_ii:w
-    \tl_to_str:n {#1} X { } X \q_stop
+    \tl_to_str:n {#1} X X \q_stop
   }
-\cs_new_nopar:Npn \str_tail_unsafe:n #1
-  { \str_tail_aux_ii:w #1 X { } X \q_stop }
-\cs_new_nopar:Npn \str_tail_aux_ii:w #1 #2 X #3 \q_stop { #2 }
-\cs_new:Npn \str_skip_do:nn #1
+\cs_new:Npn \str_tail_aux_ii:w #1 #2 X #3 \q_stop { #2 }
+\cs_new:Npn \str_skip_c_zero:w #1;
   {
-    \if_num:w \int_eval:w #1 > \c_seven
-      \exp_after:wN \str_skip_aux:nnnnnnnnn
+    \if_num:w \int_eval:w #1 > \c_eight
+      \exp_after:wN \str_skip_aux:wNNNNNNNN
     \else:
-      \exp_after:wN \str_skip_end:n
-    \fi:
-      {#1}
-  }
-\cs_new:Npn \str_skip_aux:nnnnnnnnn #1#2#3#4#5#6#7#8#9
-  { \exp_args:Nf \str_skip_do:nn { \int_eval:n { #1 - \c_seven } } {#2} }
-\cs_new:Npn \str_skip_end:n #1
-  {
-    \if_case:w \int_eval:w #1 \int_eval_end:
-         \str_skip_end_ii:nwn { XXXXXXX }
-    \or: \str_skip_end_ii:nwn { XXXXXX }
-    \or: \str_skip_end_ii:nwn { XXXXX }
-    \or: \str_skip_end_ii:nwn { XXXX }
-    \or: \str_skip_end_ii:nwn { XXX }
-    \or: \str_skip_end_ii:nwn { XX }
-    \or: \str_skip_end_ii:nwn { X }
-    \or: \str_skip_end_ii:nwn {  }
-    \else: \str_skip_end_ii:nwn { XXXXXXX }
+      \exp_after:wN \str_skip_end:w
+      \int_use:N \int_eval:w
     \fi:
+    #1 ;
+  }
+\cs_new:Npn \str_skip_aux:wNNNNNNNN #1; #2#3#4#5#6#7#8#9
+  { \exp_after:wN \str_skip_c_zero:w \int_use:N \int_eval:w #1 - \c_eight ; }
+\cs_new:Npn \str_skip_end:w #1 ;
+  {
+    \exp_after:wN \str_skip_end_ii:NNNNNNNN
+    \if_case:w \if_num:w #1 > \c_zero #1 \else: 0 \fi: \exp_stop_f:
+    \or: \or: \or: \or: \or: \or: \or: \or:
+  }
+\cs_new:Npn \str_skip_end_ii:NNNNNNNN #1#2#3#4#5#6#7#8 { \fi: \c_zero }
+\cs_new:Npn \str_collect_delimit_by_q_stop:w #1;
+  {
+    \exp_after:wN \str_collect_aux:wn
+    \int_use:N \int_eval:w #1 ;
+    { }
   }
-\cs_new:Npn \str_skip_end_ii:nwn #1#2 \fi: #3
-  { \fi: \use_i:nnnnnnnn {#3} #1 }
-\cs_new:Npn \str_collect_do:nn #1#2
-  { \str_collect_aux:n {#1} { \str_collect_end_iii:nwNNNNNNN {#2} } }
-\cs_new:Npn \str_collect_aux:n #1
-  {
-    \int_compare:nNnTF {#1} > \c_seven
-      { \str_collect_aux:nnNNNNNNN }
-      { \str_collect_end:n }
-      {#1}
-  }
-\cs_new:Npn \str_collect_aux:nnNNNNNNN #1#2 #3#4#5#6#7#8#9
-  {
-    \exp_args:Nf \str_collect_aux:n
-      { \int_eval:n { #1 - \c_seven } }
-      { #2 #3#4#5#6#7#8#9 }
-  }
-\cs_new:Npn \str_collect_end:n #1
-  {
-    \if_case:w \int_eval:w #1 \int_eval_end:
-         \str_collect_end_ii:nwn { { } { } { } { } { } { } { } }
-    \or: \str_collect_end_ii:nwn { { } { } { } { } { } { } }
-    \or: \str_collect_end_ii:nwn { { } { } { } { } { } }
-    \or: \str_collect_end_ii:nwn { { } { } { } { } }
-    \or: \str_collect_end_ii:nwn { { } { } { } }
-    \or: \str_collect_end_ii:nwn { { } { } }
-    \or: \str_collect_end_ii:nwn { { } }
-    \or: \str_collect_end_ii:nwn {  }
-    \else: \str_collect_end_ii:nwn { { } { } { } { } { } { } { } }
+\cs_new:Npn \str_collect_aux:wn #1 ;
+  {
+    \if_num:w #1 > \c_seven
+      \exp_after:wN \str_collect_aux:wnNNNNNNN
+    \else:
+      \exp_after:wN \str_collect_end:wn
     \fi:
+    #1 ;
+  }
+\cs_new:Npn \str_collect_aux:wnNNNNNNN #1; #2 #3#4#5#6#7#8#9
+  {
+    \exp_after:wN \str_collect_aux:wn
+    \int_use:N \int_eval:w #1 - \c_seven ;
+    { #2 #3#4#5#6#7#8#9 }
+  }
+\cs_new:Npn \str_collect_end:wn #1 ;
+  {
+    \exp_after:wN \str_collect_end_ii:nnnnnnnnw
+    \if_case:w \if_num:w #1 > \c_zero #1 \else: 0 \fi: \exp_stop_f:
+    \or: \or: \or: \or: \or: \or: \fi:
   }
-\cs_new:Npn \str_collect_end_ii:nwn #1#2 \fi: #3
-  { \fi: #3 \q_stop #1 }
-\cs_new:Npn \str_collect_end_iii:nwNNNNNNN #1 #2 \q_stop #3#4#5#6#7#8#9
-  { #1 {#2#3#4#5#6#7#8#9} }
+\cs_new:Npn \str_collect_end_ii:nnnnnnnnw #1#2#3#4#5#6#7#8 #9 \q_stop
+  { #1#2#3#4#5#6#7#8 }
 \cs_new_nopar:Npn \str_item:Nn { \exp_args:No \str_item:nn }
-\cs_new:Npn \str_item:nn #1#2
+\cs_new:Npn \str_item:nn #1
   {
-    \exp_args:Nf \tl_to_str:n
-      { \exp_args:Nf \str_item_unsafe:nn { \tl_to_other_str:n {#1} } {#2} }
+    \exp_last_unbraced:Nf \token_to_str:N
+      \exp_args:Nf \str_item_unsafe:nn { \tl_to_other_str:n {#1} }
   }
 \cs_new:Npn \str_item_ignore_spaces:nn #1
   { \exp_args:No \str_item_unsafe:nn { \tl_to_str:n {#1} } }
-\cs_new_nopar:Npn \str_item_unsafe:nn #1#2
+\cs_new:Npn \str_item_unsafe:nn #1#2
   {
-    \exp_args:Nff \str_item_aux:nn
-      { \int_eval:n {#2} }
-      { \str_length_unsafe:n {#1} }
+    \exp_after:wN \str_item_aux:ww
+    \int_use:N \int_eval:w #2 \exp_after:wN ;
+    \int_value:w \str_length_unsafe:n {#1} ;
       #1
     \q_stop
   }
-\cs_new_nopar:Npn \str_item_aux:nn #1#2
+\cs_new:Npn \str_item_aux:ww #1; #2;
   {
     \int_compare:nNnTF {#1} < \c_zero
       {
         \int_compare:nNnTF {#1} < {-#2}
           { \use_none_delimit_by_q_stop:w }
           {
-            \str_skip_do:nn { #1 + #2 }
-              { \use_i_delimit_by_q_stop:nw }
+            \exp_after:wN \use_i_delimit_by_q_stop:nw
+            \tex_romannumeral:D \str_skip_c_zero:w #1 + #2 ;
           }
       }
       {
         \int_compare:nNnTF {#1} < {#2}
           {
-            \str_skip_do:nn {#1}
-              { \use_i_delimit_by_q_stop:nw }
+            \exp_after:wN \use_i_delimit_by_q_stop:nw
+            \tex_romannumeral:D \str_skip_c_zero:w #1 ;
           }
           { \use_none_delimit_by_q_stop:w }
       }
@@ -335,28 +340,26 @@
     \exp_after:wN \str_substr_aux:www
     \int_value:w \str_length_unsafe:n {#1} \exp_after:wN ;
     \int_use:N \int_eval:w #2 + \c_zero \exp_after:wN ;
-    \int_use:N \int_eval:w \exp_args:Nf \str_substr_unsafe:nN {#3} \c_max_int ;
+    \int_use:N \int_eval:w
+      \exp_args:Nf \str_substr_aux:nN {#3} \c_max_int ;
       #1
     \q_stop
   }
-\cs_new:Npn \str_substr_unsafe:nN #1 #2
+\cs_new:Npn \str_substr_aux:nN #1 #2
   { \tl_if_empty:nTF {#1} {#2} {#1} }
 \cs_new:Npn \str_substr_aux:www #1; #2; #3;
   {
     \exp_args:Nf \str_substr_aux:nnw
-      { \str_aux_normalize_range:nn {#2} {#1} }
-      { \str_aux_normalize_range:nn {#3} {#1} }
+      { \str_substr_normalize_range:nn {#2} {#1} }
+      { \str_substr_normalize_range:nn {#3} {#1} }
   }
 \cs_new:Npn \str_substr_aux:nnw #1#2
   {
-    \str_skip_do:nn {#1}
-      {
-        \exp_args:Nf \str_collect_do:nn
-          { \int_eval:n { #2 - #1 } }
-          { \use_i_delimit_by_q_stop:nw }
-      }
+    \exp_after:wN \str_collect_delimit_by_q_stop:w
+    \int_use:N \int_eval:w #2 - #1 \exp_after:wN ;
+    \tex_romannumeral:D \str_skip_c_zero:w #1 ;
   }
-\cs_new:Npn \str_aux_normalize_range:nn #1#2
+\cs_new:Npn \str_substr_normalize_range:nn #1#2
   {
     \int_eval:n
       {
@@ -383,7 +386,7 @@
 \prg_new_conditional:Npnn \str_if_contains_char:NN #1#2 { T , TF }
   {
     \exp_after:wN \str_if_contains_char_aux:NN \exp_after:wN #2
-      #1 { \prg_map_break:n { ? \fi: } }
+      \tl_to_str:n \exp_after:wN {#1} { \prg_map_break:n { ? \fi: } }
     \prg_break_point:n { }
     \prg_return_false:
   }
@@ -394,14 +397,14 @@
     \prg_break_point:n { }
     \prg_return_false:
   }
-\cs_new_nopar:Npn \str_if_contains_char_aux:NN #1#2
+\cs_new:Npn \str_if_contains_char_aux:NN #1#2
   {
     \if_charcode:w #1 #2
-      \exp_after:wN \str_if_contains_char_end:
+      \exp_after:wN \str_if_contains_char_true:
     \fi:
     \str_if_contains_char_aux:NN #1
   }
-\cs_new_nopar:Npn \str_if_contains_char_end:
+\cs_new_nopar:Npn \str_if_contains_char_true:
   { \prg_map_break:n { \prg_return_true: \use_none:n } }
 \prg_new_conditional:Npnn \str_aux_octal_use:N #1 { TF }
   {
@@ -433,11 +436,11 @@
     \fi:
   }
 \group_begin:
-  \tl_clear:N \l_str_tmpa_tl
+  \tl_clear:N \l_str_internal_tl
   \char_set_catcode_other:n { \c_zero }
   \tl_gset:Nx \g_str_result_tl { \tl_to_str:n { 0123456789ABCDEF } }
-  \tl_map_inline:Nn \g_str_result_tl
-    { \char_set_lccode:nn {`#1} {`#1} }
+  \exp_args:No \tl_map_inline:nn { \g_str_result_tl " }
+    { \char_set_lccode:nn {`#1} { \c_zero } }
   \tl_map_inline:Nn \g_str_result_tl
     {
       \tl_map_inline:Nn \g_str_result_tl
@@ -448,12 +451,12 @@
               \tl_const:cx
                 { c_str_byte_ \int_eval:n {"#1##1} _tl }
                 { ^^@ #1 ##1 }
-              \tl_put_right:Nn \l_str_tmpa_tl { ^^@ }
+              \tl_put_right:Nn \l_str_internal_tl { ^^@ }
             }
         }
     }
   \tl_const:Nx \c_str_positive_bytes_tl
-    { \exp_after:wN \use_none:n \l_str_tmpa_tl }
+    { \exp_after:wN \use_none:n \l_str_internal_tl }
 \group_end:
 \tl_const:cn { c_str_byte_-1_tl } { { } \use_none:n { } }
 \cs_new:Npn \str_output_byte:n #1
@@ -474,244 +477,166 @@
   }
 \cs_new_nopar:Npn \str_output_end:
   { \int_eval_end: _tl \cs_end: }
-\cs_new_protected_nopar:Npn \str_aux_gmap_result:N #1
+\cs_new:Npn \str_output_byte_pair_be:n #1
+  {
+    \exp_args:Nf \str_output_byte_pair_aux:nnN
+      { \int_div_truncate:nn { #1 } { "100 } } {#1} \use:nn
+  }
+\cs_new:Npn \str_output_byte_pair_le:n #1
+  {
+    \exp_args:Nf \str_output_byte_pair_aux:nnN
+      { \int_div_truncate:nn { #1 } { "100 } } {#1} \use_ii_i:nn
+  }
+\cs_new:Npn \str_output_byte_pair_aux:nnN #1#2#3
+  {
+    #3
+      { \str_output_byte:n { #1 } }
+      { \str_output_byte:n { #2 - #1 * "100 } }
+  }
+\cs_new_protected:Npn \str_convert_gmap:N #1
   {
     \tl_gset:Nx \g_str_result_tl
       {
-        \exp_after:wN \str_aux_gmap_result_loop:NN
+        \exp_after:wN \str_convert_gmap_loop:NN
         \exp_after:wN #1
           \g_str_result_tl { ? \prg_map_break: }
         \prg_break_point:n { }
       }
   }
-\cs_new_nopar:Npn \str_aux_gmap_result_loop:NN #1#2
+\cs_new:Npn \str_convert_gmap_loop:NN #1#2
   {
     \use_none:n #2
     #1#2
-    \str_aux_gmap_result_loop:NN #1
+    \str_convert_gmap_loop:NN #1
   }
-\cs_new_protected_nopar:Npn \str_aux_gmap_internal_result:N #1
+\cs_new_protected:Npn \str_convert_gmap_internal:N #1
   {
     \tl_gset:Nx \g_str_result_tl
       {
-        \exp_after:wN \str_aux_gmap_internal_result_loop:Nww
+        \exp_after:wN \str_convert_gmap_internal_loop:Nww
         \exp_after:wN #1
           \g_str_result_tl \s_tl \q_stop \prg_map_break: \s_tl
         \prg_break_point:n { }
       }
   }
-\cs_new_nopar:Npn \str_aux_gmap_internal_result_loop:Nww #1 #2 \s_tl #3 \s_tl
+\cs_new:Npn \str_convert_gmap_internal_loop:Nww #1 #2 \s_tl #3 \s_tl
   {
     \use_none_delimit_by_q_stop:w #3 \q_stop
     #1 {#3}
-    \str_aux_gmap_internal_result_loop:Nww #1
-  }
-\cs_new_protected:Npn \str_input:Nn #1#2
-  {
-    \str_aux_escape:NNNn \token_to_str:N \token_to_str:N \token_to_str:N {#2}
-    \tl_set_eq:NN #1 \g_str_result_tl
-  }
-\cs_new_protected:Npn \str_ginput:Nn #1#2
-  {
-    \str_aux_escape:NNNn \token_to_str:N \token_to_str:N \token_to_str:N {#2}
-    \tl_gset_eq:NN #1 \g_str_result_tl
-  }
-\cs_new_protected:Npn \str_escape_use:NNNn #1#2#3#4
-  {
-    \str_aux_escape:NNNn #1#2#3 {#4}
-    \g_str_result_tl
-  }
-\cs_new_protected:Npn \str_aux_escape:NNNn #1#2#3#4
+    \str_convert_gmap_internal_loop:Nww #1
+  }
+\cs_new_protected:Npn \str_if_flag_error:nnx #1
+  {
+    \flag_if_raised:nTF {#1}
+      { \msg_kernel_error:nnx { str } }
+      { \use_none:nn }
+  }
+\cs_new_protected:Npn \str_if_flag_no_error:nnx #1#2#3
+  { \flag_if_raised:nT {#1} { \bool_gset_true:N \g_str_error_bool } }
+\cs_new_protected:Npn \str_if_flag_times:nT #1#2
+  { \flag_if_raised:nT {#1} { #2~(x \flag_height:n {#1} ) } }
+\cs_new_protected_nopar:Npn \str_set_convert:Nnnn
+  { \str_convert_aux_i:nNNnnn { } \tl_set_eq:NN }
+\cs_new_protected_nopar:Npn \str_gset_convert:Nnnn
+  { \str_convert_aux_i:nNNnnn { } \tl_gset_eq:NN }
+\prg_new_protected_conditional:Npnn
+    \str_set_convert:Nnnn #1#2#3#4 { T , F , TF }
+  {
+    \bool_gset_false:N \g_str_error_bool
+    \str_convert_aux_i:nNNnnn
+      { \cs_set_eq:NN \str_if_flag_error:nnx \str_if_flag_no_error:nnx }
+      \tl_set_eq:NN #1 {#2} {#3} {#4}
+    \bool_if:NTF \g_str_error_bool \prg_return_false: \prg_return_true:
+  }
+\prg_new_protected_conditional:Npnn
+    \str_gset_convert:Nnnn #1#2#3#4 { T , F , TF }
+  {
+    \bool_gset_false:N \g_str_error_bool
+    \str_convert_aux_i:nNNnnn
+      { \cs_set_eq:NN \str_if_flag_error:nnx \str_if_flag_no_error:nnx }
+      \tl_gset_eq:NN #1 {#2} {#3} {#4}
+    \bool_if:NTF \g_str_error_bool \prg_return_false: \prg_return_true:
+  }
+\cs_new_protected:Npn \str_convert_aux_i:nNNnnn #1#2#3#4#5#6
   {
     \group_begin:
-      \cs_set_nopar:Npn \str_aux_escape_unescaped:N { #1 }
-      \cs_set_nopar:Npn \str_aux_escape_escaped:N { #2 }
-      \cs_set_nopar:Npn \str_aux_escape_raw:N { #3 }
-      \int_set:Nn \tex_escapechar:D { 92 }
+      #1
       \str_gset_other:Nn \g_str_result_tl {#4}
-      \int_zero:N \l_str_tmpa_int
-      \tl_gset:Nx \g_str_result_tl
-        {
-          \exp_after:wN \str_aux_escape_loop:N \g_str_result_tl
-          \q_recursion_tail \q_recursion_stop
-        }
-      \tl_gput_left:Nx \g_str_result_tl
-        { \str_aux_toks_range:nn \c_zero \l_str_tmpa_int }
-    \group_end:
-  }
-\cs_new_nopar:Npn \str_aux_escape_loop:N #1
-  {
-    \cs_if_exist_use:cF { str_aux_escape_\token_to_str:N #1:w }
-      { \str_aux_escape_unescaped:N #1 }
-    \str_aux_escape_loop:N
-  }
-\cs_new_nopar:cpn { str_aux_escape_ \c_backslash_str :w }
-    \str_aux_escape_loop:N #1
-  {
-    \cs_if_exist_use:cF { str_aux_escape_/\token_to_str:N #1:w }
-      { \str_aux_escape_escaped:N #1 }
-    \str_aux_escape_loop:N
-  }
-\cs_new_eq:NN \str_aux_escape_unescaped:N \prg_do_nothing:
-\cs_new_eq:NN \str_aux_escape_escaped:N   \prg_do_nothing:
-\cs_new_eq:NN \str_aux_escape_raw:N       \prg_do_nothing:
-\cs_new_eq:cN
-  { str_aux_escape_ \c_backslash_str q_recursion_tail :w }
-  \use_none_delimit_by_q_recursion_stop:w
-\cs_new_eq:cN
-  { str_aux_escape_ / \c_backslash_str q_recursion_tail :w }
-  \use_none_delimit_by_q_recursion_stop:w
-\cs_new_nopar:cpn { str_aux_escape_~:w } { }
-\cs_new_nopar:cpx { str_aux_escape_/a:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^G }
-\cs_new_nopar:cpx { str_aux_escape_/t:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^I }
-\cs_new_nopar:cpx { str_aux_escape_/n:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^J }
-\cs_new_nopar:cpx { str_aux_escape_/f:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^L }
-\cs_new_nopar:cpx { str_aux_escape_/r:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^M }
-\cs_new_nopar:cpx { str_aux_escape_/e:w }
-  { \exp_not:N \str_aux_escape_raw:N \iow_char:N \^^[ }
-\cs_new_nopar:cpn { str_aux_escape_/x:w } \str_aux_escape_loop:N
-  {
-    \if_false: { \fi: }
-    \tex_toks:D \l_str_tmpa_int \exp_after:wN { \g_str_result_tl }
-    \int_incr:N \l_str_tmpa_int
-    \int_zero:N \l_str_char_int
-    \str_aux_escape_x_test:N
-  }
-\cs_new_protected_nopar:Npx \str_aux_escape_x_test:N #1
-  {
-    \exp_not:N \token_if_eq_charcode:NNTF \c_space_token #1
-      { \exp_not:N \str_aux_escape_x_test:N }
-      {
-        \l_str_char_int = "0
-          \exp_not:N \token_if_eq_charcode:NNTF \c_lbrace_str #1
-            { \exp_not:N \str_aux_escape_x_braced_loop:N }
-            { \exp_not:N \str_aux_escape_x_unbraced_i:N #1 }
-      }
-  }
-\cs_new_nopar:Npn \str_aux_escape_x_unbraced_i:N #1
-  {
-    \str_aux_hexadecimal_use:NTF #1
-      { \str_aux_escape_x_unbraced_ii:N }
-      { \exp_stop_f: \str_aux_escape_x_end: #1 }
-  }
-\cs_new_nopar:Npn \str_aux_escape_x_unbraced_ii:N #1
-  {
-    \token_if_eq_charcode:NNTF \c_space_token #1
-      { \str_aux_escape_x_unbraced_ii:N }
-      {
-        \str_aux_hexadecimal_use:NTF #1
-          { \exp_stop_f: \str_aux_escape_x_end: }
-          { \exp_stop_f: \str_aux_escape_x_end: #1 }
-      }
-  }
-\cs_new_nopar:Npn \str_aux_escape_x_braced_loop:N #1
-  {
-    \token_if_eq_charcode:NNTF \c_space_token #1
-      { \str_aux_escape_x_braced_loop:N }
-      {
-        \str_aux_hexadecimal_use:NTF #1
-          { \str_aux_escape_x_braced_loop:N }
-          { \exp_stop_f: \str_aux_escape_x_braced_end:N #1 }
-      }
-  }
-\cs_new_protected_nopar:Npx \str_aux_escape_x_braced_end:N #1
-  {
-    \exp_not:N \token_if_eq_charcode:NNTF \c_rbrace_str #1
-      { \exp_not:N \str_aux_escape_x_end: }
-      {
-        \msg_kernel_error:nn { str } { x-missing-brace }
-        \exp_not:N \str_aux_escape_x_end: #1
-      }
-  }
-\group_begin:
-  \char_set_catcode_other:N \^^@
-  \cs_new_protected_nopar:Npn \str_aux_escape_x_end:
-    {
-      \tex_lccode:D \c_zero \l_str_char_int
-      \tl_to_lowercase:n
-        {
-          \tl_gset:Nx \g_str_result_tl
-            { \if_false: } \fi:
-            \str_aux_escape_raw:N ^^@
-            \str_aux_escape_loop:N
-        }
-    }
-\group_end:
-\cs_new_protected:Npn \str_set_convert:Nnnn
-  { \str_convert_aux_i:NNnnn \tl_set_eq:NN }
-\cs_new_protected:Npn \str_gset_convert:Nnnn
-  { \str_convert_aux_i:NNnnn \tl_gset_eq:NN }
-\cs_new_protected:Npn \str_convert_aux_i:NNnnn #1#2#3#4#5
-  {
-    \group_begin:
-      \str_gset_other:Nn \g_str_result_tl {#5}
-
       \exp_after:wN \str_convert_aux_ii:wwwnn
-        \tl_to_str:n {#3} /// \q_stop
-        { from } { input } \str_convert_from_native: \use_i:nn
-
+        \tl_to_str:n {#5} /// \q_stop
+        { decode } { unescape }
+        \prg_do_nothing:
+        \str_convert_decode_:
       \exp_after:wN \str_convert_aux_ii:wwwnn
-        \tl_to_str:n {#4} /// \q_stop
-        { to } { output } \str_convert_to_native: \use_ii:nn
-
+        \tl_to_str:n {#6} /// \q_stop
+        { encode } { escape }
+        \use_ii_i:nn
+        \str_convert_encode_:
     \group_end:
-    #1 #2 \g_str_result_tl
+    #2 #3 \g_str_result_tl
   }
-\cs_new_protected:Npn \str_convert_aux_ii:wwwnn #1 / #2 // #3 \q_stop #4#5
+\cs_new_protected:Npn \str_convert_aux_ii:wwwnn
+    #1 / #2 // #3 \q_stop #4#5
   {
-    \str_convert_aux_iii:nnF {#4} {#1} {native}
-    \str_convert_aux_iii:nnF {#5} {#2} { }
-    \exp_args:Ncc \str_convert_aux_v:NNnNN
+    \str_convert_aux_iv:nnn {enc} {#4} {#1}
+    \str_convert_aux_iv:nnn {esc} {#5} {#2}
+    \exp_args:Ncc \str_convert_aux_iii:NNnNN
       { str_convert_#4_#1: } { str_convert_#5_#2: } {#2}
   }
-\cs_new_protected:Npn \str_convert_aux_iii:nnF #1#2#3
+\cs_new_protected:Npn \str_convert_aux_iii:NNnNN #1#2#3#4#5
   {
-    \cs_if_exist:cF { str_convert_#1_#2: }
-      {
-        \exp_args:Nx \str_convert_aux_iv:nnnF
-          { \str_aux_lowercase_alphanum:n {#2} }
-          {#1} {#2} {#3}
-      }
+    \if_meaning:w #1 #5
+      \tl_if_empty:nF {#3}
+        { \msg_kernel_error:nnx { str } { native-escaping } {#3} }
+      #1
+    \else:
+      #4 #2 #1
+    \fi:
   }
-\cs_new_protected:Npn \str_convert_aux_iv:nnnF #1#2#3#4
+\cs_new_protected:Npn \str_convert_aux_iv:nnn #1#2#3
   {
-    \cs_if_exist:cF { str_convert_#2_#1: }
+    \cs_if_exist:cF { str_convert_#2_#3: }
       {
-        \group_begin:
-          \str_load_catcodes:
-          \str_load_one:n {#1}
-        \group_end:
-      }
-    \cs_if_exist:cTF { str_convert_#2_#1: }
-      { \cs_gset_eq:cc { str_convert_#2_#3: } { str_convert_#2_#1: } }
-      {
-        \msg_kernel_error:nnx { str } { unknown-#2 } {#3}
-        \cs_gset_eq:cc { str_convert_#2_#3: } { str_convert_#2_#4: }
+        \exp_args:Nx \str_convert_aux_v:nnnn
+          { \str_convert_lowercase_alphanum:n {#3} }
+          {#1} {#2} {#3}
       }
   }
-\cs_new_protected:Npn \str_convert_aux_v:NNnNN #1#2#3#4#5
+\cs_new_protected:Npn \str_convert_aux_v:nnnn #1#2#3#4
   {
-    #5 { } {#1}
-    \cs_if_eq:NNTF #1 #4
+    \cs_if_exist:cF { str_convert_#3_#1: }
       {
-        \tl_if_empty:nF {#3}
-          { \msg_kernel_error:nnx { str } { native-ignore-escaping } {#3} }
+        \prop_get:NnNF \g_str_file_prop {#1} \l_str_internal_tl
+          { \tl_set:Nn \l_str_internal_tl {#1} }
+        \cs_if_exist:cF { str_convert_#3_ \l_str_internal_tl : }
+          {
+            \file_if_exist:nTF { l3str-#2- \l_str_internal_tl .def }
+              {
+                \group_begin:
+                  \str_load_catcodes:
+                  \file_input:n { l3str-#2- \l_str_internal_tl .def }
+                \group_end:
+              }
+              {
+                \tl_clear:N \l_str_internal_tl
+                \msg_kernel_error:nnxx { str } { unknown-#2 } {#4} {#1}
+              }
+          }
+        \cs_if_exist:cF { str_convert_#3_#1: }
+          {
+            \cs_gset_eq:cc { str_convert_#3_#1: }
+              { str_convert_#3_ \l_str_internal_tl : }
+          }
       }
-      { #2 }
-    #5 {#1} { }
+    \cs_gset_eq:cc { str_convert_#3_#4: } { str_convert_#3_#1: }
   }
-\cs_new:Npn \str_aux_lowercase_alphanum:n #1
+\cs_new:Npn \str_convert_lowercase_alphanum:n #1
   {
-    \exp_after:wN \str_aux_lowercase_alphanum_loop:N
+    \exp_after:wN \str_convert_lowercase_alphanum_loop:N
       \tl_to_str:n {#1} { ? \prg_map_break: }
     \prg_break_point:n { }
   }
-\cs_new:Npn \str_aux_lowercase_alphanum_loop:N #1
+\cs_new:Npn \str_convert_lowercase_alphanum_loop:N #1
   {
     \use_none:n #1
     \if_num:w `#1 < \c_ninety_one
@@ -730,312 +655,287 @@
         \fi:
       \fi:
     \fi:
-    \str_aux_lowercase_alphanum_loop:N
-  }
-\cs_new_protected_nopar:Npn \str_convert_from_internal: { }
-\cs_new_protected_nopar:Npn \str_convert_to_internal:   { }
-\cs_new_protected:Npn \str_load:n #1
-  {
-    \group_begin:
-      \str_load_catcodes:
-      \clist_map_inline:nn {#1}
-        {
-          \exp_args:Nx \str_load_one:n
-            { \str_aux_lowercase_alphanum:n {#1} }
-        }
-    \group_end:
-  }
-\cs_new_protected:Npn \str_load_one:n #1
-  {
-    \cs_if_exist:cF { str_convert_from_ #1 : }
-      {
-        \cs_if_exist:cF { str_convert_input_#1: }
-          {
-            \file_if_exist:nTF { l3str- #1 .def }
-              { \file_input:n { l3str- #1 .def } }
-              { \str_load_alias:n {#1} }
-          }
-      }
+    \str_convert_lowercase_alphanum_loop:N
   }
-\cs_new_protected:Npn \str_load_alias:n #1
-  {
-    \exp_args:NNx \prop_get:NnNTF \g_str_aliases_prop {#1} \l_str_tmpa_tl
-      {
-        \str_load_one:n { \l_str_tmpa_tl }
-        \cs_if_exist:cTF
-          { str_convert_from_ \l_str_tmpa_tl : }
-          {
-            \str_load_alias_aux:nnn {#1} { \l_str_tmpa_tl } { from }
-            \str_load_alias_aux:nnn {#1} { \l_str_tmpa_tl } { to }
-          }
-          {
-            \str_load_alias_aux:nnn {#1} { \l_str_tmpa_tl } { input }
-            \str_load_alias_aux:nnn {#1} { \l_str_tmpa_tl } { output }
-          }
-      }
-      { \msg_kernel_error:nnx { str } { file-not-found } {#1} }
-  }
-\cs_new_protected:Npn \str_load_alias_aux:nnn #1#2#3
-  { \cs_new_eq:cc { str_convert_#3_#1: } { str_convert_#3_#2: } }
 \cs_new_protected:Npn \str_load_catcodes:
   {
     \char_set_catcode_escape:N \\
     \char_set_catcode_group_begin:N \{
     \char_set_catcode_group_end:N \}
+    \char_set_catcode_math_toggle:N \$
+    \char_set_catcode_alignment:N \&
+    \char_set_catcode_parameter:N \#
     \char_set_catcode_math_superscript:N \^
     \char_set_catcode_ignore:N \ %
-    \tl_map_function:nN { abcdefghijklmnopqrstuvwxyz_:ABCDEFN }
+    \char_set_catcode_space:N \~
+    \tl_map_function:nN { abcdefghijklmnopqrstuvwxyz_:ABCDEFILNPSTUX }
       \char_set_catcode_letter:N
-    \tl_map_function:nN { 0123456789"'?*+ }
+    \tl_map_function:nN { 0123456789"'?*+-.(),`!/<>[];= }
       \char_set_catcode_other:N
     \char_set_catcode_comment:N \%
     \int_set:Nn \tex_endlinechar:D {32}
   }
-\cs_new_protected:Npn \str_convert_from_eight_bit:n #1
+\pdftex_if_engine:TF
+  { \cs_new_eq:NN \str_filter_bytes:n \use:n }
+  {
+    \cs_new:Npn \str_filter_bytes:n #1
+      {
+        \str_filter_bytes_aux:N #1
+          { ? \prg_map_break: }
+        \prg_break_point:n { }
+      }
+    \cs_new:Npn \str_filter_bytes_aux:N #1
+      {
+        \use_none:n #1
+        \if_num:w `#1 < 256 \exp_stop_f:
+          #1
+        \else:
+          \flag_raise:n { str_byte }
+        \fi:
+        \str_filter_bytes_aux:N
+      }
+  }
+\pdftex_if_engine:TF
+  { \cs_new_protected_nopar:Npn \str_convert_unescape_: { } }
+  {
+    \cs_new_protected_nopar:Npn \str_convert_unescape_:
+      {
+        \flag_clear:n { str_byte }
+        \tl_gset:Nx \g_str_result_tl
+          { \exp_args:No \str_filter_bytes:n \g_str_result_tl }
+        \str_if_flag_error:nnx { str_byte } { non-byte } { bytes }
+      }
+  }
+\cs_new_eq:NN \str_convert_unescape_bytes: \str_convert_unescape_:
+\cs_new_protected_nopar:Npn \str_convert_escape_: { }
+\cs_new_eq:NN \str_convert_escape_bytes: \str_convert_escape_:
+\cs_new_protected_nopar:Npn \str_convert_decode_:
+  { \str_convert_gmap:N \str_decode_native_char:N }
+\cs_new:Npn \str_decode_native_char:N #1
+  { #1 \s_tl \int_value:w `#1 \s_tl }
+\group_begin:
+  \char_set_catcode_other:n { 0 }
+  \pdftex_if_engine:TF
+    {
+      \cs_new_protected_nopar:Npn \str_convert_encode_:
+        {
+          \flag_clear:n { str_error }
+          \str_convert_gmap_internal:N \str_encode_native_char:n
+          \str_if_flag_error:nnx { str_error }
+            { pdfTeX-native-overflow } { }
+        }
+      \cs_new:Npn \str_encode_native_char:n #1
+        {
+          \if_num:w #1 < \c_two_hundred_fifty_six
+            \str_output_byte:n {#1}
+          \else:
+            \flag_raise:n { str_error }
+            ?
+          \fi:
+        }
+      \msg_kernel_new:nnnn { str } { pdfTeX-native-overflow }
+        { Character~code~too~large~for~pdfTeX. }
+        {
+          The~pdfTeX~engine~only~supports~8-bit~characters:~
+          valid~character~codes~are~in~the~range~[0,255].~
+          To~manipulate~arbitrary~Unicode,~use~LuaTeX~or~XeTeX.
+        }
+    }
+    {
+      \cs_new_protected_nopar:Npn \str_convert_encode_:
+        {
+          \tex_lccode:D \c_zero \c_zero
+          \int_zero:N \l_str_internal_int
+          \tl_set_eq:NN \l_str_internal_tl \g_str_result_tl
+          \tl_gclear:N \g_str_result_tl
+          \exp_after:wN \str_encode_native_loop:w
+            \l_str_internal_tl \s_tl { \q_stop \prg_map_break: } \s_tl
+          \prg_break_point:n { \str_encode_native_flush: }
+        }
+      \cs_new_protected:Npn \str_encode_native_loop:w #1 \s_tl #2 \s_tl
+        {
+          \use_none_delimit_by_q_stop:w #2 \q_stop
+          \if_num:w \l_str_internal_int = \c_two_hundred_fifty_five
+            \str_encode_native_flush:
+            \l_str_internal_int \c_zero
+          \fi:
+          \tex_advance:D \l_str_internal_int \c_one
+          \tex_lccode:D \l_str_internal_int \int_eval:w #2 \int_eval_end:
+          \str_encode_native_loop:w
+        }
+      \cs_new_protected_nopar:Npn \str_encode_native_flush:
+        {
+          \use:x
+            {
+              \tl_to_lowercase:n
+                {
+                  \tl_gput_right:Nx \exp_not:N \g_str_result_tl
+                    {
+                      \exp_after:wN \str_encode_native_filter:N
+                        \c_str_positive_bytes_tl
+                        { ? = \c_zero \fi: \prg_map_break: }
+                      \prg_break_point:n { }
+                    }
+                }
+            }
+        }
+      \cs_new:Npn \str_encode_native_filter:N #1
+        {
+          \if_num:w `#1 > \l_str_internal_int
+            \exp_after:wN \prg_map_break:
+          \fi:
+          \if_num:w \tex_lccode:D `#1 = \c_zero
+            ^^@
+          \else:
+            #1
+          \fi:
+          \str_encode_native_filter:N
+        }
+    }
+\group_end:
+\cs_new_protected:Npn \str_declare_eight_bit_encoding:nnn #1#2#3
+  {
+    \tl_set:Nn \l_str_internal_tl {#1}
+    \cs_new_protected_nopar:cpn { str_convert_decode_#1: }
+      { \str_convert_decode_eight_bit:n {#1} }
+    \cs_new_protected_nopar:cpn { str_convert_encode_#1: }
+      { \str_convert_encode_eight_bit:n {#1} }
+    \tl_const:cn { c_str_encoding_#1_tl } {#2}
+    \tl_const:cn { c_str_encoding_#1_missing_tl } {#3}
+  }
+\cs_new_protected:Npn \str_convert_decode_eight_bit:n #1
   {
     \group_begin:
-      \int_zero:N \l_str_tmpa_int
-      \exp_last_unbraced:Nx \str_convert_from_eight_bit_load:nn
+      \int_zero:N \l_str_internal_int
+      \exp_last_unbraced:Nx \str_decode_eight_bit_load:nn
         { \tl_use:c { c_str_encoding_#1_tl } }
         { \q_stop \prg_map_break: } { }
       \prg_break_point:n { }
-      \exp_last_unbraced:Nx \str_convert_from_eight_bit_load_missing:n
+      \exp_last_unbraced:Nx \str_decode_eight_bit_load_missing:n
         { \tl_use:c { c_str_encoding_#1_missing_tl } }
         { \q_stop \prg_map_break: }
       \prg_break_point:n { }
-      \str_aux_gmap_result:N \str_convert_from_eight_bit_aux:N
+      \flag_clear:n { str_error }
+      \str_convert_gmap:N \str_decode_eight_bit_char:N
+      \str_if_flag_error:nnx { str_error } { decode-8-bit } {#1}
     \group_end:
   }
-\cs_new_protected_nopar:Npn \str_convert_from_eight_bit_load:nn #1#2
+\cs_new_protected:Npn \str_decode_eight_bit_load:nn #1#2
   {
     \use_none_delimit_by_q_stop:w #1 \q_stop
-    \tex_dimen:D "#1 = \l_str_tmpa_int sp \scan_stop:
-    \tex_skip:D \l_str_tmpa_int = "#1 sp \scan_stop:
-    \tex_toks:D \l_str_tmpa_int \exp_after:wN { \int_value:w "#2 }
-    \tex_advance:D \l_str_tmpa_int \c_one
-    \str_convert_from_eight_bit_load:nn
+    \tex_dimen:D "#1 = \l_str_internal_int sp \scan_stop:
+    \tex_skip:D \l_str_internal_int = "#1 sp \scan_stop:
+    \tex_toks:D \l_str_internal_int \exp_after:wN { \int_value:w "#2 }
+    \tex_advance:D \l_str_internal_int \c_one
+    \str_decode_eight_bit_load:nn
   }
-\cs_new_protected_nopar:Npn \str_convert_from_eight_bit_load_missing:n #1
+\cs_new_protected:Npn \str_decode_eight_bit_load_missing:n #1
   {
     \use_none_delimit_by_q_stop:w #1 \q_stop
-    \tex_dimen:D "#1 = \l_str_tmpa_int sp \scan_stop:
-    \tex_skip:D \l_str_tmpa_int = "#1 sp \scan_stop:
-    \tex_toks:D \l_str_tmpa_int \exp_after:wN
+    \tex_dimen:D "#1 = \l_str_internal_int sp \scan_stop:
+    \tex_skip:D \l_str_internal_int = "#1 sp \scan_stop:
+    \tex_toks:D \l_str_internal_int \exp_after:wN
       { \int_use:N \c_str_replacement_char_int }
-    \tex_advance:D \l_str_tmpa_int \c_one
-    \str_convert_from_eight_bit_load_missing:n
+    \tex_advance:D \l_str_internal_int \c_one
+    \str_decode_eight_bit_load_missing:n
   }
-\cs_new:Npn \str_convert_from_eight_bit_aux:N #1
+\cs_new:Npn \str_decode_eight_bit_char:N #1
   {
     #1 \s_tl
-    \if_num:w \tex_dimen:D `#1 < \l_str_tmpa_int
+    \if_num:w \tex_dimen:D `#1 < \l_str_internal_int
       \if_num:w \tex_skip:D \tex_dimen:D `#1 = `#1 \exp_stop_f:
         \tex_the:D \tex_toks:D \tex_dimen:D
       \fi:
     \fi:
     \int_value:w `#1 \s_tl
   }
-\cs_new_protected:Npn \str_convert_to_eight_bit:n #1
+\cs_new_protected:Npn \str_convert_encode_eight_bit:n #1
   {
     \group_begin:
-      \int_zero:N \l_str_tmpa_int
-      \exp_last_unbraced:Nx \str_convert_to_eight_bit_load:nn
+      \int_zero:N \l_str_internal_int
+      \exp_last_unbraced:Nx \str_encode_eight_bit_load:nn
         { \tl_use:c { c_str_encoding_#1_tl } }
         { \q_stop \prg_map_break: } { }
       \prg_break_point:n { }
-      \str_aux_gmap_internal_result:N \str_convert_to_eight_bit_aux:n
+      \flag_clear:n { str_error }
+      \str_convert_gmap_internal:N \str_encode_eight_bit_char:n
+      \str_if_flag_error:nnx { str_error } { encode-8-bit } {#1}
     \group_end:
   }
-\cs_new_protected_nopar:Npn \str_convert_to_eight_bit_load:nn #1#2
+\cs_new_protected:Npn \str_encode_eight_bit_load:nn #1#2
   {
     \use_none_delimit_by_q_stop:w #1 \q_stop
-    \tex_dimen:D "#2 = \l_str_tmpa_int sp \scan_stop:
-    \tex_skip:D \l_str_tmpa_int = "#2 sp \scan_stop:
-    \exp_args:NNf \tex_toks:D \l_str_tmpa_int
+    \tex_dimen:D "#2 = \l_str_internal_int sp \scan_stop:
+    \tex_skip:D \l_str_internal_int = "#2 sp \scan_stop:
+    \exp_args:NNf \tex_toks:D \l_str_internal_int
       { \str_output_byte:n { "#1 } }
-    \tex_advance:D \l_str_tmpa_int \c_one
-    \str_convert_to_eight_bit_load:nn
+    \tex_advance:D \l_str_internal_int \c_one
+    \str_encode_eight_bit_load:nn
   }
-\cs_new:Npn \str_convert_to_eight_bit_aux:n #1
+\cs_new:Npn \str_encode_eight_bit_char:n #1
   {
     \if_num:w #1 > \c_max_register_int
-      \msg_expandable_kernel_error:nnn
-        { str } { eight-bit-to-byte-overflow } {#1}
+      \flag_raise:n { str_error }
     \else:
-      \if_num:w \tex_dimen:D #1 < \l_str_tmpa_int
+      \if_num:w \tex_dimen:D #1 < \l_str_internal_int
         \if_num:w \tex_skip:D \tex_dimen:D #1 = #1 \exp_stop_f:
           \tex_the:D \tex_toks:D \tex_dimen:D #1 \exp_stop_f:
           \exp_after:wN \exp_after:wN \exp_after:wN \use_none:nn
         \fi:
       \fi:
-      \str_convert_to_eight_bit_aux_ii:n {#1}
+      \str_encode_eight_bit_char_aux:n {#1}
     \fi:
   }
-\cs_new:Npn \str_convert_to_eight_bit_aux_ii:n #1
+\cs_new:Npn \str_encode_eight_bit_char_aux:n #1
   {
     \if_num:w #1 < \c_two_hundred_fifty_six
       \str_output_byte:n {#1}
     \else:
-      \msg_expandable_kernel_error:nn { str } { eight-bit-to-byte }
+      \flag_raise:n { str_error }
     \fi:
   }
-\cs_new_protected:Npn \str_encoding_eight_bit:n #1
+\msg_kernel_new:nnn { str } { unknown-esc }
+  { Escaping~scheme~'#1'~(filtered:~'#2')~unknown. }
+\msg_kernel_new:nnn { str } { unknown-enc }
+  { Encoding~scheme~'#1'~(filtered:~'#2')~unknown. }
+\msg_kernel_new:nnnn { str } { native-escaping }
+  { The~'native'~encoding~scheme~does~not~support~any~escaping. }
   {
-    \cs_new_protected:cpn { str_convert_from_#1: }
-      { \str_convert_from_eight_bit:n {#1} }
-    \cs_new_protected:cpn { str_convert_to_#1: }
-      { \str_convert_to_eight_bit:n {#1} }
-  }
-\pdftex_if_engine:TF
-  { \cs_new_eq:NN \str_filter_bytes:n \use:n }
-  {
-    \cs_new_nopar:Npn \str_filter_bytes:n #1
-      {
-        \str_filter_bytes_aux:N #1
-          { ? \prg_map_break: }
-        \prg_break_point:n { }
-      }
-    \cs_new_nopar:Npn \str_filter_bytes_aux:N #1
-      {
-        \use_none:n #1
-        \if_num:w `#1 < 256 \exp_stop_f: #1 \fi:
-        \str_filter_bytes_aux:N
-      }
+    Since~native~strings~do~not~consist~in~bytes,~
+    none~of~the~escaping~methods~make~sense.~
+    The~specified~escaping,~'#1',~will be ignored.
   }
-\pdftex_if_engine:TF
-  { \cs_new_protected_nopar:Npn \str_convert_input_: { } }
+\msg_kernel_new:nnn { str } { file-not-found }
+  { File~'l3str-#1.def'~not~found. }
+\pdftex_if_engine:F
   {
-    \cs_new_protected_nopar:Npn \str_convert_input_:
+    \msg_kernel_new:nnnn { str } { non-byte }
+      { String~invalid~in~escaping~'#1':~it~may~only~contain~bytes. }
       {
-        \tl_gset:Nx \g_str_result_tl
-          { \exp_args:No \str_filter_bytes:n \g_str_result_tl }
-      }
-  }
-\cs_new_eq:NN \str_convert_input_bytes: \str_convert_input_:
-\cs_new_protected_nopar:Npn \str_convert_output_: { }
-\cs_new_eq:NN \str_convert_output_bytes: \str_convert_output_:
-\cs_new_protected_nopar:Npn \str_convert_from_native:
-  { \str_aux_gmap_result:N \str_convert_from_native_aux:N }
-\cs_new:Npn \str_convert_from_native_aux:N #1
-  { #1 \s_tl \int_value:w `#1 \s_tl }
-\cs_new_protected_nopar:Npn \str_convert_to_native:
-  {
-    \tl_set_eq:NN \l_str_tmpa_tl \g_str_result_tl
-    \str_aux_convert_to_native:n
-      {
-        \exp_after:wN \str_convert_to_native_aux:w
-        \l_str_tmpa_tl \s_tl { \q_stop \prg_map_break: } \s_tl
-      }
-  }
-\cs_new_protected_nopar:Npn \str_convert_to_native_aux:w #1 \s_tl #2 \s_tl
-  {
-    \use_none_delimit_by_q_stop:w #2 \q_stop
-    \str_aux_convert_to_native_step:n {#2}
-    \str_convert_to_native_aux:w
-  }
-\cs_new_protected_nopar:Npn \str_aux_convert_to_native:n #1
-  {
-    \tex_lccode:D \c_zero \c_zero
-    \int_zero:N \l_str_tmpa_int
-    \tl_gclear:N \g_str_result_tl
-    #1
-    \prg_break_point:n { \str_aux_convert_to_native_flush: }
-  }
-\cs_new_protected_nopar:Npn \str_aux_convert_to_native_step:n #1
-  {
-    \if_num:w \l_str_tmpa_int = \c_two_hundred_fifty_five
-      \str_aux_convert_to_native_flush:
-      \l_str_tmpa_int \c_zero
-    \fi:
-    \tex_advance:D \l_str_tmpa_int \c_one
-    \if_int_compare:w #1 > \c_max_char_int
-      \msg_kernel_error:nnx { str } { overflow } {#1}
-      \tex_lccode:D \l_str_tmpa_int \c_str_replacement_char_int
-    \else:
-      \tex_lccode:D \l_str_tmpa_int \int_eval:w #1 \int_eval_end:
-    \fi:
-  }
-\cs_new_protected_nopar:Npn \str_aux_convert_to_native_flush:
-  {
-    \use:x
-      {
-        \tl_to_lowercase:n
+        Some~characters~in~the~string~you~asked~to~convert~are~not~
+        8-bit~characters.~Perhaps~the~string~is~a~'native'~Unicode~string?~
+        If~it~is,~try~using\\
+        \\
+        \iow_indent:n
           {
-            \tl_gput_right:Nx \exp_not:N \g_str_result_tl
-              {
-                \exp_after:wN \str_aux_convert_to_native_filter:N
-                  \c_str_positive_bytes_tl
-                  { ? = \c_zero \fi: \prg_map_break: }
-                \prg_break_point:n { }
-              }
+            \iow_char:N\\str_set_convert:Nnnn \\
+            \ \ <str~var>~\{~<string>~\}~\{~native~\}~\{~<target~encoding>~\}
           }
       }
   }
-\group_begin:
-  \char_set_catcode_other:n { 0 }
-  \cs_new:Npn \str_aux_convert_to_native_filter:N #1
-    {
-      \if_num:w `#1 > \l_str_tmpa_int
-        \exp_after:wN \prg_map_break:
-      \fi:
-      \if_num:w \tex_lccode:D `#1 = \c_zero
-        ^^@
-      \else:
-        #1
-      \fi:
-      \str_aux_convert_to_native_filter:N
-    }
-\group_end:
-\msg_kernel_new:nnnn { str } { x-missing-brace }
-  { Missing~closing~brace~in~ \token_to_str:N \x ~byte~sequence. }
+\msg_kernel_new:nnnn { str } { decode-8-bit }
+  { Invalid~string~in~encoding~'#1'. }
   {
-    You~wrote~something~like~
-    `\iow_char:N\\x\{ \int_to_hexadecimal:n { \l_str_char_int }'.~
-    The~closing~brace~is~missing.
+    LaTeX~came~across~a~byte~which~is~not~defined~to~represent~
+    any~character~in~the~encoding~'#1'.
   }
-\msg_kernel_new:nnnn { str } { overflow }
-  { Character~code~#1~too~big. }
+\msg_kernel_new:nnnn { str } { encode-8-bit }
+  { Unicode~string~cannot~be~converted~to~encoding~'#1'. }
   {
-    \int_compare:nNnTF {#1} > { 1114111 }
-      { The~Unicode~standard~limits~code~points~to~1114111. }
-      {
-        The~pdfTeX~engine~only~supports~8-bit~characters:~
-        valid~character~codes~are~in~the~range~[0,255].~
-        To~manipulate~arbitrary~Unicode,~use~LuaTeX~or~XeTeX.
-      }
+    The~encoding~'#1'~only~contains~a~subset~of~all~Unicode~characters.~
+    LaTeX~was~asked~to~convert~a~string~to~that~encoding,~but~that~
+    string~contains~a~character~that~'#1'~does~not~support.
   }
-\msg_kernel_new:nnn { str } { convert-input }
-  { Input~scheme~`#1'~unknown. }
-\msg_kernel_new:nnn { str } { convert-from }
-  { Encoding~`#1'~unknown. }
-\msg_kernel_new:nnn { str } { convert-to }
-  { Encoding~`#1'~unknown.~Using~UTF-8. }
-\msg_kernel_new:nnn { str } { convert-output }
-  { Output~scheme~`#1~unknown. }
-\msg_kernel_new:nnn { str } { to-native }
-  { Use~\str_set_convert:Nnn to~convert~to~native~strings. }
-\msg_kernel_new:nnn { str } { unicode-surrogate }
-  { Code~point~#1~is~an~unpaired~surrogate. }
-\msg_kernel_new:nnn { str } { utf16-surrogate }
-  { UTF-16~unpaired~surrogate~#1. }
-\msg_kernel_new:nnn { str } { utf16-odd }
-  { UTF-16~dangling~byte~#1. }
-\msg_kernel_new:nnn { str } { utf8-extra-conti }
-  { UTF-8~extra~continuation~byte~#1. }
-\msg_kernel_new:nnn { str } { utf8-missing-conti }
-  { UTF-8~missing~continuation~byte~#1. }
-\msg_kernel_new:nnn { str } { utf8-invalid-byte }
-  { Byte~#1~cannot~appear~in~UTF-8. }
-\msg_kernel_new:nnn { str } { utf8-overlong }
-  { Overlong~UTF-8~byte~sequence~for~code~point~#1. }
-\msg_kernel_new:nnn { str } { utf8-premature-end }
-  { Incomplete~last~UTF-8~character. }
-\msg_kernel_new:nnn { str } { utf8-overflow }
-  { Code~point~#1~too~large~(UTF-8). }
-\msg_kernel_new:nnn { str } { utf32-overflow }
-  { Code~point~too~large~(UTF-32~`#1'). }
-\msg_kernel_new:nnn { str } { utf32-truncated }
-  { Truncated~UTF-32~string~`...#1'. }
 \cs_set:Npn \str_length_skip_spaces:N
   { \exp_args:No \str_length_skip_spaces:n }
 \cs_set_eq:NN \str_length_skip_spaces:n \str_length_ignore_spaces:n
diff --git a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3tl-analysis.sty b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3tl-analysis.sty
index d45f996bdc4..6f82415d186 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/l3str/l3tl-analysis.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/l3str/l3tl-analysis.sty
@@ -91,32 +91,6 @@
       \group_align_safe_end:
     \group_end:
   }
-\cs_new_protected:Npn \tl_set_analysis:Nn #1#2
-  {
-    \tl_analysis:n {#2}
-    \tl_set_eq:NN #1 \g_tl_analysis_result_tl
-  }
-\cs_new_protected:Npn \tl_set_analysis_from_str:Nn #1#2
-  {
-    \str_gset_other:Nn \g_tl_analysis_result_tl {#2}
-    \tl_set:Nx #1
-      {
-        \exp_after:wN \tl_analysis_from_str_loop:N
-          \g_tl_analysis_result_tl \prg_map_break:
-        \prg_break_point:n { }
-      }
-  }
-\group_begin:
-  \char_set_catcode_other:N A
-  \char_set_catcode_other:N C
-  \cs_new_protected:Npn \tl_analysis_from_str_loop:N #1
-    {
-      #1 \s_tl
-      \if_charcode:w #1 ~ A \else: C \fi:
-      \int_value:w `#1 \s_tl
-      \tl_analysis_from_str_loop:N
-    }
-\group_end:
 \cs_new_protected:Npn \tl_analysis_setup:n #1
   {
     \int_set_eq:NN \tex_escapechar:D \c_minus_one
@@ -363,6 +337,26 @@
     32 \s_tl
     \tl_analysis_ii_loop:w #1 ;
   }
+\cs_new_protected:Npn \tl_analysis_map_inline:nn #1
+  {
+    \tl_analysis:n {#1}
+    \int_gincr:N \g_prg_map_int
+    \exp_args:Nc \tl_analysis_map_inline_aux:Nn
+      { tl_analysis_map_inline_ \int_use:N \g_prg_map_int :wNw }
+  }
+\cs_new_protected:Npn \tl_analysis_map_inline_aux:Nn #1#2
+  {
+    \cs_gset_protected:Npn #1 ##1 \s_tl ##2 ##3 \s_tl
+      {
+        \use_none:n ##2
+        #2
+        #1
+      }
+    \exp_after:wN #1
+      \g_tl_analysis_result_tl
+      \s_tl { ? \prg_map_break: } \s_tl
+    \prg_break_point:n { \int_gdecr:N \g_prg_map_int }
+  }
 \cs_new_protected:Npn \tl_show_analysis:N #1
   {
     \exp_args:No \tl_analysis:n {#1}
diff --git a/Master/texmf-dist/tex/latex/l3experimental/xgalley/l3galley.sty b/Master/texmf-dist/tex/latex/l3experimental/xgalley/l3galley.sty
index d95d1b691d5..590062f47ae 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/xgalley/l3galley.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/xgalley/l3galley.sty
@@ -14,7 +14,7 @@
 %% Do not distribute a modified version of this file.
 %% 
 %% File: l3galley.dtx Copyright (C) 1999-2001, 2004-2009 Frank Mittelbach
-%%                              (C) 2010,2011 The LaTeX3 Project
+%%                              (C) 2010-2012 The LaTeX3 Project
 %%
 %% It may be distributed and/or modified under the conditions of the
 %% LaTeX Project Public License (LPPL), either version 1.3c of this
@@ -47,8 +47,8 @@
 %%
 %% -----------------------------------------------------------------------
 %%
-\RequirePackage{l3names}
-\GetIdInfo$Id: l3galley.dtx 3205 2012-01-18 22:09:05Z joseph $
+\RequirePackage{xparse}
+\GetIdInfo$Id: l3galley.dtx 3253 2012-01-28 14:59:55Z joseph $
   {L3 Experimental galley code}
 \ProvidesExplPackage
   {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
@@ -252,7 +252,7 @@
         }
       \par
   }
-\cs_new_protected_nopar:Npn \galley_display_penalty:N #1
+\cs_new_protected:Npn \galley_display_penalty:N #1
   {
      \tl_if_empty:NF #1
        {
@@ -264,7 +264,7 @@
          \int_gset:Nn \g_galley_penalty_int {#1}
        }
   }
-\cs_new_protected_nopar:Npn \galley_display_vspace:N #1
+\cs_new_protected:Npn \galley_display_vspace:N #1
   {
      \tl_if_empty:NF #1
        {
@@ -397,7 +397,7 @@
     \g_galley_restore_running_tl
     \tl_gclear:N \g_galley_restore_running_tl
   }
-\cs_new_protected_nopar:Npn \galley_margins_set_absolute:nn #1#2
+\cs_new_protected:Npn \galley_margins_set_absolute:nn #1#2
   {
     \dim_set:Nn \l_galley_total_left_margin_dim  {#1}
     \dim_set:Nn \l_galley_total_right_margin_dim {#2}
@@ -408,7 +408,7 @@
         - \l_galley_total_right_margin_dim
       }
   }
-\cs_new_protected_nopar:Npn \galley_margins_set_relative:nn #1#2
+\cs_new_protected:Npn \galley_margins_set_relative:nn #1#2
   {
     \dim_add:Nn \l_galley_total_left_margin_dim  {#1}
     \dim_add:Nn \l_galley_total_right_margin_dim {#2}
@@ -419,7 +419,7 @@
         - \l_galley_total_right_margin_dim
       }
   }
-\cs_new_protected_nopar:Npn \galley_parshape_fixed_lines:nnn #1#2#3
+\cs_new_protected:Npn \galley_parshape_fixed_lines:nnn #1#2#3
   {
     \bool_gset_true:N \g_galley_parshape_set_bool
     \bool_set_true:N \l_galley_parshape_fixed_lines_bool
@@ -428,7 +428,7 @@
     \clist_set:Nn \l_galley_parshape_right_indent_clist {#3}
     \bool_set_true:N \l_galley_parshape_resume_std_bool
   }
-\cs_new_protected_nopar:Npn \galley_parshape_multi_par:nnnN #1#2#3#4
+\cs_new_protected:Npn \galley_parshape_multi_par:nnnN #1#2#3#4
   {
     \bool_gset_true:N \g_galley_parshape_set_bool
     \bool_set_true:N \l_galley_parshape_multipar_bool
@@ -438,7 +438,7 @@
     \clist_set:Nn \l_galley_parshape_right_indent_clist {#3}
     \bool_set_eq:NN \l_galley_parshape_resume_std_bool #4
   }
-\cs_new_protected_nopar:Npn \galley_parshape_single_par:nnnN #1#2#3#4
+\cs_new_protected:Npn \galley_parshape_single_par:nnnN #1#2#3#4
   {
     \bool_gset_true:N \g_galley_parshape_set_bool
     \bool_set_false:N \l_galley_parshape_multipar_bool
@@ -503,13 +503,12 @@
           \dim_use:N \l_galley_text_width_dim
         }
   }
-\cs_new_nopar:Npn \galley_set_parshape_map:nn #1#2
+\cs_new:Npn \galley_set_parshape_map:nn #1#2
   { \galley_set_parshape_map_aux:nw  { } #1 , \q_mark #2 , \q_stop }
 \cs_generate_variant:Nn \galley_set_parshape_map:nn { oo }
-\cs_new_nopar:Npn \galley_set_parshape_map_aux:nw
-  #1#2 , #3 \q_mark #4 , #5 \q_stop
+\cs_new:Npn \galley_set_parshape_map_aux:nw #1#2 , #3 \q_mark #4 , #5 \q_stop
   {
-    \bool_if:nTF { \tl_if_empty_p:n {#3} || \tl_if_empty_p:n {#4} }
+    \bool_if:nTF { \tl_if_empty_p:n {#3} || \tl_if_empty_p:n {#5} }
       {
         #1
         \dim_eval:n { \l_galley_total_left_margin_dim + ( #2 ) }
@@ -548,15 +547,15 @@
           \dim_use:N \l_galley_text_width_dim
       }
   }
-\cs_new_nopar:Npn \galley_generate_parshape_lines_aux:n #1
+\cs_new:Npn \galley_generate_parshape_lines_aux:n #1
   {
     \etex_parshapeindent:D #1
     ~
     \etex_parshapelength:D #1
   }
-\cs_new_protected_nopar:Npn \galley_set_user_penalty:n #1
+\cs_new_protected:Npn \galley_set_user_penalty:n #1
   { \tl_gset:Nx \g_galley_interpar_penalty_user_tl { \int_eval:n {#1} } }
-\cs_new_protected_nopar:Npn \galley_set_user_vspace:n #1
+\cs_new_protected:Npn \galley_set_user_vspace:n #1
   { \tl_gset:Nx \g_galley_interpar_vspace_user_tl { \skip_eval:n {#1} } }
 \dim_set:Nn \parskip \c_zero_dim
 \cs_undefine:N \parskip
@@ -567,7 +566,7 @@
 \cs_new_eq:NN \l_galley_par_end_skip   \tex_parfillskip:D
 \cs_new_eq:NN \l_galley_par_indent_dim \tex_parindent:D
 \cs_new_eq:NN \l_galley_last_line_fit_int \etex_lastlinefit:D
-\cs_new_protected_nopar:Npn \galley_set_interword_spacing:N #1
+\cs_new_protected:Npn \galley_set_interword_spacing:N #1
   {
     \bool_if:NTF #1
       { % TODO Hook for font changes required!
@@ -578,6 +577,8 @@
       }
       { \tex_spaceskip:D \c_zero_dim }
   }
+\int_new:N \l_galley_hyphen_left_int
+\int_set:Nn \l_galley_hyphen_left_int { \tex_lefthyphenmin:D }
 \cs_new_eq:NN \l_galley_binop_penalty_int          \tex_binoppenalty:D
 \cs_new_eq:NN \l_galley_double_hyphen_demerits_int \tex_doublehyphendemerits:D
 \cs_new_eq:NN \l_galley_emergency_stretch_skip     \tex_emergencystretch:D
@@ -589,6 +590,21 @@
 \cs_new_eq:NN \l_galley_mismatch_demerits_int      \tex_adjdemerits:D
 \cs_new_eq:NN \l_galley_relation_penalty_int       \tex_relpenalty:D
 \cs_new_eq:NN \l_galley_linebreak_tolerance_int    \tex_tolerance:D
+\cs_new_protected:Npn \galley_break_line:Nn #1#2
+  {
+    \mode_if_vertical:TF
+      { \msg_kernel_error:nn { galley } { no-line-to-end } }
+      {
+        \tex_unskip:D
+        \bool_if:NF #1
+          { \tex_vadjust:D { \tex_penalty:D \c_ten_thousand } }
+        \dim_compare:nNnF {#2} = \c_zero_dim
+          { \tex_vadjust:D { \skip_vertical:n {#2} } }
+        \tex_penalty:D \c_ten_thousand
+        \tex_hfil:D
+        \tex_penalty:D -\c_ten_thousand
+      }
+  }
 \cs_new_eq:NN \l_galley_broken_penalty_int       \tex_brokenpenalty:D
 \cs_new_eq:NN \l_galley_interline_penalty_int    \tex_interlinepenalty:D
 \cs_new_eq:NN \l_galley_parbreak_badness_int     \tex_vbadness:D
@@ -597,7 +613,7 @@
 \cs_new_eq:NN \l_galley_pre_display_penalty_int  \tex_predisplaypenalty:D
 \clist_new:N \l_galley_club_penalties_clist
 \clist_new:N \l_galley_line_penalties_clist
-\cs_new_protected_nopar:Npn \galley_set_display_widow_penalties:n #1
+\cs_new_protected:Npn \galley_set_display_widow_penalties:n #1
   {
     \etex_displaywidowpenalties:D
       \int_eval:w \clist_length:n {#1} + \c_one \int_eval_end:
@@ -605,7 +621,7 @@
       \c_zero
   }
 \cs_generate_variant:Nn \galley_set_display_widow_penalties:n { V , v }
-\cs_new_protected_nopar:Npn \galley_set_widow_penalties:n #1
+\cs_new_protected:Npn \galley_set_widow_penalties:n #1
   {
     \etex_widowpenalties:D
       \int_eval:w \clist_length:n {#1} + \c_one \int_eval_end:
@@ -613,20 +629,20 @@
       \c_zero
   }
 \cs_generate_variant:Nn \galley_set_widow_penalties:n { V , v }
-\cs_new_nopar:Npn \galley_set_aux:n #1 { #1 ~ }
-\cs_new_protected_nopar:Npn \galley_set_club_penalties:n #1
+\cs_new:Npn \galley_set_aux:n #1 { #1 ~ }
+\cs_new_protected:Npn \galley_set_club_penalties:n #1
   {
     \clist_set:Nn \l_galley_club_penalties_clist {#1}
     \galley_calc_interline_penalties:
   }
 \cs_generate_variant:Nn \galley_set_club_penalties:n { V , v }
-\cs_new_protected_nopar:Npn \galley_set_interline_penalties:n #1
+\cs_new_protected:Npn \galley_set_interline_penalties:n #1
   {
     \clist_set:Nn \l_galley_line_penalties_clist {#1}
     \galley_calc_interline_penalties:
   }
 \cs_generate_variant:Nn \galley_set_interline_penalties:n { V , v }
-\cs_new_protected_nopar:Npn \galley_set_display_club_penalties:n #1
+\cs_new_protected:Npn \galley_set_display_club_penalties:n #1
   {
     \etex_clubpenalties:D
       \int_eval:w \clist_length:n {#1} + \c_one \int_eval_end:
@@ -635,7 +651,7 @@
     \galley_calc_interline_penalties:
   }
 \cs_generate_variant:Nn \galley_set_display_club_penalties:n { V , v }
-\cs_new_protected_nopar:Npn \galley_set_interline_penalty:n #1
+\cs_new_protected:Npn \galley_set_interline_penalty:n #1
   {
     \int_compare:nNnTF { \etex_interlinepenalties:D \c_zero } = \c_zero
       {
@@ -643,7 +659,7 @@
         \galley_calc_interline_penalties:
       }
       {
-        \cs_set_nopar:Npn \galley_set_interline_penalty_aux_ii:n ##1
+        \cs_set:Npn \galley_set_interline_penalty_aux_ii:n ##1
           {
             \int_eval:w
               \etex_interlinepenalties:D ##1
@@ -655,7 +671,7 @@
           { \clist_length:N \l_galley_line_penalties_clist } {#1}
       }
   }
-\cs_new_protected_nopar:Npn \galley_set_interline_penalty_aux:nn #1#2
+\cs_new_protected:Npn \galley_set_interline_penalty_aux:nn #1#2
   {
     \etex_interlinepenalties:D
       \etex_interlinepenalties:D \c_zero
@@ -666,9 +682,9 @@
         \galley_set_interline_penalty_aux_ii:n
       \int_eval:w #2 \int_eval_end:
   }
-\cs_new_nopar:Npn \galley_set_interline_penalty_aux_i:n #1
+\cs_new:Npn \galley_set_interline_penalty_aux_i:n #1
   { \etex_interlinepenalties:D \int_eval:w #1 \int_eval_end: }
-\cs_new_nopar:Npn \galley_set_interline_penalty_aux_ii:n #1 { }
+\cs_new:Npn \galley_set_interline_penalty_aux_ii:n #1 { }
 \cs_new_protected_nopar:Npn \galley_calc_interline_penalties:
   {
     \exp_args:Nff \galley_calc_interline_penalties_aux:nn
@@ -692,8 +708,7 @@
       }
       { \clist_length:N \l_galley_line_penalties_clist }
   }
-\cs_new_protected_nopar:Npn \galley_calc_interline_penalties_aux:nn
-  #1#2
+\cs_new_protected:Npn \galley_calc_interline_penalties_aux:nn #1#2
   {
     \etex_interlinepenalties:D #1 ~
       \prg_stepwise_function:nnnN \c_one \c_one {#2}
@@ -702,8 +717,7 @@
         \galley_calc_interline_penalties_aux_ii:n
       \etex_interlinepenalties:D \etex_interlinepenalties:D \c_zero
   }
-\cs_new_nopar:Npn \galley_calc_interline_penalties_aux_i:n
-  #1
+\cs_new:Npn \galley_calc_interline_penalties_aux_i:n #1
   {
     \int_eval:w
         \clist_item:Nn \l_galley_line_penalties_clist { #1 - \c_one }
@@ -712,8 +726,7 @@
       - \etex_clubpenalties:D #1 ~
     \int_eval_end:
   }
-\cs_new_nopar:Npn \galley_calc_interline_penalties_aux_ii:n
-  #1
+\cs_new:Npn \galley_calc_interline_penalties_aux_ii:n #1
   {
     \int_eval:w
         \etex_interlinepenalties:D \etex_interlinepenalties:D \c_zero
@@ -722,11 +735,11 @@
       - \etex_clubpenalties:D #1 ~
     \int_eval_end:
   }
-\cs_new_protected_nopar:Npn \galley_save_club_penalties:N #1
+\cs_new_protected:Npn \galley_save_club_penalties:N #1
   { \clist_set_eq:NN #1 \l_galley_club_penalties_clist }
-\cs_new_protected_nopar:Npn \galley_save_interline_penalties:N #1
+\cs_new_protected:Npn \galley_save_interline_penalties:N #1
   { \clist_set_eq:NN #1 \l_galley_line_penalties_clist }
-\cs_new_protected_nopar:Npn \galley_save_display_club_penalties:N #1
+\cs_new_protected:Npn \galley_save_display_club_penalties:N #1
   {
     \clist_set:Nx #1
       {
@@ -735,9 +748,9 @@
           \galley_save_display_club_penalties:_aux:n
       }
   }
-\cs_new_nopar:Npn \galley_save_display_club_penalties:_aux:n #1
+\cs_new:Npn \galley_save_display_club_penalties:_aux:n #1
   { \int_use:N \etex_clubpenaltes:D \int_eval:w #1 \int_eval_end: , }
-\cs_new_protected_nopar:Npn \galley_save_display_widow_penalties:N #1
+\cs_new_protected:Npn \galley_save_display_widow_penalties:N #1
   {
     \clist_set:Nx #1
       {
@@ -746,9 +759,9 @@
           \galley_save_display_widow_penalties:_aux:n
       }
   }
-\cs_new_nopar:Npn \galley_save_display_widow_penalties:_aux:n #1
+\cs_new:Npn \galley_save_display_widow_penalties:_aux:n #1
   { \int_use:N \etex_displaywidowpenalties:D \int_eval:w #1 \int_eval_end: , }
-\cs_new_protected_nopar:Npn \galley_save_widow_penalties:N #1
+\cs_new_protected:Npn \galley_save_widow_penalties:N #1
   {
     \clist_set:Nx #1
       {
@@ -757,23 +770,29 @@
           \galley_save_widow_penalties:_aux:n
       }
   }
-\cs_new_nopar:Npn \galley_save_widow_penalties:_aux:n #1
+\cs_new:Npn \galley_save_widow_penalties:_aux:n #1
   { \int_use:N \etex_widowpenalties:D \int_eval:w #1 \int_eval_end: , }
 \cs_new_protected_nopar:Npn \galley_interline_penalty:
   { \int_use:N \etex_interlinepenalties:D \etex_interlinepenalties:D \c_zero }
-\cs_set_protected_nopar:Npn \nobreak
+\msg_kernel_new:nnn { galley } { no-line-to-end }
+  { There's~no~line~here~to~end. }
+\RenewDocumentCommand \nobreak { }
   { \bool_gset_true:N \g_galley_no_break_next_bool }
-\cs_set_protected_nopar:Npn \noindent
+\RenewDocumentCommand \noindent { }
   {
     \tex_noindent:D
     \bool_gset_false:N \g_galley_omit_next_indent_bool
   }
-\cs_set_protected_nopar:Npn \vspace #1
+\RenewDocumentCommand \vspace { m }
   {
     \@ifstar
       { \galley_set_user_vspace:n {#1} }
       { \galley_set_user_vspace:n {#1} }
   }
+\RenewDocumentCommand \\ { s O { 0 pt } }
+  { \galley_break_line:Nn #1 {#2} }
+\RenewDocumentCommand \newline { }
+  { \galley_break_line:Nn \c_true_bool { 0 pt } }
 \cs_set_eq:NN \@@par \galley_std_par:
 \cs_set_protected_nopar:Npn \@afterheading
   {
@@ -797,6 +816,7 @@
     \bool_gset_true:N \g_galley_omit_next_indent_bool
     \box \@tempboxa
   }
+\cs_set_eq:Nc \@normalcr { \token_to_str:N \\ }
 %% 
 %%
 %% End of file `l3galley.sty'.
diff --git a/Master/texmf-dist/tex/latex/l3experimental/xgalley/xgalley.sty b/Master/texmf-dist/tex/latex/l3experimental/xgalley/xgalley.sty
index 5ebe766a12b..3e3d251791a 100644
--- a/Master/texmf-dist/tex/latex/l3experimental/xgalley/xgalley.sty
+++ b/Master/texmf-dist/tex/latex/l3experimental/xgalley/xgalley.sty
@@ -14,7 +14,7 @@
 %% Do not distribute a modified version of this file.
 %% 
 %% File: xgalley.dtx Copyright (C) 1999-2001, 2004-2009 Frank Mittelbach
-%%                             (C) 2010,2011 The LaTeX3 Project
+%%                             (C) 2010-2012 The LaTeX3 Project
 %%
 %% It may be distributed and/or modified under the conditions of the
 %% LaTeX Project Public License (LPPL), either version 1.3c of this
@@ -48,7 +48,7 @@
 %% -----------------------------------------------------------------------
 %%
 \RequirePackage{l3names}
-\GetIdInfo$Id: xgalley.dtx 2922 2011-10-17 19:01:04Z joseph $
+\GetIdInfo$Id: xgalley.dtx 3253 2012-01-28 14:59:55Z joseph $
   {L3 Experimental galley}
 \ProvidesExplPackage
   {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}
@@ -195,11 +195,17 @@
     \int_set:Nn \tex_lefthyphenmin:D
       {
         \bool_if:NTF \l_galley_hyphen_enable_bool
-          { \l_galley_hyphen_left_int  } { 63 }
+          { \l_galley_hyphen_left_int  }
+          { 63 }
       }
     \int_set:Nn \tex_uchyph:D
-      { \bool_if:NTF \l_galley_hyphen_uppercase_bool { 1 } { 0 } }
+      {
+        \bool_if:NTF \l_galley_hyphen_uppercase_bool
+          { 1 }
+          { 0 }
+      }
   }
+\UseTemplate { hyphenation } { std } { }
 \tex_defaulthyphenchar:D 45 \scan_stop:
 \tl_new:N \l_galley_justification_other_tl
 \DeclareObjectType { justification } { 0 }
@@ -260,7 +266,7 @@
         \bool_if:NTF \l_galley_fixed_spacing_bool
           { \bool_set_true:N  \exp_not:N \l_galley_fixed_spacing_bool }
           { \bool_set_false:N \exp_not:N \l_galley_fixed_spacing_bool }
-        \galley_set_interword_space:N
+        \galley_set_interword_spacing:N
           \exp_not:N \l_galley_fixed_spacing_bool
         \dim_set:Nn \exp_not:N \l_galley_par_indent_dim
           { \dim_use:N \l_galley_par_indent_dim  }
@@ -268,8 +274,8 @@
           { \skip_use:N \l_galley_line_left_skip }
         \skip_set:Nn \exp_not:N \l_galley_line_right_skip
           { \skip_use:N \l_galley_line_right_skip }
-        \skip_set:Nn \exp_not:N \l_galley_par_start_skip
-          { \skip_use:N \l_galley_par_start_skip }
+        \skip_set:Nn \exp_not:N \l_galley_par_begin_skip
+          { \skip_use:N \l_galley_par_begin_skip }
         \int_set:Nn \exp_not:N \l_galley_last_line_fit_int
           { \int_use:N \l_galley_last_line_fit_int }
         \skip_set:Nn \exp_not:N \@rightskip