chemmacros (12sep15)

git-svn-id: svn://tug.org/texlive/trunk@38359 c570f23f-e606-0410-a88d-b1316a301751

1 files changed, 113 insertions, 4037 deletions

diff --git a/Master/texmf-dist/tex/latex/chemmacros/chemmacros.sty b/Master/texmf-dist/tex/latex/chemmacros/chemmacros.sty
index d6d1a07b195..27fcc7a93cd 100644
--- a/Master/texmf-dist/tex/latex/chemmacros/chemmacros.sty
+++ b/Master/texmf-dist/tex/latex/chemmacros/chemmacros.sty
@@ -1,7 +1,7 @@
 % --------------------------------------------------------------------------
 % the CHEMMACROS package
 %
-%   loads of little helpers for chemists
+%   comprehensive support for typesetting chemistry documents
 %
 % --------------------------------------------------------------------------
 % Clemens Niederberger
@@ -26,4089 +26,162 @@
 %
 % The Current Maintainer of this work is Clemens Niederberger.
 % --------------------------------------------------------------------------
-\RequirePackage{ expl3 , xparse , l3keys2e }
-\def\chemmacros@version{4.7}
-\def\chemmacros@date{2015/02/08}
-
-\ProvidesExplPackage
-  {chemmacros}
-  {\chemmacros@date}
-  {\chemmacros@version}
-  {loads of little helpers for chemists (CN)}
-
-% --------------------------------------------------------------------------
-% check expl3 version:
-\@ifpackagelater { expl3 } { 2013/12/14 }
-  { }
-  {
-    \PackageError { chemmacros } { Support~package~expl3~too~old }
-      {
-        You~need~to~update~your~installation~of~the~bundles~'l3kernel'~and~
-        'l3packages'.\MessageBreak
-        Loading~chemmacros~will~abort!
-      }
-    \tex_endinput:D
-  }
-
-% --------------------------------------------------------------------------
-% variants of kernel commands:
-\cs_generate_variant:Nn \prop_if_in:NnTF   { NV , Nx }
-\cs_generate_variant:Nn \prop_put:Nnn      { NV , NVV , NVx }
-\cs_generate_variant:Nn \prop_get:NnNTF    { NV }
-\cs_generate_variant:Nn \tl_set_rescan:Nnn { NnV }
-\cs_generate_variant:Nn \tl_if_eq:nnTF     { V }
-\cs_generate_variant:Nn \tl_const:cn       { cV }
-\cs_generate_variant:Nn \tl_to_lowercase:n { f }
-
-% --------------------------------------------------------------------------
-% load required packages
-% the technical ones:
-\RequirePackage { environ , scrlfile , etoolbox , translations }
-% related to other topics like mathematics or graphics:
-\RequirePackage { xfrac , siunitx , tikz, mathtools , bm }
-% other packages of this bundle -- ghsystem is not loaded here but at the end
-% of the preamble depending on a package option:
-\RequirePackage { chemformula , chemgreek }
-% TikZ libraries (the don't like expl3 syntax):
-\ExplSyntaxOff
-\usetikzlibrary{calc,arrows}
+\RequirePackage{expl3,xparse,l3keys2e}
 \ExplSyntaxOn
 
 % --------------------------------------------------------------------------
-% boolean variables for the package options
-\bool_new:N      \l__chemmacros_xspace_bool
-\bool_set_true:N \l__chemmacros_xspace_bool
-
-\bool_new:N      \l__chemmacros_circled_bool
-\bool_set_true:N \l__chemmacros_circled_bool
-\bool_new:N      \l__chemmacros_circled_formal_bool
-\bool_set_true:N \l__chemmacros_circled_formal_bool
-\bool_new:N      \l__chemmacros_circled_chem_bool
-\bool_set_true:N \l__chemmacros_circled_chem_bool
-
-\bool_new:N      \l__chemmacros_EZ_cool_bool
-\bool_new:N      \l__chemmacros_Nu_mathspec_bool
-\bool_new:N      \l__chemmacros_chemstyle_bool
-\bool_new:N      \l__chemmacros_hyperref_bool
-\bool_new:N      \l__chemmacros_varioref_bool
-\bool_new:N      \l__chemmacros_chemfig_bool
-\bool_new:N      \l__chemmacros_ghsystem_bool
-% \bool_set_true:N \l__chemmacros_ghsystem_bool
-
-\bool_new:N      \l__chemmacros_iupac_restricted_bool
-\bool_new:N      \l__chemmacros_iupac_strict_bool
-\bool_new:N      \l__chemmacros_in_document_bool
+% package information:
+\tl_const:Nn \c_chemmacros_date_tl {2015/09/11}
+\tl_const:Nn \c_chemmacros_version_major_number_tl {5}
+\tl_const:Nn \c_chemmacros_version_minor_number_tl {0}
+\tl_const:Nn \c_chemmacros_version_subrelease_tl   {}
+\tl_const:Nx \c_chemmacros_version_number_tl
+  {\c_chemmacros_version_major_number_tl.\c_chemmacros_version_minor_number_tl}
+\tl_const:Nx \c_chemmacros_version_tl
+  { \c_chemmacros_version_number_tl \c_chemmacros_version_subrelease_tl }
+\tl_const:Nn \c_chemmacros_info_tl
+  {comprehensive~ support~ for~ typesetting~ chemistry~ documents}
 
-\AtBeginDocument
-  {
-    \bool_set_true:N \l__chemmacros_in_document_bool
-    \@ifpackageloaded { chemstyle }
-      { \bool_set_true:N \l__chemmacros_chemstyle_bool }
-      { \bool_set_false:N \l__chemmacros_chemstyle_bool }
-    \@ifpackageloaded { varioref }
-      { \bool_set_true:N \l__chemmacros_varioref_bool }
-      { \bool_set_false:N \l__chemmacros_varioref_bool }
-    \@ifpackageloaded { hyperref }
-      { \bool_set_true:N \l__chemmacros_hyperref_bool }
-      { \bool_set_false:N \l__chemmacros_hyperref_bool }
-    \@ifpackageloaded { chemfig }
-      { \bool_set_true:N \l__chemmacros_chemfig_bool }
-      { \bool_set_false:N \l__chemmacros_chemfig_bool }
-  }
+\ProvidesExplPackage
+  {chemmacros}
+  {\c_chemmacros_date_tl}
+  {\c_chemmacros_version_tl}
+  {\c_chemmacros_info_tl \c_space_tl (CN)}
 
 % --------------------------------------------------------------------------
-% warning / error messages
-\msg_new:nnnn { chemmacros } { language-not-defined }
-  { The~ language~ `#1'~ is~ not~ defined~ by~ chemmacros. }
-  {
-    You~ chose~ the~ language~ `#1'~ which~ is~ not~ defined~ by~ chemmacros.~
-    `english'~ is~ used~ instead.~ If~ you~ just~ mistyped~ try~ again!~
-    Otherwise~ contact~ the~ author~ and~ he'll~ probably~ add~ your~ language.
-  }
-
-\msg_new:nnnn { chemmacros } { already-defined }
-  { The~ command~ #1~ is~ already~ defined. }
-  {
-    The~ command~ #1~ has~ already~ been~ otherwise.~ chemmacros~ also~ tries~
-    to~ define~ it~ and~ fails.~
-  }
-
-\msg_new:nnnn { chemmacros } { not-defined }
-  { The~ command~ #1~ is~ not~ defined,~ yet. }
-  {
-    The~ command~ #1~ is~ not~ defined,~ yet.~ chemmacros~ tries~ to~
-    redefine~ it~ and~ fails.~
-  }
-
-\msg_new:nnnn { chemmacros } { option-deprecated }
-  { The~ option~ `#1'~ is~ deprecated.~ I~ will~ ignore~ it. }
-  {
-    The~ package~ option~ `#1'~ is~ deprecated~ and~ not~ used~ by~
-    chemmacros~ any~ more.~ It~ will~ therefore~ simply~ be~ ignored.
-  }
-
-\msg_new:nnnn { chemmacros } { command-deprecated }
-  {
-    The~ command~ \token_to_str:N #1 \c_space_tl is~ deprecated.~ Use~
-    \token_to_str:N #2 \c_space_tl instead.
-  }
-  {
-    The~ command~ \token_to_str:N #1 \c_space_tl is~ deprecated.~ Use~
-    \token_to_str:N #2 \c_space_tl instead.
-  }
-
-\msg_new:nnnn { chemmacros } { command-dropped }
-  {
-    The~ command~ \token_to_str:N #1 \c_space_tl has~ been~ dropped.~ I'm~
-    sorry.
-  }
-  {
-    The~ command~ \token_to_str:N #1 \c_space_tl has~ been~ dropped.~ I'm~
-    sorry.
-  }
-
-\msg_new:nnnn { chemmacros } { new-particle }
-  {
-    The~ command~ sequence~ \token_to_str:N #1 \c_space_tl is~ already~
-    defined.
-  }
-  {
-    You've~ tried~ to~ define~ a~ particle~ with~ \token_to_str:N
-    \NewChemParticle ,~ but~ the~ command~ sequence~ \token_to_str:N #1
-    \c_space_tl already~ exists.~ Please~ choose~ another~ name.
-  }
-
-\msg_new:nnnn { chemmacros } { renew-particle }
-  { The~ particle~ \token_to_str:N #1 \c_space_tl is~ not~ defined. }
-  {
-    You've~ tried~ to~ renew~ the~ particle~ \token_to_str:N #1 ,~ but~ it~
-    doesn't~ exist.
-  }
-
-\msg_new:nnnn { chemmacros } { new-latin }
-  {
-    The~ command~ sequence~ \token_to_str:N #1 \c_space_tl is~ already~
-    defined.
-  }
-  {
-    You've~ tried~ to~ define~ a~ latin~ phrase~ with~\token_to_str:N
-    \NewChemLatin ,~ but~ the~ command~ sequence~ \token_to_str:N #1
-    \c_space_tl already~ exists.~ Please~ choose~ another~ name.
-  }
-
-\msg_new:nnnn { chemmacros } { renew-latin }
-  { The~ latin~ phrase \token_to_str:N #1 \c_space_tl is~ not~ defined. }
-  {
-    You've~ tried~ to~ renew~ the~ latin~ phrase~ \token_to_str:N #1 ,~ but~
-    it~ doesn't~ exist.
-  }
-
-\msg_new:nnnn { chemmacros } { new-nmr }
-  {
-    The~ command~ sequence~ \token_to_str:N #1 \c_space_tl is~ already~
-    defined.
-  }
-  {
-    You've~ tried~ to~ define~ a~ NMR~ command~ with~\token_to_str:N
-    \NewChemParticle ,~ but~ the~ command~ sequence~ \token_to_str:N #1
-    \c_space_tl already~ exists.~ Please~ choose~ another~ name.
-  }
-
-\msg_new:nnnn { chemmacros } { renew-nmr }
-  { The~ NMR~ command~ \token_to_str:N #1 \c_space_tl is~ not~ defined. }
+% messages:
+\msg_new:nnn {chemmacros} {too-low-compatibility}
   {
-    You've~ tried~ to~ renew~ the~ NMR~ command~ \token_to_str:N #1 ,~ but~
-    it~ doesn't~ exist.
+    Compatibility~ for~ versions~ below~ v4.7~ is~ not~ supported!~ You~
+    requested~ version~ v #1.~ Loading~ v4.7~ instead.
   }
 
-\msg_new:nnnn { chemmacros } { new-phase }
+\msg_new:nnn {chemmacros} {low-compatibility}
   {
-    The~ command~ sequence~ \token_to_str:N #1 \c_space_tl is~ already~
-    defined.
-  }
-  {
-    You've~ tried~ to~ define~ a~ phase~ with~ \token_to_str:N
-    \NewChemPhase ,~ but~ the~ command~ sequence~ \token_to_str:N #1
-    \c_space_tl already~ exists.~ Please~ choose~ another~ name.
-  }
-
-\msg_new:nnnn { chemmacros } { renew-phase }
-  { The~ phase~ \token_to_str:N #1 \c_space_tl is~ not~ defined. }
-  {
-    You've~ tried~ to~ renew~ the~ phase~ \token_to_str:N #1 ,~ but~ it~
-    doesn't~ exist.
-  }
-
-\msg_new:nnnn { chemmacros } { new-iupac }
-  {
-    The~ iupac~ naming~ command~ \token_to_str:N #1 \c_space_tl is~ already~
-    defined.
-  }
-  {
-    You've~ tried~ to~ define~ a~ iupac~ naming~ command~ with~
-    \token_to_str:N \NewChemIUPAC ,~ but~ the~ iupac~ command~
-    \token_to_str:N #1 \c_space_tl already~ exists.~ Choose~ another~ name~
-    or~ use~ \token_to_str:N \RenewChemIUPAC .
-  }
-
-\msg_new:nnnn { chemmacros } { renew-iupac }
-  {
-    The~ iupac~ naming~ command~ \token_to_str:N #1 \c_space_tl is~ not~
-    defined.
-  }
-  {
-    You've~ tried~ to~ renew~ the~ iupac~ command~ \token_to_str:N #1 ,~ but~
-    it~ doesn't~ exist.~ Use~ \token_to_str:N \NewChemIUPAC \c_space_tl
-    instead.
-  }
-
-\msg_new:nnnn { chemmacros } { let-iupac }
-  {
-    The~ iupac~ naming~ command~ \token_to_str:N #2 \c_space_tl is~ not~
-    defined.
-  }
-  {
-    You've~ tried~ to~ let~ the~ iupac~ command~ \token_to_str:N #1 ~ to~ the~
-    iupac~ command~ \token_to_str:N #2 ,~ but~ the~ latter~ doesn't~ exist.~
-    Use~ \token_to_str:N \NewChemIUPAC \c_space_tl instead~ or~declare~
-    \token_to_str:N #2 \c_space_tl first.
-  }
-
-\msg_new:nnnn { chemmacros } { ox }
-  { \token_to_str:N \ox \c_space_tl : ~ #1 ~ \msg_line_context: . }
-  { \token_to_str:N \ox \c_space_tl : ~ #1 ~ \msg_line_context: . }
-
-\msg_new:nnnn { chemmacros } { OX }
-  { \token_to_str:N \OX \c_space_tl : ~ #1 ~ \msg_line_context: . }
-  { \token_to_str:N \OX \c_space_tl : ~ #1 ~ \msg_line_context: . }
-
-\msg_new:nnnn { chemmacros } { redox }
-  { \token_to_str:N \redox \c_space_tl : ~ #1 ~ \msg_line_context: . }
-  { \token_to_str:N \redox \c_space_tl : ~ #1 ~ \msg_line_context: . }
-
-\msg_new:nnnn { chemmacros } { chemfig }
-  {
-    You~ need~ to~ load~ the~ `chemfig'~ package~ in~ order~ to~ make~
-    \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl work~
-    properly~ \msg_line_context: .
-  }
-  {
-    You~ need~ to~ load~ the~ `chemfig'~ package~ in~ order~ to~ make~
-    \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl work~
-    properly~ \msg_line_context: .
+    You~ requested~ compatibility~ mode~ v #1~ while~ the~ current~ version~
+    of~ chemmacros~ is~ v \c_chemmacros_version_number_tl .~ Not~ all~ features~
+    will~ be~ available!
   }
 
-\msg_new:nnnn { chemmacros } { new-state }
-  {
-    The~ state~ \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl
-    already~ exists.~ You~ need~ to~ use~ \token_to_str:N \RenewChemState
-    \c_space_tl to~ alter~ it~ \msg_line_context: .
-  }
-  {
-    The~ state~ \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl
-    already~ exists.~ You~ need~ to~ use~ \token_to_str:N \RenewChemState
-    \c_space_tl to~ alter~ it~ \msg_line_context: .
-  }
-
-\msg_new:nnnn { chemmacros } { renew-state }
-  {
-    The~ state~ \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl
-    isn't~ set~ up~ yet.~ You~ need~ to~ use~ \token_to_str:N
-    \NewChemState \c_space_tl to~ create~ it~ \msg_line_context: .
-  }
-  {
-    The~ state~ \exp_after:wN \token_to_str:N \cs:w #1 \cs_end: \c_space_tl
-    isn't~ set~ up~ yet.~ You~ need~ to~ use~ \token_to_str:N
-    \NewChemState \c_space_tl to~ create ~it~ \msg_line_context: .
-  }
-
-\msg_new:nnn { chemmacros } { state-syntax }
-  {
-    You're~ using~ a~ no~ longer~ recommended~ syntax~ to~ (re-)define~ a~
-    state~ variable~ \msg_line_context: .~ This~ syntax~ may~ deprecate~ and~
-    be~ removed~ in~ the~ future.
-  }
-
-% declare an option as deprecated:
-\cs_new_protected:Npn \chemmacros_option_deprecated:n #1
-  { \msg_warning:nnn { chemmacros } { option-deprecated } { #1 } }
-
-% define a deprecated command with hints to the corresponding new one:
-\cs_new_protected:Npn \chemmacros_define_deprecated:NN #1#2
-  {
-    \cs_set_protected:Npn #1
-      {
-        \msg_warning:nnxx { chemmacros } { command-deprecated }
-          { #1 } { #2 }
-        #2
-      }
-  }
-
-\NewDocumentCommand \DeclareChemDeprecated { mm }
-  { \chemmacros_define_deprecated:NN #1 #2 }
-
-% define a command as dropped!
-\cs_new_protected:Npn \chemmacros_define_dropped:N #1
-  {
-    \cs_set_protected:Npn #1
-      { \msg_error:nnn { chemmacros } { command-dropped } { #1 } }
-  }
-
-\NewDocumentCommand \DeclareChemDropped { m }
-  { \chemmacros_define_dropped:N #1 }
-
 % --------------------------------------------------------------------------
-% temporary variables
-\tl_new:N  \l__chemmacros_tmpa_tl
-\tl_new:N  \l__chemmacros_tmpb_tl
-\int_new:N \l__chemmacros_tmpa_int
-\box_new:N \l__chemmacros_tmpa_box
+% compatibility
+\fp_new:N \l__chemmacros_compatibility_version_fp
+\fp_set:Nn \l__chemmacros_compatibility_version_fp {\c_chemmacros_version_number_tl}
 
-% --------------------------------------------------------------------------
-% language settings:
-\bool_new:N      \l__chemmacros_language_auto_bool
-\bool_set_true:N \l__chemmacros_language_auto_bool
-% this token list will hold the chosen language for chemmacros; since the
-% language is either chosen automatically or by option it is only available at
-% begin document
-\tl_new:N        \l_chemmacros_language_tl
-\tl_set:Nn       \l_chemmacros_language_tl { english }
-\tl_new:N        \l__chemmacros_current_language_tl
-
-% translate the key #1
-\cs_new:Npn \chemmacros_translate:n #1
+\keys_define:nn {chemmacros/compatibility}
   {
-    \bool_if:NTF \l__chemmacros_language_auto_bool
-      { \GetTranslation{#1} }
-      { \GetTranslationFor{\l_chemmacros_language_tl}{#1} }
+    compatibility .fp_set:N = \l__chemmacros_compatibility_version_fp ,
+    unknown       .code:n   =
+      \PassOptionsToPackage{\CurrentOption}{chemmacros4}
+      \PassOptionsToPackage{\CurrentOption}{chemmacros5}
   }
 
-\AtBeginDocument{
-  \bool_if:NTF \l__chemmacros_language_auto_bool
-    {
-      \tl_set:Nx \l_chemmacros_language_tl
-        { \@trnslt@language{\@trnslt@current@language} }
-    }
-    {
-      \tl_set_eq:NN
-        \l_chemmacros_language_tl
-        \l__chemmacros_current_language_tl
-    }
-}
+\ProcessKeysPackageOptions {chemmacros/compatibility}
 
 % --------------------------------------------------------------------------
-% package options
-%   circled     => circle charges
-%   detect-bold => behaviour when font series bold
-%   EZ          => cool or chemmacros version of \E
-%   german      => change pKA => pKS etc
-%   iupac       => behaviour of nomenclature commands
-%   ngerman     => an alias :)
-%   ghsystem    => load ghsystem or don't
-%   method      => use `chemformula' or `mhchem'
-%   strict      => errors or warnings
-%   synchronize => let particles et.al. adapt chemformula's font selection
-%   ugreek      => behaviour of \chemDelta, \chemalpha, ...
-%   version=1   => compatibility for documents set with v1.*
-%   xspace      => add an \xspace after a whole bunch of macros
-
-% this boolean has to be public since the other packages of the bundle may
-% want to know its value
-
-\bool_new:N \l__chemmacros_detect_bold_bool
-\bool_set_true:N \l__chemmacros_detect_bold_bool
-
-\bool_new:N \l__chemmacros_option_greek_set_bool
-\bool_new:N \l__chemmacros_use_upgreek_bool
-\bool_new:N \l__chemmacros_use_textgreek_bool
-\bool_new:N \l__chemmacros_use_kpfonts_bool
-\bool_new:N \l__chemmacros_use_newtx_bool
-
-\cs_new:Npn \chemmacros_inner_font: {}
-
-\keys_define:nn { chemmacros / option }
+% compare version numbers
+% #1: number
+% #2: relation
+% #3: number
+% #4: true
+% #5: false
+\prg_new_conditional:Npnn \chemmacros_if_version:nnn #1#2#3 {p,T,F,TF}
   {
-    bpchem             .code:n = \chemmacros_option_deprecated:n { bpchem } ,
-    circletype         .choice: ,
-    circletype / math  .code:n  =
-      { \bool_set_false:N \l__chemmacros_circled_chem_bool } ,
-    circletype / chem  .code:n  =
-      { \bool_set_true:N \l__chemmacros_circled_chem_bool } ,
-    circletype         .default:n = chem ,
-    circled            .choice: ,
-    circled / none     .code:n =
-      {
-        \bool_set_false:N \l__chemmacros_circled_bool
-        \bool_set_false:N \l__chemmacros_circled_formal_bool
-      } ,
-    circled / formal   .code:n =
+    \fp_compare:nTF { floor(#1) = floor(#3) }
       {
-        \bool_set_true:N \l__chemmacros_circled_bool
-        \bool_set_true:N \l__chemmacros_circled_formal_bool
-      } ,
-    circled / all      .code:n =
-      {
-        \bool_set_true:N \l__chemmacros_circled_bool
-        \bool_set_false:N \l__chemmacros_circled_formal_bool
-      } ,
-    circled            .default:n  = all ,
-    detect-bold        .code:n = \chemmacros_option_deprecated:n { detect-bold } ,
-    EZ                 .code:n = \chemmacros_option_deprecated:n { EZ } ,
-    german             .code:n     =
-      \tl_set:Nn \l__chemmacros_current_language_tl { german } ,
-    ngerman            .code:n     =
-      \tl_set:Nn \l__chemmacros_current_language_tl { ngerman } ,
-    ghsystem           .bool_set:N = \l__chemmacros_ghsystem_bool ,
-    ghsystem           .default:n  = true ,
-    iupac              .choice: ,
-    iupac / restricted .code:n     =
-      \bool_set_true:N \l__chemmacros_iupac_restricted_bool
-      \bool_set_false:N \l__chemmacros_iupac_strict_bool ,
-    iupac / auto       .code:n     =
-      \bool_set_false:N \l__chemmacros_iupac_restricted_bool
-      \bool_set_false:N \l__chemmacros_iupac_strict_bool ,
-    iupac / strict     .code:n     =
-      \bool_set_false:N \l__chemmacros_iupac_restricted_bool
-      \bool_set_true:N \l__chemmacros_iupac_strict_bool ,
-    language           .code:n     =
-      \tl_if_eq:nnTF { #1 } { auto }
-        { \bool_set_true:N \l__chemmacros_language_auto_bool }
-        {
-          \bool_set_false:N \l__chemmacros_language_auto_bool
-          \tl_set:Nn \l__chemmacros_current_language_tl { #1 }
-        } ,
-    method             .choice: ,
-    method / chemformula   .code:n     =
-      \chemmacros_option_deprecated:n { method } ,
-    method / mhchem    .code:n     =
-      \chemmacros_option_deprecated:n { method } ,
-    Nu                 .choice: ,
-    Nu / mathspec      .code:n     =
-     \bool_set_true:N \l__chemmacros_Nu_mathspec_bool ,
-    Nu / chemmacros    .code:n     =
-     \bool_set_false:N \l__chemmacros_Nu_mathspec_bool ,
-    strict             .code:n     =
-      \chemmacros_option_deprecated:n { strict } ,
-    synchronize        .choice: ,
-    synchronize / true .code:n     =
-      \cs_set_eq:NN \chemmacros_inner_font: \chemformula_font_inner: ,
-    synchronize / false .code:n = \cs_set:Nn \chemmacros_inner_font: {} ,
-    synchronize        .default:n  = true ,
-    greek              .choice: ,
-    greek / upgreek    .code:n     =
-      \chemgreek_activate_mapping:n { upgreek }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / textgreek   .code:n    =
-      \chemgreek_activate_mapping:n { textgreek }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / kpfonts    .code:n     =
-      \chemgreek_activate_mapping:n { kpfonts }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / newtx      .code:n     =
-      \chemgreek_activate_mapping:n { newtx }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / mathdesign .code:n     =
-      \chemgreek_activate_mapping:n { mathdesign }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / fourier    .code:n     =
-      \chemgreek_activate_mapping:n { fourier }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / textalpha  .code:n     =
-      \chemgreek_activate_mapping:n { textalpha }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / math       .code:n     =
-      \chemgreek_activate_mapping:n { default }
-      \bool_set_true:N \l__chemmacros_option_greek_set_bool ,
-    greek / auto       .code:n     =
-      \bool_set_false:N \l__chemmacros_option_greek_set_bool ,
-    greek              .default:n  = auto ,
-    upgreek            .code:n = \chemmacros_option_deprecated:n { upgreek } ,
-    version            .code:n = \chemmacros_option_deprecated:n { version } ,
-    cmversion          .code:n = \chemmacros_option_deprecated:n { cmversion } ,
-    cmversion          .choice: ,
-    xspace             .bool_set:N = \l__chemmacros_xspace_bool ,
-    xspace             .default:n  = true
-  }
-
-
-
-\ProcessKeysOptions { chemmacros / option }
-
-% --------------------------------------------------------------------------
-% set up a few things:
-% - is `ghsystem' requested?
-% - do we need `xspace'?
-% - what about the greek letters?
-
-\seq_new:N  \l__chemmacros_greek_packages_seq
-\prop_new:N \l__chemmacros_greek_mapping_prop
-
-\cs_new_protected:Npn \chemmacros_add_greek_package_mapping:nn #1#2
-  {
-    \seq_put_right:Nn \l__chemmacros_greek_packages_seq {#1}
-    \prop_put:Nnn \l__chemmacros_greek_mapping_prop {#1} {#2}
-  }
-
-\cs_generate_variant:Nn \chemgreek_activate_mapping:n { V }
-
-\cs_new_protected:Npn \__chemmacros_select_greek_mapping:n #1
-  {
-    \bool_if:NF \l__chemmacros_option_greek_set_bool
+        \fp_compare:nTF
+          { (\chemmacros_get_minor:f {#1}) #2 (\chemmacros_get_minor:f {#3}) }
+          { \prg_return_true: }
+          { \prg_return_false: }
+      }
       {
-        \@ifpackageloaded { #1 }
-          {
-            \prop_get:NnN
-              \l__chemmacros_greek_mapping_prop
-              { #1 }
-              \l__chemmacros_tmpa_tl
-            \chemgreek_activate_mapping:V \l__chemmacros_tmpa_tl
-            \bool_set_true:N \l__chemmacros_option_greek_set_bool
-            \seq_map_break:
-          }
-          { }
+        \fp_compare:nTF { (#1) #2 (#3) }
+          { \prg_return_true: }
+          { \prg_return_false: }
       }
   }
 
-\chemmacros_add_greek_package_mapping:nn {upgreek}    {upgreek}
-\chemmacros_add_greek_package_mapping:nn {textgreek}  {textgreek}
-\chemmacros_add_greek_package_mapping:nn {mathdesign} {mathdesign}
-\chemmacros_add_greek_package_mapping:nn {kpfonts}    {kpfonts}
-\chemmacros_add_greek_package_mapping:nn {newtxmath}  {newtx}
-\chemmacros_add_greek_package_mapping:nn {fourier}    {fourier}
-\chemmacros_add_greek_package_mapping:nn {textalpha}  {textalpha}
-
-\AtEndPreamble
-  {
-    \bool_if:NT \l__chemmacros_ghsystem_bool
-      { \RequirePackage { ghsystem } }
-    \bool_if:NT \l__chemmacros_xspace_bool
-      { \RequirePackage { xspace } }
-    \seq_map_function:NN
-      \l__chemmacros_greek_packages_seq
-      \__chemmacros_select_greek_mapping:n
-  }
-
-\cs_new_protected:Npn \chemmacros_xspace:
-  { \bool_if:NT \l__chemmacros_xspace_bool { \xspace } }
+\cs_new:Npn \__chemmacros_get_minor:w #1.#2.#3 \q_stop
+  { \tl_if_blank:nTF {#2} {0} {#2} }
+\cs_new:Npn \chemmacros_get_minor:n #1
+  { \__chemmacros_get_minor:w #1.. \q_stop }
+\cs_generate_variant:Nn \chemmacros_get_minor:n {f}
 
-% --------------------------------------------------------------------------
-% TikZ drawings - helper macros
-\cs_new_protected:Npn \chemmacros_tikz_picture:nn #1#2
-  { \tikzpicture[#1] #2 \endtikzpicture }
-\cs_generate_variant:Nn \chemmacros_tikz_picture:nn { fn,xn }
-
-\cs_new_protected:Npn \chemmacros_tikz_draw:n #1
-  { \draw[#1] }
-\cs_generate_variant:Nn \chemmacros_tikz_draw:n { f,x }
-
-\cs_new_protected:Npn \chemmacros_tikz_node:n #1
-  { \node[#1] }
-\cs_generate_variant:Nn \chemmacros_tikz_node:n { f,x }
-
-\cs_new_protected:Npn \chemmacros_tikz_shade:n #1
-  { \shade[#1] }
-\cs_generate_variant:Nn \chemmacros_tikz_shade:n { f,x }
-
-\cs_new_protected:Npn \chemmacros_tikz_shadedraw:n #1
-  { \shadedraw[#1] }
-\cs_generate_variant:Nn \chemmacros_tikz_shadedraw:n { f,x }
-
-\cs_new_protected:Npn \chemmacros_tikz_node_in_draw:n #1
-  { node[#1] }
-\cs_generate_variant:Nn \chemmacros_tikz_node_in_draw:n { f,x }
-
-% --------------------------------------------------------------------------
-% a few general functions:
-\cs_new_eq:NN \chemmacros_leave_vmode:   \chemformula_leave_vmode:
-\cs_new_eq:NN \chemmacros_ignore_spaces: \tex_ignorespaces:D
-\cs_new_eq:NN \chemmacros_nobreak:       \chemformula_nobreak:
-\cs_new_eq:NN \chemmacros_allow_break:   \chemformula_allow_break:
-\cs_new_eq:NN \chemmacros_skip_nobreak:N \chemformula_skip_nobreak:N
-\cs_new:Npn   \chemmacros_remove_backslash:N #1
-  { \exp_after:wN \use_none:n \token_to_str:N #1 }
-
-\prg_new_protected_conditional:Npnn \chemmacros_if_is_cs:n #1 { T,F,TF }
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl { \token_if_cs:NTF #1 { } { x } }
-    \tl_if_blank:VTF \l__chemmacros_tmpa_tl
-      { \prg_return_true: }
-      { \prg_return_false: }
-  }
-
-% detection and handling of bold face:
-\prg_new_protected_conditional:Npnn \chemmacros_if_bold: { T,F,TF }
+% check compatibility
+% #1: relation
+% #2: number
+% #3: true
+% #4: false
+\prg_new_conditional:Npnn \chemmacros_if_compatiblity:nn #1#2 {p,T,F,TF}
   {
-    \seq_if_in:NVTF \l__chemmacros_if_bf_seq \f@series
+    \chemmacros_if_version:nnnTF
+      { \fp_to_decimal:N \l__chemmacros_compatibility_version_fp }
+      {#1}
+      {#2}
       { \prg_return_true: }
       { \prg_return_false: }
   }
+\cs_generate_variant:Nn \chemmacros_if_compatiblity:nnT {nV}
 
-\seq_new:N  \l__chemmacros_if_bf_seq
-
-\seq_set_split:Nnn \l__chemmacros_if_bf_seq { , }
-  {
-    b , bc , bm , bx , bux ,
-    eb , ebc , ebx , mb ,
-    sb , sbc , sbx ,
-    ub , ubc , ubx
-  }
-
-\cs_new_protected:Npn \chemmacros_bm:n #1
-  {
-    \bool_if:NTF \l__chemmacros_detect_bold_bool
-      { \bm { #1 } }
-      { #1 }
-  }
-
-\cs_new_protected:Npn \chemmacros_bf:n #1
-  {
-    \bool_if:NTF \l__chemmacros_detect_bold_bool
-      { { \normalfont \bfseries #1 } }
-      { { \normalfont #1 } }
-  }
-
-\cs_new_protected:Npn \chemmacros_detect_bold:n #1
-  {
-    \chemmacros_if_bold:TF
-      {
-        \mode_if_math:TF
-          { \chemmacros_bm:n { #1 } }
-          { \chemmacros_bf:n { #1 } }
-      }
-      { #1 }
-  }
-
-% ---------------------------------------------------------------------------
-% transition state symbol
-\cs_new_protected:Npn \__chemmacros_transition_state:
-  {
-    \text
-      {
-        \skip_horizontal:n { .1ex }
-        \hbox_overlap_right:n
-          { \rule { .6ex } { 0pt } \rule { .05ex } { 1.3ex } }
-        \hbox_overlap_right:n { \rule [ .4ex ] { 1.3ex } { .05ex } }
-        \rule [ .85ex ] { 1.3ex } { .05ex }
-        \skip_horizontal:n { .1ex }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_transition_state:
-  {
-    \ensuremath
-      {
-        \mathchoice
-          { \displaystyle }
-          { \textstyle }
-          { \scriptstyle }
-          { \scriptscriptstyle }
-        \__chemmacros_transition_state:
-      }
-  }
-
-% \DeclareDocumentCommand?
-\cs_new_eq:NN \transitionstatesymbol \chemmacros_transition_state:
-
-% --------------------------------------------------------------------------
-% let's make use of `chemformula' inside some of `chemmacros' commands:
-\cs_new_protected:Nn \chemmacros_atom:n
-  {
-    \mode_if_math:TF
-      { \text { \chemmacros_inner_font: #1 } }
-      { \group_begin: \chemmacros_inner_font: #1 \group_end: }
-  }
-\cs_generate_variant:Nn \chemmacros_atom:n { V }
-
-\cs_new_protected:Npn \chemmacros_text:n #1
-  { \mode_if_math:TF { \text { #1 } } { #1 } }
-
-\tl_new:N \l__chemmacros_chemformula_tl
-
-\cs_new_protected:Npn \chemmacros_chemformula:n #1
-  {
-    \group_begin:
-      \cs_set_eq:NN \chemformula_font_inner: \chemmacros_inner_font:
-      \chemformula_chcpd:nn {} { #1 }
-    \group_end:
-  }
-\cs_generate_variant:Nn \chemmacros_chemformula:n { x,V }
-
-% --------------------------------------------------------------------------
-% particles, charges
-\NewDocumentCommand \NewChemParticle { mm }
-  {
-    \cs_if_free:NTF #1
-      { \chemmacros_define_particle:Nn #1 { #2 } }
-      { \msg_error:nnn { chemmacros } { new-particle } { #1 } }
-  }
-
-\NewDocumentCommand \RenewChemParticle { mm }
-  {
-    \cs_if_free:NTF #1
-      { \msg_error:nnn { chemmacros } { renew-particle } { #1 } }
-      { \chemmacros_define_particle:Nn #1 { #2 } }
-  }
-
-\NewDocumentCommand \DeclareChemParticle { mm }
-  { \chemmacros_define_particle:Nn #1 { #2 } }
-
-\cs_new_protected:Nn \chemmacros_define_particle:Nn
-  {
-    \cs_set_protected:Npn #1
-      {
-        \chemformula_chcpd:nn {} { #2 }
-        \chemmacros_xspace:
-      }
-  }
-
-\NewChemParticle \el  { e- }
-\NewChemParticle \prt { p+ }
-\NewChemParticle \ntr { n^0 }
-
-% --------------------------------------------------------------------------
-% charges
-% circled charge signs: they are defined in the `chemformula' module:
-% use directly:
-
-\cs_new_protected:Npn \fplus  { { \chemformula_fplus:  } }
-\cs_new_protected:Npn \fminus { { \chemformula_fminus: } }
-
-% change output depending on circled-option
-\cs_new_eq:NN \chemmacros_plus: \chemformula_plus:
-\cs_new_eq:NN \chemmacros_minus: \chemformula_minus:
-
-\cs_new_protected:Npn \chemmacros_formal_plus:
-  {
-    \group_begin:
-      \bool_set_true:N \l__chemformula_formal_charges_bool
-      \chemformula_plus:
-    \group_end:
-  }
-
-\cs_new_protected:Npn \chemmacros_formal_minus:
-  {
-    \group_begin:
-      \bool_set_true:N \l__chemformula_formal_charges_bool
-      \chemformula_minus:
-    \group_end:
-  }
-
-\cs_new_protected:Npn \chemmacros_charge:n #1
-  {
-    \chemformula_superscript:n
-      { \chemmacros_detect_bold:n { #1 } }
-  }
-
-\keys_define:nn { chemmacros / charges }
-  { append .code:n = \chemmacros_option_deprecated:n { append } }
-
-\NewDocumentCommand \mch { o }
-  {
-    \IfNoValueTF { #1 }
-      { \chemmacros_charge:n { \chemmacros_minus: } }
-      { \chemmacros_charge:n { #1 \chemmacros_minus: } }
-  }
-
-\NewDocumentCommand \pch { o }
-  {
-    \IfNoValueTF { #1 }
-      { \chemmacros_charge:n { \chemmacros_plus: } }
-      { \chemmacros_charge:n { #1 \chemmacros_plus: } }
-  }
-
-\NewDocumentCommand \fmch { o }
-  {
-    \IfNoValueTF { #1 }
-      { \chemmacros_charge:n { \chemmacros_formal_minus: } }
-      { \chemmacros_charge:n { #1 \chemmacros_formal_minus: } }
-  }
-
-\NewDocumentCommand \fpch { o }
-  {
-    \IfNoValueTF { #1 }
-      { \chemmacros_charge:n { \chemmacros_formal_plus: } }
-      { \chemmacros_charge:n { #1 \chemmacros_formal_plus: } }
-  }
-
-\tl_new:N  \l__chemmacros_partial_charge_format_tl
-\tl_set:Nn \l__chemmacros_partial_charge_format_tl { \tiny }
-
-\cs_new_protected:Npn \delm
-  {
-    \mbox {
-      \l__chemmacros_partial_charge_format_tl
-      \c_math_toggle_token \delta \chemmacros_minus: \c_math_toggle_token
-    }
-    \chemmacros_xspace:
-  }
-\cs_new_protected:Npn \delp
-  {
-    \mbox {
-      \l__chemmacros_partial_charge_format_tl
-      \c_math_toggle_token \delta \chemmacros_plus: \c_math_toggle_token
-    }
-    \chemmacros_xspace:
-  }
-\cs_new_protected:Npn \fdelm
-  {
-    \mbox {
-      \l__chemmacros_partial_charge_format_tl
-      \c_math_toggle_token \delta \chemmacros_formal_minus: \c_math_toggle_token
-    }
-    \chemmacros_xspace:
-  }
-\cs_new_protected:Npn \fdelp
-  {
-    \mbox {
-      \l__chemmacros_partial_charge_format_tl
-      \c_math_toggle_token \delta \chemmacros_formal_plus: \c_math_toggle_token
-    }
-    \chemmacros_xspace:
-  }
-
-\cs_new_protected:Npn \scrm
-  { \ensuremath { \scriptstyle \chemmacros_minus: } }
-\cs_new_protected:Npn \scrp
-  { \ensuremath { \scriptstyle \chemmacros_plus: } }
-\cs_new_protected:Npn \fscrm
-  { \ensuremath { \scriptstyle \chemmacros_formal_minus: } }
-\cs_new_protected:Npn \fscrp
-  { \ensuremath { \scriptstyle \chemmacros_formal_plus: } }
-\cs_new_protected:Npn \fsscrm
-  { \ensuremath { \scriptscriptstyle \chemmacros_formal_minus: } }
-\cs_new_protected:Npn \fsscrp
-  { \ensuremath { \scriptscriptstyle \chemmacros_formal_plus: } }
-
-\keys_define:nn { chemmacros / charges }
-  {
-    partial-format .tl_set:N = \l__chemmacros_partial_charge_format_tl
-  }
-
-% --------------------------------------------------------------------------
-% ions, molecules
-% proton, hydroxide, hydronium/oxonium, water, nucleophile, electrophile
-\NewChemParticle \Hpl { H+ }
-\NewChemParticle \Hyd { OH- }
-\NewChemParticle \HtO { H3O+ }
-\NewChemParticle \El  { E+ }
-\NewChemParticle \water { H2O }
-
-\NewDocumentCommand \chemmacros_Nu:w { o }
-  {
-    \IfNoValueF { #1 } { \keys_set:nn { chemmacros / particle } { #1 } }
-    \bool_if:NTF \l__chemmacros_particle_elpair_bool
-      { \chemmacros_elpair:n { Nu } \mch }
-      { \chemmacros_chemformula:n { Nu- } }
-    \chemmacros_xspace:
-  }
-
-\AtBeginDocument
-  {
-    \bool_if:NTF \l__chemmacros_Nu_mathspec_bool
-      { \cs_set_eq:NN \Nuc \chemmacros_Nu:w }
-      { \cs_set_eq:NN \Nu \chemmacros_Nu:w }
-  }
-
-\cs_new_protected:Npn \chemmacros_ba:
-  {
-    \bool_if:NTF \l__chemmacros_particle_elpair_bool
-      { \chemmacros_elpair:n { ba } \mch }
-      { \chemmacros_chemformula:n { ba- } }
-    \chemmacros_xspace:
-  }
-
-\NewDocumentCommand \ba { o }
-  {
-    \group_begin:
-      \IfNoValueF { #1 } { \keys_set:nn { chemmacros / particle } { #1 } }
-      \chemmacros_ba:
-    \group_end:
-  }
-
-\cs_new_protected:Npn \chemmacros_elpair:n #1
-  {
-    \bool_if:NTF \l__chemmacros_chemfig_bool
-      {
-        \bool_if:NTF \l__chemmacros_elpair_dots_bool
-          { \chlewis { 0: } { #1 } }
-          { \chlewis { 0| } { #1 } }
-%          { { \chemmacros_inner_font: #1 \chlewis { 0=| } { \vphantom { #1 } } } }
-      }
-      {
-        \msg_error:nnn { chemmacros } { chemfig } { #1 }
-        \chemmacros_atom:n { #1 }
-      }
-  }
+% user checks:
+\NewDocumentCommand \IfChemCompatibilityTF {mm+m+m}
+  { \chemmacros_if_compatiblity:nnTF {#1} {#2} {#3} {#4} }
 
-\bool_new:N \l__chemmacros_particle_elpair_bool
-\bool_new:N \l__chemmacros_elpair_dots_bool
+\NewDocumentCommand \IfChemCompatibilityT {mm+m}
+  { \chemmacros_if_compatiblity:nnT {#1} {#2} {#3} }
 
-\keys_define:nn { chemmacros / particle }
-  {
-    elpair         .choice: ,
-    elpair / false .code:n    =
-      { \bool_set_false:N \l__chemmacros_particle_elpair_bool } ,
-    elpair / dots  .code:n    =
-      {
-        \bool_set_true:N \l__chemmacros_particle_elpair_bool
-        \bool_set_true:N \l__chemmacros_elpair_dots_bool
-      } ,
-    elpair / dash  .code:n    =
-      {
-        \bool_set_true:N \l__chemmacros_particle_elpair_bool
-        \bool_set_false:N \l__chemmacros_elpair_dots_bool
-      } ,
-    elpair         .default:n = dots
-  }
+\NewDocumentCommand \IfChemCompatibilityF {mm+m}
+  { \chemmacros_if_compatiblity:nnF {#1} {#2} {#3} }
 
 % --------------------------------------------------------------------------
-% IUPAC
-\prop_new:N \l__chemmacros_iupac_prop
-
-\cs_new_protected:Npn \chemmacros_new_iupac:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \prop_if_in:NVTF \l__chemmacros_iupac_prop \l__chemmacros_tmpa_tl
-      { \msg_error:nnn { chemmacros } { new-iupac } { #1 } }
-      {
-        \prop_put:NVn \l__chemmacros_iupac_prop
-          \l__chemmacros_tmpa_tl
-          { #2 }
-      }
-    \chemmacros_make_iupac:
-  }
-
-\cs_new_protected:Npn \chemmacros_define_iupac:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \prop_put:NVn \l__chemmacros_iupac_prop
-      \l__chemmacros_tmpa_tl
-      { #2 }
-    \chemmacros_make_iupac:
-  }
-
-\cs_new_protected:Npn \chemmacros_renew_iupac:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \prop_if_in:NVTF \l__chemmacros_iupac_prop \l__chemmacros_tmpa_tl
-      {
-        \prop_put:NVn \l__chemmacros_iupac_prop
-          \l__chemmacros_tmpa_tl
-          { #2 }
-      }
-      { \msg_error:nnn { chemmacros } { renew-iupac } { #1 } }
-    \chemmacros_make_iupac:
-  }
-
-\cs_new_protected:Npn \chemmacros_let_iupac:NN #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \tl_set:Nx \l__chemmacros_tmpb_tl
-      { \chemmacros_remove_backslash:N #2 }
-    \prop_get:NVNTF \l__chemmacros_iupac_prop
-      \l__chemmacros_tmpb_tl
-      \l__chemmacros_tmpc_tl
-      {
-        \prop_put:NVV \l__chemmacros_iupac_prop
-          \l__chemmacros_tmpa_tl
-          \l__chemmacros_tmpc_tl
-      }
-      { \msg_error:nnnn { chemmacros } { let-iupac } { #1 } { #2 } }
-    \chemmacros_make_iupac:
-  }
-
-\cs_new_protected:Npn \chemmacros_define_deprecated_iupac:NN #1#2
-  {
-    \chemmacros_define_iupac:Nn #1
-      {
-        \msg_warning:nnnn { chemmacros } { command-deprecated }
-          { #1 } { #2 }
-        #2
-      }
-  }
-
-
-\cs_new_protected:Npn \chemmacros_make_iupac:
-  {
-    \bool_if:NT \l__chemmacros_in_document_bool
-      {
-        \bool_if:NTF \l__chemmacros_inside_iupac_bool
-          {
-            \prop_map_inline:Nn \l__chemmacros_iupac_prop
-              { \cs_set_protected:cpn { ##1 } { ##2 } }
-          }
-          {
-            \bool_if:NF \l__chemmacros_iupac_restricted_bool
-              {
-                \bool_if:NTF \l__chemmacros_iupac_strict_bool
-                  {
-                    \prop_map_inline:Nn \l__chemmacros_iupac_prop
-                      { \cs_set_protected:cpn { ##1 } { ##2 } }
-                  }
-                  {
-                    \prop_map_inline:Nn \l__chemmacros_iupac_prop
-                      {
-                        \cs_if_exist:cF { ##1 }
-                          { \cs_set_protected:cpn { ##1 } { ##2 } }
-                      }
-                  }
-              }
-          }
-      }    
-  }
-
-\AtBeginDocument { \chemmacros_make_iupac: }
-
-\NewDocumentCommand \DeclareChemIUPAC { mm }
-  { \chemmacros_define_iupac:Nn #1 { #2 } }
-
-\NewDocumentCommand \NewChemIUPAC { mm }
-  { \chemmacros_new_iupac:Nn #1 { #2 } }
-
-\NewDocumentCommand \RenewChemIUPAC { mm }
-  { \chemmacros_renew_iupac:Nn #1 { #2 } }
-
-\NewDocumentCommand \LetChemIUPAC { mm }
-  { \chemmacros_let_iupac:NN #1 #2 }
-
-\NewDocumentCommand \DeprecateChemIUPAC { mm }
-  { \chemmacros_define_deprecated_iupac:NN #1 #2 }
-
-% stereo descriptors and other nomenclature commands
-% Cahn-Ingold-Prelog
-\dim_new:N  \l__chemmacros_cip_kern_dim
-\dim_set:Nn \l__chemmacros_cip_kern_dim { .075em }
-
-\keys_define:nn { chemmacros / iupac }
-  { cip-kern .dim_set:N = \l__chemmacros_cip_kern_dim }
-
-\NewDocumentCommand \cip { m }
-  { \chemmacros_cip:n { #1 } }
-
-\cs_new_protected:Npn \chemmacros_cip:n #1
-  { ( \textit{#1} \tex_kern:D \l__chemmacros_cip_kern_dim ) }
-
-\DeprecateChemIUPAC \Rcip \rectus
-\DeprecateChemIUPAC \Scip \sinister
-
-\NewChemIUPAC \rectus   { \cip { R } }
-\NewChemIUPAC \sinister { \cip { S } }
-
-\LetChemIUPAC \R \rectus
-\LetChemIUPAC \S \sinister
-
-% TikZ needs : to be other
-\ExplSyntaxOff
-\protected\def\chemmacros@sconf#1%
-  {%
-    \begingroup
-    \tikz[baseline,text height=1.5ex,text depth=.25ex]
-      {
-        \node[anchor=base] (chemmacros@@Sconf) {#1} ;
-        \draw[->,thick,rotate=90]
-          ($(chemmacros@@Sconf.center)+(20:.8em)$) arc (20:340:.8em);
-      }%
-    \endgroup
-  }
-
-\protected\def\chemmacros@rconf#1%
-  {%
-    \begingroup
-    \tikz[baseline,text height=1.5ex,text depth=.25ex]
-      {
-        \node[anchor=base] (chemmacros@@Rconf) {#1} ;
-        \draw[<-,thick,rotate=90]
-          ($(chemmacros@@Rconf.center)+(20:.8em)$) arc (20:340:.8em) ;
-      }%
-    \endgroup
-  }
-\ExplSyntaxOn
-
-\NewDocumentCommand \Sconf { O{S} } { \chemmacros@sconf { #1 } }
-\NewDocumentCommand \Rconf { O{R} } { \chemmacros@rconf { #1 } }
-
-% E(ntgegen)/Z(usammen)
-\NewChemIUPAC \entgegen { \cip { E } }
-\NewChemIUPAC \zusammen { \cip { Z } }
-
-\LetChemIUPAC \E \entgegen
-\LetChemIUPAC \Z \zusammen
-
-% cis/trans
-\NewChemIUPAC \cis   { \textit { cis } }
-\NewChemIUPAC \trans { \textit { trans } }
-
-% fac/mer
-\NewChemIUPAC \fac { \textit { fac } }
-\NewChemIUPAC \mer { \textit { mer } }
-
-% tert
-\NewChemIUPAC \tert  { \textit { tert } }
-
-% Fischer
-\NewChemIUPAC \dexter { \textsc { d } }
-\NewChemIUPAC \laevus { \textsc { l } }
-
-\LetChemIUPAC \D \dexter
-\LetChemIUPAC \L \laevus
-
-% ortho/meta/para
-\NewChemIUPAC \ortho { \textit { o } }
-\NewChemIUPAC \meta  { \textit { m } }
-\NewChemIUPAC \para  { \textit { p } }
-
-% syn/anti
-\NewChemIUPAC \syn  { \textit { syn } }
-\NewChemIUPAC \anti { \textit { anti } }
-
-% coordination chemistry
-\bool_new:N \l__chemmacros_bridge_super_bool
-
-\keys_define:nn { chemmacros / iupac }
-  {
-    bridge-number         .choice: ,
-    bridge-number / sub   .code:n     =
-      \bool_set_false:N \l__chemmacros_bridge_super_bool ,
-    bridge-number / super .code:n     =
-      \bool_set_true:N \l__chemmacros_bridge_super_bool ,
-    coord-use-hyphen      .bool_set:N = \l__chemmacros_coord_use_hyphen_bool ,
-    coord-use-hyphen      .default:n  = true
-  }
-
-\cs_new_protected:Npn \chemformula_hapto:n #1
-  {
-    \chemeta \chemformula_superscript:n { #1 }
-    \bool_if:NT \l__chemmacros_coord_use_hyphen_bool
-      { \chemmacros_break_point_hyphen: }
-  }
-
-\cs_new_protected:Npn \chemformula_dento:n #1
-  {
-    \chemkappa \chemformula_superscript:n { #1 }
-    \bool_if:NT \l__chemmacros_coord_use_hyphen_bool
-      { \chemmacros_break_point_hyphen: }
-  }
-
-\cs_new_protected:Npn \chemformula_bridge:n #1
-  {
-    \chemmu
-    \tl_if_blank:nF { #1 }
-      {
-        \bool_if:NTF \l__chemmacros_bridge_super_bool
-          { \chemformula_superscript:n { #1 } }
-          { \chemformula_subscript:n { #1 } }
-      }
-    \bool_if:NT \l__chemmacros_coord_use_hyphen_bool
-      { \chemmacros_break_point_hyphen: }
-  }
-
-\NewChemIUPAC \hapto  { \chemformula_hapto:n }
-\NewChemIUPAC \dento  { \chemformula_dento:n }
-\NewChemIUPAC \bridge { \chemformula_bridge:n }
-
-% attachments to heteroatoms / added hydrogen
-\NewChemIUPAC \hydrogen   { \textit { H } }
-\NewChemIUPAC \oxygen     { \textit { O } }
-\NewChemIUPAC \nitrogen   { \textit { N } }
-\NewChemIUPAC \sulfur     { \textit { S } }
-\NewChemIUPAC \phosphorus { \textit { P } }
-
-\LetChemIUPAC \H  \hydrogen
-\LetChemIUPAC \O  \oxygen
-\LetChemIUPAC \N  \nitrogen
-\LetChemIUPAC \Sf \sulfur
-\LetChemIUPAC \P  \phosphorus
-
-% language specific settings
-\AtBeginDocument
-  {
-    \bool_if:NT \l__chemmacros_italian_bool
-      {
-        \NewChemIUPAC \sin  { \textit { sin } }
-        \NewChemIUPAC \ter  { \textit { ter } }
-      }
-  }
-
-% greek letters
-\NewChemIUPAC \a { \chemalpha }
-\NewChemIUPAC \b { \chembeta }
-\NewChemIUPAC \g { \chemgamma }
-\NewChemIUPAC \d { \chemdelta }
-\NewChemIUPAC \k { \chemkappa }
-\NewChemIUPAC \m { \chemmu }
-\NewChemIUPAC \n { \chemeta }
-\NewChemIUPAC \w { \chemomega }
-
-% \iupac (basically the same as bpchem's \IUPAC)
-% - allows multiple breaking points as compound names can get really long and
-%   especially in multicolumn documents can span more than two lines
-% - add a (very) little space before the hyphen and a little negative space
-%   after it
-% - add a little space at breaking points if not broken
-% - enables all naming commands regardless if they're definied otherwise or not
-\cs_new_protected:Nn \chemmacros_allow_hyphens:
-  {
-    \chemmacros_nobreak:
-    \skip_horizontal:N \c_zero_dim
-  }
-
-\dim_new:N  \l__chemmacros_iupac_hyphen_pre_dim
-\dim_set:Nn \l__chemmacros_iupac_hyphen_pre_dim { .01em }
-\dim_new:N  \l__chemmacros_iupac_hyphen_post_dim
-\dim_set:Nn \l__chemmacros_iupac_hyphen_post_dim { -.03em }
-\dim_new:N  \l__chemmacros_iupac_break_dim
-\dim_set:Nn \l__chemmacros_iupac_break_dim { .03em }
-
-\keys_define:nn { chemmacros / iupac }
-  {
-    hyphen-pre-space  .dim_set:N = \l__chemmacros_iupac_hyphen_pre_dim ,
-    hyphen-post-space .dim_set:N = \l__chemmacros_iupac_hyphen_post_dim ,
-    break-space       .dim_set:N = \l__chemmacros_iupac_break_dim
-  }
-
-\cs_new_protected:Nn \chemmacros_break_point_hyphen:
-  {
-    \chemmacros_nobreak:
-    \tex_discretionary:D { - } { }
-      {
-        \tex_kern:D \l__chemmacros_iupac_hyphen_pre_dim
-        -
-        \tex_kern:D \l__chemmacros_iupac_hyphen_post_dim
-      }
-    \chemmacros_allow_hyphens:
-  }
-
-\cs_new_protected:Npn \chemmacros_break_point:
-  {
-    \chemmacros_nobreak:
-    \tex_discretionary:D { - } { }
-      { \tex_kern:D \l__chemmacros_iupac_break_dim }
-    \chemmacros_allow_hyphens:
-  }
-
-\cs_new_protected:Npn \chemmacros_superscript:
-  { \mode_if_math:TF { \sb } { \textsuperscript } }
+% compatibility coding:
+\cs_new_protected:Npn \ChemCompatibility #1#2 \EndChemCompatibility
+  { \chemmacros_if_compatiblity:nnT {=} {#1} {#2} }
   
-\bool_new:N \l__chemmacros_inside_iupac_bool
-
-\group_begin:
-\char_set_catcode_active:N \~
-\char_set_lccode:nn {`~} {`|}
-\tl_to_lowercase:n { \group_end: \cs_set_eq:NN ~ } \chemmacros_break_point:
-
-\group_begin:
-\char_set_catcode_active:N \~
-\char_set_lccode:nn {`~} {`^}
-\tl_to_lowercase:n { \group_end: \cs_set_protected:Npn ~ }
-  { \chemmacros_superscript: }
-
-\group_begin:
-\char_set_catcode_active:N \|
-\char_set_catcode_active:N \^
-
-\cs_new_protected:Npn \chemmacros_iupac:n #1
-  {
-    \group_begin:
-      \bool_set_true:N \l__chemmacros_inside_iupac_bool
-      \chemmacros_make_iupac:
-      \chemmacros_ignore_spaces:
-      \cs_set_eq:NN \- \chemmacros_break_point_hyphen:
-      \chemmacros_define_deprecated:NN \| |
-      \chemmacros_define_deprecated:NN \^ ^
-      \tl_set_rescan:Nnn \l__chemmacros_tmpa_tl
-        {
-          \char_set_catcode_active:N \|
-          \char_set_catcode_active:N \^
-        }
-        {#1}
-      \l__chemmacros_tmpa_tl
-    \group_end:
-  }
-
-% \cs_new_protected:Npn \chemmacros_iupac_aux:n #1
-%   {
-%       #1
-%     \group_end:
-%   }
-\group_end:
-
-% Thanks to Joseph Wright and Enrico Gregorio for the help on the curious
-% redefinition of \- and the end of the compilation
-% see http://tex.stackexchange.com/q/42405/5049 for reference
-\cs_set_protected:Npx \| { \exp_not:o { \| } }
-\cs_set_protected:Npx \- { \exp_not:o { \- } }
-\cs_set_eq:NN \@dischyph \-
-
-\NewDocumentCommand \iupac { }
-  { \chemmacros_iupac:n }
-
-% --------------------------------------------------------------------------
-% latin phrases
-\tl_new:N  \l__chemmacros_latin_format_tl
-\tl_set:Nn \l__chemmacros_latin_format_tl { \itshape }
-
-\keys_define:nn { chemmacros / latin }
-  { format . tl_set:N = \l__chemmacros_latin_format_tl }
-
-\cs_new_protected:Npn \chemmacros_latin:n #1
-  { { \l__chemmacros_latin_format_tl #1 } }
-
-\prop_new:N \l__chemmacros_latin_prop
-
-\cs_new_protected:Npn \chemmacros_new_latin:Nn #1#2
-  {
-    \cs_if_free:NTF #1
-      {
-        \cs_new_protected:Npn #1
-          { \chemmacros_latin:n { #2 } \chemmacros_xspace: }
-        \prop_put:Nnn \l__chemmacros_latin_prop { #1 } { #2 }
-      }
-      { \msg_error:nnn { chemmacros } { new-latin } { #1 } }
-  }
-
-\cs_new_protected:Npn \chemmacros_define_latin:Nn #1#2
-  {
-    \cs_if_free:NTF #1
-      {
-        \cs_new_protected:Npn #1
-          { \chemmacros_latin:n { #2 } \chemmacros_xspace: }
-        \prop_put:Nnn \l__chemmacros_latin_prop { #1 } { #2 }
-      }
-      {
-        \cs_set_protected:Npn #1
-          { \chemmacros_latin:n { #2 } \chemmacros_xspace: }
-        \prop_put:Nnn \l__chemmacros_latin_prop { #1 } { #2 }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_renew_latin:Nn #1#2
-  {
-    \prop_if_in:NnTF \l__chemmacros_latin_prop { #1 }
-      { \cs_set:Npn #1 { \chemmacros_latin:n { #2 } \chemmacros_xspace: } }
-      { \msg_error:nnn { chemmacros } { renew-latin } { #1 } }
-  }
-
-\NewDocumentCommand \NewChemLatin { mm }
-  { \chemmacros_new_latin:Nn #1 { #2 } }
-
-\NewDocumentCommand \RenewChemLatin { mm }
-  { \chemmacros_renew_latin:Nn #1 { #2 } }
-
-\NewDocumentCommand \DeclareChemLatin { mm }
-  { \chemmacros_define_latin:Nn #1 { #2 } }
-
-\AtBeginDocument
-  {
-    \bool_if:NTF \l__chemmacros_chemstyle_bool
-      {
-        \AfterPackage* { chemstyle }
-          {
-            \cs_undefine:N \invacuo
-            \cs_set_eq:NN \chemmacros_latin:n \cst@latin
-          }
-      }
-      {
-        \cs_new_eq:NN  \latin \chemmacros_latin:n
-      }
-    \NewChemLatin \insitu   { in~situ }
-    \NewChemLatin \abinitio { ab~initio }
-    \NewChemLatin \invacuo  { in~vacuo }
-  }
-
-% --------------------------------------------------------------------------- %
-% acid / base
-\tl_new:N  \l__chemmacros_k_acid_tl
-\tl_new:N  \l__chemmacros_k_base_tl
-\tl_new:N  \l__chemmacros_k_water_tl
-
-% \bool_new:N \l__chemmacros_subscript_lowercase_bool
-
-\tl_set:Nn \l__chemmacros_k_acid_tl
-  { \chemmacros_translate:n {K-acid} }
-
-\tl_set:Nn \l__chemmacros_k_base_tl
-  { \chemmacros_translate:n {K-base} }
-
-\tl_set:Nn \l__chemmacros_k_water_tl
-  { \chemmacros_translate:n {K-water} }
-
-\keys_define:nn { chemmacros / acid-base }
-  {
-    p-style             .choice: ,
-    p-style / slanted   .code:n   = \cs_set_eq:NN \chemmacros_p_style:n \textsl ,
-    p-style / italics   .code:n   = \cs_set_eq:NN \chemmacros_p_style:n \textit ,
-    p-style / upright   .code:n   = \cs_set_eq:NN \chemmacros_p_style:n \textup ,
-    K-acid              .tl_set:N = \l__chemmacros_k_acid_tl ,
-    K-base              .tl_set:N = \l__chemmacros_k_base_tl ,
-    K-water             .tl_set:N = \l__chemmacros_k_water_tl ,
-    subscript           .code:n   = \chemmacros_option_deprecated:n {#1}
-    % subscript / lowercase .code:n =
-    %   \bool_set_true:N \l__chemmacros_subscript_lowercase_bool ,
-    % subscript / uppercase .code:n =
-    %   \bool_set_false:N \l__chemmacros_subscript_lowercase_bool
-  }
-
-\cs_new_eq:NN \chemmacros_p_style:n \textup
-
-\cs_new_protected:Npn \Ka
-  {
-    \ensuremath
-      {
-        \chemmacros_detect_bold:n
-          {
-            K
-            \c_math_subscript_token
-              { \l__chemmacros_k_acid_tl }
-          }
-      }
-    \chemmacros_xspace:
-  }
-
-\cs_new_protected:Npn \Kb
-  {
-    \ensuremath
-      {
-        \chemmacros_detect_bold:n
-          {
-            K
-            \c_math_subscript_token
-              { \l__chemmacros_k_base_tl }
-          }
-      }
-    \chemmacros_xspace:
-  }
-
-\cs_new_protected:Npn \Kw
-  {
-    \ensuremath
-      {
-        \chemmacros_detect_bold:n
-          {
-            K
-            \c_math_subscript_token
-              { \l__chemmacros_k_water_tl }
-          }
-      }
-    \chemmacros_xspace:
-  }
-
-\cs_new_protected:Npn \chemmacros_p:n #1
-  {
-    \group_begin:
-      \mbox
-        {
-          \chemmacros_p_style:n { p }
-          \ensuremath { #1 }
-        }
-    \group_end:
-  }
-
-\NewDocumentCommand \p { m }
-  { \chemmacros_p:n { #1 } }
-
-\cs_new_protected:Npn \pH
-  {
-    \chemmacros_p:n { \chemmacros_chemformula:n { H } }
-    \chemmacros_xspace:
-  }
-
-\cs_new_protected:Npn \pOH
-  {
-    \chemmacros_p:n { \chemmacros_chemformula:n { OH } }
-    \chemmacros_xspace:
-  }
-
-\NewDocumentCommand \pKa { o }
-  {
-    \chemmacros_p:n
-      {
-        \Ka \IfNoValueF { #1 }
-          { {} \c_math_subscript_token { \chemmacros_detect_bold:n { #1 } } }
-      }
-    \chemmacros_xspace:
-  }
-
-\NewDocumentCommand \pKb { o }
-  {
-    \chemmacros_p:n
-      {
-        \Kb \IfNoValueF { #1 }
-          { {} \c_math_subscript_token { \chemmacros_detect_bold:n { #1 } } }
-      }
-    \chemmacros_xspace:
-  }
-
-% --------------------------------------------------------------------------
-% units
-\DeclareSIUnit { \atm        } { atm }
-\DeclareSIUnit { \atmosphere } { atm }
-\DeclareSIUnit { \calory     } { cal }
-\DeclareSIUnit { \cal        } { cal }
-
-\AtBeginDocument
-  {
-    \bool_if:NF \l__chemmacros_chemstyle_bool
-      {
-        \DeclareSIUnit { \cmc   } { \cubic\centi\metre }
-        \DeclareSIUnit { \molar } { \mole\per\cubic\deci\metre }
-        \DeclareSIUnit { \Molar } { \textsc{m} }
-      }
-  }
-
-\DeclareSIUnit { \moLar   } { \mole\per\liter }
-\DeclareSIUnit { \MolMass } { \gram\per\mole }
-\DeclareSIUnit { \normal  } { \textsc{n} }
-\DeclareSIUnit { \torr    } { torr }
-
-% --------------------------------------------------------------------------
-% reaction mechanisms
-% \mech[<type>]
-% <type> - substitutions: {}, 1, 2, se, 1e, 2e, ar
-%        - eliminations:  e, e1, e2, cb
-\tl_new:N \l__chemmacros_mech_type_tl
-\tl_new:N \l__chemmacros_mech_mol_tl
-\tl_new:N \l__chemmacros_mech_ar_tl
-
-\cs_new_protected:Npn \__chemmacros_set_mech:nnn #1#2#3
-  {
-    \tl_set:Nn \l__chemmacros_mech_type_tl { #1 }
-    \tl_set:Nn \l__chemmacros_mech_mol_tl  { #2 }
-    \tl_set:Nn \l__chemmacros_mech_ar_tl   { #3 }
-  }
-
-\keys_define:nn { chemmacros / mech }
-  {
-    type      .choice: ,
-    type /    .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {N} }
-            \c_math_toggle_token
-          }
-          { }
-      } ,
-    type / 1  .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {N} }
-            \c_math_toggle_token
-            1
-          }
-          { }
-      } ,
-    type / 2  .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {N} }
-            \c_math_toggle_token
-            2
-          }
-          { }
-      } ,
-    type / se .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {E} }
-            \c_math_toggle_token
-          }
-          { }
-      } ,
-    type / 1e .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {E} }
-            \c_math_toggle_token
-            1
-          }
-          { }
-      } ,
-    type / 2e .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {E} }
-            \c_math_toggle_token
-            2
-          }
-          { }
-      } ,
-    type / ar .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { S }
-          {
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {E} }
-            \c_math_toggle_token
-          }
-          { Ar - }
-      } ,
-    type / e  .code:n    =
-      { \__chemmacros_set_mech:nnn { E } { } { } } ,
-    type / e1 .code:n    =
-      { \__chemmacros_set_mech:nnn { E } { 1 } { } } ,
-    type / e2 .code:n    =
-      { \__chemmacros_set_mech:nnn { E } { 2 } { } } ,
-    type / cb .code:n    =
-      {
-        \__chemmacros_set_mech:nnn { E }
-          {
-            1
-            \c_math_toggle_token
-              \c_math_subscript_token { \text {cb} }
-            \c_math_toggle_token
-          }
-          { }
-      } ,
-    type      .default:n = 
-  }
-
-\cs_new_protected:Npn \chemmacros_mech:n #1
-  {
-    \tl_if_blank:nTF { #1 }
-      { \keys_set:nn { chemmacros / mech } { type } }
-      { \keys_set:nn { chemmacros / mech } { type = #1 } }
-    \mbox
-      {
-        \tl_use:N \l__chemmacros_mech_ar_tl
-        \tl_use:N \l__chemmacros_mech_type_tl
-        \tl_use:N \l__chemmacros_mech_mol_tl
-      }
-    \chemmacros_xspace:
-  }
-
-\NewDocumentCommand \mech { o }
-  {
-    \IfNoValueTF { #1 }
-      { \chemmacros_mech:n { } }
-      { \chemmacros_mech:n { #1 } }
-  }
-
-% --------------------------------------------------------------------------
-% oxidation numbers
-% \ox{<number>,<atom>}
-\bool_new:N       \l__chemmacros_ox_sign_bool
-\bool_new:N       \l__chemmacros_ox_integer_bool
-\bool_new:N       \l__chemmacros_ox_explicit_sign_bool
-\bool_set_false:N \l__chemmacros_ox_explicit_sign_bool
-\bool_new:N       \l__chemmacros_ox_format_roman_bool
-\bool_set_true:N  \l__chemmacros_ox_format_roman_bool
-\bool_new:N       \l__chemmacros_ox_decimal_marker_comma_bool
-\bool_set_false:N \l__chemmacros_ox_decimal_marker_comma_bool
-\bool_new:N       \l__chemmacros_ox_parse_bool
-\bool_set_true:N  \l__chemmacros_ox_parse_bool
-\bool_new:N       \l__chemmacros_ox_side_bool
-\bool_new:N       \l__chemmacros_ox_super_bool
-\bool_new:N       \l__chemmacros_ox_top_bool
-\bool_set_true:N  \l__chemmacros_ox_top_bool
-\bool_new:N       \l__chemmacros_ox_align_center_bool
-
-\int_new:N \l__chemmacros_ox_number_int
-\fp_new:N  \l__chemmacros_ox_number_fp
-
-\cs_new_protected:Npn \__chemmacros_ox_process_number:n #1
-  {
-    \bool_if:NTF \l__chemmacros_ox_parse_bool
-      {
-        \tl_if_in:nnTF { #1 } { / }
-          { \__chemmacros_ox_fraction:w #1 \q_stop }
-          {
-            \__chemmacros_ox_sign:n { #1 }
-            \__chemmacros_ox_value:n { #1 }
-          }
-      }
-      { #1 }
-  }
-
-\DeclareInstance { xfrac } { chemmacros-ox-frac } { text }
-  {
-    scale-factor        = 1.2 ,
-    denominator-bot-sep = -.5ex ,
-    numerator-top-sep   = -.3ex ,
-    slash-left-kern     = -.2em ,
-    slash-right-kern    = -.2em ,
-    slash-symbol-font   = lmr
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_fraction:w #1/#2 \q_stop
-  {
-    \bool_set_false:N \l__chemmacros_ox_format_roman_bool
-    \__chemmacros_ox_sign:n { #1 }
-    \bool_if:NTF \l__chemmacros_ox_side_bool
-      { \sfrac { \__chemmacros_ox_value:n { #1 } } { #2 } }
-      {
-        \sfrac [ chemmacros-ox-frac ]
-          { \__chemmacros_ox_value:n { #1 } }
-          { #2 }
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_sign:n #1
-  {
-    \fp_compare:nNnT { #1 } > { 0 }
-      {
-        \bool_if:NT \l__chemmacros_ox_explicit_sign_bool
-          { \c_math_toggle_token + \c_math_toggle_token }
-      }
-    \fp_compare:nNnT { #1 } = { 0 }
-      {
-        \bool_if:NT \l__chemmacros_ox_explicit_sign_bool
-          { \c_math_toggle_token \pm \c_math_toggle_token }
-      }
-    \fp_compare:nNnT { #1 } < { 0 }
-      { \c_math_toggle_token - \c_math_toggle_token }
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_value:n #1
-  {
-    \fp_set:Nn \l__chemmacros_ox_number_fp { abs(#1) }
-    \__chemmacros_ox_is_integer:V \l__chemmacros_ox_number_fp
-    \bool_if:NTF \l__chemmacros_ox_format_roman_bool
-      { \__chemmacros_fp_to_Roman:V \l__chemmacros_ox_number_fp }
-      {
-        \bool_if:NTF \l__chemmacros_ox_integer_bool
-          {
-            \c_math_toggle_token
-              \__chemmacros_fp_to_arabic:V \l__chemmacros_ox_number_fp
-            \c_math_toggle_token
-          }
-          {
-            \c_math_toggle_token
-              \__chemmacros_fp_show:V \l__chemmacros_ox_number_fp
-            \c_math_toggle_token
-          }
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_is_integer:n #1
-  {
-    \fp_set:Nn \l__chemmacros_tmpa_fp { round(#1 + 1 , 0 ) - 1 }
-    \fp_compare:nNnTF { \l__chemmacros_tmpa_fp } = { #1 }
-      { \bool_set_true:N \l__chemmacros_ox_integer_bool }
-      {
-        \bool_set_false:N \l__chemmacros_ox_integer_bool
-        \bool_set_false:N \l__chemmacros_ox_format_roman_bool
-      }
-  }
-\cs_generate_variant:Nn \__chemmacros_ox_is_integer:n { V }
-
-\cs_new_protected:Npn \__chemmacros_fp_to_Roman:n #1
-  {
-    \group_begin:
-      \fp_set:Nn \l__chemmacros_tmpa_fp { round(#1 , 0 ) }
-      \int_set:Nn \l__chemmacros_tmpa_int
-        { \fp_to_tl:N \l__chemmacros_tmpa_fp } 
-      \int_compare:nTF { \l__chemmacros_tmpa_int = 0 }
-        { 0 }
-        { \int_to_Roman:n { \l__chemmacros_tmpa_int } }
-    \group_end:
-  }
-\cs_generate_variant:Nn \__chemmacros_fp_to_Roman:n { V }
-
-\cs_new_protected:Npn \__chemmacros_fp_to_arabic:n #1
-  {
-    \group_begin:
-      \fp_set:Nn \l__chemmacros_tmpa_tl { #1 }
-      \fp_to_tl:N \l__chemmacros_tmpa_tl
-    \group_end:
-  }
-\cs_generate_variant:Nn \__chemmacros_fp_to_arabic:n { V }
-
-\cs_new_protected:Npn \__chemmacros_fp_show:n #1
-  {
-    \group_begin:
-      \fp_set:Nn \l__chemmacros_tmpa_tl { #1 }
-      \bool_if:NTF \l__chemmacros_ox_decimal_marker_comma_bool
-        {
-          \tl_set:Nx \l__chemmacros_tmpb_tl
-            { \fp_to_tl:N \l__chemmacros_tmpa_tl }
-          \tl_replace_once:Nnn \l__chemmacros_tmpb_tl { . } { {,} }
-          \tl_use:N \l__chemmacros_tmpb_tl
-        }
-        { \fp_to_tl:N \l__chemmacros_tmpa_tl }
-    \group_end:
-  }
-\cs_generate_variant:Nn \__chemmacros_fp_show:n { V }
-
-\cs_new_protected:Npn \__chemmacros_ox_write:nn #1#2
-  {
-    \tl_if_blank:nT { #1 }
-      { \msg_error:nnx { chemmacros } { ox } { oxidation~number~missing } }
-    \tl_if_blank:nT { #2 }
-      { \msg_error:nnx { chemmacros } { ox } { atom~missing } }
-    \ensuremath
-      {
-        \bool_if:NT \l__chemmacros_ox_super_bool
-          {
-            \chemmacros_text:n
-              {
-                #2
-                \c_math_toggle_token
-                  \c_math_superscript_token
-                    { \text { \tiny \__chemmacros_ox_process_number:n { #1 } } }
-                \c_math_toggle_token
-              }
-          }
-        \bool_if:NT \l__chemmacros_ox_side_bool
-          {
-            \chemmacros_text:n
-              { #2 ( \text { \__chemmacros_ox_process_number:n { #1 } } ) }
-          }
-        \bool_if:NT \l__chemmacros_ox_top_bool
-          {
-            \overset
-              {
-                \bool_if:NTF \l__chemmacros_ox_align_center_bool
-                  { \clap } { \rlap }
-                {
-                  \chemmacros_text:n
-                    { \tiny \__chemmacros_ox_process_number:n { #1 } }
-                }
-              }
-              { \chemmacros_text:n { #2 } }
-          }
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_pos_top:
-  {
-    \bool_set_true:N  \l__chemmacros_ox_top_bool
-    \bool_set_false:N \l__chemmacros_ox_super_bool
-    \bool_set_false:N \l__chemmacros_ox_side_bool
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_pos_super:
-  {
-    \bool_set_false:N \l__chemmacros_ox_top_bool
-    \bool_set_true:N  \l__chemmacros_ox_super_bool
-    \bool_set_false:N \l__chemmacros_ox_side_bool
-  }
-
-\cs_new_protected:Npn \__chemmacros_ox_pos_side:
-  {
-    \bool_set_false:N \l__chemmacros_ox_top_bool
-    \bool_set_false:N \l__chemmacros_ox_super_bool
-    \bool_set_true:N  \l__chemmacros_ox_side_bool
-  }
-
-\keys_define:nn { chemmacros / ox }
-  {
-    pos            .choice: ,
-    pos / top      .code:n     = \__chemmacros_ox_pos_top: ,
-    pos / super    .code:n     = \__chemmacros_ox_pos_super: ,
-    pos / side     .code:n     = \__chemmacros_ox_pos_side: ,
-    roman          .bool_set:N = \l__chemmacros_ox_format_roman_bool ,
-    roman          .default:n  = true ,
-    parse          .bool_set:N = \l__chemmacros_ox_parse_bool ,
-    parse          .default:n  = true ,
-    explicit-sign  .bool_set:N = \l__chemmacros_ox_explicit_sign_bool ,
-    explicit-sign  .default:n  = true ,
-    decimal-marker .choice: ,
-    decimal-marker / comma .code:n =
-      { \bool_set_true:N \l__chemmacros_ox_decimal_marker_comma_bool } ,
-    decimal-marker / point .code:n =
-      { \bool_set_false:N \l__chemmacros_ox_decimal_marker_comma_bool } ,
-    align          .choice: ,
-    align / center .code:n    = \bool_set_true:N \l__chemmacros_ox_align_center_bool ,
-    align / right  .code:n    = \bool_set_false:N \l__chemmacros_ox_align_center_bool
-  }
-
-% \ox[<keyval>]{<num>,<atom>}
-% \ox*[<keyval>]{<num>,<atom>} => always number on the side
-\cs_new_protected:Npn \chemmacros_ox:nnnn #1#2#3#4
-  {
-    \group_begin:
-      \tl_if_blank:nF { #1 } { \__chemmacros_ox_pos_super: }
-      \keys_set:nn { chemmacros / ox } { #2 }
-      \__chemmacros_ox_write:nn { #3 } { #4 }
-    \group_end:
-  }
-
-\NewDocumentCommand \ox { s o > { \SplitArgument { 1 } { , } } m }
-  {
-    \IfBooleanTF { #1 }
-      {
-        \IfNoValueTF { #2 }
-          { \chemmacros_ox:nnnn { #1 } {    } #3 }
-          { \chemmacros_ox:nnnn { #1 } { #2 } #3 }
-      }
-      {
-        \IfNoValueTF { #2 }
-          { \chemmacros_ox:nnnn { } {    } #3 }
-          { \chemmacros_ox:nnnn { } { #2 } #3 }
-      }
-  }
-
-% --------------------------------------------------------------------------- %
-% - oxidation arrows
-\tl_new:N   \l__chemmacros_redox_begin_tl
-\tl_new:N   \l__chemmacros_redox_end_tl
-\tl_new:N   \l__chemmacros_redox_tikz_tl
-\tl_new:N   \l__chemmacros_redox_shift_tl
-\tl_new:N   \l__chemmacros_redox_anchor_tl
-\tl_new:N   \l__chemmacros_redox_side_tl
-
-\fp_new:N   \l__chemmacros_redox_shift_fp
-
-\dim_new:N  \l__chemmacros_redox_sep_dim
-\dim_new:N  \l__chemmacros_redox_sep_default_dim
-\dim_set:Nn \l__chemmacros_redox_sep_default_dim { .2em }
-\dim_new:N  \l__chemmacros_redox_dist_dim
-\dim_set:Nn \l__chemmacros_redox_dist_dim {.6em}
-
-% place and name nodes:
-% \OX{<name>,<atom>}
-\NewDocumentCommand \OX { > { \SplitArgument { 1 } { , } } m }
-  { \chemmacros_redox_partner:nn #1 }
-
-\cs_new_protected:Npn \chemmacros_redox_partner:nn #1#2
-  {
-    \chemformula_latex_if:nTF { measuring@ }
-      {
-        \group_begin:
-        \tikz[baseline=(#1.base)]
-          { \node [inner~sep=0pt] (#1) { #2 } ; }
-        \group_end:
-      }
-      {
-        \tl_if_blank:nT { #1 }
-          { \msg_error:nnx { chemmacros } { OX } { node~name~missing } }
-        \tl_if_blank:nT { #2 }
-          { \msg_error:nnx { chemmacros } { OX } { atom~missing } }
-        \tikz[baseline=(#1.base),remember~picture]
-          { \node [inner~sep=0pt] (#1) { #2 } ; }
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_redox_coordinates:nn #1#2
-  {
-    \tl_set:Nn \l__chemmacros_redox_begin_tl { #1 }
-    \tl_set:Nn \l__chemmacros_redox_end_tl   { #2 }
-  }
-
-\cs_new_protected:Npn \chemmacros_redox:nnnnn #1#2#3#4#5
-  {
-    \tl_clear:N \l__chemmacros_redox_begin_tl
-    \tl_clear:N \l__chemmacros_redox_end_tl
-    \tl_clear:N \l__chemmacros_redox_tikz_tl
-    \__chemmacros_redox_coordinates:nn { #1 } { #2 }
-    \tl_if_blank:nF { #3 }
-      { \tl_set:Nn \l__chemmacros_redox_tikz_tl { #3 } }
-    \tl_if_blank:nTF { #4 }
-      {
-        \fp_set:Nn \l__chemmacros_redox_shift_fp  { 1 }
-        \tl_set:Nn \l__chemmacros_redox_anchor_tl { above }
-        \tl_set:Nn \l__chemmacros_redox_side_tl { north }
-        \dim_set_eq:NN
-          \l__chemmacros_redox_sep_dim
-          \l__chemmacros_redox_sep_default_dim
-      }
-      {
-        \fp_compare:nNnTF { #4 } < { 0 }
-          {
-            \tl_set:Nn \l__chemmacros_redox_anchor_tl { below }
-            \tl_set:Nn \l__chemmacros_redox_side_tl { south }
-            \exp_args:NNo \dim_set:Nn \l__chemmacros_redox_sep_dim
-              { - \l__chemmacros_redox_sep_default_dim }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_redox_anchor_tl { above }
-            \tl_set:Nn \l__chemmacros_redox_side_tl { north }
-            \dim_set_eq:NN
-              \l__chemmacros_redox_sep_dim
-              \l__chemmacros_redox_sep_default_dim
-          }
-        \fp_set:Nn \l__chemmacros_redox_shift_fp { #4 }
-      }
-      \tl_set:Nn \l__chemmacros_redox_shift_tl
-        { \fp_to_tl:N \l__chemmacros_redox_shift_fp }
-    \tikz[remember~picture,overlay]
-      {
-        \chemmacros_tikz_draw:f { \tl_use:N \l__chemmacros_redox_tikz_tl }
-        ($
-          (\l__chemmacros_redox_begin_tl .
-          \l__chemmacros_redox_side_tl)+(0,\l__chemmacros_redox_sep_dim)
-        $)
-        -- 
-        ++(0,\l__chemmacros_redox_shift_tl * \l__chemmacros_redox_dist_dim) -|
-        node [pos=.25,\l__chemmacros_redox_anchor_tl] { { #5 } }
-        ($
-          (\l__chemmacros_redox_end_tl .
-          \l__chemmacros_redox_side_tl)+(0,\l__chemmacros_redox_sep_dim)
-        $) ;
-      }
-  }
-
-\NewDocumentCommand \redox { > { \SplitArgument { 1 } { , } } r() o o G{} }
-  {
-    \IfNoValueT { #1 }
-      {
-        \msg_error:nnx { chemmacros } { redox }
-          { You~need~to~specify~coordinates }
-      }
-    \IfNoValueTF { #2 }
-      { \chemmacros_redox:nnnnn #1 { } { } { #4 } }
-      {
-        \IfNoValueTF { #3 }
-          { \chemmacros_redox:nnnnn #1 { #2 } {    } { #4 } }
-          { \chemmacros_redox:nnnnn #1 { #2 } { #3 } { #4 } }
-      }
-  }
-
-% redox-keys
-\keys_define:nn { chemmacros / redox }
-  {
-    dist .dim_set:N = \l__chemmacros_redox_dist_dim ,
-    dist .default:n = { .6em } ,
-    sep  .dim_set:N = \l__chemmacros_redox_sep_default_dim ,
-    sep  .default:n = { .2em }
-  }
-
-% --------------------------------------------------------------------------- %
-% spectroscopy
-\tl_new:N  \g__chemmacros_nmr_isotope_tl
-\tl_new:N  \l__chemmacros_nmr_isotope_default_tl
-\tl_set:Nn \l__chemmacros_nmr_isotope_default_tl { 1 }
-\tl_new:N  \l__chemmacros_nmr_coupling_nuclei_tl
-\tl_new:N  \l__chemmacros_nmr_coupling_nuclei_pre_tl
-\tl_set:Nn \l__chemmacros_nmr_coupling_nuclei_pre_tl { ( }
-\tl_new:N  \l__chemmacros_nmr_coupling_nuclei_post_tl
-\tl_set:Nn \l__chemmacros_nmr_coupling_nuclei_post_tl { ) }
-\tl_new:N  \l__chemmacros_nmr_coupling_bonds_tl
-\tl_new:N  \l__chemmacros_nmr_coupling_bonds_pre_tl
-\tl_set:Nn \l__chemmacros_nmr_coupling_bonds_pre_tl { }
-\tl_set:Nn \l__chemmacros_nmr_coupling_bonds_post_tl { \! }
-\tl_new:N  \l__chemmacros_nmr_coupling_symbol_tl
-\tl_set:Nn \l__chemmacros_nmr_coupling_symbol_tl { J }
-\tl_new:N  \g__chemmacros_nmr_element_coupled_tl
-\tl_new:N  \g__chemmacros_nmr_element_tl
-\tl_new:N  \l__chemmacros_nmr_element_default_tl
-\tl_set:Nn \l__chemmacros_nmr_element_default_tl { H }
-\tl_new:N  \l__chemmacros_nmr_format_tl
-\tl_new:N  \l__chemmacros_nmr_delta_tl
-\tl_new:N  \l__chemmacros_nmr_coupling_unit_tl
-\tl_set:Nn \l__chemmacros_nmr_coupling_unit_tl { \hertz }
-\tl_new:N  \l__chemmacros_nmr_unit_tl
-\tl_set:Nn \l__chemmacros_nmr_unit_tl { \mega\hertz }
-\tl_new:N  \l__chemmacros_nmr_list_setup_tl
-\tl_set:Nn \l__chemmacros_nmr_list_setup_tl
-  {
-    \topsep\z@skip \partopsep\z@skip 
-    \itemsep\z@ \parsep\z@ \itemindent\z@
-    \leftmargin\z@
-  }
-\tl_new:N  \l__chemmacros_nmr_position_tl
-\tl_new:N  \l__chemmacros_nmr_element_method_connector_tl
-\tl_set:Nn \l__chemmacros_nmr_element_method_connector_tl {-}
-\tl_new:N  \l__chemmacros_nmr_method_tl
-\tl_set:Nn \l__chemmacros_nmr_method_tl {NMR}
-
-\bool_new:N      \l__chemmacros_nmr_coupling_nuclei_sub_bool
-\bool_new:N      \l__chemmacros_nmr_frequency_bool
-\bool_new:N      \l__chemmacros_nmr_solvent_bool
-\bool_new:N      \l__chemmacros_nmr_delimiters_bool
-\bool_new:N      \l__chemmacros_nmr_comma_bool
-\bool_new:N      \l__chemmacros_nmr_inner_bool
-\bool_new:N      \l__chemmacros_nmr_position_side_bool
-\bool_new:N      \l__chemmacros_nmr_parse_bool
-\bool_set_true:N \l__chemmacros_nmr_parse_bool
-\bool_new:N      \l__chemmacros_nmr_list_bool
-\bool_new:N      \l__chemmacros_nmr_use_equal_bool
-\bool_new:N      \l__chemmacros_nmr_custom_command_active_bool
-\bool_new:N      \l__chemmacros_nmr_custom_command_used_bool
-
-\cs_new_protected:Npn \__chemmacros_nmr_nucleus:nn #1#2
-  {
-    \tl_gset:Nn \g__chemmacros_nmr_isotope_tl { #1 }
-    \tl_if_in:nnTF { #2 } { [ }
-      { \__chemmacros_nmr_element:w #2 \q_stop }
-      {
-        \tl_gset:No \g__chemmacros_nmr_element_tl { #2 }
-        \tl_gclear:N \g__chemmacros_nmr_element_coupled_tl
-      }
-  }
-\cs_generate_variant:Nn \__chemmacros_nmr_nucleus:nn { VV }
-
-\cs_new_protected:Npn \__chemmacros_nmr_nucleus:w #1,#2 \q_stop
-  {
-    \tl_gset:Nn \g__chemmacros_nmr_isotope_tl { #1 }
-    \tl_if_in:nnTF { #2 } { [ }
-      { \__chemmacros_nmr_element:w #2 \q_stop }
-      {
-        \tl_gset:No \g__chemmacros_nmr_element_tl { #2 }
-        \tl_gclear:N \g__chemmacros_nmr_element_coupled_tl
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_element:w #1[#2] \q_stop
-  {
-    \tl_gset:Nn \g__chemmacros_nmr_element_tl { #1 }
-    \tl_gset:Nn \g__chemmacros_nmr_element_coupled_tl { #2 }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_default_nucleus:w #1,#2 \q_stop
-  {
-    \tl_set:Nn \l__chemmacros_nmr_isotope_default_tl { #1 }
-    \tl_set:Nn \l__chemmacros_nmr_element_default_tl { #2 }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_base:nn #1#2
-  {
-    \tl_if_blank:VF \g__chemmacros_nmr_element_coupled_tl
-      {
-        \tl_put_left:Nn \g__chemmacros_nmr_element_coupled_tl { \{ }
-        \tl_put_right:Nn \g__chemmacros_nmr_element_coupled_tl { \} }
-      }
-    \tl_put_left:Nn \g__chemmacros_nmr_element_coupled_tl { #2 }
-    \iupac { ^ { #1 } }
-    \bool_if:NTF \l__chemmacros_nmr_parse_bool
-      { \chemformula_ch:nV {} \g__chemmacros_nmr_element_coupled_tl }
-      { \chemmacros_atom:V \g__chemmacros_nmr_element_coupled_tl }
-    \tl_use:N \l__chemmacros_nmr_element_method_connector_tl
-    \tl_use:N \l__chemmacros_nmr_method_tl
-  }
-\cs_generate_variant:Nn \__chemmacros_nmr_base:nn { VV }
-
-\cs_new_protected:Npn \__chemmacros_nmr_frequency:n #1
-  {
-    \tl_if_in:nnTF { #1 } { , }
-      { \__chemmacros_nmr_frequency_aux_i:w #1 \q_stop }
-      { \__chemmacros_nmr_frequency_aux_ii:n { #1 } }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_frequency_aux_i:w #1,#2 \q_stop
-  { \SI { #1 } { #2 } }
-
-\cs_new_protected:Npn \__chemmacros_nmr_frequency_aux_ii:n #1
-  { \SI { #1 } { \tl_use:N \l__chemmacros_nmr_unit_tl } }
-
-\cs_new_eq:NN \__chemmacros_nmr_number:n \use:n
-\cs_new_eq:NN \__chemmacros_nmr_position:n \use:n
-
-\keys_define:nn { chemmacros / nmr }
-  {
-    unit          .tl_set:N      = \l__chemmacros_nmr_unit_tl ,
-    unit          .default:n     = \mega\hertz ,
-    nucleus       .code:n        =
-      { \__chemmacros_nmr_default_nucleus:w #1 \q_stop } ,
-    nucleus       .default:n     = { 1,H } ,
-    format        .tl_set:N      = \l__chemmacros_nmr_format_tl ,
-    method        .tl_set:N      = \l__chemmacros_nmr_method_tl ,
-    connector     .tl_set:N      = \l__chemmacros_nmr_element_method_connector_tl ,
-    pos-number    .choice: ,
-    pos-number / sub  .code:n =
-      \tl_set:Nn \l__chemmacros_nmr_position_tl { _ }
-      \bool_set_false:N \l__chemmacros_nmr_position_side_bool ,
-    pos-number / super .code:n =
-      \tl_set:Nn \l__chemmacros_nmr_position_tl { ^ }
-      \bool_set_false:N \l__chemmacros_nmr_position_side_bool ,
-    pos-number / side .code:n =
-      \tl_set:Nn \l__chemmacros_nmr_position_tl { - }
-      \bool_set_true:N \l__chemmacros_nmr_position_side_bool ,
-    coupling-unit .tl_set:N   = \l__chemmacros_nmr_coupling_unit_tl ,
-    coupling-pos  .choice: ,
-    coupling-pos / sub .code:n =
-      \bool_set_true:N \l__chemmacros_nmr_coupling_nuclei_sub_bool ,
-    coupling-pos / side .code:n =
-      \bool_set_false:N \l__chemmacros_nmr_coupling_nuclei_sub_bool ,
-    coupling-nuclei-pre  .tl_set:N =
-      \l__chemmacros_nmr_coupling_nuclei_pre_tl ,
-    coupling-nuclei-post .tl_set:N =
-      \l__chemmacros_nmr_coupling_nuclei_post_tl ,
-    coupling-bonds-pre   .tl_set:N =
-      \l__chemmacros_nmr_coupling_bonds_pre_tl ,
-    coupling-bonds-post  .tl_set:N =
-      \l__chemmacros_nmr_coupling_bonds_post_tl ,
-    coupling-symbol .tl_set:N    =
-      \l__chemmacros_nmr_coupling_symbol_tl ,
-    atom-number-cs .code:n       =
-      \cs_set_eq:NN \__chemmacros_nmr_number:n #1 ,
-    coupling-pos-cs .code:n      =
-      \cs_set_eq:NN \__chemmacros_nmr_position:n #1 ,
-    parse         .bool_set:N    = \l__chemmacros_nmr_parse_bool ,
-    delta         .code:n        =
-      \tl_set:Nn \l__chemmacros_nmr_delta_tl { \, #1 } ,
-    list          .bool_set:N    = \l__chemmacros_nmr_list_bool ,
-    list          .default:n     = true ,
-    list-setup    .tl_set:N      = \l__chemmacros_nmr_list_setup_tl ,
-    use-equal     .bool_set:N    = \l__chemmacros_nmr_use_equal_bool ,
-    use-equal     .default:n     = true
-  }
-
-\prop_new:N \l__chemmacros_nmr_prop
-
-\cs_new_protected:Npn \chemmacros_new_nmr:Nn #1#2
-  {
-    \bool_if:nTF
-      {
-        \prop_if_in_p:Nn \l__chemmacros_nmr_prop { #1 }
-        ||
-        \cs_if_exist_p:N #1
-      }
-      { \msg_error:nnn { chemmacros } { new-nmr } { #1 } }
-      {
-        \prop_put:Nnn \l__chemmacros_nmr_prop { #1 } { #2 }
-        \NewDocumentCommand #1 { s }
-          { \IfBooleanTF {##1} { \NMR*{#2} } { \NMR{#2} } }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_define_nmr:Nn #1#2
-  {
-    \prop_put:Nnn \l__chemmacros_nmr_prop { #1 } { #2 }
-    \cs_if_exist:NTF #1
-      {
-        \RenewDocumentCommand #1 { s }
-          { \IfBooleanTF {##1} { \NMR*{#2} } { \NMR{#2} } }
-      }
-      {
-        \NewDocumentCommand #1 { s }
-          { \IfBooleanTF {##1} { \NMR*{#2} } { \NMR{#2} } }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_renew_nmr:Nn #1#2
-  {
-    \bool_if:nTF
-      {
-        \prop_if_in_p:Nn \l__chemmacros_nmr_prop { #1 }
-        &&
-        \cs_if_exist_p:N #1
-      }
-      {
-        \prop_put:Nnn \l__chemmacros_nmr_prop { #1 } { #2 }
-        \RenewDocumentCommand #1 { s }
-          { \IfBooleanTF {##1} { \NMR*{#2} } { \NMR{#2} } }
-      }
-      { \msg_error:nnn { chemmacros } { renew-nmr } { #1 } }
-  }
-
-\NewDocumentCommand \NewChemNMR { mm }
-  { \chemmacros_new_nmr:Nn #1 { #2 } }
-
-\NewDocumentCommand \RenewChemNMR { mm }
-  { \chemmacros_renew_nmr:Nn #1 { #2 } }
-
-\NewDocumentCommand \DeclareChemNMR { mm }
-  { \chemmacros_define_nmr:Nn #1 { #2 } }
-
-\NewDocumentCommand \NMR { s G{} D(){} O{} }
-  {
-    \IfBooleanTF { #1 }
-      { \chemmacros_nmr:nnnn { * } { #2 } { #3 } { #4 } }
-      { \chemmacros_nmr:nnnn {   } { #2 } { #3 } { #4 } }
-  }
-
-\AtBeginDocument
-  {
-    % \NMR{<num>,<elem>}(<num>,<unit>)[<solvent>] ALL arguments are optional
-    % \NMR* same but without ": $\delta$" at end
-    \cs_new_protected:Npn \chemmacros_nmr:nnnn #1#2#3#4
-      {
-        \bool_if:NT \l__chemmacros_nmr_list_bool { \item \scan_stop: }
-        \group_begin:
-          \chemmacros_leave_vmode:
-          \bool_set_false:N \l__chemmacros_nmr_frequency_bool
-          \bool_set_false:N \l__chemmacros_nmr_solvent_bool
-          \tl_if_empty:nF { #3 }
-            { \bool_set_true:N \l__chemmacros_nmr_frequency_bool }
-          \tl_if_empty:nF { #4 }
-            { \bool_set_true:N \l__chemmacros_nmr_solvent_bool }
-          \bool_if:nT
-            {
-              \l__chemmacros_nmr_frequency_bool
-              ||
-              \l__chemmacros_nmr_solvent_bool
-            }
-            { \bool_set_true:N \l__chemmacros_nmr_delimiters_bool }
-          \bool_if:nT
-            {
-              \l__chemmacros_nmr_frequency_bool
-              &&
-              \l__chemmacros_nmr_solvent_bool
-            }
-            { \bool_set_true:N \l__chemmacros_nmr_comma_bool }
-          \tl_if_empty:nTF { #2 }
-            {
-              \__chemmacros_nmr_nucleus:VV
-                \l__chemmacros_nmr_isotope_default_tl
-                \l__chemmacros_nmr_element_default_tl
-            }
-            { \__chemmacros_nmr_nucleus:w #2 \q_stop }
-          \mode_if_math:TF
-            {
-              \text
-                {
-                  \group_begin:
-                    \tl_use:N \l__chemmacros_nmr_format_tl
-                    \__chemmacros_nmr_base:VV
-                      \g__chemmacros_nmr_isotope_tl
-                      \g__chemmacros_nmr_element_tl
-                    \bool_if:NT \l__chemmacros_nmr_delimiters_bool
-                      { ~ ( }
-                    \bool_if:NT \l__chemmacros_nmr_frequency_bool
-                      { \__chemmacros_nmr_frequency:n { #3 } }
-                    \bool_if:NT \l__chemmacros_nmr_comma_bool
-                      { , ~ }
-                    \bool_if:NT \l__chemmacros_nmr_solvent_bool
-                      { \chemmacros_atom:n { #4 } }
-                    \bool_if:NT \l__chemmacros_nmr_delimiters_bool
-                      { ) }
-                    \tl_if_blank:nT { #1 } { : ~ }
-                  \group_end:
-                }
-              \tl_if_blank:nT { #1 }
-                {
-                  \delta
-                  \text { \l__chemmacros_nmr_delta_tl }
-                  \bool_if:NT \l__chemmacros_nmr_use_equal_bool { = }
-                }
-            }
-            {
-              \group_begin:
-                \tl_use:N \l__chemmacros_nmr_format_tl
-                \__chemmacros_nmr_base:VV
-                  \g__chemmacros_nmr_isotope_tl
-                  \g__chemmacros_nmr_element_tl
-                \bool_if:NT \l__chemmacros_nmr_delimiters_bool
-                  { ~ ( }
-                \bool_if:NT \l__chemmacros_nmr_frequency_bool
-                  { \__chemmacros_nmr_frequency:n { #3 } }
-                \bool_if:NT \l__chemmacros_nmr_comma_bool
-                  { , ~ }
-                \bool_if:NT \l__chemmacros_nmr_solvent_bool
-                  {
-                    \bool_if:NTF \l__chemmacros_nmr_parse_bool
-                      { \chemformula_ch:nn { } { #4 } }
-                      { #4 }
-                  }
-                \bool_if:NT \l__chemmacros_nmr_delimiters_bool
-                  { ) }
-                \tl_if_blank:nT { #1 } { : }
-              \group_end:
-              \tl_if_blank:nT { #1 }
-                {
-                  \tl_use:N \c_space_tl
-                  \c_math_toggle_token
-                    \delta
-                  \c_math_toggle_token
-                  \l__chemmacros_nmr_delta_tl
-                  \bool_if:NT \l__chemmacros_nmr_use_equal_bool { ~ = }
-                }
-              \bool_if:NF \l__chemmacros_nmr_comma_bool
-                { \tl_if_blank:nT { #1 } { \chemmacros_xspace: } }
-            }
-        \group_end:
-      }
-  }
-
-\NewDocumentCommand \chemmacros_data:w { smo }
-  {
-    \bool_if:NT \l__chemmacros_nmr_list_bool { \item }
-    {
-      \tl_use:N \l__chemmacros_nmr_format_tl #2
-      \IfNoValueF { #3 } { ~ ( #3 ) }
-      \IfBooleanT { #1 } { \bool_if:NT \l__chemmacros_nmr_use_equal_bool { : } }
-    }
-    \IfBooleanF { #1 } { \bool_if:NT \l__chemmacros_nmr_use_equal_bool { ~ = } }
-  }
-
-\cs_new_protected:Npn \chemmacros_val:n #1
-  {
-    \tl_if_in:nnTF { #1 } { -- }
-      { \chemmacros_val_aux:w #1 \q_nil }
-      { \num { #1 } }
-  }
-
-\cs_new_protected:Npn \chemmacros_val_aux:w #1--#2 \q_nil
-  { \numrange { #1 } { #2 } }
-
-\NewDocumentEnvironment { experimental } { o }
-  {
-    \group_begin:
-    \IfNoValueF { #1 } { \keys_set:nn { chemmacros / nmr } { #1 } }
-    \bool_set_true:N \l__chemmacros_nmr_inner_bool
-    \cs_set_eq:NN \#    \chemmacros_nmr_number:n
-    \cs_set_eq:NN \pos  \chemmacros_nmr_position:n
-    \cs_set_eq:NN \J    \chemmacros_nmr_coupling:w
-    \cs_set_eq:NN \data \chemmacros_data:w
-    \cs_set_eq:NN \val  \chemmacros_val:n
-    \bool_if:NT \l__chemmacros_nmr_list_bool
-      { \list {} { \l__chemmacros_nmr_list_setup_tl } }
-  }
-  {
-    \bool_if:NT \l__chemmacros_nmr_list_bool
-      { \endlist }
-    \group_end:
-    \chemmacros_ignore_spaces:
-  }
-
-\cs_new_protected:Npn \chemmacros_nmr_number:n #1
-  {
-    \__chemmacros_nmr_number:n { #1 } \,
-    \chemmacros_atom:V \g__chemmacros_nmr_element_tl
-  }
-
-\cs_new_protected:Npn \chemmacros_nmr_position:n #1
-  {
-    \chemmacros_chemformula:x
-      {
-        \exp_not:V \g__chemmacros_nmr_element_tl
-        \bool_if:NF \l__chemmacros_nmr_position_side_bool
-          {
-            \exp_not:V \l__chemmacros_nmr_position_tl
-            \exp_not:n { {#1} }
-          }
-      }
-    \bool_if:NT \l__chemmacros_nmr_position_side_bool
-      {
-        \tl_use:N \l__chemmacros_nmr_position_tl
-        \__chemmacros_nmr_position:n { #1 }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_nmr_coupling:w
-  {
-    \tl_clear:N \l__chemmacros_nmr_coupling_nuclei_tl
-    \tl_clear:N \l__chemmacros_nmr_coupling_bonds_tl
-    \peek_meaning:NTF (
-      { \__chemmacros_nmr_coupling:w }
-      { \__chemmacros_nmr_coupling_aux_i:w }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_coupling:w (#1;#2)
-  {
-    \tl_set:Nn \l__chemmacros_nmr_coupling_bonds_tl
-      {
-        \l__chemmacros_nmr_coupling_bonds_pre_tl
-        #1
-        \l__chemmacros_nmr_coupling_bonds_post_tl
-      }
-    \bool_if:NTF \l__chemmacros_nmr_coupling_nuclei_sub_bool
-      {
-        \tl_set:Nn \l__chemmacros_nmr_coupling_nuclei_tl
-          {
-            \c_math_subscript_token
-              { \chemmacros_chemformula:n {#2} }
-          }
-      }
-      {
-        \tl_set:Nn \l__chemmacros_nmr_coupling_nuclei_tl
-          {
-            \l__chemmacros_nmr_coupling_nuclei_pre_tl
-            \chemmacros_chemformula:n {#2}
-            \l__chemmacros_nmr_coupling_nuclei_post_tl
-          }
-      }
-    \__chemmacros_nmr_coupling_aux_i:w
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_coupling_aux_i:w
-  {
-    \peek_meaning:NTF [
-      { \__chemmacros_nmr_coupling_aux_ii:w }
-      { \__chemmacros_nmr_coupling_aux_iii:n }
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_coupling_aux_ii:w [#1]#2
-  {
-    \group_begin:
-      \sisetup
-        {
-          list-final-separator={,~},
-          list-pair-separator={,~},
-          list-units=single
-        }
-      \c_math_toggle_token
-        ^{ \l__chemmacros_nmr_coupling_bonds_tl }
-        \l__chemmacros_nmr_coupling_symbol_tl
-        \l__chemmacros_nmr_coupling_nuclei_tl = \SIlist{#2}{#1}
-      \c_math_toggle_token
-    \group_end:
-  }
-
-\cs_new_protected:Npn \__chemmacros_nmr_coupling_aux_iii:n #1
-  {
-    \group_begin:
-      \sisetup
-        {
-          list-final-separator={,~},
-          list-pair-separator={,~},
-          list-units=single
-        }
-      \c_math_toggle_token
-         ^{ \l__chemmacros_nmr_coupling_bonds_tl }
-         \l__chemmacros_nmr_coupling_symbol_tl
-         \l__chemmacros_nmr_coupling_nuclei_tl
-         = \exp_args:Nno \SIlist { #1 } { \l__chemmacros_nmr_coupling_unit_tl }
-      \c_math_toggle_token
-    \group_end:
-  }
-
-% --------------------------------------------------------------------------
-% deprecated mhName:
-\keys_define:nn { chemmacros }
-  { mhName .code:n = \chemmacros_option_deprecated:n { mhName } }
-
-% --------------------------------------------------------------------------- %
-% - phases
-\bool_new:N \l__chemmacros_phases_sub_bool
-\dim_new:N  \l__chemmacros_phases_space_dim
-\dim_set:Nn \l__chemmacros_phases_space_dim { .1333 em }
-\prop_new:N \l__chemmacros_phases_prop
-\prop_new:N \l__chemmacros_phases_german_prop
-
-\keys_define:nn { chemmacros / phases }
-  {
-    pos        .choice: ,
-    pos / sub  .code:n    = \bool_set_true:N \l__chemmacros_phases_sub_bool ,
-    pos / side .code:n    = \bool_set_false:N \l__chemmacros_phases_sub_bool ,
-    space      .dim_set:N = \l__chemmacros_phases_space_dim
-  }
-
-\cs_new_protected:Npn \chemmacros_new_phase:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \cs_if_free:NF #1
-      { \msg_error:nnn {chemmacros} {new-phase} {#1} }
-    \exp_args:Nx \@trnslt@declare@translation
-      { phase-\l__chemmacros_tmpa_tl } {fallback} {#2}
-    \__chemmacros_define_phase:Nx #1
-      {
-        \exp_not:N \chemmacros_translate:n
-          { phase-\l__chemmacros_tmpa_tl }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_define_phase:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \exp_args:Nx \@trnslt@declare@translation
-      { phase-\l__chemmacros_tmpa_tl } {fallback} {#2}
-    \__chemmacros_define_phase:Nx #1
-      {
-        \exp_not:N \chemmacros_translate:n
-          { phase-\l__chemmacros_tmpa_tl }
-      }
-  }
-
-\cs_new_protected:Npn \chemmacros_renew_phase:Nn #1#2
-  {
-    \tl_set:Nx \l__chemmacros_tmpa_tl
-      { \chemmacros_remove_backslash:N #1 }
-    \cs_if_exist:NF #1
-      { \msg_error:nnn {chemmacros} {renew-phase} {#1} }
-    \exp_args:Nx \@trnslt@declare@translation
-      { phase-\l__chemmacros_tmpa_tl } {fallback} {#2}
-    \__chemmacros_define_phase:Nx #1
-      {
-        \exp_not:N \chemmacros_translate:n
-          { phase-\l__chemmacros_tmpa_tl }
-      }
-  }
-
-\NewDocumentCommand \NewChemPhase { mom }
-  { \chemmacros_new_phase:Nn #1 {#3} }
-
-\NewDocumentCommand \DeclareChemPhase { mom }
-  { \chemmacros_define_phase:Nn #1 {#3} }
-
-\NewDocumentCommand \RenewChemPhase { mom }
-  { \chemmacros_renew_phase:Nn #1 {#3} }
-
-\cs_new_protected:Npn \__chemmacros_define_phase:Nn #1#2
-  {
-    \cs_if_exist:NF #1 { \cs_new:Npn #1 {} }
-    \DeclareDocumentCommand #1 { o }
-      {
-        \bool_if:NTF \l__chemmacros_phases_sub_bool
-          {
-            \bool_if:NTF \l_chemformula_inside_ch_bool
-              { \chemformula_subscript:n { ( #2 \IfNoValueF {##1} {,~##1} ) } }
-              {
-                \ensuremath
-                  {
-                    \c_math_subscript_token
-                    { \text { ( #2 \IfNoValueF {##1} {,~##1} ) } }
-                  }
-              }
-          }
-          {
-            \ensuremath
-              {
-                \skip_horizontal:N \l__chemmacros_phases_space_dim
-                \text { ( #2 \IfNoValueF {##1} {,~##1} ) }
-              }
-          }
-      }
-  }
-\cs_generate_variant:Nn \__chemmacros_define_phase:Nn { Nx }
-
-\NewChemPhase \sld {s}
-\NewChemPhase \lqd {l}
-\NewChemPhase \gas {g}
-\NewChemPhase \aq  {aq}
-
-\cs_new_protected:Npn \chemmacros_phase:n #1
-  {
-    \bool_if:NTF \l__chemmacros_phases_sub_bool
-      { \ensuremath { \c_math_subscript_token { \text { (#1) } } } }
-      {
-        \ensuremath
-          {
-            \skip_horizontal:N \l__chemmacros_phases_space_dim
-            \text { (#1) }
-          }
-      }
-  }
-
-\NewDocumentCommand \phase { m }
-  { \chemmacros_phase:n {#1} }
-
-% --------------------------------------------------------------------------
-% reaction environments
-\cs_new_protected:Npn \__chemmacros_record_for_lor:nnnnn #1#2#3#4#5
-  {
-    \tl_if_eq:nnT { #1 } { reaction }
-      {
-        \group_begin:
-          % we need to prevent \Hy@make@anchor from being written to the lor
-          % file:
-          \bool_if:NT \l__chemmacros_hyperref_bool
-            { \cs_set:Npn \Hy@make@anchor {} }
-          \addcontentsline { lor } { reaction }
-            {
-              \tl_use:N \l__chemmacros_reaction_lorname_tl
-              \tl_use:N \c_space_tl
-              #2 #3 #4 #5
-              \tl_use:N \g__chemmacros_reaction_description_tl
-            }
-          \tl_gclear:N \g__chemmacros_reaction_description_tl
-        \group_end:
-      }
-  }
-
-% redefine mathtools' command \MT_define_tagform:nwnn to ensure we add an
-% entry to the list of reactions even if the user redefines the reaction tag
-% this should probably be done via patching...
-\AfterPackage* { mathtools }
-  {
-    \cs_set_protected:Npn \MT_define_tagform:nwnn #1[#2]#3#4
-      {
-        \@namedef{MT_tagform_#1:n}##1
-          {
-            % this is the original part:
-            \maketag@@@{#3\ignorespaces#2{##1}\unskip\@@italiccorr#4}
-            % this is added => this disturbs hyperref:
-            \__chemmacros_record_for_lor:nnnnn
-              { #1 } { #3 } { #2 } { ##1 } { #4 }
-          }
-      }
-  }
-
-\tl_new:N \g__chemmacros_reaction_description_tl
-
-\cs_new_protected:Npn \chemmacros_add_reaction_description:n #1
-  {
-    \tl_if_blank:nF { #1 }
-      { \tl_gset:Nn \g__chemmacros_reaction_description_tl { : ~ #1 } }
-  }
-
-\NewDocumentCommand \AddRxnDesc { m }
-  { \chemmacros_add_reaction_description:n { #1 } }
-
-% define \listofreactions
-\tl_new:N \l__chemmacros_reaction_lorname_tl
-\tl_new:N \reactionlistname
-\tl_new:N \l__chemmacros_reaction_heading_tl
-
-\cs_new:Npn \__chemmacros_reaction_heading:n #1
-  { \l__chemmacros_reaction_heading_tl { #1 } }
-\cs_generate_variant:Nn \__chemmacros_reaction_heading:n { V }
-
-\cs_new_protected:Npn \listofreactions
-  {
-    \__chemmacros_reaction_heading:V \reactionlistname
-    \@starttoc { lor }
-  }
-
-\cs_new_protected:Npn \l@reaction #1#2
-  { \@dottedtocline { 1 } { 1.5em } { 2.3em } { #1 } { #2 } }
-
-% create tagform
-\newtagform { reaction } { \{ } { \} }
-\newcounter { chemmacros_save_reaction }
-\newcounter { reaction }
-
-% switch to reaction tags
-\cs_new_protected:Npn \__chemmacros_begin_reaction:
-  {
-    % create individual names for `hyperref':
-    \bool_if:NT \l__chemmacros_hyperref_bool
-      {
-        \cs_set:Npn \theHequation
-          { R . \theHsection . \arabic { reaction } }
-      }
-    % enable labelformat `reaction':
-    \bool_if:NT \l__chemmacros_varioref_bool
-      { \cs_set_eq:NN \p@equation \p@reaction }
-    \setcounter { chemmacros_save_reaction } { \value { equation } }
-    \setcounter { equation } { \value { reaction } }
-    \usetagform { reaction }
-  }
-
-% switch back to equation tags
-\cs_new_protected:Npn \__chemmacros_end_reaction:
-  {
-    \setcounter { reaction } { \value { equation } }
-    \setcounter { equation } { \value { chemmacros_save_reaction } }
-  }
-
-% --------------------------------------------------------------------------- %
-\bool_new:N \l__chemmacros_reactions_star_bool
-\bool_new:N \l__chemmacros_reactions_args_bool
-
-\keys_define:nn { chemmacros / reaction }
-  {
-    star         .bool_set:N = \l__chemmacros_reactions_star_bool ,
-    star         .default:n  = true ,
-    arg          .bool_set:N = \l__chemmacros_reactions_args_bool ,
-    arg          .default:n  = true ,
-    list-name    .tl_set:N   = \reactionlistname ,
-    list-entry   .code:n     =
-      \tl_set:Nn \l__chemmacros_reaction_lorname_tl { #1 } ,
-    list-heading .tl_set:N   = \l__chemmacros_reaction_heading_tl
-  }
-
-% \DeclareChemReaction[<keyval>]{<name>}{<type>}
-\cs_new_protected:Npn \__chemmacros_define_reaction:Nnnn #1#2#3#4
-  {
-    \bool_set_false:N \l__chemmacros_reactions_star_bool
-    \bool_set_false:N \l__chemmacros_reactions_args_bool
-    \keys_set:nn { chemmacros / reaction } { #2 }
-    \bool_if:NTF \l__chemmacros_reactions_args_bool
-      {
-        #1 { #3 } [ 2 ] []
-          {
-            \__chemmacros_begin_reaction:
-            \AddRxnDesc { ##1 }
-            \begin { #4 } { ##2 }
-              \chemmacros_equation_chemformula:V \BODY
-            \end{ #4 }
-            \__chemmacros_end_reaction:
-          }
-        \bool_if:NT \l__chemmacros_reactions_star_bool
-          {
-            #1 { #3* } [ 1 ]
-              {
-                \begin { #4* } { ##1 }
-                  \chemmacros_equation_chemformula:V \BODY
-                \end { #4* }
-              }
-          }
-      }
-      {
-        #1 { #3 } [ 1 ] []
-          {
-            \__chemmacros_begin_reaction:
-            \AddRxnDesc { ##1 }
-            \begin { #4 }
-              \chemmacros_equation_chemformula:V \BODY
-            \end { #4 }
-            \__chemmacros_end_reaction:
-          }
-        \bool_if:NT \l__chemmacros_reactions_star_bool
-          {
-            #1 { #3* }
-              {
-                \begin { #4* }
-                  \chemmacros_equation_chemformula:V \BODY
-                \end { #4* }
-              }
-          }
-      }
-    \ignorespaces
-  }
-
-\cs_new_protected:Npn \chemmacros_define_reaction:nnn #1#2#3
-  {
-    \cs_if_exist:cTF { #2 }
-      { \__chemmacros_define_reaction:Nnnn \RenewEnviron { #1 } { #2 } { #3 } }
-      { \__chemmacros_define_reaction:Nnnn \NewEnviron { #1 } { #2 } { #3 } }
-  }
-
-\cs_new_protected:Npn \chemmacros_new_reaction:nnn #1#2#3
-  {
-    \cs_if_exist:cTF { #2 }
-      { \msg_error:nnx { chemmacros } { already-defined } { #2 } }
-      { \__chemmacros_define_reaction:Nnnn \NewEnviron { #1 } { #2 } { #3 } }
-  }
-
-\cs_new_protected:Npn \chemmacros_renew_reaction:nnn #1#2#3
-  {
-    \cs_if_exist:cTF { #2 }
-      { \__chemmacros_define_reaction:Nnnn \RenewEnviron { #1 } { #2 } { #3 } }
-      { \msg_error:nnx { chemmacros } { not-defined } { #2 } }
-  }
-
-\NewDocumentCommand \NewChemReaction { O{} m m }
-  { \chemmacros_new_reaction:nnn { #1 } { #2 } { #3 } }
-\NewDocumentCommand \RenewChemReaction { O{} m m }
-  { \chemmacros_renew_reaction:nnn { #1 } { #2 } { #3 } }
-\NewDocumentCommand \DeclareChemReaction { O{} m m }
-  { \chemmacros_declare_reaction:nnn { #1 } { #2 } { #3 } }
-\DeclareChemDeprecated \newreaction \NewChemReaction
-
-\cs_new_protected:Npn \chemmacros_equation_chemformula:n #1
-  { \chemformula_ch:nn { } { #1 } }
-\cs_generate_variant:Nn \chemmacros_equation_chemformula:n { V }
-
-% predefined:
-\NewChemReaction [ star ] { reaction }  { equation }
-\NewChemReaction [ star ] { reactions } { align }
-
-% --------------------------------------------------------------------------
-% thermodynamics et.al.
-% \standardstate as defined by the chemstyle package. Thanks to Joseph Wright
-% the `chemstyle' provides it with \providecommand so it doesn't matter which
-% package defines it first
-\ProvideDocumentCommand \standardstate {}
-  { { \ensuremath { \chemmacros_standardstate: } } }
-
-\cs_new_protected:Npn \chemmacros_standardstate:
-  { \mathpalette \chemmacros_standardstate_aux: \circ }
-
-\cs_new_protected:Npn \chemmacros_standardstate_aux: #1#2
-  {
-    \ooalign
-      {
-        \tex_hfil:D
-        \c_math_toggle_token #1- \c_math_toggle_token
-        \tex_hfil:D
-        \tex_cr:D
-        \tex_hfil:D
-        \c_math_toggle_token #1#2 \c_math_toggle_token
-        \tex_hfil:D
-        \tex_cr:D
-      }
-  }
-
-\cs_new_protected:Npn \changestate
-  { \mathop{} \! \chemDelta }
-
-% --------------------------------------------------------------------------
-% \State
-\tl_new:N  \l__chemmacros_State_delta_tl
-\tl_set:Nn \l__chemmacros_State_delta_tl { \changestate }
-\tl_new:N  \l__chemmacros_State_exponent_tl
-\tl_set:Nn \l__chemmacros_State_exponent_tl { \standardstate }
-
-\bool_new:N      \l__chemmacros_State_delta_bool
-\bool_set_true:N \l__chemmacros_State_delta_bool
-\bool_new:N      \l__chemmacros_State_subscript_left_bool
-\bool_set_true:N \l__chemmacros_State_subscript_left_bool
-\bool_new:N      \l__chemmacros_State_exponent_bool
-\bool_set_true:N \l__chemmacros_State_exponent_bool
-
-\keys_define:nn { chemmacros / state }
-  {
-    delta     .code:n     =
-      {
-        \exp_args:Nf \tl_if_eq:nnTF { #1 } { false }
-          { \bool_set_false:N \l__chemmacros_State_delta_bool }
-          {
-            \bool_set_true:N \l__chemmacros_State_delta_bool
-            \tl_set:Nn \l__chemmacros_State_delta_tl { #1 }
-          }
-      } ,
-    subscript-left .bool_set:N = \l__chemmacros_State_subscript_left_bool ,
-    subscript-left .default:n  = true ,
-    exponent  .code:n     =
-      {
-        \exp_args:Nf \tl_if_eq:nnTF { #1 } { false }
-          { \bool_set_false:N \l__chemmacros_State_exponent_bool }
-          {
-            \bool_set_true:N \l__chemmacros_State_exponent_bool
-            \tl_set:Nn \l__chemmacros_State_exponent_tl { #1 }
-          }
-      } ,
-    exponent  .default:n  = \standardstate
-  }
-
-% old syntax (v1.1):
-% \State[<exp>,<Delta>,<subscript pos>]{<Symbol>}{<subscript>}
-% old syntax (v2.0):
-% \State[<keyval>]{<Symbol>}{<subscript>}
-% {<subscript>} is an optional argument!
-\cs_new_protected:Npn \chemmacros_state:nnn #1#2#3
-  {
-    \group_begin:
-      \keys_set:nn { chemmacros / state } { #1 }
-      \ensuremath
-       {
-          \bool_if:NT \l__chemmacros_State_delta_bool
-            { \tl_use:N \l__chemmacros_State_delta_tl }
-          \bool_if:NT \l__chemmacros_State_subscript_left_bool
-            { \c_math_subscript_token { \text { #3 } } }
-          #2
-          \bool_if:NF \l__chemmacros_State_subscript_left_bool
-            { \c_math_subscript_token { \text { #3 } } }
-          \bool_if:NT \l__chemmacros_State_exponent_bool
-            { ^ { \tl_use:N \l__chemmacros_State_exponent_tl } }
-        }
-    \group_end:
-  }
-\cs_generate_variant:Nn \chemmacros_state:nnn { xnV }
-
-\NewDocumentCommand \State { s O{} m G{} }
-  {
-    \group_begin:
-      \IfBooleanT { #1 }
-        {
-          \keys_set:nn { chemmacros / state }
-            { subscript-left = false , exponent = }
-        }
-      \chemmacros_state:nnn { #2 } { #3 } { #4 }
-    \group_end:
-  }
-
-% --------------------------------------------------------------------------
-\tl_new:N  \l__chemmacros_thermod_subscript_left_tl
-\tl_new:N  \l__chemmacros_thermod_subscript_left_default_tl
-\tl_new:N  \l__chemmacros_thermod_subscript_tl
-\tl_new:N  \l__chemmacros_thermod_subscript_default_tl
-\tl_new:N  \l__chemmacros_thermod_unit_tl
-\tl_new:N  \l__chemmacros_thermod_exponent_tl
-\tl_new:N  \l__chemmacros_thermod_exponent_default_tl
-\tl_set:Nn \l__chemmacros_thermod_exponent_default_tl { \standardstate }
-\tl_new:N  \l__chemmacros_thermod_delta_tl
-\tl_new:N  \l__chemmacros_thermod_delta_default_tl
-\tl_set:Nn \l__chemmacros_thermod_delta_default_tl { \changestate }
-
-\bool_new:N \l__chemmacros_renewstate_bool
-\bool_new:N \l__chemmacros_state_overwrite_error_bool
-
-\keys_define:nn { chemmacros }
-  {
-    State / subscript         .choice: ,
-    State / subscript / left  .code:n   =
-      { \tl_set:Nn \l__chemmacros_thermod_subscript_left_tl { true } } ,
-    State / subscript / right .code:n   =
-      { \tl_set:Nn \l__chemmacros_thermod_subscript_left_tl { false } } ,
-    State / exponent          .tl_set:N =
-      \l__chemmacros_thermod_exponent_tl ,
-    State / delta             .tl_set:N =
-      \l__chemmacros_thermod_delta_tl ,
-    State / unit              .tl_set:N =
-      \l__chemmacros_thermod_unit_tl ,
-    setnewstate / subscript-left .tl_set:N =
-      \l__chemmacros_thermod_subscript_left_default_tl ,
-    setnewstate / subscript   .tl_set:N =
-      \l__chemmacros_thermod_subscript_default_tl ,
-    setnewstate / exponent    .tl_set:N =
-      \l__chemmacros_thermod_exponent_default_tl ,
-    setnewstate / delta       .tl_set:N =
-      \l__chemmacros_thermod_delta_default_tl
-  }
-
-% \NewChemState{<name>}[<keyval>]{<symbol>}{<unit>}
-\NewDocumentCommand \NewChemState { omO{}mm }
-  {
-    \bool_set_false:N \l__chemmacros_renewstate_bool
-    \bool_set_true:N \l__chemmacros_state_overwrite_error_bool
-    \__chemmacros_setnewstate_reset:
-    \IfNoValueTF { #1 }
-      { \chemmacros_define_state:nnnn { #3 } { #2 } { #4 } { #5 } }
-      {
-        \msg_warning:nn { chemmacros } { state-syntax }
-        \chemmacros_define_state:nnnn { #1#3 } { #2 } { #4 } { #5 }
-      }
-  }
-% \DeclareChemState{<name>}[<keyval>]{<symbol>}{<unit>}
-\NewDocumentCommand \DeclareChemState { omO{}mm }
-  {
-    \bool_set_false:N \l__chemmacros_renewstate_bool
-    \bool_set_false:N \l__chemmacros_state_overwrite_error_bool
-    \__chemmacros_setnewstate_reset:
-    \IfNoValueTF { #1 }
-      { \chemmacros_define_state:nnnn { #3 } { #2 } { #4 } { #5 } }
-      {
-        \msg_warning:nn { chemmacros } { state-syntax }
-        \chemmacros_define_state:nnnn { #1#3 } { #2 } { #4 } { #5 }
-      }
-  }
-% \RenewChemState{<name>}[<keyval>]{<symbol>}{<unit>}
-\NewDocumentCommand \RenewChemState { omO{}mm }
-  {
-    \bool_set_true:N \l__chemmacros_renewstate_bool
-    \bool_set_true:N \l__chemmacros_state_overwrite_error_bool
-    \__chemmacros_setnewstate_reset:
-    \IfNoValueTF { #1 }
-      { \chemmacros_define_state:nnnn { #3 } { #2 } { #4 } { #5 } }
-      {
-        \msg_warning:nn { chemmacros } { state-syntax }
-        \chemmacros_define_state:nnnn { #1#3 } { #2 } { #4 } { #5 }
-      }
-  }
-% TODO
-\cs_set_protected:Npn \setnewstate
-  {
-    \msg_warning:nnnn { chemmacros } { command-deprecated }
-      { \setnewstate } { \NewChemState }
-    \NewChemState
-  }
-\cs_set_protected:Npn \renewstate
-  {
-    \msg_warning:nnnn { chemmacros } { command-deprecated }
-      { \renewstate } { \RenewChemState }
-    \RenewChemState
-  }
-
-\cs_new_protected:Npn \__chemmacros_setnewstate_reset:
-  {
-    \tl_set:Nn  \l__chemmacros_thermod_subscript_left_default_tl { true }
-    \tl_clear:N \l__chemmacros_thermod_subscript_default_tl
-    \tl_set:Nn  \l__chemmacros_thermod_exponent_default_tl { \standardstate }
-    \tl_set:Nn  \l__chemmacros_thermod_delta_default_tl { \changestate }
-  }
-
-\cs_new_protected:Npn \chemmacros_define_state:nnnn #1#2#3#4
-  {
-    \keys_set:nn { chemmacros / setnewstate } { #1 }
-    \chemmacros_if_is_cs:nTF { #2 }
-      { \__chemmacros_set_state:xnn { \cs_to_str:N #2 } { #3 } { #4 } }
-      {
-        \msg_warning:nn { chemmacros } { state-syntax }
-        \__chemmacros_set_state:nnn { #2 } { #3 } { #4 }
-      }
-  }
-
-\cs_new_protected:Npn \__chemmacros_set_state:nnn #1#2#3
-  {
-    \bool_if:NT \l__chemmacros_state_overwrite_error_bool
-      {
-        \bool_if:NTF \l__chemmacros_renewstate_bool
-          {
-            \cs_if_exist:cF { #1 }
-              { \msg_error:nnx { chemmacros } { nenew-state } { #1 } }
-          }
-          {
-            \cs_if_exist:cT { #1 }
-              { \msg_error:nnx { chemmacros } { new-state } { #1 } }
-          }
-      }
-    \cs_undefine:c { chemmacros_ #1 _reset: }
-    \cs_undefine:c { c__chemmacros_ #1 _subscript_tl }
-    \cs_undefine:c { c__chemmacros_ #1 _exponent_tl }
-    \cs_undefine:c { c__chemmacros_ #1 _delta_tl }
-    \cs_undefine:c { c__chemmacros_ #1 _left_tl }
-    \cs_undefine:c { c__chemmacros_ #1 _unit_tl }
-    \cs_undefine:c { #1 }
-    \cs_undefine:c { #1 _aux_i:n }
-    \cs_undefine:c { #1 _aux_ii:n }
-    \cs_undefine:c { #1 _aux_iii:n }
-    \group_begin:
-      \tl_const:cV
-        { c__chemmacros_ #1 _subscript_tl }
-        \l__chemmacros_thermod_subscript_default_tl
-      \tl_const:cV
-        { c__chemmacros_ #1 _exponent_tl }
-        \l__chemmacros_thermod_exponent_default_tl
-      \tl_const:cV
-        { c__chemmacros_ #1 _delta_tl }
-        \l__chemmacros_thermod_delta_default_tl
-      \tl_const:cV
-        { c__chemmacros_ #1 _left_tl }
-        \l__chemmacros_thermod_subscript_left_default_tl
-      \tl_const:cn
-        { c__chemmacros_ #1 _unit_tl }
-        { #3 }
-      \cs_new_protected:cpn {chemmacros_ #1 _reset: }
-        {
-          \tl_set_eq:Nc
-            \l__chemmacros_thermod_subscript_tl
-            { c__chemmacros_ #1 _subscript_tl }
-          \tl_set_eq:Nc
-            \l__chemmacros_thermod_exponent_tl
-            { c__chemmacros_ #1 _exponent_tl }
-          \tl_set_eq:Nc
-            \l__chemmacros_thermod_delta_tl
-            { c__chemmacros_ #1 _delta_tl }
-          \tl_set_eq:Nc
-            \l__chemmacros_thermod_subscript_left_tl
-            { c__chemmacros_ #1 _left_tl }
-          \tl_set_eq:Nc
-            \l__chemmacros_thermod_unit_tl
-            { c__chemmacros_ #1 _unit_tl }
-        }
-      \cs_new_protected:cpn { #1 }
-        {
-          \use:c {chemmacros_ #1 _reset: }
-          \peek_meaning:NTF [
-            { \tl_use:c { #1 _aux_i:n } }
-            {
-              \peek_meaning:NTF (
-                { \tl_use:c { #1 _aux_ii:n } }
-                { \tl_use:c { #1 _aux_iii:n } }
-            }
-        }
-      \cs_new_protected:cpn { #1 _aux_i:n } [##1]
-        {
-          \keys_set:nn { chemmacros / State } { ##1 }
-          \peek_meaning:NTF (
-            { \tl_use:c { #1 _aux_ii:n } }
-            { \tl_use:c { #1 _aux_iii:n } }
-        }
-      \cs_new_protected:cpn { #1 _aux_ii:n } (##1)
-        {
-          \tl_set:Nn \l__chemmacros_thermod_subscript_tl { ##1 }
-          \tl_use:c { #1 _aux_iii:n }
-        }
-      \cs_new_protected:cpn { #1 _aux_iii:n } ##1
-        {
-          \ensuremath
-            {
-              \tl_if_eq:VnTF
-                \l__chemmacros_thermod_subscript_left_tl { true }
-                {
-                  \chemmacros_state:xnV
-                    {
-                      subscript-left = true ,
-                      exponent       =
-                        { \exp_not:V \l__chemmacros_thermod_exponent_tl } ,
-                      delta          =
-                        { \exp_not:V \l__chemmacros_thermod_delta_tl }
-                    }
-                    { #2 }
-                }
-                {
-                  \chemmacros_state:xnV
-                    {
-                      subscript-left = false ,
-                      exponent       =
-                        { \exp_not:V \l__chemmacros_thermod_exponent_tl } ,
-                      delta          =
-                        { \exp_not:V \l__chemmacros_thermod_delta_tl }
-                    }
-                    { #2 }
-                }
-                \l__chemmacros_thermod_subscript_tl
-                =
-                \exp_args:NnV \SI { ##1 } \l__chemmacros_thermod_unit_tl
-            }
-        }
-    \group_end:
-    \ignorespaces
-  }
-\cs_generate_variant:Nn \__chemmacros_set_state:nnn { x }
-
-% predefined:
-\NewChemState \Enthalpy {H} {\kilo\joule\per\mole}
-\NewChemState \Entropy [ delta=false, subscript-left=false ]
-  {S} {\joule\per\kelvin\per\mole}
-\NewChemState \Gibbs {G} {\kilo\joule\per\mole}
-
-% --------------------------------------------------------------------------
-% Newman projections
-\fp_new:N  \l__chemmacros_newman_rel_angle_fp
-\fp_zero:N \l__chemmacros_newman_rel_angle_fp
-\fp_new:N  \l__chemmacros_newman_tmp_angle_fp
-\fp_new:N  \l__chemmacros_newman_abs_angle_fp
-\fp_zero:N \l__chemmacros_newman_abs_angle_fp
-\fp_new:N  \l__chemmacros_newman_scale_fp
-\fp_set:Nn \l__chemmacros_newman_scale_fp { 1 }
-\fp_new:N  \l__chemmacros_newman_x_fp
-\fp_new:N  \l__chemmacros_newman_y_fp
-
-\tl_new:N \l__chemmacros_newman_tikz_ring_tl
-\tl_new:N \l__chemmacros_newman_tikz_front_tl
-\tl_new:N \l__chemmacros_newman_tikz_back_tl
-
-\bool_new:N \l__chemmacros_newman_tikz_back_bool
-
-\keys_define:nn { chemmacros / newman }
-  {
-    ring       .tl_set:N  = \l__chemmacros_newman_tikz_ring_tl ,
-    atoms      .tl_set:N  = \l__chemmacros_newman_tikz_front_tl ,
-    back-atoms .code:n    =
-      {
-        \bool_set_true:N \l__chemmacros_newman_tikz_back_bool
-        \tl_set:Nn \l__chemmacros_newman_tikz_back_tl { #1 }
-      } ,
-    scale       .fp_set:N  = \l__chemmacros_newman_scale_fp ,
-    scale       .default:n = 1 ,
-    angle       .fp_set:N  = \l__chemmacros_newman_abs_angle_fp ,
-    angle       .default:n = 0
-  }
-
-% \newman[<keyval>](<angle>){<1>,<2>,<3>,<4>,<5>,<6>}
-\NewDocumentCommand \newman { o d() > { \SplitArgument { 5 } { , } } m }
-  {
-    \group_begin:
-      \IfNoValueF { #1 } { \keys_set:nn { chemmacros / newman } { #1 } }
-      \IfNoValueTF { #2 }
-        { \chemmacros_newman_atoms:nnnnnnn {    } #3 }
-        { \chemmacros_newman_atoms:nnnnnnn { #2 } #3 }
-    \group_end:
-  }
-
-% place atoms:
-% #1: angle
-% #2 - #7: atoms
-\cs_new_protected:Npn \chemmacros_newman_atoms:nnnnnnn #1#2#3#4#5#6#7
-  {
-    \tl_if_blank:nTF { #1 }
-      {
-        \fp_set_eq:NN
-          \l__chemmacros_newman_rel_angle_fp
-          \l__chemmacros_newman_abs_angle_fp
-      }
-      { \fp_set:Nn \l__chemmacros_newman_rel_angle_fp { #1 } }
-    \chemmacros_tikz_picture:xn
-      {
-        scale = \fp_to_tl:N \l__chemmacros_newman_scale_fp ,
-        chemmacros_newman_atom_front / .style =
-          {
-            inner~sep=0pt,
-            outer~sep=0pt,
-            \tl_use:N \l__chemmacros_newman_tikz_front_tl
-          },
-        chemmacros_newman_atom_back / .style =
-          {
-            inner~sep=0pt,
-            outer~sep=0pt,
-            \bool_if:NTF \l__chemmacros_newman_tikz_back_bool
-              { \tl_use:N \l__chemmacros_newman_tikz_back_tl }
-              { \tl_use:N \l__chemmacros_newman_tikz_front_tl }
-          }
-      }
-      {
-        \chemmacros_tikz_draw:f
-          { \tl_use:N \l__chemmacros_newman_tikz_ring_tl }
-          (0pt,0pt) circle (\fp_to_dim:N \l__chemmacros_newman_scale_fp * 15) ;
-        \chemmacros_newman_back_node:nn
-          { 30 }
-          { \IfNoValueF { #6 } { #6 } }
-        \chemmacros_newman_back_node:nf
-          { 150 }
-          { \IfNoValueF { #7 } { #7 } }
-        \chemmacros_newman_back_node:nf
-          { 270 }
-          { \IfNoValueF { #5 } { #5 } }
-        \chemmacros_newman_front_node:nf
-          { 90 }
-          { \IfNoValueF { #2 } { #2 } }
-        \chemmacros_newman_front_node:nf
-          { 210 }
-          { \IfNoValueF { #3 } { #3 } }
-        \chemmacros_newman_front_node:nf
-          { 330 }
-          { \IfNoValueF { #4 } { #4 } }
-    }
-  }
-
-% provide cartesian coordiantes from polar coordinates
-% #1: fp variable for x
-% #2: fp variable for y
-% #3: angle
-% #4: radius
-\cs_new_protected:Npn \chemmacros_polar_to_cartesian:NNnn #1#2#3#4
-  {
-    \fp_set:Nn #1 { #4 * cos( #3 / 180 * pi ) }% x
-    \fp_set:Nn #2 { #4 * sin( #3 / 180 * pi ) }% y
-  }
-
-% place back nodes
-\cs_new_protected:Npn \chemmacros_newman_back_node:nn #1#2
-  {
-    \group_begin:
-      \fp_add:Nn \l__chemmacros_newman_rel_angle_fp { #1 }
-      \chemmacros_polar_to_cartesian:NNnn
-        \l__chemmacros_newman_x_fp
-        \l__chemmacros_newman_y_fp
-        { \l__chemmacros_newman_rel_angle_fp }
-        { \l__chemmacros_newman_scale_fp }
-      \chemmacros_tikz_draw:f
-        { \tl_use:N \l__chemmacros_newman_tikz_ring_tl }
-        (
-          15 * \fp_to_dim:N \l__chemmacros_newman_x_fp ,
-          15 * \fp_to_dim:N \l__chemmacros_newman_y_fp
-        )
-        --
-        (
-          30 * \fp_to_dim:N \l__chemmacros_newman_x_fp ,
-          30 * \fp_to_dim:N \l__chemmacros_newman_y_fp
-        ) ;
-      \chemmacros_polar_to_cartesian:NNnn
-        \l__chemmacros_newman_x_fp
-        \l__chemmacros_newman_y_fp
-        { \l__chemmacros_newman_rel_angle_fp }
-        { \l__chemmacros_newman_scale_fp }
-      \chemmacros_tikz_node:f
-        {
-          chemmacros_newman_atom_back,
-          anchor = -180 + \fp_to_int:N \l__chemmacros_newman_rel_angle_fp
-        }
-        at
-        (
-          31 * \fp_to_dim:N \l__chemmacros_newman_x_fp ,
-          31 * \fp_to_dim:N \l__chemmacros_newman_y_fp
-        )
-        { #2 } ;
-    \group_end:
-  }
-\cs_generate_variant:Nn \chemmacros_newman_back_node:nn { nf }
-
-% place front nodes:
-\cs_new_protected:Npn \chemmacros_newman_front_node:nn #1#2
-  {
-    \chemmacros_polar_to_cartesian:NNnn
-      \l__chemmacros_newman_x_fp
-      \l__chemmacros_newman_y_fp
-      { #1 }
-      { \l__chemmacros_newman_scale_fp }
-    \chemmacros_tikz_draw:f
-      { \tl_use:N \l__chemmacros_newman_tikz_ring_tl }
-      (0pt,0pt) -- ++
-      (
-        30 * \fp_to_dim:N \l__chemmacros_newman_x_fp ,
-        30 * \fp_to_dim:N \l__chemmacros_newman_y_fp
-      ) ;
-    \chemmacros_polar_to_cartesian:NNnn
-      \l__chemmacros_newman_x_fp
-      \l__chemmacros_newman_y_fp
-      { #1 }
-      { \l__chemmacros_newman_scale_fp }
-    \chemmacros_tikz_node:f
-      { chemmacros_newman_atom_front, anchor = -180 + #1 }
-      at
-      (
-        31 * \fp_to_dim:N \l__chemmacros_newman_x_fp ,
-        31 * \fp_to_dim:N \l__chemmacros_newman_y_fp
-      )
-      { #2 } ;
-  }
-\cs_generate_variant:Nn \chemmacros_newman_front_node:nn { nf }
-
-% --------------------------------------------------------------------------
-% \orbital[<keyval>]{<type>}
-% variables:
-\bool_new:N      \l__chemmacros_orbital_type_s_bool
-\bool_new:N      \l__chemmacros_orbital_type_p_bool
-\bool_new:N      \l__chemmacros_orbital_type_sp_bool
-\bool_new:N      \l__chemmacros_orbital_type_sptwo_bool
-\bool_new:N      \l__chemmacros_orbital_type_spthree_bool
-\bool_new:N      \l__chemmacros_orbital_s_phase_bool
-\bool_set_true:N \l__chemmacros_orbital_s_phase_bool
-\bool_new:N      \l__chemmacros_orbital_p_phase_bool
-\bool_set_true:N \l__chemmacros_orbital_p_phase_bool
-\bool_new:N      \l__chemmacros_orbital_sp_phase_bool
-\bool_set_true:N \l__chemmacros_orbital_sp_phase_bool
-\bool_new:N      \l__chemmacros_orbital_sptwo_phase_bool
-\bool_set_true:N \l__chemmacros_orbital_sptwo_phase_bool
-\bool_new:N      \l__chemmacros_orbital_spthree_phase_bool
-\bool_set_true:N \l__chemmacros_orbital_spthree_phase_bool
-\bool_new:N      \l__chemmacros_orbital_p_half_bool
-\bool_new:N      \l__chemmacros_orbital_overlay_bool
-\bool_new:N      \l__chemmacros_orbital_opacity_bool
-
-\tl_new:N  \l__chemmacros_orbital_s_color_tl
-\tl_set:Nn \l__chemmacros_orbital_s_color_tl { black }
-\tl_new:N  \l__chemmacros_orbital_s_phase_color_tl
-\tl_new:N  \l__chemmacros_orbital_p_color_tl
-\tl_set:Nn \l__chemmacros_orbital_p_color_tl { black }
-\tl_new:N  \l__chemmacros_orbital_p_pphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_p_mphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_sp_color_tl
-\tl_set:Nn \l__chemmacros_orbital_sp_color_tl { black }
-\tl_new:N  \l__chemmacros_orbital_sp_pphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_sp_mphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_sptwo_color_tl
-\tl_set:Nn \l__chemmacros_orbital_sptwo_color_tl { black }
-\tl_new:N  \l__chemmacros_orbital_sptwo_pphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_sptwo_mphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_spthree_color_tl
-\tl_set:Nn \l__chemmacros_orbital_spthree_color_tl { black }
-\tl_new:N  \l__chemmacros_orbital_spthree_pphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_spthree_mphase_color_tl
-\tl_new:N  \l__chemmacros_orbital_s_scale_tl
-\tl_set:Nn \l__chemmacros_orbital_s_scale_tl { 1 }
-\tl_new:N  \l__chemmacros_orbital_p_scale_tl
-\tl_set:Nn \l__chemmacros_orbital_p_scale_tl { 1 }
-\tl_new:N  \l__chemmacros_orbital_sp_scale_tl
-\tl_set:Nn \l__chemmacros_orbital_sp_scale_tl { 1 }
-\tl_new:N  \l__chemmacros_orbital_sptwo_scale_tl
-\tl_set:Nn \l__chemmacros_orbital_sptwo_scale_tl { 1 }
-\tl_new:N  \l__chemmacros_orbital_spthree_scale_tl
-\tl_set:Nn \l__chemmacros_orbital_spthree_scale_tl { 1 }
-
-\fp_new:N  \l__chemmacros_orbital_angle_fp
-\fp_set:Nn \l__chemmacros_orbital_angle_fp { 90 }
-\fp_new:N  \l__chemmacros_orbital_opacity_fp
-\fp_set:Nn \l__chemmacros_orbital_opacity_fp { 0.5 }
-
-\cs_new:Npn \__chemmacros_orbital_options:
-  {
-    \__chemmacros_orbital_overlay: , \__chemmacros_orbital_opacity: ,
-    inner~sep=0 , outer~sep=0 , line~width=.2pt ,
-    rotate = { \fp_use:N \l__chemmacros_orbital_angle_fp - 90 } ,
-    baseline ,
-    minimum~size = 0
-  }
-
-\cs_new:Npn \__chemmacros_orbital_overlay:
-  { \bool_if:NT \l__chemmacros_orbital_overlay_bool { overlay } }
-
-\cs_new:Npn \__chemmacros_orbital_opacity:
-  {
-    \bool_if:NT \l__chemmacros_orbital_opacity_bool
-      { opacity = { \fp_use:N \l__chemmacros_orbital_opacity_fp } }
-  }
-
-% --------------------------------------------------------------------------
-% s-orbitals
-\cs_new_protected:Npn \__chemmacros_orbital_type_s:
-  {
-    \bool_set_true:N \l__chemmacros_orbital_type_s_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_p_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sp_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sptwo_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_spthree_bool
-  }
-
-\keys_define:nn { chemmacros / orbital / s }
-  {
-    phase .choice: ,
-    phase / + .code:n =
-      { \bool_set_true:N \l__chemmacros_orbital_s_phase_bool } ,
-    phase / - .code:n =
-      { \bool_set_false:N \l__chemmacros_orbital_s_phase_bool } ,
-    scale .tl_set:N   = \l__chemmacros_orbital_s_scale_tl ,
-    color .tl_set:N   = \l__chemmacros_orbital_s_color_tl
-  }
-
-\cs_new_protected:Npn \__chemmacros_orbital_s_draw:n #1
-  {
-    \keys_set:nn { chemmacros / orbital / s } { #1 }
-    \bool_if:NTF \l__chemmacros_orbital_s_phase_bool
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_s_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_s_phase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_s_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_s_phase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_s_color_tl ! 90 }
-          }
-      }
-      {
-        \tl_set:Nn \l__chemmacros_orbital_s_phase_color_tl
-          { black ! 5 }
-      }
-    \chemmacros_tikz_picture:xn{ \__chemmacros_orbital_options: }
-      {
-        \chemmacros_tikz_shade:f
-          { ball~color = \l__chemmacros_orbital_s_phase_color_tl }
-          (0pt,0pt) circle (\l__chemmacros_orbital_s_scale_tl * .6em) ;
-      }
-  }
-
-% --------------------------------------------------------------------------
-% p-orbitals
-\cs_new_protected:Npn \__chemmacros_orbital_type_p:
-  {
-    \bool_set_false:N \l__chemmacros_orbital_type_s_bool
-    \bool_set_true:N  \l__chemmacros_orbital_type_p_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sp_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sptwo_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_spthree_bool
-  }
-
-\keys_define:nn { chemmacros / orbital / p }
-  {
-    phase .choice: ,
-    phase / + .code:n =
-      { \bool_set_true:N \l__chemmacros_orbital_p_phase_bool } ,
-    phase / - .code:n =
-      { \bool_set_false:N \l__chemmacros_orbital_p_phase_bool } ,
-    scale .tl_set:N   = \l__chemmacros_orbital_p_scale_tl ,
-    angle .fp_set:N   = \l__chemmacros_orbital_angle_fp ,
-    color .tl_set:N   = \l__chemmacros_orbital_p_color_tl ,
-    half  .bool_set:N = \l__chemmacros_orbital_p_half_bool ,
-    half  .default:n  = true
-  }
-
-\cs_new_protected:Npn \__chemmacros_orbital_p_draw:n #1
-  {
-    \keys_set:nn { chemmacros / orbital / p } { #1 }
-    \bool_if:NTF \l__chemmacros_orbital_p_phase_bool
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_p_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_p_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_p_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_p_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_p_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_p_mphase_color_tl
-          { black ! 5 }
-        
-      }
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_p_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_p_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_p_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_p_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_p_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_p_pphase_color_tl
-          { black ! 5 }
-      }
-    \chemmacros_tikz_picture:xn { \__chemmacros_orbital_options: }
-      {
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_p_pphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_p_pphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_p_scale_tl * 2em ,
-            \l__chemmacros_orbital_p_scale_tl * 2em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_p_scale_tl * 2em ,
-            \l__chemmacros_orbital_p_scale_tl * 2em
-          )
-          .. (0pt,0pt);
-        \bool_if:NF \l__chemmacros_orbital_p_half_bool
-          {
-            \chemmacros_tikz_shadedraw:f
-              {
-                draw = \l__chemmacros_orbital_p_mphase_color_tl ,
-                ball~color = \l__chemmacros_orbital_p_mphase_color_tl
-              }
-              (0pt,0pt) .. controls ++
-              (
-                - \l__chemmacros_orbital_p_scale_tl * 2em ,
-                - \l__chemmacros_orbital_p_scale_tl * 2em
-              )
-              and ++
-              (
-                \l__chemmacros_orbital_p_scale_tl * 2em ,
-                - \l__chemmacros_orbital_p_scale_tl * 2em
-              )
-              .. (0pt,0pt);
-          }
-      }
-  }
-
-% --------------------------------------------------------------------------
-% sp-orbitals
-\cs_new_protected:Npn \__chemmacros_orbital_type_sp:
-  {
-    \bool_set_false:N \l__chemmacros_orbital_type_s_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_p_bool
-    \bool_set_true:N  \l__chemmacros_orbital_type_sp_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sptwo_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_spthree_bool
-  }
-
-\keys_define:nn { chemmacros / orbital / sp }
-  {
-    phase .choice: ,
-    phase / + .code:n =
-      { \bool_set_true:N \l__chemmacros_orbital_sp_phase_bool } ,
-    phase / - .code:n =
-      { \bool_set_false:N \l__chemmacros_orbital_sp_phase_bool } ,
-    scale .tl_set:N   = \l__chemmacros_orbital_sp_scale_tl ,
-    angle .fp_set:N   = \l__chemmacros_orbital_angle_fp ,
-    color .tl_set:N   = \l__chemmacros_orbital_sp_color_tl
-  }
-
-\cs_new_protected:Npn \__chemmacros_orbital_sp_draw:n #1
-  {
-    \keys_set:nn { chemmacros / orbital / sp } { #1 }
-    \bool_if:NTF \l__chemmacros_orbital_sp_phase_bool
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_sp_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sp_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sp_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sp_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sp_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_sp_mphase_color_tl
-          { black ! 5 }
-        
-      }
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_sp_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sp_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sp_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sp_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sp_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_sp_pphase_color_tl
-          { black ! 5 }
-      }
-    \chemmacros_tikz_picture:xn { \__chemmacros_orbital_options: }
-      {
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_sp_pphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_sp_pphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_sp_scale_tl * 2em ,
-            \l__chemmacros_orbital_sp_scale_tl * 2em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_sp_scale_tl * 2em ,
-            \l__chemmacros_orbital_sp_scale_tl * 2em
-          )
-          .. (0pt,0pt);
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_sp_mphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_sp_mphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_sp_scale_tl * .6em ,
-            - \l__chemmacros_orbital_sp_scale_tl * .6em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_sp_scale_tl * .6em ,
-            - \l__chemmacros_orbital_sp_scale_tl * .6em
-          )
-          .. (0pt,0pt);
-      }
-  }
-
-% --------------------------------------------------------------------------
-% sp2-orbitals
-\cs_new_protected:Npn \__chemmacros_orbital_type_sptwo:
-  {
-    \bool_set_false:N \l__chemmacros_orbital_type_s_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_p_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sp_bool
-    \bool_set_true:N  \l__chemmacros_orbital_type_sptwo_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_spthree_bool
-  }
-
-\keys_define:nn { chemmacros / orbital / sp2 }
-  {
-    phase .choice: ,
-    phase / + .code:n =
-      { \bool_set_true:N \l__chemmacros_orbital_sptwo_phase_bool } ,
-    phase / - .code:n =
-      { \bool_set_false:N \l__chemmacros_orbital_sptwo_phase_bool } ,
-    scale .tl_set:N   = \l__chemmacros_orbital_sptwo_scale_tl ,
-    angle .fp_set:N   = \l__chemmacros_orbital_angle_fp ,
-    color .tl_set:N   = \l__chemmacros_orbital_sptwo_color_tl
-  }
-
-\cs_new_protected:Npn \__chemmacros_orbital_sptwo_draw:n #1
-  {
-    \keys_set:nn { chemmacros / orbital / sp2 } { #1 }
-    \bool_if:NTF \l__chemmacros_orbital_sptwo_phase_bool
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_sptwo_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sptwo_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sptwo_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sptwo_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sptwo_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_sptwo_mphase_color_tl
-          { black ! 5 }
-        
-      }
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_sptwo_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sptwo_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sptwo_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_sptwo_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_sptwo_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_sptwo_pphase_color_tl
-          { black ! 5 }
-      }
-    \chemmacros_tikz_picture:xn { \__chemmacros_orbital_options: }
-      {
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_sptwo_pphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_sptwo_pphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_sptwo_scale_tl * 2em ,
-            \l__chemmacros_orbital_sptwo_scale_tl * 2em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_sptwo_scale_tl * 2em ,
-            \l__chemmacros_orbital_sptwo_scale_tl * 2em
-          )
-          .. (0pt,0pt);
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_sptwo_mphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_sptwo_mphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_sptwo_scale_tl * .8em ,
-            - \l__chemmacros_orbital_sptwo_scale_tl * .8em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_sptwo_scale_tl * .8em ,
-            - \l__chemmacros_orbital_sptwo_scale_tl * .8em
-          )
-          .. (0pt,0pt);
-      }
-  }
-
-% --------------------------------------------------------------------------
-% sp3-orbitals
-\cs_new_protected:Npn \__chemmacros_orbital_type_spthree:
-  {
-    \bool_set_false:N \l__chemmacros_orbital_type_s_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_p_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sp_bool
-    \bool_set_false:N \l__chemmacros_orbital_type_sptwo_bool
-    \bool_set_true:N  \l__chemmacros_orbital_type_spthree_bool
-  }
-
-\keys_define:nn { chemmacros / orbital / sp3 }
-  {
-    phase .choice: ,
-    phase / + .code:n =
-      { \bool_set_true:N \l__chemmacros_orbital_spthree_phase_bool } ,
-    phase / - .code:n =
-     { \bool_set_false:N \l__chemmacros_orbital_spthree_phase_bool } ,
-    scale .tl_set:N   = \l__chemmacros_orbital_spthree_scale_tl ,
-    angle .fp_set:N   = \l__chemmacros_orbital_angle_fp ,
-    color .tl_set:N   = \l__chemmacros_orbital_spthree_color_tl
-  }
+\cs_new_protected:Npn \ChemCompatibilityFrom #1#2 \EndChemCompatibility
+  { \chemmacros_if_compatiblity:nnT {>=} {#1} {#2} }
 
-\cs_new_protected:Npn \__chemmacros_orbital_spthree_draw:n #1
-  {
-    \keys_set:nn { chemmacros / orbital / sp3 } { #1 }
-    \bool_if:NTF \l__chemmacros_orbital_spthree_phase_bool
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_spthree_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_spthree_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_spthree_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_spthree_pphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_spthree_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_spthree_mphase_color_tl
-          { black ! 5 }
-        
-      }
-      {
-        \tl_if_in:NnTF \l__chemmacros_orbital_spthree_color_tl { ! }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_spthree_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_spthree_color_tl }
-          }
-          {
-            \tl_set:Nn \l__chemmacros_orbital_spthree_mphase_color_tl
-              { \tl_use:N \l__chemmacros_orbital_spthree_color_tl ! 90 }
-          }
-        \tl_set:Nn \l__chemmacros_orbital_spthree_pphase_color_tl
-          { black ! 5 }
-      }
-    \chemmacros_tikz_picture:xn { \__chemmacros_orbital_options: }
-      {
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_spthree_pphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_spthree_pphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_spthree_scale_tl * 2em ,
-            \l__chemmacros_orbital_spthree_scale_tl * 2em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_spthree_scale_tl * 2em ,
-            \l__chemmacros_orbital_spthree_scale_tl * 2em
-          )
-          .. (0pt,0pt);
-        \chemmacros_tikz_shadedraw:f
-          {
-            draw = \l__chemmacros_orbital_spthree_mphase_color_tl ,
-            ball~color = \l__chemmacros_orbital_spthree_mphase_color_tl
-          }
-          (0pt,0pt) .. controls ++
-          (
-            - \l__chemmacros_orbital_spthree_scale_tl * 1em ,
-            - \l__chemmacros_orbital_spthree_scale_tl * 1em
-          )
-          and ++
-          (
-            \l__chemmacros_orbital_spthree_scale_tl * 1em ,
-            - \l__chemmacros_orbital_spthree_scale_tl * 1em
-          )
-          .. (0pt,0pt);
-      }
-  }
+\cs_new_protected:Npn \ChemCompatibilityTo #1#2 \EndChemCompatibility
+  { \chemmacros_if_compatiblity:nnT {<=} {#1} {#2} }
 
-% --------------------------------------------------------------------------
-% main command
-\keys_define:nn { chemmacros / orbital }
+\cs_new_protected:Npn \ChemCompatibilityBetween #1#2#3 \EndChemCompatibility
   {
-    overlay .bool_set:N = \l__chemmacros_orbital_overlay_bool ,
-    overlay .default:n  = true ,
-    opacity .code:n     =
+    \bool_if:nT
       {
-        \fp_compare:nTF { #1 = 1 }
-          { \bool_set_false:N \l__chemmacros_orbital_opacity_bool }
-          { \bool_set_true:N \l__chemmacros_orbital_opacity_bool }
-        \fp_set:Nn \l__chemmacros_orbital_opacity_fp { #1 }
+        \chemmacros_if_compatiblity_p:nn {>=} {#1} &&
+        \chemmacros_if_compatiblity_p:nn {<=} {#2}
       }
+      {#3}
   }
 
-\keys_define:nn { chemmacros / orbital / type }
-  {
-    s   .code:n = { \__chemmacros_orbital_type_s: } ,
-    p   .code:n = { \__chemmacros_orbital_type_p: } ,
-    sp  .code:n = { \__chemmacros_orbital_type_sp: } ,
-    sp2 .code:n = { \__chemmacros_orbital_type_sptwo: } ,
-    sp3 .code:n = { \__chemmacros_orbital_type_spthree: }
-  }
-
-\cs_new_protected:Npn \chemmacros_orbital:n #1
-  {
-    \bool_if:NT \l__chemmacros_orbital_type_s_bool
-      { \__chemmacros_orbital_s_draw:n { #1 } }
-    \bool_if:NT \l__chemmacros_orbital_type_p_bool
-      { \__chemmacros_orbital_p_draw:n { #1 } }
-    \bool_if:NT \l__chemmacros_orbital_type_sp_bool
-      { \__chemmacros_orbital_sp_draw:n { #1 } }
-    \bool_if:NT \l__chemmacros_orbital_type_sptwo_bool
-      { \__chemmacros_orbital_sptwo_draw:n { #1 } }
-    \bool_if:NT \l__chemmacros_orbital_type_spthree_bool
-      { \__chemmacros_orbital_spthree_draw:n { #1 } }
-  }
-
-\NewDocumentCommand \orbital { o m }
+% let's see that the max number is the newest (=current) version
+\chemmacros_if_compatiblity:nnT {>} { \c_chemmacros_version_number_tl }
   {
-    \group_begin:
-      \keys_set:nn { chemmacros / orbital / type } { #2 }
-      \IfNoValueTF { #1 }
-        { \chemmacros_orbital:n {    } }
-        { \chemmacros_orbital:n { #1 } }
-    \group_end:
+    \fp_set:Nn \l__chemmacros_compatibility_version_fp
+      { \c_chemmacros_version_number_tl }
   }
 
 % --------------------------------------------------------------------------
-% arrow tips for electron movement
-\dim_new:N \l__chemmacros_el_length_dim
-
-% full tip for pairs
-\pgfarrowsdeclare { el } { el }
-  {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfarrowsleftextend { -\l__chemmacros_el_length_dim }
-    \pgfarrowsrightextend { .5\pgflinewidth }
-  }
+% compatibility too low:
+\chemmacros_if_compatiblity:nnT {<} {4.7}
   {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfsetdash {} { 0pt }
-    \pgfsetroundjoin
-    \pgfsetroundcap
-    \pgfpathmoveto { \pgfpoint { 0pt } { 0pt } }
-    \pgfpathlineto
-      {
-        \pgfpoint
-          { -\l__chemmacros_el_length_dim }
-          { .3\l__chemmacros_el_length_dim }
-      }
-    \pgfpathlineto
-      { \pgfpoint { -.5\l__chemmacros_el_length_dim } { 0pt } }
-    \pgfpathlineto
-      {
-        \pgfpoint
-          { -\l__chemmacros_el_length_dim }
-          { -.3\l__chemmacros_el_length_dim }
-      }
-    \pgfpathlineto { \pgfpoint { 0pt } { 0pt } }
-    \pgfusepathqfillstroke
+    \msg_warning:nnx {chemmacros} {too-low-compatibility}
+      { \fp_to_tl:N \l__chemmacros_compatibility_version_fp }
   }
 
-% half tip on the left
-\pgfarrowsdeclare { left~el } { left~el }
+% not the newest version:
+\chemmacros_if_compatiblity:nnT {<} { \c_chemmacros_version_number_tl }
   {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfarrowsleftextend { -\l__chemmacros_el_length_dim }
-    \pgfarrowsrightextend { .5\pgflinewidth }
+    \msg_warning:nnx {chemmacros} {low-compatibility}
+      { \fp_to_tl:N \l__chemmacros_compatibility_version_fp }
   }
-  {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfsetdash {} { 0pt }
-    \pgfsetroundjoin
-    \pgfsetroundcap
-    \pgfpathmoveto { \pgfpoint { 0pt } { 0pt } }
-    \pgfpathlineto
-      {
-        \pgfpoint
-          { -\l__chemmacros_el_length_dim }
-          { .3\l__chemmacros_el_length_dim }
-      }
-    \pgfpathlineto { \pgfpoint { -.5\l__chemmacros_el_length_dim } { 0pt } }
-    \pgfpathlineto { \pgfpoint { 0pt } { 0pt } }
-    \pgfusepathqfillstroke
-  }
-
-% half tip in the right
-\pgfarrowsdeclare { right~el } { right~el }
-  {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfarrowsleftextend { -\l__chemmacros_el_length_dim }
-    \pgfarrowsrightextend { .5\pgflinewidth }
-  }
-  {
-    \dim_set:Nn \l__chemmacros_el_length_dim
-      { 2.5pt + 2.5\pgflinewidth }
-    \pgfsetdash {} { 0pt }
-    \pgfsetroundjoin
-    \pgfsetroundcap
-    \pgfpathmoveto { \pgfpoint { 0pt } { 0pt } }
-    \pgfpathlineto
-      {
-        \pgfpoint
-          { -\l__chemmacros_el_length_dim }
-          { -.3\l__chemmacros_el_length_dim }
-      }
-    \pgfpathlineto { \pgfpoint { -.5\l__chemmacros_el_length_dim } { 0pt } }
-    \pgfpathlineto { \pgfpoint { 0pt } { 0pt } }
-    \pgfusepathqfillstroke
-  }
-
-% --------------------------------------------------------------------------
-% setup
-\NewDocumentCommand \chemsetup { o m }
-  {
-    \IfNoValueTF { #1 }
-      { \keys_set:nn { chemmacros } { #2 } }
-      {
-        \tl_if_eq:nnTF { #1 } { chemformula }
-          { \setchemformula { #2 } }
-          { \keys_set:nn { chemmacros / #1 } { #2 } }
-      }
-    \ignorespaces
-  }
-
-
+  
 % --------------------------------------------------------------------------
-% hyperref support
-% ?? unsure about adding IUPAC commands
-\AfterPackage* { hyperref }
-  {
-    \pdfstringdefDisableCommands
-      {
-        % \cs_set:Npn \- { - } % maybe not a good idea...
-        \cs_set:Npn \| { }
-        \cs_set:Npn \pH { pH }
-        \cs_set:Npn \pOH { pOH }
-        \cs_set:Npn \iupac #1 { #1 }
-        \cs_set:Npn \cip #1 { (#1) }
-        \cs_set:Npn \cis { cis }
-        \cs_set:Npn \trans { trans }
-        \cs_set:Npn \tert { tert }
-        \cs_set:Npn \ortho { o }
-        \cs_set:Npn \meta { m }
-        \cs_set:Npn \para { p }
-        \cs_set:Npn \syn { syn }
-        \cs_set:Npn \anti { anti }
-      }
-  }
+\chemmacros_if_compatiblity:nnTF {<} {5.0}
+  { \RequirePackage{chemmacros4} }
+  { \RequirePackage{chemmacros5} }
 
 % --------------------------------------------------------------------------
-% language support -- provided through `translations'
-% equilibrium constants:
-\DeclareTranslationFallback {K-acid}  {\mathrm{a}}
-\DeclareTranslation{German} {K-acid}  {\mathrm{s}}
-\DeclareTranslation{Dutch}  {K-acid}  {\mathrm{z}}
-
-\DeclareTranslationFallback {K-base}  {\mathrm{b}}
-
-\DeclareTranslationFallback {K-water} {\mathrm{w}}
-
-% phases:
-\DeclareTranslation{German}{phase-sld}{ f }
-\DeclareTranslation{German}{phase-lqd}{ f{}l }
-% list of reactions:
-\DeclareTranslationFallback  {list-of-reactions} { List~ of~ reactions }
-\DeclareTranslation{English} {list-of-reactions} { List~ of~ reactions }
-\DeclareTranslation{German}  {list-of-reactions} { Reaktionsverzeichnis }
-\DeclareTranslation{Italian} {list-of-reactions} { Elenco~ delle~ reazioni }
-\DeclareTranslation{French}  {list-of-reactions} { Table~ des~ r\'eactions }
-\DeclareTranslation{Dutch}   {list-of-reactions} { Lijst~ van~ reacties }
-%
-\DeclareTranslationFallback  {reaction} { Reaction }
-\DeclareTranslation{English} {reaction} { Reaction }
-\DeclareTranslation{German}  {reaction} { Reaktion }
-\DeclareTranslation{Italian} {reaction} { Reazione }
-\DeclareTranslation{French}  {reaction} { R\'eaction }
-\DeclareTranslation{Dutch}   {reaction} { Reactie }
-
-\tl_set:Nn \l__chemmacros_reaction_lorname_tl
-  { \chemmacros_translate:n {reaction} }
-\tl_set:Nn \reactionlistname
-  { \chemmacros_translate:n {list-of-reactions} }
-
 \tex_endinput:D
 
 % --------------------------------------------------------------------------
@@ -4284,7 +357,7 @@ Version history
                             the new package in the family: `chemgreek'
                           - \OX and \redox now work in `amsmath's environment
                             by ignoring the measuring phase
-                          - language management with the halp of the
+                          - language management with the help of the
                             `translations' package =>
                             recognize document language automatically and use
                             it if it a) is known to `chemmacros' and b) has
@@ -4374,10 +447,13 @@ Version history
                           - allow \NewChemPhase and friends after \begin{document}
                           - new optional argument to phase commands
                           - new options `nmr/method' and `nmr/connector'
-
-% --------------------------------------------------------------------------- %
-% TODO:
-- add d-orbitals
-- make electron movement arrow tips (`el', `left el' and `right el') public
-- phase commands with arguments (see http://texwelt.de/wissen/fragen/9264)
-
+2015/09/11 - version 5.0  - the former chemmacros.sty is now chemmacros4.sty
+                            and can be loaded through the `compatibility'
+                            option
+                          - chemmacros is now organized in separate modules
+                            which either are preloaded or can be loaded by the
+                            user with \usechemmodule
+                          - various changes, see
+                            http://www.mychemistry.eu/2015/06/chemmacros-development/
+                            and the manual section 3.4. Upgrading from version < 5.0
+                            for details