%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% - chemnum - chemnum.sty
% - a comprehensive approach for the numbering of chemical compounds
% -----------------------------------------------------------------------------
% - Clemens NIEDERBERGER
% - contact@mychemistry.eu
% -----------------------------------------------------------------------------
% - If you have any ideas, questions, suggestions or bugs to report, please
% - feel free to contact me.
% -----------------------------------------------------------------------------
% - Copyright 2011-2012 Clemens Niederberger
% -
% - This work may be distributed and/or modified under the
% - conditions of the LaTeX Project Public License, either version 1.3
% - of this license or (at your option) any later version.
% - The latest version of this license is in
% -   http://www.latex-project.org/lppl.txt
% - and version 1.3 or later is part of all distributions of LaTeX
% - version 2005/12/01 or later.
% -
% - This work has the LPPL maintenance status `maintained'.
% -
% - The Current Maintainer of this work is Clemens Niederberger.
% -
% - This work consists of the files
% -   chemnum.sty, chemnum_de.tex, chemnum_en.tex, chemnum_it.tex
% -   scheme-tmp.ps, scheme-bla.ps,
% -   README
% -   chemnum_de.pdf, chemnum_en.pdf, chemnum_it.pdf
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\RequirePackage { expl3 , xparse , l3keys2e , etoolbox , psfrag }

\ProvidesExplPackage
  {chemnum}
  {2012/12/29}
  {0.5f}
  {a comprehensive approach for the numbering of chemical compounds}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% CHECK FOR SUPPORT
% this part of the code is based on the corresponding part of siunitx.sty
% l3 support:
\cs_if_exist:NTF \msg_set:nnnn
  {
    \msg_set:nnnn { chemnum } { support-outdated }
      { Support~package~#1~too~old. }
      {
        Please~install~an~up~to~date~version~of~#1. \\
        Best~would~be~to~update~both~l3kernel~and~l3packages~bundles. \\
        Loading~chemnum~will~abort!
      }
  }
  {
    \PackageError { chemnum } { Support~bundle~l3kernel~too~old. }
      {
        Please~install~an~up~to~date~version~of~the~l3kernel~bundle. \\
        Loading~chemnum~will~abort!
      }
    \tex_endinput:D
  }
\@ifpackagelater { expl3 } { 2011/12/27 }
  { }
  {
    \msg_error:nnx { chemnum } { support-outdated } { expl3 }
    \tex_endinput:D
  }

\@ifpackagelater { xparse } { 2011/12/27 }
  { }
  {
    \msg_error:nnx { chemnum } { support-outdated } { xparse }
    \tex_endinput:D
  }

% error for missing packages
\msg_set:nnnn { chemnum } { support-missing }
  { Support~package~#1~missing. }
  {
    Support~package~#1~seems~to~be~missing. \\
    Please~install~an~up~to~date~version~of~#1. \\
  }

% warning, if textgreek has already been loaded AND option
% "textgreek = <value>" is used
\msg_set:nnnn { chemnum } { textgreek-loaded }
  {
    The~package~textgreek~has~already~been~loaded. \\
    \tl_if_blank:nF { #1 } { Option~#1~will~not~be~used. }
  }
  {
    The~package~textgreek~has~already~been~loaded. \\
    \tl_if_blank:nF { #1 } { Option~#1~will~not~be~used. }
  }

% textgreek support and package options:
\bool_new:N \l_chemnum_textgreek_bool
\bool_set_false:N \l_chemnum_textgreek_bool

\cs_new_nopar:Npn \chemnum_load_textgreek:n #1
  {
    \AtEndPreamble
      {
        \exp_args:No \file_if_exist:nTF { textgreek . sty }
          {
            \@ifpackageloaded { textgreek }
              { \msg_warning:nnx { chemnum } { textgreek-loaded } { #1 } }
              { \RequirePackage [ #1 ] { textgreek } }
            \bool_set_true:N \l_chemnum_textgreek_bool
          }
          {
            \msg_warning:nnx { chemnum } { support-missing } { textgreek }
            \bool_set_false:N \l_chemnum_textgreek_bool
          }
      }
  }

\cs_new:Npn \chemnum_package_options:n #1
  { \keys_set:nn { chemnum / package } { #1 } }

\keys_define:nn { chemnum / package } {
  textgreek .choice: ,
  textgreek / artemisia .code:n     = \chemnum_load_textgreek:n { #1 } ,
  textgreek / cbgreek   .code:n     = \chemnum_load_textgreek:n { #1 } ,
  textgreek / euler     .code:n     = \chemnum_load_textgreek:n { #1 } ,
  textgreek / false     .code:n     =
    { \bool_set_false:N \l_chemnum_textgreek_bool } ,
  textgreek             .default:n  = cbgreek
}

\ProcessKeysOptions { chemnum / package }

\AtBeginDocument{
\bool_if:NTF \l_chemnum_textgreek_bool
  {
    \cs_new_eq:NN \chemnum_alpha:   \textalpha
    \cs_new_eq:NN \chemnum_beta:    \textbeta
    \cs_new_eq:NN \chemnum_gamma:   \textgamma
    \cs_new_eq:NN \chemnum_delta:   \textdelta
    \cs_new_eq:NN \chemnum_epsilon: \textepsilon
    \cs_new_eq:NN \chemnum_zeta:    \textzeta
    \cs_new_eq:NN \chemnum_eta:     \texteta
    \cs_new_eq:NN \chemnum_theta:   \texttheta
    \cs_new_eq:NN \chemnum_iota:    \textiota
    \cs_new_eq:NN \chemnum_kappa:   \textkappa
    \cs_new_eq:NN \chemnum_lambda:  \textlambda
    \cs_new_eq:NN \chemnum_mu:      \textmugreek
    \cs_new_eq:NN \chemnum_nu:      \textnu
    \cs_new_eq:NN \chemnum_xi:      \textxi
    \cs_new_eq:NN \chemnum_omikron: \textomikron
    \cs_new_eq:NN \chemnum_pi:      \textpi
    \cs_new_eq:NN \chemnum_rho:     \textrho
    \cs_new_eq:NN \chemnum_sigma:   \textsigma
    \cs_new_eq:NN \chemnum_tau:     \texttau
    \cs_new_eq:NN \chemnum_upsilon: \textupsilon
    \cs_new_eq:NN \chemnum_phi:     \textphi
    \cs_new_eq:NN \chemnum_chi:     \textchi
    \cs_new_eq:NN \chemnum_psi:     \textpsi
    \cs_new_eq:NN \chemnum_omega:   \textomega
    \cs_new_eq:NN \chemnum_Alpha:   \textAlpha
    \cs_new_eq:NN \chemnum_Beta:    \textBeta
    \cs_new_eq:NN \chemnum_Gamma:   \textGamma
    \cs_new_eq:NN \chemnum_Delta:   \textDelta
    \cs_new_eq:NN \chemnum_Epsilon: \textEpsilon
    \cs_new_eq:NN \chemnum_Zeta:    \textZeta
    \cs_new_eq:NN \chemnum_Eta:     \textEta
    \cs_new_eq:NN \chemnum_Theta:   \textTheta
    \cs_new_eq:NN \chemnum_Iota:    \textIota
    \cs_new_eq:NN \chemnum_Kappa:   \textKappa
    \cs_new_eq:NN \chemnum_Lambda:  \textLambda
    \cs_new_eq:NN \chemnum_Mu:      \textMugreek
    \cs_new_eq:NN \chemnum_Nu:      \textNu
    \cs_new_eq:NN \chemnum_Xi:      \textXi
    \cs_new_eq:NN \chemnum_Omikron: \textOmikron
    \cs_new_eq:NN \chemnum_Pi:      \textPi
    \cs_new_eq:NN \chemnum_Rho:     \textRho
    \cs_new_eq:NN \chemnum_Sigma:   \textSigma
    \cs_new_eq:NN \chemnum_Tau:     \textTau
    \cs_new_eq:NN \chemnum_Upsilon: \textUpsilon
    \cs_new_eq:NN \chemnum_Phi:     \textPhi
    \cs_new_eq:NN \chemnum_Chi:     \textChi
    \cs_new_eq:NN \chemnum_Psi:     \textPsi
    \cs_new_eq:NN \chemnum_Omega:   \textOmega
  }
  {
    \RequirePackage { bm }% abhängig machen von textoption bold
    \cs_new_nopar:Npn \chemnum_bm:n #1
      {
        \bool_if:NTF \l_chemnum_cmpd_bold_bool
          { \bm { #1 } }
          { #1 }
      }
    \cs_new_nopar:Npn \chemnum_alpha:   { \ensuremath { \chemnum_bm:n { \mathrm { \alpha } } } }
    \cs_new_nopar:Npn \chemnum_beta:    { \ensuremath { \chemnum_bm:n { \mathrm { \beta } } } }
    \cs_new_nopar:Npn \chemnum_gamma:   { \ensuremath { \chemnum_bm:n { \mathrm { \gamma } } } }
    \cs_new_nopar:Npn \chemnum_delta:   { \ensuremath { \chemnum_bm:n { \mathrm { \delta } } } }
    \cs_new_nopar:Npn \chemnum_epsilon: { \ensuremath { \chemnum_bm:n { \mathrm { \varepsilon } } } }
    \cs_new_nopar:Npn \chemnum_zeta:    { \ensuremath { \chemnum_bm:n { \mathrm { \zeta } } } }
    \cs_new_nopar:Npn \chemnum_eta:     { \ensuremath { \chemnum_bm:n { \mathrm { \eta } } } }
    \cs_new_nopar:Npn \chemnum_theta:   { \ensuremath { \chemnum_bm:n { \mathrm { \theta } } } }
    \cs_new_nopar:Npn \chemnum_iota:    { \ensuremath { \chemnum_bm:n { \mathrm { \iota } } } }
    \cs_new_nopar:Npn \chemnum_kappa:   { \ensuremath { \chemnum_bm:n { \mathrm { \kappa } } } }
    \cs_new_nopar:Npn \chemnum_lambda:  { \ensuremath { \chemnum_bm:n { \mathrm { \lampda } } } }
    \cs_new_nopar:Npn \chemnum_mu:      { \ensuremath { \chemnum_bm:n { \mathrm { \mu } } } }
    \cs_new_nopar:Npn \chemnum_nu:      { \ensuremath { \chemnum_bm:n { \mathrm { \nu } } } }
    \cs_new_nopar:Npn \chemnum_xi:      { \ensuremath { \chemnum_bm:n { \mathrm { \xi } } } }
    \cs_new_nopar:Npn \chemnum_omikron: { \ensuremath { \chemnum_bm:n { \mathrm { o } } } }
    \cs_new_nopar:Npn \chemnum_pi:      { \ensuremath { \chemnum_bm:n { \mathrm { \pi } } } }
    \cs_new_nopar:Npn \chemnum_rho:     { \ensuremath { \chemnum_bm:n { \mathrm { \rho } } } }
    \cs_new_nopar:Npn \chemnum_sigma:   { \ensuremath { \chemnum_bm:n { \mathrm { \sigma } } } }
    \cs_new_nopar:Npn \chemnum_tau:     { \ensuremath { \chemnum_bm:n { \mathrm { \tau } } } }
    \cs_new_nopar:Npn \chemnum_upsilon: { \ensuremath { \chemnum_bm:n { \mathrm { \upsilon } } } }
    \cs_new_nopar:Npn \chemnum_phi:     { \ensuremath { \chemnum_bm:n { \mathrm { \varphi } } } }
    \cs_new_nopar:Npn \chemnum_chi:     { \ensuremath { \chemnum_bm:n { \mathrm { \chi } } } }
    \cs_new_nopar:Npn \chemnum_psi:     { \ensuremath { \chemnum_bm:n { \mathrm { \psi } } } }
    \cs_new_nopar:Npn \chemnum_omega:   { \ensuremath { \chemnum_bm:n { \mathrm { \omega } } } }
    \cs_new_nopar:Npn \chemnum_Alpha:   { \ensuremath { \chemnum_bm:n { \mathrm { A } } } }
    \cs_new_nopar:Npn \chemnum_Beta:    { \ensuremath { \chemnum_bm:n { \mathrm { B } } } }
    \cs_new_nopar:Npn \chemnum_Gamma:   { \ensuremath { \chemnum_bm:n { \mathrm { \Gamma } } } }
    \cs_new_nopar:Npn \chemnum_Delta:   { \ensuremath { \chemnum_bm:n { \mathrm { \Delta } } } }
    \cs_new_nopar:Npn \chemnum_Epsilon: { \ensuremath { \chemnum_bm:n { \mathrm { E } } } }
    \cs_new_nopar:Npn \chemnum_Zeta:    { \ensuremath { \chemnum_bm:n { \mathrm { Z } } } }
    \cs_new_nopar:Npn \chemnum_Eta:     { \ensuremath { \chemnum_bm:n { \mathrm { H } } } }
    \cs_new_nopar:Npn \chemnum_Theta:   { \ensuremath { \chemnum_bm:n { \mathrm { \Theta } } } }
    \cs_new_nopar:Npn \chemnum_Iota:    { \ensuremath { \chemnum_bm:n { \mathrm { I } } } }
    \cs_new_nopar:Npn \chemnum_Kappa:   { \ensuremath { \chemnum_bm:n { \mathrm { K } } } }
    \cs_new_nopar:Npn \chemnum_Lambda:  { \ensuremath { \chemnum_bm:n { \mathrm { \Lambda } } } }
    \cs_new_nopar:Npn \chemnum_Mu:      { \ensuremath { \chemnum_bm:n { \mathrm { M } } } }
    \cs_new_nopar:Npn \chemnum_Nu:      { \ensuremath { \chemnum_bm:n { \mathrm { N } } } }
    \cs_new_nopar:Npn \chemnum_Xi:      { \ensuremath { \chemnum_bm:n { \mathrm { \Xi } } } }
    \cs_new_nopar:Npn \chemnum_Omikron: { \ensuremath { \chemnum_bm:n { \mathrm { O } } } }
    \cs_new_nopar:Npn \chemnum_Pi:      { \ensuremath { \chemnum_bm:n { \mathrm { \Pi } } } }
    \cs_new_nopar:Npn \chemnum_Rho:     { \ensuremath { \chemnum_bm:n { \mathrm { P } } } }
    \cs_new_nopar:Npn \chemnum_Sigma:   { \ensuremath { \chemnum_bm:n { \mathrm { \Sigma } } } }
    \cs_new_nopar:Npn \chemnum_Tau:     { \ensuremath { \chemnum_bm:n { \mathrm { T } } } }
    \cs_new_nopar:Npn \chemnum_Upsilon: { \ensuremath { \chemnum_bm:n { \mathrm { \Upsilon } } } }
    \cs_new_nopar:Npn \chemnum_Phi:     { \ensuremath { \chemnum_bm:n { \mathrm { \Phi } } } }
    \cs_new_nopar:Npn \chemnum_Chi:     { \ensuremath { \chemnum_bm:n { \mathrm { X } } } }
    \cs_new_nopar:Npn \chemnum_Psi:     { \ensuremath { \chemnum_bm:n { \mathrm { \Psi } } } }
    \cs_new_nopar:Npn \chemnum_Omega:   { \ensuremath { \chemnum_bm:n { \mathrm { \Omega } } } }
  }
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% TOOLS
\int_new:N \g_chemnum_cmpd_main_int
\prop_new:N \g_chemnum_label_prop
\int_new:N \g_chemnum_cmpd_int
\tl_new:N \l_chemnum_tmpa_tl
\tl_new:N \l_chemnum_tmpb_tl
\clist_new:N \g_chemnum_cmpd_save_clist

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% READ FROM PREVIOUS RUN, SAVE FOR NEXT RUN
% save all labels in a clist
\cs_new:Npn \chemnum_cmpd_save:n #1
  { \clist_gput_right:Nn \g_chemnum_cmpd_save_clist { { #1 } } }

\msg_set:nnn { chemnum } { missing-cmpd-file }
  {
    The~file~ \c_job_name_tl .cmpd~hasn't~been~available~yet. \\
    Please~rerun~to~get~referencing~compound~labels~right.
  }

\file_if_exist:nTF { ./ \c_job_name_tl . cmpd }
  { \file_input:n { ./ \c_job_name_tl . cmpd } }
  { \msg_warning:nn { chemnum }{ missing-cmpd-file } }

% write ref commands for all labels in <jobname>.cmpd file to make them
% available at the next run
\AtEndDocument
  {
    \iow_new:N \chemnum_aux_file:
    \iow_open:Nn \chemnum_aux_file: { ./ \c_job_name_tl . cmpd }
    \clist_map_inline:Nn \g_chemnum_cmpd_save_clist
      {
        \iow_now:Nx \chemnum_aux_file:
          {
            \use:c { cs_new_nopar:cpn } { chemnum_cmpd_ #1 _ref: }
              { \exp_not:f { \use:c { chemnum_cmpd_ #1 : } } }
          }
        \cs_if_exist:cT { chemnum_cmpd_ #1 _min: }
          {
            \iow_now:Nx \chemnum_aux_file:
              {
                \use:c { cs_new_nopar:cpn } { chemnum_cmpd_ #1 _min_ref: }
                  { \exp_not:f { \use:c { chemnum_cmpd_ #1 _min: } } }
              }
          }
        \cs_if_exist:cT { chemnum_cmpd_ #1 _max: }
          {
            \iow_now:Nx \chemnum_aux_file:
              {
                \use:c { cs_new_nopar:cpn } { chemnum_cmpd_ #1 _max_ref: }
                  { \exp_not:f { \use:c { chemnum_cmpd_ #1 _max: } } }
              }
          }
      }
    \iow_close:N \chemnum_aux_file:
  }

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% COMPOUND LABELS
% STYLE OF COMPOUND LABEL
\tl_new:N \l_chemnum_style_tmp_tl
\bool_new:N \l_chemnum_cmpd_style_is_macro_bool

% default style
\cs_new_nopar:Npn \chemnum_cmpd_style_value:n {  }

% error message
\msg_set:nnn { chemnum } { cmpd-style }
  {
    The~value~of~"cmpd-style~=~<style>"~needs~to~be~a~(or~more)~macro~
    \msg_line_context: .
  }

% set style %TODO
\cs_new_nopar:Npn \chemnum_cmpd_set_style:n #1
%   {
%     \tl_clear:N \l_chemnum_style_tmp_tl
%     \tl_map_variable:nNn { #1 } \l_chemnum_style_tmp_tl
%       {
%         \exp_args:No \token_if_cs:NTF \l_chemnum_style_tmp_tl
%           { \bool_set_true:N \l_chemnum_cmpd_style_is_macro_bool }
%           { \bool_set_false:N \l_chemnum_cmpd_style_is_macro_bool }
%       }
%     \bool_if:NTF \l_chemnum_cmpd_style_is_macro_bool
      { \cs_set_nopar:Npn \chemnum_cmpd_style_value:n { #1 } }
%       { \msg_error:nnx { chemnum } { cmpd-style } { #1 } }
%   }

% use style
\bool_new:N \l_chemnum_cmpd_bold_bool
\bool_set_true:N \l_chemnum_cmpd_bold_bool

\cs_new_nopar:Npn \chemnum_cmpd_use_style:n #1
  {
    \group_begin:
      \bool_if:NT \l_chemnum_cmpd_bold_bool
        { \bfseries }
      \chemnum_cmpd_style_value:n { #1 }
    \group_end:
  }

%-----------------------------------------------------------------------------%
% prefix, suffix, delimiters, format and separator of compound label
\tl_new:N \l_chemnum_cmpd_prefix_tl
\tl_new:N \l_chemnum_cmpd_suffix_tl

\tl_new:N \l_chemnum_cmpd_space_tl
\tl_set:Nn \l_chemnum_cmpd_space_tl { \penalty\@m\  }

\tl_new:N \l_chemnum_cmpd_separator_tl

\tl_new:N \l_chemnum_cmpd_odelim_tl
\tl_new:N \l_chemnum_cmpd_cdelim_tl

% error message for wrong argument length of delim-keys
\msg_set:nnn { chemnum } { delimiters }
  {
    "#1-delim~=~<odelim><cdelim>"~needs~two~tokens~or~token~groups~as~a~value~
    \msg_line_context: .
  }

% set compound delimiters
\cs_new_nopar:Npn \chemnum_cmpd_delim:n #1
  {
    \tl_if_blank:nTF { #1 }
      {
        \tl_clear:N \l_chemnum_cmpd_odelim_tl
        \tl_clear:N \l_chemnum_cmpd_cdelim_tl
      }
      {
        \int_compare:nNnTF { \tl_length:n { #1 } } = 2
          {
            \tl_set:Nx \l_chemnum_cmpd_odelim_tl { \tl_head:n { #1 } }
            \tl_set:Nx \l_chemnum_cmpd_cdelim_tl { \tl_tail:n { #1 } }
          }
          { \msg_error:nnx { chemnum } { delimiters } { cmpd } }
      }
  } 

% format of numbering
\cs_new_nopar:Npn \chemnum_cmpd_kind:nn #1#2
  { \cs:w int_to_#1:n \cs_end: #2 }

% default format
\tl_new:N \l_chemnum_cmpd_kind_value_tl
\tl_set:Nn \l_chemnum_cmpd_kind_value_tl { arabic }

% format of sub-numbering
\cs_new_nopar:Npn \chemnum_cmpd_sub_kind:nn #1#2
  { \cs:w int_to_ #1 :n \cs_end: #2 }
\cs_generate_variant:Nn \chemnum_cmpd_sub_kind:nn { Nc }

% default format
\tl_new:N \l_chemnum_cmpd_sub_kind_value_tl
\tl_set:Nn \l_chemnum_cmpd_sub_kind_value_tl { alph }

%-----------------------------------------------------------------------------%
% add greek letters and symbols as numbering format
% define \int_to_greek function
\cs_new:Npn \int_to_greek:n { }
% \bool_if:NTF \l_chemnum_textgreek_bool
%   {
    \cs_set:Npn \int_to_greek:n #1
      {
        \int_to_symbols:nnn {#1} { 24 }
          {
            {  1 } { \exp_not:o \chemnum_alpha: }
            {  2 } { \exp_not:o \chemnum_beta: }
            {  3 } { \exp_not:o \chemnum_gamma: }
            {  4 } { \exp_not:o \chemnum_delta: }
            {  5 } { \exp_not:o \chemnum_epsilon: }
            {  6 } { \exp_not:o \chemnum_zeta: }
            {  7 } { \exp_not:o \chemnum_eta: }
            {  8 } { \exp_not:o \chemnum_theta: }
            {  9 } { \exp_not:o \chemnum_iota: }
            { 10 } { \exp_not:o \chemnum_kappa: }
            { 11 } { \exp_not:o \chemnum_lambda: }
            { 12 } { \exp_not:o \chemnum_mu: }
            { 13 } { \exp_not:o \chemnum_nu: }
            { 14 } { \exp_not:o \chemnum_xi: }
            { 15 } { \exp_not:o \chemnum_omikron: }
            { 16 } { \exp_not:o \chemnum_pi: }
            { 17 } { \exp_not:o \chemnum_rho: }
            { 18 } { \exp_not:o \chemnum_sigma: }
            { 19 } { \exp_not:o \chemnum_tau: }
            { 20 } { \exp_not:o \chemnum_upsilon: }
            { 21 } { \exp_not:o \chemnum_phi: }
            { 22 } { \exp_not:o \chemnum_chi: }
            { 23 } { \exp_not:o \chemnum_psi: }
            { 24 } { \exp_not:o \chemnum_omega: }
          }
      }
%   }
%   {
%     \cs_set_eq:NN \int_to_greek:n \int_to_alph:n
%   }

% define \int_to_Greek function
\cs_new:Npn \int_to_Greek:n { }
\bool_if:NTF \l_chemnum_textgreek_bool
  {
    \cs_set:Npn \int_to_Greek:n #1
      {
        \int_to_symbols:nnn { #1 } { 24 }
          {
            {  1 } { \exp_not:o \chemnum_Alpha: }
            {  2 } { \exp_not:o \chemnum_Beta: }
            {  3 } { \exp_not:o \chemnum_Gamma: }
            {  4 } { \exp_not:o \chemnum_Delta: }
            {  5 } { \exp_not:o \chemnum_Epsilon: }
            {  6 } { \exp_not:o \chemnum_Zeta: }
            {  7 } { \exp_not:o \chemnum_Eta: }
            {  8 } { \exp_not:o \chemnum_Theta: }
            {  9 } { \exp_not:o \chemnum_Iota: }
            { 10 } { \exp_not:o \chemnum_Kappa: }
            { 11 } { \exp_not:o \chemnum_Lambda: }
            { 12 } { \exp_not:o \chemnum_Mu: }
            { 13 } { \exp_not:o \chemnum_Nu: }
            { 14 } { \exp_not:o \chemnum_Xi: }
            { 15 } { \exp_not:o \chemnum_Omikron: }
            { 16 } { \exp_not:o \chemnum_Pi: }
            { 17 } { \exp_not:o \chemnum_Rho: }
            { 18 } { \exp_not:o \chemnum_Sigma: }
            { 19 } { \exp_not:o \chemnum_Tau: }
            { 20 } { \exp_not:o \chemnum_Upsilon: }
            { 21 } { \exp_not:o \chemnum_Phi: }
            { 22 } { \exp_not:o \chemnum_Chi: }
            { 23 } { \exp_not:o \chemnum_Psi: }
            { 24 } { \exp_not:o \chemnum_Omega: }
          }
      }
  }
  {
    \cs_set_eq:NN \int_to_Greek:n \int_to_Alph:n
  }

% define \int_to_Symbol function
\cs_new:Npn \int_to_Symbol:n #1
  {
    \int_to_symbols:nnn { #1 } { 9 }
      {
        { 1 } {\exp_not:o \textasteriskcentered }
        { 2 } {\exp_not:o \textdagger}
        { 3 } {\exp_not:o \textdaggerdbl}
        { 4 } {\exp_not:o \textsection}
        { 5 } {\exp_not:o \textparagraph}
        { 6 } {\exp_not:o \textbardbl}
        { 7 } {\exp_not:o \textasteriskcentered \textasteriskcentered}
        { 8 } {\exp_not:o \textdagger \textdagger}
        { 9 } {\exp_not:o \textdaggerdbl \textdaggerdbl}
      }
  }

%-----------------------------------------------------------------------------%
% lists of sublabels
\clist_new:N \l_chemnum_sublabel_clist
\tl_new:N \l_chemnum_sublabel_list_sep_tl
\tl_set:Nn \l_chemnum_sublabel_list_sep_tl { , }
\tl_new:N \l_chemnum_cmpd_sublabel_list_tl
\int_new:N \l_chemnum_sublabel_list_current_int
\int_new:N \l_chemnum_sublabel_list_length_int
\bool_new:N \l_chemnum_sublabel_list_bool

\cs_new_nopar:Npn \chemnum_cmpd_sublabel_list:nn #1#2
  {
    \clist_clear:N \l_chemnum_sublabel_clist
    \clist_set_eq:NN \l_chemnum_sublabel_clist #2
    \int_set:Nn \l_chemnum_sublabel_list_length_int
      { \clist_length:N \l_chemnum_sublabel_clist }
    \clist_map_variable:NNn \l_chemnum_sublabel_clist \l_chemnum_tmpb_tl
      {
        \int_incr:N \l_chemnum_sublabel_list_current_int
        \exp_after:wN \chemnum_cmpd_sublabelsep:n \l_chemnum_tmpb_tl \q_stop
        \use:c { chemnum_cmpd_#1_ \l_chemnum_cmpd_sub_one_label_tl _ref: }
        \exp_args:No \tl_if_blank:nF { \l_chemnum_cmpd_sub_two_label_tl }
          {
            \tl_use:N \l_chemnum_sub_range_sep_tl
            \use:c { chemnum_cmpd_#1_ \l_chemnum_cmpd_sub_two_label_tl _ref: }
          }
        \int_compare:nT
          {
            \l_chemnum_sublabel_list_current_int
            <
            \l_chemnum_sublabel_list_length_int
          }
          { \tl_use:N \l_chemnum_sublabel_list_sep_tl }
      }
  }

%-----------------------------------------------------------------------------%
% variables
\tl_new:N \l_chemnum_cmpd_name_tl

\bool_new:N \l_chemnum_cmpd_name_bool
\bool_set_false:N \l_chemnum_cmpd_name_bool

\bool_new:N \l_chemnum_cmpd_all_bool
\bool_set_false:N \l_chemnum_cmpd_all_bool

\bool_new:N \l_chemnum_cmpd_range_bool
\bool_set_false:N \l_chemnum_cmpd_range_bool

\tl_new:N \l_chemnum_cmpd_labelsep_tl
\tl_set:Nn \l_chemnum_cmpd_labelsep_tl { . }

\tl_new:N \l_chemnum_sublist_input_separator_tl
\tl_set:Nn \l_chemnum_sublist_input_separator_tl { , }

\tl_new:N \l_chemnum_sublist_output_separator_tl
\tl_set:Nn \l_chemnum_sublist_output_separator_tl { , }

\tl_new:N \l_chemnum_sublabel_range_marker_tl
\tl_set:Nn \l_chemnum_sublabel_range_marker_tl { .. }

\tl_new:N \l_chemnum_sub_range_sep_tl
\tl_set:Nn \l_chemnum_sub_range_sep_tl { -- }

\bool_new:N \l_chemnum_sub_label_only_bool
\bool_set_false:N \l_chemnum_sub_label_only_bool

%-----------------------------------------------------------------------------%
% hyperref support
\tl_new:N \l_chemnum_cmpd_hyper_name_tl

\bool_new:N \l_chemnum_use_hyperref_bool
\bool_new:N \l_chemnum_hypertarget_bool
\bool_new:N \l_chemnum_hyperlink_bool

\cs_new_eq:NN \chemnum_make_hyper:nn \use_ii:nn

% #1: main label, #2: sub labels, #3: invisible
\cs_new_nopar:Npn \chemnum_hyperref:nnn #1#2#3
   {
     \bool_if:nF { #3 || !\l_chemnum_use_hyperref_bool }
       {
         \bool_if:NT \l_chemnum_hypertarget_bool
           {
             \cs_set_nopar:Npn \chemnum_make_hyper:nn ##1##2
               {
                 \raisebox { 3ex } [ 0pt ]
                   { \hypertarget { ##1 } { } } ##2
               }
           }
         \bool_if:NT \l_chemnum_hyperlink_bool
           { \cs_set_eq:NN \chemnum_make_hyper:nn \hyperlink }
         \bool_if:nT
           { !\l_chemnum_hypertarget_bool && !\l_chemnum_hyperlink_bool }
           {
             \tl_if_blank:nTF { #2 }
               { % no sublabel
                 \tl_set:Nn \l_chemnum_cmpd_hyper_name_tl
                   { chemnum_cmpd_#1 }
                 \cs_if_exist:cTF { chemnum_cmpd_#1_hyper: }
                   {
                     \bool_set_false:N \l_chemnum_hypertarget_bool
                     \cs_set_eq:NN \chemnum_make_hyper:nn \hyperlink
                   }
                   {
                     \bool_set_true:N \l_chemnum_hypertarget_bool
                     \cs_set_nopar:Npn \chemnum_make_hyper:nn ##1##2
                       {
                         \raisebox { 3ex } [ 0pt ]
                           { \hypertarget { ##1 } { } } ##2
                       }
                     \cs_new_nopar:cpn { chemnum_cmpd_#1_hyper: } { }
                   }
               }
               {
                 \chemnum_cmpd_sublist:n { #2 }
                 \int_compare:nT { \l_chemnum_cmpd_sublist_length_int < 2 }
                   { % no sublabel list
                     \chemnum_cmpd_subrange_separate:n { #2 }
                     \tl_if_blank:VT \l_tmpb_tl
                       { % no sublabel range
                         \tl_set:Nn \l_chemnum_cmpd_hyper_name_tl
                           { chemnum_cmpd_#1_\l_tmpa_tl }
                         \cs_if_exist:cTF
                           { chemnum_cmpd_#1_ \l_tmpa_tl _hyper: }
                           {
                             \bool_set_false:N \l_chemnum_hypertarget_bool
                             \cs_set_eq:NN \chemnum_make_hyper:nn \hyperlink
                           }
                           {
                             \bool_set_true:N \l_chemnum_hypertarget_bool
                             \cs_set_nopar:Npn \chemnum_make_hyper:nn ##1##2
                               {
                                 \raisebox { 3ex } [ 0pt ]
                                   { \hypertarget { ##1 } { } } ##2
                               }
                             \cs_new_nopar:cpn
                               { chemnum_cmpd_#1_ \l_tmpa_tl _hyper: } { }
                           }
                       }
                   }
               }
           }
       }
   }

%-----------------------------------------------------------------------------%
% property keys for compounds
\keys_define:nn { chemnum } {
  cmpd-style           .code:n             = \chemnum_cmpd_set_style:n { #1 } ,
  cmpd-weight          .choice: ,
  cmpd-weight / bold   .code:n             =
    \bool_set_true:N \l_chemnum_cmpd_bold_bool ,
  cmpd-weight / normal .code:n             =
    \bool_set_false:N \l_chemnum_cmpd_bold_bool ,
  cmpd-label           .code:n             =
    {
      \bool_set_true:N \l_chemnum_cmpd_name_bool
      \tl_set:Nn \l_chemnum_cmpd_name_tl { #1 }
    } ,
  cmpd-prefix          .tl_set:N           = \l_chemnum_cmpd_prefix_tl ,
  cmpd-prefix          .default:n          = { } ,
  cmpd-suffix          .tl_set:N           = \l_chemnum_cmpd_suffix_tl ,
  cmpd-suffix          .default:n          = { } ,
  cmpd-space           .tl_set:N           = \l_chemnum_cmpd_space_tl ,
  cmpd-space           .default:n          = { \penalty\@m\  },
  cmpd-delim           .code:n             = \chemnum_cmpd_delim:n { #1 },
  cmpd-delim           .default:n          = { ( } { ) } ,
  cmpd-odelim          .tl_set:N           = \l_chemnum_cmpd_odelim_tl ,
  cmpd-odelim          .default:n          = { } ,
  cmpd-cdelim          .tl_set:N           = \l_chemnum_cmpd_cdelim_tl ,
  cmpd-cdelim          .default:n          = { } ,
  cmpd-all             .bool_set:N         = \l_chemnum_cmpd_all_bool ,
  cmpd-all             .default:n          = true ,
  cmpd-counter         .choice: ,
  cmpd-counter         .choice_code:n      =
    \tl_set_eq:NN \l_chemnum_cmpd_kind_value_tl \l_keys_choice_tl ,
  cmpd-counter         .generate_choices:n =
    { arabic , alph , Alph , greek, Greek , roman , Roman , Symbol } ,
  cmpd-counter         .default:n          = arabic ,
  hyper-use            .choice: ,
  hyper-use / true     .code:n             =
    {
      \bool_set_true:N \l_chemnum_use_hyperref_bool
      \bool_set_false:N \l_chemnum_hypertarget_bool
      \bool_set_false:N \l_chemnum_hyperlink_bool
    } ,
  hyper-use / false    .code:n             =
    {
      \bool_set_false:N \l_chemnum_use_hyperref_bool
      \bool_set_false:N \l_chemnum_hypertarget_bool
      \bool_set_false:N \l_chemnum_hyperlink_bool
    } ,
  hyper-use            .default:n          = true ,
  hyper-target         .code:n             =
    {
      \tl_set:Nn \l_chemnum_cmpd_hyper_name_tl { #1 }
      \bool_set_true:N \l_chemnum_use_hyperref_bool
      \bool_set_true:N \l_chemnum_hypertarget_bool
      \bool_set_false:N \l_chemnum_hyperlink_bool
    } ,
  hyper-link           .code:n             =
    {
      \tl_set:Nn \l_chemnum_cmpd_hyper_name_tl { #1 }
      \bool_set_true:N \l_chemnum_use_hyperref_bool
      \bool_set_false:N \l_chemnum_hypertarget_bool
      \bool_set_true:N \l_chemnum_hyperlink_bool
    } ,
  sub-counter          .choice: ,
  sub-counter          .choice_code:n      =
    \tl_set_eq:NN \l_chemnum_cmpd_sub_kind_value_tl \l_keys_choice_tl ,
  sub-counter          .generate_choices:n =
    { arabic , alph , Alph , greek , Greek , roman , Roman , Symbol } ,
  sub-counter          .default:n          = alph ,
  sub-input-sep        .code:n             = \chemnum_subcmpdsep:n { #1 } ,
  sub-input-sep        .default:n          = . ,
  sub-output-sep       .tl_set:N           = \l_chemnum_cmpd_separator_tl ,
  sub-output-sep       .default:n          = { } ,
  sublist-input-sep    .tl_set:N           =
    \l_chemnum_sublist_input_separator_tl ,
  sublist-input-sep    .default:n          = { , } ,
  sublist-output-sep   .tl_set:N           =
    \l_chemnum_sublist_output_separator_tl ,
  sublist-output-sep   .default:n          = { , } ,
  sub-only             .bool_set:N         = \l_chemnum_sub_label_only_bool ,
  sub-only             .default:n          = true ,
  subrange-output-sep  .tl_set:N           = \l_chemnum_sub_range_sep_tl ,
  subrange-output-sep  .default:n          = { -- } ,
  subrange-input-sep   .code:n             =
    \chemnum_sublabel_range_marker:n { #1 } ,
  subrange-input-sep   .default:n          = { .. }
}

%-----------------------------------------------------------------------------%
% list separators, delimiters, prefix and suffix
\bool_new:N \l_chemnum_no_serial_comma_bool
\bool_set_false:N \l_chemnum_no_serial_comma_bool

\tl_new:N \l_chemnum_list_input_separator_tl
\tl_set:Nn \l_chemnum_list_input_separator_tl { , }

\tl_new:N \l_chemnum_list_separator_tl
\tl_set:Nn \l_chemnum_list_separator_tl { , }

\tl_new:N \l_chemunm_list_space_tl
\tl_set:Nn \l_chemnum_list_space_tl { \penalty\@m\  }

\tl_new:N \l_chemnum_list_last_separator_lang_tl
\tl_set:Nn \l_chemnum_list_last_separator_lang_tl { and }

\tl_new:N \l_chemnum_list_last_separator_tl
\tl_set:Nn \l_chemnum_list_last_separator_tl
  { \tl_use:N \l_chemnum_list_last_separator_lang_tl }

\tl_new:N \l_chemnum_list_prefix_tl { }
\tl_set:Nn \l_chemnum_list_prefix_tl { }

\tl_new:N \l_chemnum_list_suffix_tl { }
\tl_set:Nn \l_chemnum_list_suffix_tl { }

\tl_new:N \l_chemnum_list_odelim_tl { }
\tl_new:N \l_chemnum_list_cdelim_tl { }

\cs_new_nopar:Npn \chemnum_list_delim:n #1 {
  \tl_if_blank:nTF { #1 } {
    \tl_clear:N \l_chemnum_list_odelim_tl
    \tl_clear:N \l_chemnum_list_cdelim_tl
  }{
    \int_compare:nNnTF { \tl_length:n { #1 } } = 2 {
      \tl_set:Nx \l_chemnum_list_odelim_tl { \tl_head:n { #1 } }
      \tl_set:Nx \l_chemnum_list_cdelim_tl { \tl_tail:n { #1 } }
    }{ \msg_error:nnx { chemnum } { delimiters } { list } }
  }
}

%-----------------------------------------------------------------------------%
% property keys for lists
\keys_define:nn { chemnum } {
  list-prefix        .tl_set:N   = \l_chemnum_list_prefix_tl ,
  list-prefix        .default:n  = { } ,
  list-suffix        .tl_set:N   = \l_chemnum_list_suffix_tl ,
  list-suffix        .default:n  = { } ,
  list-delim         .code:n     = \chemnum_list_delim:n { #1 } ,
  list-delim         .default:n  = { ( } { ) } ,
  list-odelim        .tl_set:N   = \l_chemnum_list_odelim_tl ,
  list-odelim        .default:n  = { } ,
  list-cdelim        .tl_set:N   = \l_chemnum_list_cdelim_tl ,
  list-cdelim        .default:n  = { } ,
  list-space         .tl_set:N   = \l_chemnum_list_space_tl ,
  list-space         .default:n  = { \penalty\@m\  } ,
  list-input-sep     .tl_set:N   = \l_chemnum_list_input_separator_tl ,
  list-input-sep     .default:n  = { , } ,
  list-output-sep    .tl_set:N   = \l_chemnum_list_separator_tl ,
  list-output-sep    .default:n  = { , } ,
  list-last-sep      .tl_set:N   = \l_chemnum_list_last_separator_tl ,
  list-last-sep      .default:n  = \l_chemnum_list_last_separator_lang_tl ,
  list-serial-comma  .choice: ,
  list-serial-comma / true .code:n =
    \bool_set_false:N \l_chemnum_no_serial_comma_bool ,
  list-serial-comma / false .code:n =
    \bool_set_true:N \l_chemnum_no_serial_comma_bool ,
  list-serial-comma  .default:n  = true ,
  list-lang          .choice: ,
  list-lang / US     .code:n     =
    {
      \bool_set_false:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { and }
    } ,
  list-lang / GB     .code:n     =
    {
      \bool_set_true:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { and }
    } ,
  list-lang / DE     .code:n     =
    {
      \bool_set_true:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { und }
    } ,
  list-lang / FR     .code:n     =
    {
      \bool_set_true:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { et }
    } ,
  list-lang / IT     .code:n     =
    {
      \bool_set_true:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { e }
    } ,
  list-lang / ES     .code:n     =
    {
      \bool_set_true:N \l_chemnum_no_serial_comma_bool
      \tl_set:Nn \l_chemnum_list_last_separator_lang_tl { y }
    } ,
  list-lang          .default:n  = US
}

%-----------------------------------------------------------------------------%
% label and sublabel declaration
\cs_new:Npn \chemnum_cmpd_declare:n #1
  {
    \cs_if_exist:cF { chemnum_cmpd_#1: }
      {
        \int_gincr:N \g_chemnum_cmpd_main_int
        \prop_gput:Nnx \g_chemnum_label_prop
          { #1 }
          { \int_use:N \g_chemnum_cmpd_main_int }
        \chemnum_cmpd_save:n { #1 }
        \bool_if:NF \l_chemnum_cmpd_name_bool
          { \int_gincr:N \g_chemnum_cmpd_int }
        \cs_new_nopar:cpx { chemnum_cmpd_#1: } {
          \bool_if:NTF \l_chemnum_cmpd_name_bool
            { \l_chemnum_cmpd_name_tl }
            {
              \chemnum_cmpd_kind:nn
                \l_chemnum_cmpd_kind_value_tl
                \g_chemnum_cmpd_int
            }
        }
      }
  }

\cs_new:Npn \chemnum_cmpd_sub_declare:nn #1#2
  {
    \cs_if_exist:cF { chemnum_cmpd_#1_#2: }
      {
        \chemnum_cmpd_save:n { #1 _ #2 }
        \cs_new_nopar:cpx { chemnum_cmpd_#1_#2: } { }
        \int_gincr:c { g_chemnum_cmpd_#1_int }
        % why is the next line working when \cs_gset_nopar:cpx doesn't?
        % (in case ":" is part of #1)
        \exp_after:wN \cs_gset_nopar:Npx \cs:w chemnum_cmpd_#1_#2: \cs_end:
          {
            \chemnum_cmpd_sub_kind:Nc
              \l_chemnum_cmpd_sub_kind_value_tl
              { g_chemnum_cmpd_#1_int }
          }
        \int_compare:nT { \int_use:c { g_chemnum_cmpd_#1_int } = 1 }
          {
            \cs_gset_eq:cc { chemnum_cmpd_#1_min: } { chemnum_cmpd_#1_#2: }
          }
        \cs_gset_eq:cc { chemnum_cmpd_#1_max: } { chemnum_cmpd_#1_#2: }
      }
  }
\cs_generate_variant:Nn \chemnum_cmpd_sub_declare:nn { no }

\cs_new_nopar:Npn \chemnum_cmpd_sub_initiate:nn #1#2
  {
    \cs_if_exist:cF { chemnum_cmpd_ #1 _ #2 _init: }
      {
        \bool_if:NTF \l_chemnum_cmpd_init_strict_bool
          {
            \msg_error:nnx   { chemnum } { cmpd-init-sub }
              { #1 \l_chemnum_cmpd_labelsep_tl #2 }
          }
          {
            \msg_warning:nnx { chemnum } { cmpd-init-sub }
               { #1 \l_chemnum_cmpd_labelsep_tl #2 }
          }
      }
  }

%-----------------------------------------------------------------------------%
% label and sublabel initiation
\cs_new:Npn \chemnum_cmpd_initiate:nn #1#2
  {
    \cs_if_exist:cTF { chemnum_cmpd_#1_init: }
      {
        \bool_if:NT \l_chemnum_cmpd_sub_init_bool
          {
            \tl_if_blank:nF { #2 }
              {
                \chemnum_cmpd_sublist:n { #2 }
                \exp_args:No \tl_map_inline:nn  { \l_chemnum_cmpd_sublist_tl }
                  {
                    \chemnum_cmpd_subrange_separate:n { ##1 }
                    \chemnum_cmpd_sub_initiate:nn { #1 } { \l_tmpa_tl }
                    \tl_if_blank:VF \l_tmpb_tl
                      { \chemnum_cmpd_sub_initiate:nn { #1 } { \l_tmpb_tl } }
                  }
              }
          }
      }
      {
        \bool_if:NTF \l_chemnum_cmpd_init_strict_bool
          { \msg_error:nnx { chemnum } { cmpd-init } { #1 } }
          { \msg_warning:nnx { chemnum } { cmpd-init } { #1 } }
      }
  }

%-----------------------------------------------------------------------------%
% sub label separator
% error message if no separator is chosen
\msg_set:nnnn { chemnum } { sub-label-separator }
  {
    Missing~separator~token~as~value~for~the~key~sub-cmpd-sep \c_space_tl
    \msg_line_context: !
  }
  {
    You~used~the~key~sub-cmpd-sep \c_space_tl \msg_line_context: ~but~left~the~
    argument~empty.\\
    This~can't~work.~Please~select~a~token~as~separator.
  }

%-----------------------------------------------------------------------------%
% variables

\tl_new:N \l_chemnum_cmpd_main_label_tl
\tl_new:N \l_chemnum_cmpd_sub_label_tl

\tl_new:N \l_chemnum_labelsep_tmp_tl

% set sublabel-separator
\cs_new_nopar:Npn \chemnum_subcmpdsep:n #1 {
  \tl_if_blank:nTF { #1 }
    { \msg_error:nn { chemnum } { sub-label-separator } }
    { \tl_set:Nn \l_chemnum_cmpd_labelsep_tl { #1 } }
}

\cs_new_nopar:Npn \chemnum_sublabel_range_marker:n #1 {
  \tl_if_blank:nTF { #1 }
    { \msg_error:nn { chemnum } { sub-label-range_sep } }
    { \tl_set:Nn \l_chemnum_sublabel_range_marker_tl { #1 } }
}

% actual separating
\cs_new_nopar:Npn \chemnum_cmpd_labelsep:n #1 \q_stop {
  \tl_clear:N \l_chemnum_labelsep_tmp_tl
  \exp_args:Noo \tl_if_in:nnTF { #1 } { \l_chemnum_cmpd_labelsep_tl }
    { 
      \tl_set:Nn \l_chemnum_labelsep_tmp_tl { #1 }
      \exp_args:NNo \tl_replace_once:Nnn \l_chemnum_labelsep_tmp_tl
        { \l_chemnum_cmpd_labelsep_tl }
        { \q_nil }
      \exp_after:wN \chemnum_cmpd_labelsep_aux_ii:n
        \l_chemnum_labelsep_tmp_tl \q_stop
    }
    { \chemnum_cmpd_labelsep_aux_i:n { #1 } }
}

\cs_new_nopar:Npn \chemnum_cmpd_labelsep_aux_i:n #1
  {
    \tl_set:Nn \l_chemnum_cmpd_main_label_tl { #1 }
    \tl_clear:N \l_chemnum_cmpd_sub_label_tl
  }

\cs_new_nopar:Npn \chemnum_cmpd_labelsep_aux_ii:n #1 \q_nil #2 \q_stop
  {
    \tl_set:Nn \l_chemnum_cmpd_main_label_tl { #1 }
    \tl_set:Nn \l_chemnum_cmpd_sub_label_tl { #2 }
  }

% sublabel separating to display a list and/or range
\tl_new:N \l_chemnum_cmpd_sublist_tl
\int_new:N \l_chemnum_cmpd_sublist_length_int

\NewDocumentCommand \chemnum_cmpd_sublist:n
  { > { \exp_args:No \SplitList { \l_chemnum_sublist_input_separator_tl } } m }
  {
    \tl_set:Nn \l_chemnum_cmpd_sublist_tl { #1 }
    \int_zero:N \l_chemnum_cmpd_sublist_length_int
    \exp_args:No \tl_map_inline:nn { \l_chemnum_cmpd_sublist_tl }
      { \int_incr:N \l_chemnum_cmpd_sublist_length_int }
  }

\cs_new_nopar:Npn \chemnum_cmpd_subrange_separate:n #1
  {
    \tl_clear:N \l_tmpa_tl
    \tl_clear:N \l_tmpb_tl
    \tl_if_in:noTF { #1 } { \l_chemnum_sublabel_range_marker_tl }
      {
        \tl_set:Nn \l_tmpa_tl { #1 }
        \exp_args:NNo \tl_replace_once:Nnn \l_tmpa_tl
          { \l_chemnum_sublabel_range_marker_tl } { \q_nil }
        \exp_after:wN \chemnum_cmpd_subrange_separate_aux:n \l_tmpa_tl \q_stop
      }
      { \tl_set:Nn \l_tmpa_tl { #1 } }
  }

\cs_new_nopar:Npn \chemnum_cmpd_subrange_separate_aux:n
  #1 \q_nil #2 \q_stop
  {
    \tl_set:Nn \l_tmpa_tl { #1 }
    \tl_set:Nn \l_tmpb_tl { #2 }
  }

%-----------------------------------------------------------------------------%
% print compound label
\cs_new_nopar:Npn \chemnum_cmpd_print:n #1
  {
    \tl_if_blank:VF \l_chemnum_cmpd_prefix_tl
      {
        \tl_use:N \l_chemnum_cmpd_prefix_tl
        \tl_use:N \l_chemnum_cmpd_space_tl
      }
    \tl_use:N \l_chemnum_cmpd_odelim_tl
    \chemnum_cmpd_use_style:n { #1 }
    \tl_use:N \l_chemnum_cmpd_cdelim_tl
    \tl_if_blank:VF \l_chemnum_cmpd_suffix_tl
      {
        \tl_use:N \l_chemnum_cmpd_space_tl
        \tl_use:N \l_chemnum_cmpd_suffix_tl
      }
  }

%-----------------------------------------------------------------------------%
% main internal compound label command
% #1: <main label> #2: <sub label> #3: <invisible> #4: <no delim>
% #2 may be a list of sublabels
\cs_new_nopar:Npn \chemnum_cmpd_aux_i:nnnn #1#2#3#4
  {
    \bool_if:NT \l_chemnum_cmpd_initiated_bool
      { \chemnum_cmpd_initiate:nn { #1 } { #2 } }
    \bool_if:NF \l_chemnum_cmpd_ref_bool
      { \chemnum_cmpd_declare:n { #1 } }
    \chemnum_hyperref:nnn { #1 } { #2 } { #3 }
    \tl_if_blank:nF { #2 }
      {
        \cs_if_exist:cF { g_chemnum_cmpd_#1_int }
          { \int_new:c { g_chemnum_cmpd_#1_int } }
        \chemnum_cmpd_sublist:n { #2 }
        \bool_if:NF \l_chemnum_cmpd_ref_bool
          {
            \exp_args:No \tl_map_inline:nn { \l_chemnum_cmpd_sublist_tl }
              {
                \chemnum_cmpd_subrange_separate:n { ##1 }
                \chemnum_cmpd_sub_declare:no { #1 } { \l_tmpa_tl }
                \tl_if_blank:VF \l_tmpb_tl
                  { \chemnum_cmpd_sub_declare:no { #1 } { \l_tmpb_tl } }
              }
          }
      }
    \bool_if:NTF #3
      { \mode_if_horizontal:T { \tex_unskip:D } }
      { 
        \bool_if:NT #4
          {
            \tl_clear:N \l_chemnum_cmpd_odelim_tl
            \tl_clear:N \l_chemnum_cmpd_cdelim_tl
          }
        \chemnum_make_hyper:nn { \l_chemnum_cmpd_hyper_name_tl }
        {
        \chemnum_cmpd_print:n
          {
            \bool_if:NF \l_chemnum_sub_label_only_bool
              {
                \bool_if:NTF \l_chemnum_cmpd_ref_bool
                  { \use:c { chemnum_cmpd_ #1 _ref: } }
                  { \use:c { chemnum_cmpd_ #1 : } }
              }
            \bool_if:NTF \l_chemnum_cmpd_all_bool
              {
                \tl_use:N \l_chemnum_cmpd_separator_tl
                \use:c { chemnum_cmpd_ #1 _min_ref: }
                \cs_if_eq:ccF
                  { chemnum_cmpd_ #1 _min_ref: }
                  { chemnum_cmpd_ #1 _max_ref: }
                  {
                    \tl_use:N \l_chemnum_sub_range_sep_tl
                    \use:c { chemnum_cmpd_ #1 _max_ref: }
                  }
              }
              {
                \bool_if:NTF \l_chemnum_sublabel_list_bool
                  {
                    \chemnum_cmpd_sublabel_list:nn { #1 }
                      { \l_chemnum_cmpd_sublabel_list_tl }
                  }
                  {
                    \tl_if_blank:nF { #2 }
                      {
                        \tl_use:N \l_chemnum_cmpd_separator_tl
                        \int_zero:N \l_tmpa_int
                        \exp_args:No \tl_map_inline:nn
                          { \l_chemnum_cmpd_sublist_tl }
                          {
                            \int_incr:N \l_tmpa_int
                            \chemnum_cmpd_subrange_separate:n { ##1 }
                            \bool_if:NTF \l_chemnum_cmpd_ref_bool
                              { \use:c { chemnum_cmpd_ #1 _ \l_tmpa_tl _ref: } }
                              { \use:c { chemnum_cmpd_ #1 _ \l_tmpa_tl : } }
                            \tl_if_blank:VF \l_tmpb_tl
                              {
                                \tl_use:N \l_chemnum_sub_range_sep_tl
                                \bool_if:NTF \l_chemnum_cmpd_ref_bool
                                  { \use:c { chemnum_cmpd_ #1 _ \l_tmpb_tl _ref: } }
                                  { \use:c { chemnum_cmpd_ #1 _ \l_tmpb_tl : } }
                              }
                            \int_compare:nF
                              { \l_tmpa_int = \l_chemnum_cmpd_sublist_length_int }
                              { \l_chemnum_sublist_output_separator_tl }
                          }
                      }
                  }
              }
          } }
      }
  }

\cs_generate_variant:Nn \chemnum_cmpd_aux_i:nnnn { oonn }

%-----------------------------------------------------------------------------%
% create compound label
% #1: label name #2: star (invisible) #3: minus (no delimiters)
\cs_new_nopar:Npn \chemnum_cmpd:nnn #1#2#3 {
  \group_begin:
    \tl_clear:N \l_chemnum_cmpd_main_label_tl
    \tl_clear:N \l_chemnum_cmpd_sub_label_tl
    \chemnum_cmpd_labelsep:n #1 \q_stop
    \tl_remove_all:Nn \l_chemnum_cmpd_sub_label_tl { ~ }
    \chemnum_cmpd_aux_i:oonn
      { \l_chemnum_cmpd_main_label_tl }
      { \l_chemnum_cmpd_sub_label_tl }
      { #2 }
      { #3 }
  \group_end:
}

\cs_generate_variant:Nn \chemnum_cmpd:nnn { onn }

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% DOCUMENT COMMANDS
% variables:
\int_new:N \l_chemnum_list_items_int
\int_new:N \l_chemnum_list_separate_int

\tl_new:N \l_chemnum_list_last_sep_empty_tl
\tl_set:Nn \l_chemnum_list_last_sep_empty_tl { empty }

\bool_new:N \l_chemnum_cmpd_ref_bool

\msg_set:nnnn { chemnum } { fatal-combination }
  {
    You~can't~use \c_space_tl \token_to_str:N \cmpd \c_space_tl
    with~star~and~#1 \c_space_tl \msg_line_context: .
  }
  {
    You~used \c_space_tl \token_to_str:N \cmpd \c_space_tl
    with~both~star~and~#1 \c_space_tl \msg_line_context: .\\
    ~This~is~not~possible~since~it~doesn't~make~any~sense.
  }

%-----------------------------------------------------------------------------%
% MAIN COMMAND
% \cmpd*+-[<key-value-list>]{<(possibly comma separated list of) compound
% label(s)>}
\NewDocumentCommand \chemnum_input_separator:n
  { > { \exp_args:No \SplitList { \l_chemnum_list_input_separator_tl } } m }
  { \tl_set:Nn \l_tmpa_tl { #1 } }

\NewDocumentCommand \cmpd_main_command:w { s t+ t- o m }
  {
    \IfBooleanT #2
      {
        \bool_set_true:N \l_chemnum_cmpd_ref_bool
        \IfBooleanT #1
          { \msg_error:nnx { chemnum } { fatal-combination } { plus } }
      }
    \tl_clear:N \l_chemnum_tmpa_tl
    \group_begin:
      \int_zero:N \l_chemnum_list_items_int
      \int_zero:N \l_chemnum_list_separate_int
      \IfNoValueF { #4 }
        { \keys_set:nn { chemnum } { #4 } }
      \chemnum_input_separator:n { #5 }
      \tl_map_variable:NNn \l_tmpa_tl \l_chemnum_tmpa_tl
        {
          \tl_if_blank:VF \l_chemnum_tmpa_tl
            { \int_incr:N \l_chemnum_list_items_int }
        }
      \tl_map_variable:NNn \l_tmpa_tl \l_chemnum_tmpa_tl
        {
          \tl_remove_all:Nn \l_chemnum_tmpa_tl { ~ }
          \tl_if_blank:VF \l_chemnum_tmpa_tl
            {
              \int_incr:N \l_chemnum_list_separate_int
              \IfBooleanF #1
                {
                  \if_int_compare:w \l_chemnum_list_separate_int = 1
                    \if_int_compare:w \l_chemnum_list_items_int = 1
                    \else:
                      \tl_use:N \l_chemnum_list_prefix_tl
                      \tl_if_blank:VF { \l_chemnum_list_prefix_tl }
                        { \l_chemnum_list_space_tl }
                      \tl_use:N \l_chemnum_list_odelim_tl
                    \fi:
                  \fi:
                }
              \IfBooleanTF #1
                {
                  \chemnum_cmpd:onn
                    { \l_chemnum_tmpa_tl }
                    { \BooleanTrue }
                    { \BooleanFalse }
                  \IfBooleanT #3
                    {
                      \msg_error:nnx { chemnum }
                        { fatal-combination } { minus }
                    }
                }
                { 
                  \IfBooleanTF #3
                    {
                      \chemnum_cmpd:onn
                        { \l_chemnum_tmpa_tl }
                        { \BooleanFalse }
                        { \BooleanTrue }
                    }
                    {
                      \chemnum_cmpd:onn
                        { \l_chemnum_tmpa_tl }
                        { \BooleanFalse }
                        { \BooleanFalse }
                    }
                  \int_compare:nTF
                    { \l_chemnum_list_separate_int = \l_chemnum_list_items_int }
                    {
                      \int_compare:nNnF { \l_chemnum_list_items_int } = { 1 }
                        {
                          \tl_use:N \l_chemnum_list_cdelim_tl
                          \tl_if_blank:VF
                            { \l_chemnum_list_suffix_tl }
                            { \l_chemnum_list_space_tl }
                          \tl_use:N \l_chemnum_list_suffix_tl
                        }
                    }
                    {
                      \int_compare:nTF
                        {
                          \l_chemnum_list_separate_int
                          =
                          \int_eval:n { \l_chemnum_list_items_int - 1 }
                        }
                        {
                          \tl_if_eq:NNTF
                            \l_chemnum_list_last_separator_tl
                            \l_chemnum_list_last_sep_empty_tl
                            {
                              \tl_use:N \l_chemnum_list_separator_tl
                              \l_chemnum_list_space_tl
                            }
                            {
                              \int_compare:nNnF
                                { \l_chemnum_list_separate_int } = { 1 }
                                {
                                  \bool_if:NF \l_chemnum_no_serial_comma_bool
                                    { \l_chemnum_list_separator_tl }
                                }
                              \tl_if_blank:VF \l_chemnum_list_last_separator_tl
                                { \l_chemnum_list_space_tl }
                              \tl_use:N \l_chemnum_list_last_separator_tl
                              \l_chemnum_list_space_tl
                            }
                        }
                        {
                          \tl_use:N \l_chemnum_list_separator_tl
                          \l_chemnum_list_space_tl
                        }
                  }
                }
            }
        }
    \group_end:
    \bool_set_false:N \l_chemnum_cmpd_ref_bool
  }

\cs_set_eq:NN \cmpd \cmpd_main_command:w

%-----------------------------------------------------------------------------%
% INITIALISING LABELS
\bool_new:N \l_chemnum_cmpd_initiated_bool
\bool_new:N \l_chemnum_cmpd_init_strict_bool
\bool_new:N \l_chemnum_cmpd_sub_init_bool
\bool_new:N \l_chemnum_cmpd_init_declare_bool

\tl_new:N \l_chemnum_cmpd_init_separator_tl
\tl_set:Nn \l_chemnum_cmpd_init_separator_tl { , }

% property keys for \cmpdinit command
% strict=true will produce an error instead of a warning
\keys_define:nn { chemnum } {
  init-strict    .bool_set:N = \l_chemnum_cmpd_init_strict_bool ,
  init-strict    .default:n  = true ,
  init-sub       .bool_set:N = \l_chemnum_cmpd_sub_init_bool ,
  init-sub       .default:n  = true ,
  init-input-sep .tl_set:N   = \l_chemnum_cmpd_init_separator_tl ,
  init-input-sep .default:n  = { , }
}

% warning/error messages
\msg_set:nnn { chemnum } { cmpd-init }
  {
    You~used~\token_to_str:N \cmpdinit \c_space_tl but~didn't~initiate~
    compound~"#1"~\msg_line_context: .
  }

\msg_set:nnn { chemnum } { cmpd-init-sub }
  {
    You~used~\token_to_str:N \cmpdinit \c_space_tl and~"init-sub~=~true"~
    but~didn't~initiate~sub-compound~"#1"~\msg_line_context: .
  }

% initialize (and maybe declare) labels
\cs_new_nopar:Npn \chemnum_cmpd_init:n #1
  {
    \tl_clear:N \l_chemnum_tmpa_tl
    \tl_set:Nn \l_chemnum_tmpa_tl { #1 }
    \tl_remove_all:Nn \l_chemnum_tmpa_tl { ~ }
    \tl_clear:N \l_chemnum_cmpd_main_label_tl
    \tl_clear:N \l_chemnum_cmpd_sub_label_tl
    \exp_after:wN \chemnum_cmpd_labelsep:n \l_chemnum_tmpa_tl \q_stop
    \cs_if_exist:cF { chemnum_cmpd_ \l_chemnum_cmpd_main_label_tl  _init: }
      {
        \cs_new_nopar:cpn
          { chemnum_cmpd_ \l_chemnum_cmpd_main_label_tl _init: }
          { }
      }
    \bool_if:NT \l_chemnum_cmpd_sub_init_bool
      {
        \tl_if_blank:VF \l_chemnum_cmpd_sub_label_tl
          {
            \exp_args:No \chemnum_cmpd_sublist:n
              { \l_chemnum_cmpd_sub_label_tl }
            \exp_args:No \tl_map_inline:nn { \l_chemnum_cmpd_sublist_tl }
              {
                \cs_if_exist:cF
                  {
                    chemnum_cmpd_ 
                    \l_chemnum_cmpd_main_label_tl
                    _
                    ##1
                    _init:
                  }
                  {
                    \cs_new_nopar:cpn
                      {
                        chemnum_cmpd_
                        \l_chemnum_cmpd_main_label_tl
                        _
                        ##1
                        _init:
                      }
                      { }
                  }
              }
          }
      }
    \bool_if:NT \l_chemnum_cmpd_init_declare_bool
      {
        \chemnum_cmpd:onn
          { \l_chemnum_tmpa_tl }
          { \BooleanTrue }
          { \BooleanFalse }
      }
  }

% \cmpdinit*[strict=<bool>]{<comma separated list of label names>}
\NewDocumentCommand \cmpdinit { s o m }
  {
    \bool_set_true:N \l_chemnum_cmpd_initiated_bool
    \IfBooleanTF #1
      { \bool_set_false:N \l_chemnum_cmpd_init_declare_bool }
      { \bool_set_true:N \l_chemnum_cmpd_init_declare_bool }
    \IfNoValueF { #2 } { \keys_set:nn { chemnum } { #2 } }
    \chemnum_input_separator:n { #3 }
    \tl_map_function:NN \l_tmpa_tl \chemnum_cmpd_init:n
  }

%-----------------------------------------------------------------------------%
% RESET LABEL NUMBERS
% \cmpdreset[<number>]
\NewDocumentCommand \cmpdreset { o }
  {
    \IfNoValueTF { #1 }
      { \int_zero:N \g_chemnum_cmpd_int }
      { \int_set:Nn \g_chemnum_cmpd_int { #1 - 1 } }
  }

%-----------------------------------------------------------------------------%
% CHEMNUM SETUP COMMAND
% \cmpdsetup{<key-value-list>}
\NewDocumentCommand \cmpdsetup { m }
  { \keys_set:nn { chemnum } { #1 } \tex_ignorespaces:D }

%-----------------------------------------------------------------------------%
% REPLACE TAG IN EPS PICTURE WITH LABEL
% works similar to \schemeref command of the chemscheme package
% \cmpdref-[<keyval>][<tag>]{<label name>}
\tl_new:N \l_chemnum_cmpdref_tl
\tl_new:N \l_chemnum_cmpdref_style_tl
\tl_set:Nn \l_chemnum_cmpdref_style_tl { \sffamily }
\tl_new:N \l_chemnum_cmpdref_marker_tl
\tl_set:Nn \l_chemnum_cmpdref_marker_tl { TMP }
\tl_new:N \l_chemnum_psfrag_texpos_tl
\tl_new:N \l_chemnum_psfrag_texpos_current_tl
\tl_set:Nn \l_chemnum_psfrag_texpos_tl { b }
\tl_new:N \l_chemnum_psfrag_pspos_tl
\tl_new:N \l_chemnum_psfrag_pspos_current_tl
\tl_set:Nn \l_chemnum_psfrag_pspos_tl { b }

\int_new:N \l_chemnum_cmpdref_int

\cs_new_nopar:Npn \chemnum_set_psfrag_pos:nn #1#2
  {
    \tl_set:Nn \l_chemnum_psfrag_texpos_tl { #1 }
    \tl_set:Nn \l_chemnum_psfrag_pspos_tl { #2 }
  }

\cs_new_nopar:Npn \chemnum_psfrag:nnnn #1#2#3#4
  { \psfrag { #1 } [ #2 ] [ #3 ] { #4 } }
\cs_generate_variant:Nn \chemnum_psfrag:nnnn { VVVn }

\cs_new:Npn \chemnum_set_psfrag_pos_local:w #1 ref-pos #2 = #3#4 , #5 \q_stop
  {
    \tl_set_eq:NN \l_chemnum_psfrag_texpos_current_tl \l_chemnum_psfrag_texpos_tl
    \tl_set_eq:NN \l_chemnum_psfrag_pspos_current_tl \l_chemnum_psfrag_pspos_tl
    \tl_set:Nn \l_chemnum_psfrag_texpos_tl { #3 }
    \tl_set:Nn \l_chemnum_psfrag_pspos_tl { #4 }
  }

\keys_define:nn { chemnum }
  {
    ref-tag   .tl_set:N  = \l_chemnum_cmpdref_marker_tl ,
    ref-tag   .default:n = { TMP } ,
    ref-style .tl_set:N  = \l_chemnum_cmpdref_style_tl ,
    ref-style .default:n = { } ,
    ref-pos   .code:n    = \chemnum_set_psfrag_pos:nn #1 ,
    ref-pos   .default:n = bb
  }

\NewDocumentCommand \cmpdref { t- o o m }
  {
      \IfBooleanT { #1 }
        { \keys_set:nn { chemnum } { cmpd-delim = } }
      \IfNoValueTF { #2 }
        {
          \int_incr:N \l_chemnum_cmpdref_int
          \tl_set:No \l_chemnum_cmpdref_tl
            {
              \tl_use:N \l_chemnum_cmpdref_marker_tl
              \int_use:N \l_chemnum_cmpdref_int
            }
        }
        {
          \tl_if_blank:nTF { #2 }
            {
              \int_incr:N \l_chemnum_cmpdref_int
              \tl_set:No \l_chemnum_cmpdref_tl
                {
                  \tl_use:N \l_chemnum_cmpdref_marker_tl
                  \int_use:N \l_chemnum_cmpdref_int
                }
            }
            { \tl_set:Nn \l_chemnum_cmpdref_tl { #2 } }
        }
    \IfNoValueTF { #3 }
        {
          % need to call it once invisible in case it's the first time the label
          % is called. Somehow it otherwise “vanishes” inside \psfrag
          \cmpd_main_command:w * { #4 }
          \chemnum_psfrag:VVVn
            \l_chemnum_cmpdref_tl
            \l_chemnum_psfrag_texpos_tl
            \l_chemnum_psfrag_pspos_tl
            {
              \group_begin:
                \keys_set:nn { chemnum }
                  { cmpd-style = \l_chemnum_cmpdref_style_tl }
                \cmpd_main_command:w { #4 }
              \group_end:
            }
        }
        {
          % TODO: set psfrag positions before \chemnum_psfrag is called
          % ?? hat sich erledigt, oder?
          \cmpd_main_command:w * [ #3 ] { #4 }
          \tl_if_in:nnT { #3 } { ref-pos }
            { \chemnum_set_psfrag_pos_local:w #3 , \q_stop }
          \chemnum_psfrag:VVVn
            \l_chemnum_cmpdref_tl
            \l_chemnum_psfrag_texpos_tl
            \l_chemnum_psfrag_pspos_tl
            {
              \group_begin:
                \keys_set:nn { chemnum }
                  { cmpd-style = \l_chemnum_cmpdref_style_tl }
                \cmpd_main_command:w [ #3 ] { #4 }
              \group_end:
            }
          \tl_if_in:nnT { #3 } { ref-pos }
            {
              \tl_set_eq:NN
                \l_chemnum_psfrag_texpos_tl \l_chemnum_psfrag_texpos_current_tl
              \tl_set_eq:NN
                \l_chemnum_psfrag_pspos_tl \l_chemnum_psfrag_pspos_current_tl
            }
        }
  }

% --------------------------------------------------------------------------- %
% one for the hackers: get the label numbers in an expandable way:
\cs_new:Npn \cmpd@main #1 { \use:c { chemnum_cmpd_#1: } }
\cs_new:Npn \cmpd@sub #1#2 { \use:c { chemnum_cmpd_#1_#2: } }

% usage - main label of \cmpd{<label>.<sub>} => \cmpd@main{<label>}
%       - sublabel   of \cmpd{<label>.<sub>} => \cmpd@aub{<label>}{<sub>}
% Please be aware that this will _not_ be expandable when you use greek labels

% --------------------------------------------------------------------------- %
% language support:

\RequirePackage { translations }
\DeclareTranslationFallback     { and~(list~seperator) } { and }
\DeclareTranslation { English } { and~(list~seperator) } { and }
\DeclareTranslation { French  } { and~(list~seperator) } { et }
\DeclareTranslation { German  } { and~(list~seperator) } { und }
\DeclareTranslation { Italian } { and~(list~seperator) } { e }
\DeclareTranslation { Spanish } { and~(list~seperator) } { y }
\tl_set:Nn \l_chemnum_list_last_separator_lang_tl
  { \GetTranslation { and~(list~seperator) } }

\AtBeginDocument
  {
    \@ifpackageloaded { babel }
      {
        \iflanguage { american }
          { \bool_set_false:N \l_chemnum_no_serial_comma_bool }
          { \bool_set_true:N \l_chemnum_no_serial_comma_bool }
        \cs_new_eq:NN \chemnum_selectlanguage:n \selectlanguage
        \cs_set_nopar:Npn \selectlanguage #1
          {
            \chemnum_selectlanguage:n { #1 }
            \iflanguage { american }
              { \bool_set_false:N \l_chemnum_no_serial_comma_bool }
              { \bool_set_true:N \l_chemnum_no_serial_comma_bool }
          }
      }
      {}
  }

\tex_endinput:D

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
HISTORY:
 2011/06/27 version 0.1
 2011/06/29 version 0.1a - bugfixes
 2011/07/17 version 0.2  - instead of two commands (\cmpd and \cmpdlist ) only 
                         one (\cmpd) for both tasks
                         - setup with a keyval system
                         - possibility to initiate sublabels
                         - choices "greek" and "Greek" for the cmpd-counter
                         keys, choice "symbol" changed to "Symbol"
                         - package option "textgreek = <value>" to control
                         usage of the `textgreek' package
                         - former \cmpd+ is now \cmpd-
                         - new \cmpd+ added which reads label from
                         <jobname>.cmpd
                         - bugfix: wrong declaration in \cmpdinit and \cmpd
                         when used with line break fixed
                         - bugfix: error when \cmpd was used in vertical mode
                         fixed
                         - bugfix: corrected up to date support test
                         - bugfix: wrong output in \cmpd* list removed
                         - commented and cleaned up code
 2011/08/02 version 0.3  - keys "cmpd-all", "sub-list", "sub-range-sep" and
                         "sub-range-marker" added, key "cmpd-sub-counter"
                         renamed into "sub-counter", key "sub-cmpd-sep"
                         renamed into "sub-marker"
                         - \cmpdref-[<keyval>][<tag>]{<label name>} added
                         - key "ref-tag" added
                         - cleaned up code
 2011/09/03 version 0.3a - it is now impossible to use the (conflicting or 
                         better: senseless) \cmpd*+ and \cmpd*- command
                         versions. An error message is produced.
                         - made sure code has no more than 80 tokens per line
                         to improve readability on small screens
                         - bug (unwanted whitespace) in \cmpdsetup fixed
 2011/11/03 version 0.3b - key "sub-only" added, see schema 23 at
                         http://www.arkat-usa.org/get-file/29257/ or scheme 4
                         at http://www.arkat-usa.org/get-file/27301/ for
                         reasons, why
 2011/11/08 version 0.3c - localization via `babel' is now supported with the
                         help of the `translator' package
                         - key "list-serial-comma" added
 2011/12/01 version 0.3d - greek letters without `textgreek' package
                         - new key cmpd-weight = bold/normal
                         - bugfix: sublabels are now possible, when main label
                         name contains a colon
                         - it is now possible to change the list input
                         separator; this means the comma may be part of the
                         label name
 2011/12/01 version 0.3e - bugfix: labels have been saved in a wrong way, when
                         "list-input-sep" had been changed. this is fixed
 2011/12/09 version 0.4  - new input of sublabel lists and ranges
                         - new key: "sublist-input-sep"
                         - new key: "sublist-output-sep"
                         - new key: "init-input-sep"
                         - "sub-marker"       => "sub-input-sep"
                         - "cmpd-sep"         => "sub-output-sep"
                         - "sub-range-sep"    => "subrange-output-sep"
                         - "sub-range-marker" => "subrange-input-sep"
                         - "strict"           => "init-strict"
                         - "sub-init"         => "init-sub"
                         - key removed: "sub-list"
                         - it is now possible, to mark the labels with
                         \hypertarget and \hyperlink if `hyperref' is loaded
                         - new key: "hyper-use"
                         - new key: "hyper-target"
                         - new key: "hyper-link"
                         - new key: "ref-style"
                         - documentation got an index
 2012/02/22 version 0.4a - corrected outdated expl3 function
 2012/04/15 version 0.4b - bugfix in \cmpdref
 2012/04/20 version 0.5  - new option "ref-pos"
                         - switched order of optional arguments of \cmpdref
 2012/05/03 version 0.5a - corrected stupid typos in documentation
 2012/05/17 version 0.5b - retrieve label numbers in an expandable (LaTeX2e) way
                           see
                           https://groups.google.com/d/topic/de.comp.text.tex/LF0knPIuqrM/discussio
                           for possible reasons why
 2012/07/24 version 0.5c - adapted to changes in l3kernel
 2012/08/15 version 0.5d - fixed bug in \cmpdref
 2012/09/17 version 0.5e - fixed bug in \cmpdinit
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% TODO:
 - add a possibility to \ref{} the compounds
 - (rudimentäre) Unterstützung für hyperref und pdfstrings
 - provide expandable makro which gives the label and/or sublabel without any
   formatting