<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">% ----------------------------------------------------------------------------
% the EXSHEETS package
% 
%   Yet another package for the creation of exercise sheets
% 
% ----------------------------------------------------------------------------
% Clemens Niederberger
% Web:    http://www.mychemistry.eu/forums/forum/exsheets
% E-Mail: contact@mychemistry.eu
% ----------------------------------------------------------------------------
% Copyright 2011-2019 Clemens Niederberger
% 
% This work may be distributed and/or modified under the
% conditions of the LaTeX Project Public License, either version 1.3
% of this license or (at your option) any later version.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3 or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
% 
% This work has the LPPL maintenance status `maintained'.
% 
% The Current Maintainer of this work is Clemens Niederberger.
% ----------------------------------------------------------------------------
% If you have any ideas, questions, suggestions or bugs to report, please
% feel free to contact me.
% ----------------------------------------------------------------------------
\RequirePackage { expl3 , xparse }
\ExplSyntaxOn

\tl_const:Nn \c_exsheets_date_tl    {2019/09/30}
\tl_const:Nn \c_exsheets_version_tl {0.21k}
\tl_const:Nn \c_exsheets_info_tl
  {Yet~ another~ package~ for~ the~ creation~ of~ exercise~ sheets~ and~ exams.}

\ProvidesExplPackage
  {exsheets}
  {\c_exsheets_date_tl}
  {\c_exsheets_version_tl}
  {\c_exsheets_info_tl}

% ----------------------------------------------------------------------------
% variants of kernel functions:
\cs_generate_variant:Nn \prop_get:NnN    { NV , Nx , cV , cx }
\cs_generate_variant:Nn \prop_get:NnNF   { NV , Nx , cV , cx }
\cs_generate_variant:Nn \prop_get:NnNT   { NV , Nx , cV , cx }
\cs_generate_variant:Nn \prop_get:NnNTF  { NV , Nx , cV , cx }
\cs_generate_variant:Nn \prop_gput:Nnn   { Nf , Nff , Nfx , Nx , Nxx , NxV , cx , cxx }
\cs_generate_variant:Nn \prop_gput_if_new:Nnn { Nxx }
\cs_generate_variant:Nn \tl_if_blank:nTF { x }
\cs_generate_variant:Nn \tl_if_eq:nnF    { x }
\cs_generate_variant:Nn \int_to_arabic:n { V }
\cs_generate_variant:Nn \seq_set_split:Nnn { NnV }
\cs_generate_variant:Nn \quark_if_no_value:nTF { V }

% ----------------------------------------------------------------------------
% temporary variables
\tl_new:N    \l__exsheets_tmpa_tl
\tl_new:N    \l__exsheets_tmpb_tl
\tl_new:N    \l__exsheets_tmpc_tl
\int_new:N   \l__exsheets_tmpa_int
\int_new:N   \l__exsheets_tmpb_int
\int_new:N   \l__exsheets_tmpc_int
\int_new:N   \l__exsheets_tmpd_int
\int_new:N   \l__exsheets_tmpe_int
\int_new:N   \g__exsheets_tmpa_int
\dim_new:N   \l__exsheets_tmpa_dim
\dim_new:N   \l__exsheets_tmpb_dim
\seq_new:N   \l__exsheets_tmpa_seq
\fp_new:N    \l__exsheets_tmpa_fp
\clist_new:N \l__exsheets_tmpa_clist
\bool_new:N  \l__exsheets_tmpa_bool

% ----------------------------------------------------------------------------
% messages
\msg_new:nnn {exsheets} {file-not-found}
  {
    You've~ requested~ the~ file~ `\tl_to_str:n {#1}'~ but~ I~ cannot~ find~
    it~ \msg_line_context: .
  }

\msg_new:nnn {exsheets} {totalpoints}
  {
    You~ need~ to~ activate~ `points/parse'~ if~ you~ want~ to~ use~
    \token_to_str:N \totalpoints .~ I~ will~ do~ nothing~ instead.
  }

\msg_new:nnn {exsheets} {parse-points}
  {
    You~ need~ to~ activate~ `points/parse'~ if~ you~ want~ to~ use~
    \token_to_str:N #1 .~ I~ will~ do~ nothing~ instead.
  }

\msg_new:nnn {exsheets} {headings}
  {
    You~ requested~ the~ headings~ instance~ `#1'~ \msg_line_context: \c_space_tl
    which~ is~ not~ defined.~ Is~ this~ a~ typo?~ Anyway,~ I~ will~ use~ the~
    instance~ `block'~ instead~ and~pretend~ nothing~ happened.
  }

\msg_new:nnn {exsheets} {random-file}
  {
    You~ asked~ me~ to~ select~ #1~ questions~ from~ file~ #2~ which~
    contains~ #3~ questions.~ I'll~ select~ all~ of~ them.
  }

\msg_new:nnn {exsheets} {random-selectable}
  {
    You~ asked~ me~ to~ select~ #1~ questions~ from~ file~ #2~ which~
    contains~ #3~ questions.~ #4~ of~ these~ are~ selectable,~ so~ I'll~
    select~ all~ of~ them.
  }

\msg_new:nnn {exsheets} {only-inside-question}
  {
    The~ command~ `~ \token_to_str:N #1 \c_space_tl'~ can~ only~ be~ used~
    inside~ the~ question~ environment.
  }

\msg_new:nnn {exsheets} {loading-configurations}
  { Loading~ custom~ configurations~ file~ `exsheets_configurations.cfg'. }

\msg_new:nnn {exsheets} {deprecated-command}
  {
    The~ command~ `#1'~ is~ deprecated.~ Use~ `#2'~ instead.
  }

\msg_new:nnn {exsheets} {dropped-option}
  { The~ option~ `#1'~ has~ been~ dropped. }

\msg_new:nnn {exsheets} {grade-missing}
  { The~ grade~ `#1'~ has~ never~ been~ declared. }

\msg_new:nnn {exsheets} {grade-parse}
  {
    I~ cannot~ calculate~ the~ points~ for~ grade~ `#1'~ since~ you're~ using~
    the~ option~ `points/parse=false'.
  }

\msg_new:nnn {exsheets} {variations}
  {
    The~ number~ of~ variations~ must~ at~ least~ be~ `2'.~ You~ chose~ `#1'~
    hence~ I'm~ doing~ nothing.
  }

\msg_new:nnn {exsheets} {variant}
  {
    You~ must~ choose~ an~ integer~ between~ `1'~ and~ `#1'.~ You~ chose~
    `#2'~ hence~ I'm~ doing~ nothing.
  }

\cs_new_protected:Npn \exsheets_deprecate_cs:Npnn #1#2#
  { \__exsheets_deprecate_cs:Nnnn #1 {#2} }
\cs_new_protected:Npn \__exsheets_deprecate_cs:Nnnn #1#2#3#4
  {
    \cs_new_protected:Npn #1 #2
      {
        \tl_if_blank:nTF {#3}
          { \msg_warning:nnnn {exsheets} { deprecated-command } {#1} {#4} }
          { \msg_warning:nnnn {exsheets} { deprecated-command } {#1} {#3} }
        #4
      }
  }

\cs_new_protected:Npn \exsheets_option_dropped:n #1
  { \msg_warning:nnn {exsheets} {dropped-option} {#1} }

% ----------------------------------------------------------------------------
\RequirePackage
  { xtemplate , l3keys2e , etoolbox , environ , pgfcore }

% ----------------------------------------------------------------------------
% write to aux file:
\cs_new_protected:Npn \exsheets_write_to_aux_x:n #1
  { \if@filesw \iow_now:Nx \@auxout {#1} \fi }

% prevent compilatin errors when exsheets is removed from a document:
\AtBeginDocument{
  \exsheets_write_to_aux_x:n
    {
      \exp_not:N \providecommand \exp_not:N \exsheets@question@property[3]{} ^^J
      \exp_not:N \providecommand \exp_not:N \exsheets@save@number[2]{} ^^J
      \exp_not:N \providecommand \exp_not:N \exsheets@sum@of@points[1]{} ^^J
      \exp_not:N \providecommand \exp_not:N \exsheets@sum@of@bonus[1]{} ^^J
      \exp_not:N \providecommand \exp_not:N \exsheets@used@id[2]{} ^^J
    }
}

% ----------------------------------------------------------------------------
% variables:
\bool_new:N       \l__exsheets_print_number_bool
\bool_set_true:N  \l__exsheets_print_number_bool
\bool_new:N       \l__exsheets_solutions_by_ref_bool
\bool_new:N       \l__exsheets_questions_totoc_bool
\bool_new:N       \l__exsheets_solutions_totoc_bool
\bool_new:N       \l__exsheets_auto_label_bool
\bool_new:N       \l__exsheets_no_skip_after_bool
\bool_new:N       \l__exsheets_points_questions_default_bool
\bool_set_false:N \l__exsheets_points_questions_default_bool
\bool_new:N       \l__exsheets_parse_points_bool
\bool_set_true:N  \l__exsheets_parse_points_bool
\bool_new:N       \l__exsheets_points_name_bool
\bool_set_true:N  \l__exsheets_points_name_bool
\bool_new:N       \l__exsheets_points_separate_bonus_bool
\bool_new:N       \l__exsheets_grades_half_bool
\bool_new:N       \g__exsheets_questions_use_bool
\bool_gset_true:N \g__exsheets_questions_use_bool
\bool_new:N       \l__exsheets_questions_use_bool
\bool_set_true:N  \l__exsheets_questions_use_bool
\bool_new:N       \l__exsheets_questions_deactivate_bool
\bool_new:N       \l__exsheets_save_question_body_to_aux_bool
\bool_set_false:N \l__exsheets_save_question_body_to_aux_bool
\bool_new:N       \l__exsheets_solutions_use_bool
\bool_set_true:N  \l__exsheets_solutions_use_bool
\bool_new:N       \l__exsheets_use_this_question_bool
\bool_new:N       \l__exsheets_questions_print_bool
\bool_set_true:N  \l__exsheets_questions_print_bool
\bool_new:N       \l__exsheets_inside_question_bool
\bool_new:N       \l__exsheets_only_print_points_bool
\bool_new:N       \l__exsheets_exam_bool
\bool_set_false:N \l__exsheets_exam_bool
\bool_new:N       \l__exsheets_questions_runin_bool
\bool_set_false:N \l__exsheets_questions_runin_bool
\bool_new:N       \l__exsheets_questions_debug_bool
\bool_set_false:N \l__exsheets_questions_debug_bool
\bool_new:N       \l__exsheets_select_questions_bool
\bool_new:N       \l__exsheets_include_all_bool
\bool_new:N       \l__exsheets_include_random_bool
\bool_new:N       \l__exsheets_include_by_id_bool
\bool_set_true:N  \l__exsheets_include_all_bool
\bool_new:N       \l__exsheets_include_questions_no_duplicates_bool
\bool_new:N       \l__exsheets_use_selection_bool
\bool_new:N       \l__exsheets_solutions_print_bool
\bool_set_false:N \l__exsheets_solutions_print_bool
\bool_new:N       \l__exsheets_solutions_print_section_bool
\bool_set_false:N \l__exsheets_solutions_print_section_bool
\bool_new:N       \l__exsheets_solutions_print_chapter_bool
\bool_set_false:N \l__exsheets_solutions_print_chapter_bool
\bool_new:N       \l__exsheets_solutions_print_all_bool
\bool_set_false:N \l__exsheets_solutions_print_all_bool
\bool_new:N       \l__exsheets_inside_solution_bool
\bool_set_false:N \l__exsheets_inside_solution_bool
\bool_new:N       \l__exsheets_solutions_runin_bool
\bool_set_false:N \l__exsheets_solutions_runin_bool
\bool_new:N       \l__exsheets_print_byID_sorted_bool
\bool_set_true:N  \l__exsheets_print_byID_sorted_bool
\bool_new:N       \l__exsheets_blank_width_bool
\bool_new:N       \l__exsheets_blank_linespread_bool

\tl_new:N  \l__exsheets_points_name_tl
\tl_set:Nn \l__exsheets_points_name_tl {P.}
\tl_new:N  \l__exsheets_points_name_plural_tl
\tl_set:Nn \l__exsheets_points_name_plural_tl {P.}
\tl_new:N  \l__exsheets_bonus_name_tl
\tl_set:Nn \l__exsheets_bonus_name_tl {P.}
\tl_new:N  \l__exsheets_bonus_name_plural_tl
\tl_set:Nn \l__exsheets_bonus_name_plural_tl {P.}
\tl_new:N  \l__exsheets_points_number_format_tl
\tl_new:N  \l__exsheets_bonus_number_format_tl
\tl_new:N  \l__exsheets_points_pre_bonus_marker_tl
\tl_set:Nn \l__exsheets_points_pre_bonus_marker_tl { \space(+ }
\tl_new:N  \l__exsheets_points_post_bonus_marker_tl
\tl_set:Nn \l__exsheets_points_post_bonus_marker_tl { ) }
\tl_new:N  \l__exsheets_points_format_tl
\tl_set:Nn \l__exsheets_points_format_tl { \use:n }
\tl_new:N  \l__exsheets_qu_counter_pattern_tl
\tl_set:Nn \l__exsheets_qu_counter_pattern_tl { qu. }
\tl_new:N  \l__exsheets_qu_counter_interpretation_tl
\tl_new:N  \l__exsheets_counter_patterns_tl
\tl_new:N  \l__exsheets_heading_instance_tl
\tl_set:Nn \l__exsheets_heading_instance_tl {block}
\tl_new:N  \l__exsheets_question_heading_instance_tl
\tl_new:N  \l__exsheets_solution_heading_instance_tl
\tl_new:N  \l_exsheets_heading_title_question_format_tl
\tl_new:N  \l_exsheets_heading_title_solution_format_tl
\tl_new:N  \l_exsheets_heading_subtitle_question_format_tl
\tl_new:N  \l_exsheets_heading_subtitle_solution_format_tl
\tl_new:N  \l__exsheets_questions_toclevel_tl
\tl_set:Nn \l__exsheets_questions_toclevel_tl {subsection}
\tl_new:N  \l__exsheets_solutions_toclevel_tl
\tl_set:Nn \l__exsheets_solutions_toclevel_tl {subsection}
\tl_new:N  \l__exsheets_new_chapter_hook_tl
\tl_new:N  \l__exsheets_new_section_hook_tl
\tl_new:N  \g__exsheets_use_current_question_tl
\tl_new:N  \l__exsheets_questions_name_tl
\tl_set:Nn \l__exsheets_questions_name_tl {Question}
\tl_new:N  \l__exsheets_exercise_name_tl
\tl_set:Nn \l__exsheets_exercise_name_tl  {Exercise}
\tl_new:N  \l__exsheets_questions_pre_hook_tl
\tl_new:N  \l__exsheets_questions_post_hook_tl
\tl_new:N  \l__exsheets_questions_pre_body_hook_tl
\tl_new:N  \l__exsheets_questions_post_body_hook_tl
\tl_new:N  \l__exsheets_after_begin_question_tl
\tl_new:N  \CurrentQuestionID
\tl_new:N  \l__exsheets_questions_id_tl
\tl_new:N  \l__exsheets_questions_subtitle_tl
\tl_new:N  \g__exsheets_questions_current_id_tl
\tl_new:N  \l__exsheets_questions_title_tl
\tl_new:N  \l__exsheets_questions_label_tl
\tl_new:N  \l__exsheets_questions_points_tl
\tl_new:N  \l__exsheets_include_id_tl
\tl_new:N  \l__exsheets_solutions_name_tl
\tl_set:Nn \l__exsheets_solutions_name_tl {Solution}
\tl_new:N  \l__exsheets_solutions_pre_body_hook_tl
\tl_new:N  \l__exsheets_solutions_post_body_hook_tl
\tl_new:N  \l__exsheets_solutions_pre_hook_tl
\tl_new:N  \l__exsheets_solutions_post_hook_tl
\tl_new:N  \l__exsheets_blank_linespread_tl
\tl_set:Nn \l__exsheets_blank_linespread_tl { 1 }
\tl_new:N  \l__exsheets_blank_scale_tl
\tl_set:Nn \l__exsheets_blank_scale_tl { 1 }
\tl_new:N  \l__exsheets_use_solution_tl
\tl_new:N  \l_exsheets_solutions_name_style_tl
\tl_set:Nn \l_exsheets_solutions_name_style_tl { \normalsize \bfseries }

\int_zero_new:N \l__exsheets_variations_int
\int_new:N      \g__exsheets_questions_id_int
\int_gzero:N    \g__exsheets_questions_id_int
\int_new:N      \g__exsheets_questions_used_int
\int_zero_new:N \l__exsheets_include_random_int
\int_new:N      \l__exsheets_questions_set_int
\int_new:N      \g__exsheets_select_random_int
\int_new:N      \g__exsheets_selection_number_int
\int_new:N      \l__exsheets_counter_ch_int
\int_new:N      \l__exsheets_current_ch_int
\int_new:N      \l__exsheets_counter_sec_int
\int_new:N      \l__exsheets_current_sec_int
\int_new:N      \l_exsheets_counter_qu_int

\fp_new:N  \g__exsheets_points_sum_fp
\fp_new:N  \l__exsheets_points_default_fp
\fp_set:Nn \l__exsheets_points_default_fp {1}
\fp_new:N  \l__exsheets_question_points_fp
\fp_new:N  \g_exsheets_total_points_fp
\fp_new:N  \g__exsheets_bonus_sum_fp
\fp_new:N  \l__exsheets_question_bonus_fp
\fp_new:N  \g_exsheets_total_bonus_fp
\fp_new:N  \l__exsheets_grade_round_fp
\fp_zero:N \l__exsheets_grade_round_fp
\fp_new:N  \g__exsheets_this_question_points_fp
\fp_new:N  \g__exsheets_this_question_bonus_fp

\dim_new:N  \l__exsheets_questions_skip_below_dim
\dim_set:Nn \l__exsheets_questions_skip_below_dim { .5\baselineskip }
\dim_new:N  \l__exsheets_solutions_skip_below_dim
\dim_set:Nn \l__exsheets_solutions_skip_below_dim { .5\baselineskip }
\dim_new:N  \l__exsheets_blank_dim
\dim_new:N  \l__exsheets_blank_line_increment_dim
\dim_new:N  \l__exsheets_blank_line_minimum_length_dim

\seq_new:N \l__exsheets_use_tags_seq
\seq_new:N \g_exsheets_included_questions_seq

\prop_new:N \l__exsheets_relgrades_prop
\prop_new:N \l__exsheets_class_prop
\prop_new:N \g__exsheets_tags_prop
\prop_new:N \g__exsheets_questions_id_prop
\prop_new:N \g__exsheets_questions_subtitle_prop
\prop_new:N \g__exsheets_questions_used_prop
\prop_new:N \g_exsheets_question_identification_prop
\prop_new:N \g__exsheets_included_questions_prop
\prop_new:N \g__exsheets_solutions_content_prop
\prop_new:N \g__exsheets_solutions_questions_id_prop
\prop_new:N \g__exsheets_solutions_names_prop
\prop_new:N \g__exsheets_solutions_counter_prop

\clist_new:N \l__exsheets_include_id_clist
\clist_new:N \l__exsheets_exclude_id_clist
\clist_new:N \questionsincludedlast

\box_new:N \l__exsheets_blank_box

% ----------------------------------------------------------------------------
% how are questions/solutions/... counted?
\RequirePackage {cntformats}

\cs_if_exist:NT \thechapter
  {
    \AddCounterPattern* [exsheets] {chapter} {ch}
    \ReadCounterFrom    [exsheets] {chapter} \l__exsheets_counter_ch_int
  }

\AddCounterPattern* [exsheets] {section} {se}
\ReadCounterFrom    [exsheets] {section} \l__exsheets_counter_sec_int

\NewCounterPattern* [exsheets] {question} {qu}
\ReadCounterFrom    [exsheets] {question} \l_exsheets_counter_qu_int

% ----------------------------------------------------------------------------
% (also) package options:
\keys_define:nn {exsheets}
  {
    counter-format            .code:n     =
      \SaveCounterPattern [exsheets]
        \l__exsheets_qu_counter_pattern_tl
        \l__exsheets_qu_counter_interpretation_tl
        {#1} ,
    counter-format            .initial:n  = qu. ,
    counter-within            .code:n     = \@addtoreset {question} {#1} ,
    headings                  .tl_set:N   = \l__exsheets_heading_instance_tl ,
    load-headings             .code:n     =
      \exsheets_option_dropped:n {load-headings} ,
    question/headings-format  .tl_set:N   =
      \l_exsheets_heading_title_question_format_tl ,
    solution/headings-format  .tl_set:N   =
      \l_exsheets_heading_title_solution_format_tl ,
    headings-format           .meta:n     =
      {
        question/headings-format = {#1} ,
        solution/headings-format = {#1}
      } ,
    headings-format           .initial:n  = \normalsize\bfseries ,
    question/subtitle-format  .tl_set:N   =
      \l_exsheets_heading_subtitle_question_format_tl ,
    solution/subtitle-format  .tl_set:N   =
      \l_exsheets_heading_subtitle_solution_format_tl ,
    subtitle-format           .meta:n     =
      {
        question/subtitle-format = {#1} ,
        solution/subtitle-format = {#1}
      } ,
    subtitle-format           .initial:n  = \normalsize\itshape ,
    load-tasks                .code:n     =
      \exsheets_option_dropped:n {load-tasks} ,
    use-ref                   .bool_set:N = \l__exsheets_solutions_by_ref_bool ,
    totoc                     .choice: ,
    totoc / true              .code:n     =
      \bool_set_true:N \l__exsheets_questions_totoc_bool
      \bool_set_true:N \l__exsheets_solutions_totoc_bool ,
    totoc / false             .code:n     =
      \bool_set_false:N \l__exsheets_questions_totoc_bool
      \bool_set_false:N \l__exsheets_solutions_totoc_bool ,
    totoc                     .default:n  = true ,
    questions-totoc           .bool_set:N = \l__exsheets_questions_totoc_bool ,
    solutions-totoc           .bool_set:N = \l__exsheets_solutions_totoc_bool ,
    toc-level                 .code:n     =
      \tl_set:Nn \l__exsheets_questions_toclevel_tl {#1}
      \tl_set:Nn \l__exsheets_solutions_toclevel_tl {#1} ,
    questions-toc-level       .tl_set:N   = \l__exsheets_questions_toclevel_tl ,
    solutions-toc-level       .tl_set:N   = \l__exsheets_solutions_toclevel_tl ,
    skip-below                .code:n     =
      \dim_set:Nn \l__exsheets_questions_skip_below_dim {#1}
      \dim_set:Nn \l__exsheets_solutions_skip_below_dim {#1} ,
    no-skip-below             .bool_set:N = \l__exsheets_no_skip_after_bool ,
    auto-label                .bool_set:N = \l__exsheets_auto_label_bool ,
    label-format              .code:n     =
      \cs_set:Npn \exsheets_label_format:n ##1 {#1}
      \exsheets_update_referencing_commands: ,
    label-cmd                 .code:n     =
      \cs_set:Npn \__exsheets_label:n {#1}
      \exsheets_update_referencing_commands: ,
    ref-cmd                   .code:n     =
      \cs_set:Npn \__exsheets_ref:n {#1}
      \exsheets_update_referencing_commands: ,
    page-ref-cmd              .code:n     =
      \cs_set:Npn \__exsheets_pageref:n {#1}
      \exsheets_update_referencing_commands: ,
    chapter-hook              .tl_set:N   = \l__exsheets_new_chapter_hook_tl ,
    section-hook              .tl_set:N   = \l__exsheets_new_section_hook_tl %,
%    use-saved-counter-format  .bool_set:N = \l__exsheets_use_saved_pattern_bool
  }

% TODO: remove this in a v1.0:
% process package options:
\ProcessKeysOptions {exsheets}

% ----------------------------------------------------------------------------
% points for exercises
\cs_new_protected:Npn \__exsheets_set_points_name:nNN #1#2#3
  {
    \tl_if_in:nnTF {#1} { / }
      { \__exsheets_set_points_name_aux:wNN #1 \q_mark #2#3 }
      { \__exsheets_set_points_name_aux:wNN #1 / \q_mark #2#3 }
  }

\cs_new_protected:Npn \__exsheets_set_points_name_aux:wNN #1/#2 \q_mark #3#4
  {
    \tl_set:Nn #3 {#1}
    \tl_set:Nn #4 { #1#2 }
  }

\cs_new_protected:Npn \exsheets_set_points_name:n #1
  {
    \__exsheets_set_points_name:nNN {#1}
      \l__exsheets_points_name_tl
      \l__exsheets_points_name_plural_tl
  }

\cs_new_protected:Npn \exsheets_set_bonus_name:n #1
  {
    \__exsheets_set_points_name:nNN {#1}
      \l__exsheets_bonus_name_tl
      \l__exsheets_bonus_name_plural_tl
  }

% FIXME: \fp_add will deprecate!
\cs_new_protected:Npn \exsheets_add_points:n #1
  { 
    \fp_gadd:Nn \g__exsheets_points_sum_fp {#1}
    \fp_gadd:Nn \g__exsheets_this_question_points_fp {#1}
  }
\cs_generate_variant:Nn \exsheets_add_points:n { V }

\cs_new_protected:Npn \exsheets_add_bonus:n #1
  {
    \fp_gadd:Nn \g__exsheets_bonus_sum_fp {#1}
    \fp_gadd:Nn \g__exsheets_this_question_bonus_fp {#1}
  }
\cs_generate_variant:Nn \exsheets_add_bonus:n { V }

\cs_new_protected:Npn \exsheets@sum@of@points #1
  { \fp_gset:Nn \g_exsheets_total_points_fp {#1} }

\cs_new_protected:Npn \exsheets@sum@of@bonus #1
  { \fp_gset:Nn \g_exsheets_total_bonus_fp {#1} }

\cs_new:Npn \__exsheets_parse_points:nN #1#2
  {
    \group_begin:
      \tl_use:N #2
        {
          \bool_if:NTF \l__exsheets_parse_points_bool
            { \exsheets_num:n {#1} }
            { \use:n {#1} }
        }
    \group_end:
  }
\cs_new:Npn \exsheets_parse_points:n #1
  {
    \__exsheets_parse_points:nN {#1}
      \l__exsheets_points_number_format_tl
  }
\cs_generate_variant:Nn \exsheets_parse_points:n { V }

\cs_new:Npn \exsheets_parse_bonus:n #1
  {
    \__exsheets_parse_points:nN {#1}
      \l__exsheets_bonus_number_format_tl
  }
\cs_generate_variant:Nn \exsheets_parse_bonus:n { V }

\cs_new:Npn \exsheets_num:n #1
  { \fp_to_decimal:n {#1} }
\cs_generate_variant:Nn \exsheets_num:n { V,x }

\cs_new:Npn \__exsheets_print_points_name:nNN #1#2#3
  {
    \bool_if:NT \l__exsheets_points_name_bool
      {
        \,
        \hbox:n
          {
            \bool_if:NTF \l__exsheets_parse_points_bool
              {
                \tl_if_eq:nnTF {#1} { ?? }
                  { \tl_use:N #3 }
                  {
                    \fp_compare:nTF { #1 =  1 }
                      { \tl_use:N #2 }
                      { \tl_use:N #3 }
                  }
              }
              { \tl_use:N #3 }
          }
      }
  }

\cs_new:Npn \exsheets_points_name:n #1
  {
    \__exsheets_print_points_name:nNN {#1}
      \l__exsheets_points_name_tl
      \l__exsheets_points_name_plural_tl
  }
\cs_generate_variant:Nn \exsheets_points_name:n { V }

\cs_new:Npn \exsheets_bonus_name:n #1
  {
    \__exsheets_print_points_name:nNN {#1}
      \l__exsheets_bonus_name_tl
      \l__exsheets_bonus_name_plural_tl
  }
\cs_generate_variant:Nn \exsheets_bonus_name:n { V }

\NewDocumentCommand \addpoints { sm }
  {
    \bool_if:NTF \l__exsheets_inside_question_bool
      {
        \exsheets_add_points:n {#2}
        \IfBooleanF {#1} { \exsheets_print_points:n {#2} }
      }
      { \msg_error:nnn {exsheets} {only-inside-question} {\addpoints} }
  }

\NewDocumentCommand \addbonus { sm }
  {
    \bool_if:NTF \l__exsheets_inside_question_bool
      {
        \exsheets_add_bonus:n {#2}
        \IfBooleanF {#1} { \exsheets_print_bonus:n {#2} }
      }
      { \msg_error:nnn {exsheets} {only-inside-question} {\addbonus} }
  }

\NewDocumentCommand \points { sm }
  {
    \IfBooleanTF {#1}
      { \exsheets_parse_points:n {#2} }
      { \exsheets_print_points:n {#2} }
  }

\NewDocumentCommand \bonus { sm }
  {
    \IfBooleanTF {#1}
      { \exsheets_parse_bonus:n {#2} }
      { \exsheets_print_bonus:n {#2} }
  }

\cs_new_protected:Npn \exsheets_print_points:n #1
  {
    \group_begin:
      \tl_use:N \l__exsheets_points_format_tl
        {
          \exsheets_parse_points:n {#1}
          \exsheets_points_name:n {#1}
        }
    \group_end:
  }
\cs_generate_variant:Nn \exsheets_print_points:n { V }

\cs_new_protected:Npn \exsheets_print_bonus:n #1
  {
    \exsheets_parse_bonus:n {#1}
    \exsheets_bonus_name:n {#1}
  }
\cs_generate_variant:Nn \exsheets_print_bonus:n { V }

\NewDocumentCommand \pointssum { s }
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      {
        \IfBooleanTF {#1}
          { \exsheets_parse_points:n { \g_exsheets_total_points_fp } }
          { \exsheets_print_points:n { \g_exsheets_total_points_fp } }
      }
      { \msg_warning:nnn {exsheets} {parse-points} {\pointssum} }
  }

\NewDocumentCommand \bonussum { s }
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      {
        \IfBooleanTF {#1}
          { \exsheets_parse_bonus:n { \g_exsheets_total_bonus_fp } }
          { \exsheets_print_bonus:n { \g_exsheets_total_bonus_fp } }
      }
      { \msg_warning:nnn {exsheets} {parse-points} {\bonussum} }
  }

\NewDocumentCommand \currentpointssum { s }
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      {
        \IfBooleanTF {#1}
          { \exsheets_parse_points:n { \g__exsheets_points_sum_fp } }
          { \exsheets_print_points:n { \g__exsheets_points_sum_fp } }
      }
      { \msg_warning:nnn {exsheets} {parse-points} {\currentpointssum} }
  }

\NewDocumentCommand \currentbonussum { s }
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      {
        \IfBooleanTF {#1}
          { \exsheets_parse_bonus:n { \g__exsheets_bonus_sum_fp } }
          { \exsheets_print_bonus:n { \g__exsheets_bonus_sum_fp } }
      }
      { \msg_warning:nnn {exsheets} {parse-points} {\currentbonussum} }
  }

\NewDocumentCommand \totalpoints { s }
  {
    \group_begin:
      \tl_use:N \l__exsheets_points_format_tl
      {
        \exsheets_totalpoints:
        \IfBooleanF {#1}
          {
            \bool_if:nT
              {
                \l__exsheets_points_separate_bonus_bool ||
                \fp_compare_p:n { \g_exsheets_total_bonus_fp = 0 }
              }
              { \exsheets_points_name:n { \g_exsheets_total_points_fp } }
          }
        \exsheets_totalbonus:
        \IfBooleanF {#1}
          {
            \fp_compare:nF { \g_exsheets_total_bonus_fp = 0 }
              {
                \bool_if:NTF \l__exsheets_points_separate_bonus_bool
                  { \exsheets_bonus_name:n { \g_exsheets_total_bonus_fp } }
                  {
                    \exsheets_points_name:n
                      { \g_exsheets_total_points_fp + \g_exsheets_total_bonus_fp }
                  }
              }
          }
      }
    \group_end:
  }

\exsheets_deprecate_cs:Npnn \sumpoints {} { \totalpoints* }

\cs_new_protected:Npn \exsheets_totalpoints:
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      {
        \fp_compare:nTF { \g_exsheets_total_points_fp = 0 }
          { ?? \, \exsheets_points_name:n { ?? } }
          {
            \exsheets_parse_points:n
              { \g_exsheets_total_points_fp }
          }
      }
      { \msg_warning:nn {exsheets} {totalpoints} }
  }

\cs_new:Npn \exsheets_totalbonus:
  {
    \bool_if:NT \l__exsheets_parse_points_bool
      {
        \fp_compare:nF { \g_exsheets_total_bonus_fp = 0 }
          {
            \tl_use:N \l__exsheets_points_pre_bonus_marker_tl
            \exsheets_parse_bonus:n
              { \g_exsheets_total_bonus_fp }
            \tl_use:N \l__exsheets_points_post_bonus_marker_tl
          }
      }
  }

\keys_define:nn { exsheets / points }
  {
    name                 .code:n     =
      \exsheets_set_points_name:n {#1}
      \exsheets_set_bonus_name:n {#1} ,
    name-plural          .code:n     =
      \tl_set:Nn \l__exsheets_points_name_plural_tl {#1}
      \tl_set:Nn \l__exsheets_bonus_name_plural_tl {#1} ,
    bonus-name           .code:n     = \exsheets_set_bonus_name:n {#1} ,
    bonus-plural         .tl_set:N   = \l__exsheets_bonus_name_plural_tl ,
    pre-bonus            .tl_set:N   = \l__exsheets_points_pre_bonus_marker_tl ,
    post-bonus           .tl_set:N   = \l__exsheets_points_post_bonus_marker_tl ,
    use-name             .bool_set:N = \l__exsheets_points_name_bool ,
    format               .tl_set:N   = \l__exsheets_points_format_tl ,
    number-format        .tl_set:N   = \l__exsheets_points_number_format_tl ,
    bonus-format         .tl_set:N   = \l__exsheets_bonus_number_format_tl ,
    parse                .bool_set:N = \l__exsheets_parse_points_bool ,
    separate-bonus       .bool_set:N = \l__exsheets_points_separate_bonus_bool
  }

% ----------------------------------------------------------------------------
% variations of an exam, see http://tex.stackexchange.com/q/57012/5049 for
% inspiration of the following features
\cs_new_protected:Npn \exsheets_set_variations:n #1
  {
    \int_compare:nNnTF {#1} &lt; { 2 }
      { \msg_warning:nnn {exsheets} {variations} {#1} }
      {
        \int_set:Nn \l__exsheets_variations_int {#1}
        \int_zero:N \l__exsheets_tmpa_int
        \int_do_while:nNnn
          { \l__exsheets_tmpa_int } &lt; { \l__exsheets_variations_int }
          {
            \int_incr:N \l__exsheets_tmpa_int
            \__exsheets_generate_variation_auxiliary:n
              { \l__exsheets_tmpa_int }
            \__exsheets_reset_variation_auxiliary:x
              { \int_use:N \l__exsheets_tmpa_int }
          }
        \__exsheets_generate_variation_auxiliary:n
          { \l__exsheets_variations_int + 1 }
        \exsheets_variant:n { 1 }
      }
  }

\cs_new_protected:Npn \exsheets_variant:n #1
  {
    \bool_if:nTF
      {
        \int_compare_p:nNn {#1} &gt; { 0 } &amp;&amp;
        \int_compare_p:nNn {#1} &lt; { \l__exsheets_variations_int + 1 }
      }
      {
        \int_zero:N \l__exsheets_tmpa_int
        \int_do_while:nNnn
          { \l__exsheets_tmpa_int } &lt; { \l__exsheets_variations_int }
          {
            \int_incr:N \l__exsheets_tmpa_int
            \__exsheets_reset_variation_auxiliary:x
              { \int_use:N \l__exsheets_tmpa_int }
          }
        \cs_set:cpn { __exsheets_variation_ \int_to_roman:n {#1} :n } ##1
          {
            ##1
            \cs_set:Npn \exsheets_last_variant: {##1}
            \use:c { __exsheets_variation_ \int_to_roman:n { #1 + 1 } :n }
          }
      }
      {
        \msg_warning:nnxx {exsheets} {variant}
          { \int_use:N \l__exsheets_variations_int } {#1}
      }
  }

\cs_new_protected:Npn \exsheets_vary:w
  { \__exsheets_variation_i:n }
  
\cs_new:Npn \exsheets_last_variant: { }

\cs_new_protected:Npn \__exsheets_generate_variation_auxiliary:n #1
  {
    \cs_if_exist:cTF { __exsheets_variation_ \int_to_roman:n {#1} :n }
      { \cs_set:cpn { __exsheets_variation_ \int_to_roman:n {#1} :n } { } }
      { \cs_new:cpn { __exsheets_variation_ \int_to_roman:n {#1} :n } { } }
  }

\cs_new_protected:Npn \__exsheets_reset_variation_auxiliary:n #1
  {
    \cs_set:cpn { __exsheets_variation_ \int_to_roman:n {#1} :n } ##1
      { \use:c { __exsheets_variation_ \int_to_roman:n { #1 + 1 } :n } }
  }
\cs_generate_variant:Nn \__exsheets_reset_variation_auxiliary:n { x }

\NewDocumentCommand \SetVariations { m }
  { \exsheets_set_variations:n {#1} }

\NewDocumentCommand \variant { m }
  { \exsheets_variant:n {#1} }

\NewDocumentCommand \vary { }
  { \exsheets_vary:w }

\NewDocumentCommand \lastvariant { }
  { \exsheets_last_variant: }

% initiate: two variations, first is default
\SetVariations { 2 }
\variant    { 1 }

% ----------------------------------------------------------------------------
% grades distribution
\cs_new:Npn \__exsheets_fp_round_to_half:n #1
  { round( 2*(#1),0)/2 }

\cs_new:Npn \__exsheets_grades_round:n #1
  { round ( #1 , \l__exsheets_grade_round_fp ) }

\cs_new:Npn \__exsheets_grade_rounded:
  {
    \bool_if:NTF { \l__exsheets_grades_half_bool }
      { \__exsheets_fp_round_to_half:n }
      { \__exsheets_grades_round:n }
    { \g_exsheets_total_points_fp * \l__exsheets_tmpa_fp }
  }

\cs_new:Npn \exsheets_strip_braces:N #1
  { \exp_after:wN \__exsheets_strip_braces:w \exp_after:wN #1#1 \q_stop }
\cs_new_protected:Npn \__exsheets_strip_braces:w #1#2 \q_stop
  { \tl_set:Nn #1 {#2} }

\cs_new_protected:Npn \__exsheets_declare_relgrades:n #1
  {
    \clist_set:Nn \l__exsheets_tmpa_clist {#1}
    \clist_map_inline:Nn \l__exsheets_tmpa_clist
      { \__exsheets_declare_relgrade:w ##1 \q_stop }
  }

\cs_new_protected:Npn \__exsheets_declare_relgrade:w #1 = #2 \q_stop
  {
    \tl_set:Nn \l__exsheets_tmpa_tl {#1}
    \tl_set:Nn \l__exsheets_tmpb_tl {#2}
    \tl_trim_spaces:N \l__exsheets_tmpa_tl
    \exsheets_strip_braces:N \l__exsheets_tmpa_tl
    \tl_trim_spaces:N \l__exsheets_tmpb_tl
    \exsheets_strip_braces:N \l__exsheets_tmpb_tl
    \prop_put:NVV \l__exsheets_relgrades_prop
      \l__exsheets_tmpa_tl
      \l__exsheets_tmpb_tl
  }

\NewDocumentCommand \DeclareRelGrades { m }
  { \__exsheets_declare_relgrades:n {#1} }
\@onlypreamble \DeclareRelGrades

\cs_new_protected:Npn \__exsheets_grade:nn #1#2
  {
    \prop_get:NnNTF \l__exsheets_relgrades_prop {#2} \l__exsheets_tmpa_fp
      {
        \bool_if:NTF \l__exsheets_parse_points_bool
          {
            \exsheets_parse_points:n
              { min( \__exsheets_grade_rounded: , \g_exsheets_total_points_fp ) }
            \int_compare:nT { #1 = 1 }
              {
                \exsheets_points_name:n
                  { min( \__exsheets_grade_rounded: , \g_exsheets_total_points_fp ) }
              }
          }
          { \msg_warning:nnn {exsheets} {grade-parse} {#1} \textbf{??} }
      }
      { \msg_warning:nnn {exsheets} {grade-missing} {#1} \textbf{??} }
  }

\NewDocumentCommand \grade { sm }
  {
    \IfBooleanTF {#1}
      { \__exsheets_grade:nn { 0 } {#2} }
      { \__exsheets_grade:nn { 1 } {#2} }
  }

\keys_define:nn { exsheets / grades }
  {
    round .fp_set:N   = \l__exsheets_grade_round_fp ,
    half  .bool_set:N = \l__exsheets_grades_half_bool
  }

% ----------------------------------------------------------------------------
% Aufgaben und Lösungen
\cs_new:Npn \exsheets_glue:N #1
  { \cleaders \vbox:n {} \skip_vertical:N #1 }

% classes, topics and other group concepts:
\cs_new_protected:Npn \exsheets_new_question_class:nn #1#2
  {
    \prop_put:Nnn \l__exsheets_class_prop {#2} {#1}
    \prop_new:c { g__exsheets_questions_#1_prop }
    \prop_new:c { g__exsheets_#2_prop }
    \prop_new:c { g__exsheets_#2_active_prop }
    \bool_new:c { l__exsheets_questions_#1_bool }
    \bool_new:c { g__exsheets_use_#2_bool }
    \bool_new:c { l__exsheets_#1_active_bool }
    \tl_new:c   { l__exsheets_questions_#1_tl }
    \keys_define:nn {exsheets}
      {
        use-#2 .code:n =
          {
            \bool_gset_true:c { g__exsheets_use_#2_bool }
            \use:c { __exsheets_activate_#2:n } {##1}
          } ,
        question / #1 .code:n =
          \bool_set_true:c { l__exsheets_questions_#1_bool }
          \tl_set:cn { l__exsheets_questions_#1_tl } {##1}
      }
    \cs_new_protected:cpn { __exsheets_activate_#2:n } ##1
      {
        \prop_gclear:c { g__exsheets_#2_active_prop }
        \seq_set_split:Nnn \l__exsheets_tmpa_seq { , } {##1}
        \seq_map_inline:Nn \l__exsheets_tmpa_seq
          {
            \prop_gput:cnn { g__exsheets_#2_active_prop }
              {####1} { \__exsheets_dummy: }
          }
      }
    \cs_new_protected:cpn { __exsheets_questions_use_#2: }
      {
        % is there a #1 provided?
        \bool_if:cT { l__exsheets_questions_#1_bool }
          {
            % add #1 to questions property
            \prop_gput:cxx { g__exsheets_questions_#1_prop }
              { \int_to_arabic:n { \g__exsheets_questions_id_int } }
              { \exp_not:v { l__exsheets_questions_#1_tl } }
            % add to #2 list, if it's a new one
            \prop_get:cxNF { g__exsheets_#2_prop }
              { \exp_not:v { l__exsheets_questions_#1_tl } }
              \l__exsheets_tmpa_tl
              {
                \prop_gput:cxn { g__exsheets_#2_prop }
                  { \exp_not:v { l__exsheets_questions_#1_tl } }
                  { \__exsheets_dummy: }
              }
          }
        % are we using #2?
        \bool_if:cT { g__exsheets_use_#2_bool }
          {
            % is this question an active one?
            \prop_get:cxNTF { g__exsheets_#2_active_prop }
              { \exp_not:v { l__exsheets_questions_#1_tl } }
              \l__exsheets_tmpa_tl
              {
                \bool_set_true:c { l__exsheets_#1_active_bool }
                \bool_set_true:N \l__exsheets_use_this_question_bool
              }
              {
                \bool_set_false:c { l__exsheets_#1_active_bool }
                \bool_set_false:N \l__exsheets_questions_print_bool
              }
          }
      }
    \cs_new_protected:cpn { __exsheets_solutions_use_#2: }
      {
        % are we using #2?
        \bool_if:cT { g__exsheets_use_#2_bool }
          {
            % is the question to this solution an active one?
            % get question number from ID
            \prop_get:NVN \g__exsheets_questions_id_prop
              \g__exsheets_questions_current_id_tl
              \l__exsheets_tmpa_tl
            % get question #1 from number
            \prop_get:cVN { g__exsheets_questions_#1_prop }
              \l__exsheets_tmpa_tl
              \l__exsheets_tmpb_tl
            % test if #1 is active
            \prop_get:cVNF { g__exsheets_#2_active_prop }
              \l__exsheets_tmpb_tl
              \l__exsheets_tmpc_tl
              { \bool_set_false:N \l__exsheets_solutions_use_bool }
              % \bool_show:N \l__exsheets_solutions_use_bool
          }
      }
  }

\cs_new_protected:Npn \exsheets_declare_question_class:nn #1#2
  {
    \prop_if_in:NnTF \l__exsheets_class_prop {#2}
      {}
      { \exsheets_new_question_class:nn {#1} {#2} }
  }

\NewDocumentCommand \DeclareQuestionClass { mm }
  { \exsheets_declare_question_class:nn {#1} {#2} }
\@onlypreamble \DeclareQuestionClass

% #1: class name
\cs_new:Npn \exsheets_get_question_class:n #1
  {
    \cs_if_exist:cT { l__exsheets_questions_#1_tl }
      { \tl_use:c { l__exsheets_questions_#1_tl } }
  }

% #1: class name
\DeclareExpandableDocumentCommand \GetQuestionClass { m }
  { \exsheets_get_question_class:n {#1} }

% #1: class name
\prg_new_conditional:Npnn \exsheets_if_question_class:n #1 {T,F,TF}
  {
    \tl_if_blank:fTF { \exsheets_get_question_class:n {#1} }
      { \prg_return_false: }
      { \prg_return_true: }
  }
\cs_generate_variant:Nn \tl_if_blank:nTF {f}

% #1: class name
\cs_new_protected:Npn \exsheets_print_question_class:nTF #1#2#3
  {
    \exsheets_if_question_class:nTF {#1}
      {
        \cs_set_protected:Npn \__exsheets_print_question_class:n ##1 {#2}
        \__exsheets_print_question_class:n
          { \exsheets_get_question_class:n {#1} }
      }
      {#3}
  }

\NewDocumentCommand \PrintQuestionClassTF { mmm }
  { \exsheets_print_question_class:nTF {#1} {#2} {#3} }
\NewDocumentCommand \PrintQuestionClassT { mm }
  { \exsheets_print_question_class:nTF {#1} {#2} {  } }
\NewDocumentCommand \PrintQuestionClassF { mm }
  { \exsheets_print_question_class:nTF {#1} {  } {#2} }

% ----------------------------------------------------------------------------
% question tags:
% #1: ID
% #2: tags
\cs_new_protected:Npn \exsheets_set_question_tags:nn #1#2
  { \prop_gput:Nnn \g__exsheets_tags_prop {#1} {#2} }
\cs_generate_variant:Nn \exsheets_set_question_tags:nn {V}

\cs_new_protected:Npn \exsheets_set_this_question_tags:n #1
  { \exsheets_set_question_tags:Vn \g__exsheets_questions_current_id_tl {#1} }

\keys_define:nn {exsheets}
  {
    use-tags .code:n = \seq_set_split:Nnn \l__exsheets_use_tags_seq {,} {#1} ,
    question / tags .code:n =
      \exsheets_after_begin_question:n { \exsheets_set_this_question_tags:n {#1} }
  }

% #1: ID
\prg_new_protected_conditional:Npnn \exsheets_check_question_tags:n #1 {T,F,TF}
  {
    \bool_set_false:N \l__exsheets_tmpa_bool
    \seq_if_empty:NTF \l__exsheets_use_tags_seq
      { \bool_set_true:N \l__exsheets_tmpa_bool }
      {
        \prop_get:NnN \g__exsheets_tags_prop {#1} \l__exsheets_tmpa_tl
        \seq_map_inline:Nn \l__exsheets_use_tags_seq
          {
            \tl_if_in:NnT \l__exsheets_tmpa_tl {##1}
              {
                \bool_set_true:N \l__exsheets_tmpa_bool
                \seq_map_break:
              }
          }
       }
     \bool_if:NTF \l__exsheets_tmpa_bool
       { \prg_return_true: }
       { \prg_return_false: }
  }
\cs_generate_variant:Nn \exsheets_check_question_tags:nF {V}

% ----------------------------------------------------------------------------
% die 'question' Umgebung
\cs_new:Npn \IfInsideQuestionTF
  { \bool_if:NTF \l__exsheets_inside_question_bool }
\cs_new:Npn \IfInsideQuestionT
  { \bool_if:NT \l__exsheets_inside_question_bool }
\cs_new:Npn \IfInsideQuestionF
  { \bool_if:NF \l__exsheets_inside_question_bool }

\cs_new_eq:NN \exsheets_par: \par

\cs_new_protected:Npn \exsheets_after_begin_question:n #1
  { \tl_put_right:Nn \l__exsheets_after_begin_question_tl {#1} }

\cs_new_protected:Npn \exsheets_add_space:N #1
  {
    \bool_if:nF
      {
        % \l__exsheets_heading_runin_bool ||
        \l__exsheets_heading_inline_bool ||
        \l__exsheets_no_skip_after_bool
      }
      {
        \exsheets_par:
        \dim_compare:nNnT { \parskip } = { 0pt }
          { \exsheets_glue:N #1 }
      }
  }

% #1: pre question hook
% #2: post question hook
\NewEnviron { __exsheets_questions_internal: } [2]
  {
    \__exsheets_start_question_if_used:n {#1}
    \bool_if:nT
      {
        % \l__exsheets_questions_print_bool &amp;&amp;
        \g__exsheets_questions_use_bool &amp;&amp;
        !\l__exsheets_questions_deactivate_bool
      }
      {
        \exsheets_if_current_question_is_used:T
          {
            % label:
            \tl_if_blank:VTF \l__exsheets_questions_label_tl
              {
                \bool_if:NT \l__exsheets_auto_label_bool
                  {
                    \exsheets_label:V \g__exsheets_questions_current_id_tl
                    \exsheets_set_ref_properties:V \CurrentQuestionID
                  }
              }
              {
                \exsheets_label:V \l__exsheets_questions_label_tl
                \exsheets_set_ref_properties:V \l__exsheets_questions_label_tl
              }
            \__exsheets_save_number_in:N \g_exsheets_question_identification_prop
            % TODO: don't print, only save if \l__exsheets_questions_print_bool is false
            \__exsheets_save_and_print_question_body:VVV
              \BODY
              \l__exsheets_questions_pre_body_hook_tl
              \l__exsheets_questions_post_body_hook_tl
            \exsheets_set_question_properties:x
              {
                \tl_if_blank:VF \l__exsheets_questions_subtitle_tl
                  { subtitle = { \exp_not:V \l__exsheets_questions_subtitle_tl } , }
                counter = \l__exsheets_qu_counter_interpretation_tl ,
                % number  = \int_to_arabic:V \g__exsheets_questions_id_int ,
                \bool_if:NF \l__exsheets_points_questions_default_bool
                  {
                    \fp_compare:nT { \g__exsheets_this_question_points_fp &gt; 0 }
                      { points = \fp_to_decimal:N \g__exsheets_this_question_points_fp , }
                    \fp_compare:nT { \g__exsheets_this_question_bonus_fp &gt; 0 }
                      { bonus-points = \fp_to_decimal:N \g__exsheets_this_question_bonus_fp }
                  }
              }
            \bool_if:NT \l__exsheets_questions_print_bool {#2}
          }
      }
  }

% #1: body
% #2: pre body hook
% #3: post body hook
\cs_new_protected:Npn \__exsheets_save_and_print_question_body:nnn #1#2#3
  {
    \group_begin:
      \bool_if:NF \l__exsheets_save_question_body_to_aux_bool
        { \@fileswfalse }
      \exsheets_set_question_properties:n { question-body = {#1} }
    \group_end:
    \bool_if:NT \l__exsheets_questions_print_bool
      {
        #2 { #1 } #3
        \exsheets_add_space:N \l__exsheets_questions_skip_below_dim
      }
  }
\cs_generate_variant:Nn \__exsheets_save_and_print_question_body:nnn { VVV }

\prg_new_conditional:Npnn \exsheets_if_question_subtitle: { p,T,F,TF }
  {
    \tl_if_blank:VTF \l__exsheets_questions_subtitle_tl
      { \prg_return_false: }
      { \prg_return_true: }
  }

\cs_new:Npn \IfQuestionSubtitleTF { \exsheets_if_question_subtitle:TF }
\cs_new:Npn \IfQuestionSubtitleT  { \exsheets_if_question_subtitle:T }
\cs_new:Npn \IfQuestionSubtitleF  { \exsheets_if_question_subtitle:F }

\cs_new_protected:Npn \__exsheets_read_points:w #1 ! #2 ! #3 \q_stop
  {
    \tl_if_blank:nTF {#1}
      {
        \bool_set_true:N \l__exsheets_only_print_points_bool
        \tl_set:Nn \l__exsheets_questions_points_tl {#2}
      }
      {
        \bool_set_false:N \l__exsheets_only_print_points_bool
        \__exsheets_read_points_aux:w #1++ \q_stop
      }
  }

\cs_new_protected:Npn \__exsheets_read_points_aux:w #1+#2+#3 \q_stop
  {
    \tl_if_blank:nTF {#1}
      { \fp_zero:N \l__exsheets_question_points_fp }
      { \fp_set:Nn \l__exsheets_question_points_fp {#1} }
    \tl_if_blank:nTF {#2}
      { \fp_zero:N \l__exsheets_question_bonus_fp }
      {
        \tl_if_blank:nTF {#3}
          { \fp_zero:N \l__exsheets_question_bonus_fp }
          { \fp_set:Nn \l__exsheets_question_bonus_fp {#2} }
      }
  }
\cs_new_protected:Npn \__exsheets_read_points:n #1
  {
    \bool_if:NTF \l__exsheets_parse_points_bool
      { \__exsheets_read_points:w #1!! \q_stop }
      { \tl_set:Nn \l__exsheets_questions_points_tl {#1} }
  }

\cs_new:Npn \exsheets_label_format:n #1 { qu:#1 }
\cs_new:Npn \__exsheets_label:n { \label }
\cs_new:Npn \exsheets_label:n { }
\cs_generate_variant:Nn \exsheets_label:n { V }
\cs_new:Npn \__exsheets_ref:n { \ref }
\cs_new:Npn \exsheets_ref:n { }
\cs_new:Npn \__exsheets_pageref:n { \pageref }
\cs_new:Npn \exsheets_pageref:n { }

\cs_new_protected:Npn \exsheets_update_referencing_command:NN #1#2
  {
    \cs_set:Npx #1 ##1
      { \exp_not:o {#2} { \exsheets_label_format:n {##1} } }
  }

\cs_new_protected:Npn \exsheets_update_referencing_commands:
  {
    \exsheets_update_referencing_command:NN \exsheets_label:n \__exsheets_label:n
    \exsheets_update_referencing_command:NN \exsheets_ref:n \__exsheets_ref:n
    \exsheets_update_referencing_command:NN \exsheets_pageref:n \__exsheets_pageref:n
  }

\cs_new_protected:Npn \exsheets_set_ref_properties:n #1
  {
    \exsheets_set_question_properties:x
      {
        ref = \exp_not:o { \exsheets_ref:n {#1} } ,
        pageref = \exp_not:o { \exsheets_pageref:n {#1} }
      }
  }
\cs_generate_variant:Nn \exsheets_set_ref_properties:n { V }

\exsheets_update_referencing_commands:

\cs_new_protected:Npn \__exsheets_determine_question_usage:
  {
    \tl_gclear:N \g__exsheets_use_current_question_tl
    \prop_map_inline:Nn \l__exsheets_class_prop
      {
        \use:c { __exsheets_questions_use_##1: }
        \bool_if:nTF
          {
            (
              \l__exsheets_use_this_question_bool
                &amp;&amp;
              \bool_if_p:c { l__exsheets_##2_active_bool }
            )
              ||
            ! \bool_if_p:c { g__exsheets_use_##1_bool }
          }
          { \tl_gput_right:Nn \g__exsheets_use_current_question_tl { y } }
          { \tl_gput_right:Nn \g__exsheets_use_current_question_tl { n } }
      }
  }

\prg_new_protected_conditional:Npnn \exsheets_if_current_question_is_used: { T,F,TF }
  {
    \tl_if_in:NnTF \g__exsheets_use_current_question_tl { n }
      { \prg_return_false: }
      { \prg_return_true: }
  }

% #1: options
\cs_new_protected:Npn \__exsheets_question_start:n #1
  {
    \bool_set_true:N \l__exsheets_inside_question_bool
    \bool_if:NT \l__exsheets_questions_use_bool
      { \bool_gset_true:N \g__exsheets_questions_use_bool }
    % Optionen:
    \tl_if_blank:nF {#1} { \keys_set:nn { exsheets / question } {#1} }
    % ID:
    \__exsheets_determine_question_usage:
    \bool_if:nT
      { 
        (\l__exsheets_questions_deactivate_bool &amp;&amp; \l__exsheets_select_questions_bool)
          ||
        !\l__exsheets_select_questions_bool
      }
      {
        \int_gincr:N \g__exsheets_questions_id_int
        \tl_if_blank:VTF \l__exsheets_questions_id_tl
          {
            \tl_gset:Nx \g__exsheets_questions_current_id_tl
              { \int_use:N \g__exsheets_questions_id_int }
          }
          {
            \tl_gset:Nx \g__exsheets_questions_current_id_tl
              { \tl_use:N \l__exsheets_questions_id_tl }
          }
      }
    \tl_use:N \l__exsheets_after_begin_question_tl
    \tl_clear:N \l__exsheets_after_begin_question_tl
  }

% #1: points or blank
\cs_new_protected:Npn \__exsheets_question_points:n #1
  {
    % Punktevergabe:
    \fp_gzero:N \g__exsheets_this_question_points_fp
    \fp_gzero:N \g__exsheets_this_question_bonus_fp
    \tl_if_blank:nTF {#1}
      {
        \__exsheets_read_points:n { 0 }
        \bool_if:NT \l__exsheets_points_questions_default_bool
          {
            \fp_set_eq:NN
              \l__exsheets_question_points_fp
              \l__exsheets_points_default_fp
            % check if moving this to a later point has negative effects...
            % \exsheets_set_question_properties:x
            %   { points = \fp_to_tl:N \l__exsheets_points_default_fp }
          }
      }
      {
        \fp_gset_eq:NN
          \g__exsheets_this_question_points_fp
          \l__exsheets_question_points_fp
        \fp_gset_eq:NN
          \g__exsheets_this_question_bonus_fp
          \l__exsheets_question_bonus_fp
        \__exsheets_read_points:n {#1}
        % check if moving this to a later point has negative effects...
        % \exsheets_set_question_properties:n { points = #2 }
      }
  }

% #1: pre question hook
\cs_new_protected:Npn \__exsheets_start_question_if_used:n #1
  {
    \tl_if_blank:VT \l__exsheets_question_heading_instance_tl
      {
        \tl_set_eq:NN
          \l__exsheets_question_heading_instance_tl
          \l__exsheets_heading_instance_tl
      }
    % Auswahl der Frage:
    \__exsheets_select_question:V \g__exsheets_questions_current_id_tl
    \prop_map_inline:Nn \l__exsheets_class_prop
      { \use:c { __exsheets_questions_use_##1: } }
    \exsheets_check_question_tags:VF \g__exsheets_questions_current_id_tl
      { \bool_gset_false:N \g__exsheets_questions_use_bool }
    \bool_if:nT
      {
        \g__exsheets_questions_use_bool &amp;&amp;
        !\l__exsheets_questions_deactivate_bool
      }
      {
        \exsheets_if_current_question_is_used:T
          { \refstepcounter {question} }
        \__exsheets_get_sectioning_numbers:
        \bool_if:nT
          {
            (
              \l__exsheets_points_questions_default_bool &amp;&amp;
              \l__exsheets_parse_points_bool
            ) ||
            (
              \l__exsheets_parse_points_bool%  &amp;&amp;
              % \l__exsheets_questions_print_bool
            )
          }
          {
            \exsheets_if_current_question_is_used:T
              {
                \exsheets_add_points:V \l__exsheets_question_points_fp
                \exsheets_add_bonus:V  \l__exsheets_question_bonus_fp
              }
          }
        \tl_if_blank:VTF \l__exsheets_questions_id_tl
          {
            \tl_set:Nx \l__exsheets_tmpa_tl
               { \int_use:N \g__exsheets_questions_id_int }
          }
          {
            \tl_set_eq:NN
              \l__exsheets_tmpa_tl
              \l__exsheets_questions_id_tl
          }
        \tl_set_eq:NN \CurrentQuestionID \l__exsheets_tmpa_tl
        \bool_if:NT \l__exsheets_questions_print_bool
          {
            \bool_if:NTF \l__exsheets_exam_bool
              {
                \tl_set_eq:NN
                  \l__exsheets_questions_title_tl
                  \l__exsheets_questions_name_tl
              }
              {
                \tl_set_eq:NN
                  \l__exsheets_questions_title_tl
                  \l__exsheets_exercise_name_tl
              }
            \bool_if:nTF
              { \l__exsheets_parse_points_bool &amp;&amp; !\l__exsheets_only_print_points_bool }
              {
                #1
                \exsheets_use_heading:VVVVnV
                  \l__exsheets_question_heading_instance_tl
                  \l__exsheets_questions_title_tl
                  \l__exsheets_qu_counter_interpretation_tl
                  \l__exsheets_question_points_fp
                  { \l__exsheets_question_bonus_fp }
                  \l__exsheets_tmpa_tl
              }
              {
                \bool_if:NT \l__exsheets_only_print_points_bool
                  { \bool_set_false:N \l__exsheets_parse_points_bool }
                % might be dangerous to expand here...
                \tl_if_blank:xTF { \l__exsheets_questions_points_tl }
                  {
                    #1
                    \exsheets_use_heading:VVVnnV
                      \l__exsheets_question_heading_instance_tl
                      \l__exsheets_questions_title_tl
                      \l__exsheets_qu_counter_interpretation_tl
                      {0}
                      {0}
                      \l__exsheets_tmpa_tl
                  }
                  {
                    #1
                    \exsheets_use_heading:VVVVnV
                      \l__exsheets_question_heading_instance_tl
                      \l__exsheets_questions_title_tl
                      \l__exsheets_qu_counter_interpretation_tl
                      \l__exsheets_questions_points_tl
                      {0}
                      \l__exsheets_tmpa_tl
                  }
              }
          }
      }
  }
\cs_generate_variant:Nn \__exsheets_start_question_if_used:n {V}

\newenvironment { __exsheets_question: } [2]
  {
    \__exsheets_question_start:n {#1}
    \__exsheets_question_points:n {#2}
    \exp_args:NVV \__exsheets_questions_internal:
      \l__exsheets_questions_pre_hook_tl
      \l__exsheets_questions_post_hook_tl
  }
  {
    \end__exsheets_questions_internal:
  }

% current question number:
\cs_new_protected:Npn \exsheets@save@number #1#2
  { \expandafter\global\expandafter\edef\csname exsheets@question@#1\endcsname{#2} }

\cs_new_protected:Npn \__exsheets_save_number_in_aux_x:Nnn #1#2#3
  {
    \prop_gput:Nfx #1 {#2} {#3}
    \exsheets_write_to_aux_x:n { \exsheets@save@number {#2} {#3} }
  }

\cs_new_protected:Npn \__exsheets_save_number_in:N #1
  {
    \bool_if:NTF \l__exsheets_print_number_bool
      {
        \cs_if_exist:NTF \thechapter
          {
            \__exsheets_save_number_in_aux_x:Nnn #1
              { \int_use:N \g__exsheets_questions_id_int }
              { \arabic{chapter}-\arabic{section}-\arabic{question} }
          }
          {
            \__exsheets_save_number_in_aux_x:Nnn #1
              { \int_use:N \g__exsheets_questions_id_int }
              { -\arabic{section}-\arabic{question} }
          }
      }
      {
        \cs_if_exist:NTF \thechapter
          {
            \__exsheets_save_number_in_aux_x:Nnn #1
              { \int_use:N \g__exsheets_questions_id_int }
              { @@@\arabic{chapter}-\arabic{section}-\arabic{question} }
          }
          {
            \__exsheets_save_number_in_aux_x:Nnn #1
              { \int_use:N \g__exsheets_questions_id_int }
              { @@@-\arabic{section}-\arabic{question} }
          }
      }
  }

% #1: prop
% #2: id
% #3: code
\cs_new_protected:Npn \__exsheets_restore_number_from_and_do:Nnn #1#2#3
  {
    \prop_get:NnNT #1 {#2} \l__exsheets_tmpc_tl
      {
        \exp_after:wN
        \__exsheets_read_number:w \l__exsheets_tmpc_tl \q_stop
        #3
      }
    % use \exsheets_read_counter_settings:V \l__exsheets_qu_counter_format_tl
    % afterwards to print the number
  }
\cs_generate_variant:Nn \__exsheets_restore_number_from_and_do:Nnn { NV }

\DeclareExpandableDocumentCommand \QuestionNumber {m}
  { \exsheets_question_number:n {#1} }

\cs_new:Npn \exsheets_question_number:n #1
  { \exsheets_get_question_property:nn {counter} {#1} }
 
% \cs_new_protected:Npn \__exsheets_question_number:N #1
%   {
%     \cs_if_exist:NTF #1
%       {
%         \exp_after:wN \__exsheets_get_question_number:w #1 \q_stop
%         \ReadCounterPatternFrom [exsheets] \l__exsheets_qu_counter_pattern_tl
%       }
%       { \textbf {??} }
%   }
% \cs_generate_variant:Nn \__exsheets_question_number:N { c }

% \cs_new_protected:Npn \__exsheets_get_question_number:w #1-#2-#3 \q_stop
%   {
%     \cs_if_exist:NT \thechapter
%       { \int_set:Nn \l__exsheets_counter_ch_int {#1} }
%     \int_set:Nn \l__exsheets_counter_sec_int {#2}
%     \int_set:Nn \l_exsheets_counter_qu_int {#3}
%   }

% map ID's to number of used questions
\cs_new_protected:Npn \exsheets@used@id #1#2
  { \prop_gput:Nnn \g__exsheets_questions_used_prop {#1} {#2} }

\cs_new_protected:Npn \__exsheets_mark_as_used:n #1
  {
    \int_gincr:N \g__exsheets_questions_used_int
    \prop_gput_if_new:Nxx \g__exsheets_questions_used_prop
      {#1}
      { \int_use:N \g__exsheets_questions_used_int }
    \exsheets_write_to_aux_x:n
      { \exsheets@used@id {#1} { \int_use:N \g__exsheets_questions_used_int } }
  }

% ----------------------------------------------------------------------------
% title of a question:
\cs_if_exist:NF \exsheets_headings_files_loaded:
  {
    \file_input:n {exsheets_headings.def}
    \file_input:n {exsheets_headings.cfg}
  }

% #1: instance
% #2: title
% #3: number
% #4: points
% #5: bonus
% #6: id
\cs_new_protected:Npn \exsheets_use_heading:nnnnnn #1#2#3#4#5#6
  {
    \IfInstanceExistTF {exsheets-heading} {#1}
      { \UseInstance {exsheets-heading} {#1} }
      {
        \msg_warning:nnx {exsheets} {headings} {#1}
        \UseInstance {exsheets-heading} {block}
      }
    {#2} {#3} {#4} {#5} {#6}
  }
\cs_generate_variant:Nn \exsheets_use_heading:nnnnnn { V , VVVnnV , VVVVnV }

\NewDocumentCommand \ExSheetsHeading { mmmmmm }
  { \exsheets_use_heading:nnnnnn {#1} {#2} {#3} {#4} {#5} {#6} }

% options for the questions:
\keys_define:nn { exsheets / question }
  {
    type            .choice: ,
    type / exam     .code:n      =
      \bool_set_true:N \l__exsheets_exam_bool ,
    type / exercise .code:n      =
      \bool_set_false:N \l__exsheets_exam_bool ,
    name            .code:n      =
      \tl_set:Nn \l__exsheets_exercise_name_tl {#1}
      \tl_set:Nn \l__exsheets_questions_name_tl {#1} ,
    headings        .tl_set:N    = \l__exsheets_question_heading_instance_tl ,
    subtitle        .tl_set:N    = \l__exsheets_questions_subtitle_tl ,
    print           .bool_set:N  = \l__exsheets_questions_print_bool ,
    print           .default:n   = true ,
    ID              .tl_set:N    = \l__exsheets_questions_id_tl ,
    label           .tl_set:N    = \l__exsheets_questions_label_tl ,
    use             .choice: ,
    use / true      .code:n      =
      \bool_gset_true:N \g__exsheets_questions_use_bool
      \bool_set_true:N  \l__exsheets_questions_use_bool ,
    use / false     .code:n      =
      \bool_gset_false:N \g__exsheets_questions_use_bool
      \bool_set_false:N  \l__exsheets_questions_use_bool ,
    use             .default:n   = true ,
    skip-below      .dim_set:N   = \l__exsheets_questions_skip_below_dim ,
    no-skip-below   .bool_set:N  = \l__exsheets_no_skip_after_bool ,
    pre-hook        .tl_set:N    = \l__exsheets_questions_pre_hook_tl ,
    post-hook       .tl_set:N    = \l__exsheets_questions_post_hook_tl ,
    pre-body-hook   .tl_set:N    = \l__exsheets_questions_pre_body_hook_tl ,
    post-body-hook  .tl_set:N    = \l__exsheets_questions_post_body_hook_tl ,
    save-to-aux     .bool_set:N  = \l__exsheets_save_question_body_to_aux_bool
  }

% ----------------------------------------------------------------------------
% using ``metadata'':
\cs_new_protected:Npn \exsheets_declare_question_property:n #1
  {
    \prop_new:c { g__exsheets_question_property_#1_prop }
    \keys_define:nn { question / meta }
      { #1 .code:n = \__exsheets_question_set_property:nn {#1} {##1} }
  }

\NewDocumentCommand \DeclareQuestionProperty { m }
  { \exsheets_declare_question_property:n {#1} }
\@onlypreamble \DeclareQuestionProperty

\cs_new_protected:Npn \exsheets_set_question_properties:n #1
  {
    \@bsphack
      \bool_if:NTF \l__exsheets_inside_question_bool
        { \keys_set:nn { question / meta } {#1} }
        { \msg_error:nnn {exsheets} {only-inside-question} {\SetQuestionProperties} }
    \@esphack
  }
\cs_generate_variant:Nn \exsheets_set_question_properties:n { x }

% #1: property
% #2: ID
\prg_new_conditional:Npnn \exsheets_if_question_property:nn #1#2 {T,F,TF}
  {
    \prop_if_in:cnTF { g__exsheets_question_property_#1_prop } {#2}
      { \prg_return_true: }
      { \prg_return_false: }
  }
\DeclareExpandableDocumentCommand \IfQuestionPropertyTF { }
  { \exsheets_if_question_property:nnTF }
\DeclareExpandableDocumentCommand \IfQuestionPropertyT { }
  { \exsheets_if_question_property:nnT }
\DeclareExpandableDocumentCommand \IfQuestionPropertyF { }
  { \exsheets_if_question_property:nnF }

\NewDocumentCommand \SetQuestionProperties { +m }
  { \exsheets_set_question_properties:n {#1} }

% #1: ID
% #2: property
% #3: value
\cs_new_protected:Npn \exsheets@question@property #1#2#3
  {
    \prop_gput:cnn { g__exsheets_question_property_#2_prop }
      {#1} {#3}
  }

% #1: property
% #2: value
\cs_new_protected:Npn \__exsheets_question_set_property:nn #1#2
  {
    \prop_gput:cVn { g__exsheets_question_property_#1_prop }
      \CurrentQuestionID {#2}
    % watch if this has negativ effects:
    \exsheets_write_to_aux_x:n
      {
        \exp_not:N \exsheets@question@property
          { \CurrentQuestionID }
          { \exp_not:n {#1} }
          { \exp_not:n {#2} }
      }
  }

% #1: property
% #2: ID
\DeclareExpandableDocumentCommand \GetQuestionProperty { mm }
  { \exsheets_get_question_property:no {#1} {#2} }

\cs_new:Npn \exsheets_get_question_property:nn #1#2
  {
    \prop_if_in:cnTF { g__exsheets_question_property_#1_prop } {#2}
      { \prop_item:cn { g__exsheets_question_property_#1_prop } {#2} }
      { ?? }
  }
\cs_generate_variant:Nn \exsheets_get_question_property:nn { no , nV }

\cs_new_protected:Npn \exsheets_for_each_question_do:n #1
  {
    \int_gzero:N \g__exsheets_tmpa_int
    \prop_map_inline:Nn \g__exsheets_questions_used_prop
      { \int_gincr:N \g__exsheets_tmpa_int #1 }
  }

\NewDocumentCommand \ForEachQuestion {m}
  { \exsheets_for_each_question_do:n {#1} }

\cs_new:Npn \iflastquestion
  {
    \int_compare:nTF
      { \numberofquestions = \g__exsheets_tmpa_int }
  }

\cs_if_exist:NF \numberofquestions
  {
    \cs_new:Npn \numberofquestions
      { \int_to_arabic:V \g__exsheets_questions_used_int }
  }

% ----------------------------------------------------------------------------
% debug-Info:
\RequirePackage {xcolor}
\colorlet {exsheetsdebugcolor} {yellow}

\keys_define:nn {exsheets}
  {
    debug .bool_set:N = \l__exsheets_questions_debug_bool
  }

\cs_new_protected:Npn \exsheets_debug_box:nn #1#2
  {
    \par
    \noindent
    \group_begin:
      \normalfont\normalsize\normalcolor
      \colorbox {exsheetsdebugcolor}
        { \parbox { \dim_eval:n { #1  - 2 \fboxsep } } {#2} }
    \group_end:
    \par
  }

\cs_new:Npn \__exsheets_list_comma: {}

\cs_new_protected:Npn \exsheets_questions_debug:n #1
  {
    \bool_if:nT
      { \l__exsheets_questions_debug_bool &amp;&amp; \l__exsheets_inside_question_bool }
      {
        \exsheets_debug_box:nn { \linewidth }
          {
            \textbf {ID} :~ \textit {#1}
            \prop_map_inline:Nn \l__exsheets_class_prop
              {
                \bool_if:cT { l__exsheets_questions_##2_bool }
                  {
                    ;~  \textbf {##2} :~
                    \textit { \tl_use:c { l__exsheets_questions_##2_tl } }
                  }
              }
            \prop_get:NnN \g__exsheets_tags_prop
              {#1}
              \l__exsheets_tmpa_tl
            \quark_if_no_value:VTF \l__exsheets_tmpa_tl
              { ;~ \textbf {not~tagged} }
              {
                ;~ \textbf {tags} : ~
                \seq_set_split:NnV \l__exsheets_tmpa_seq
                  {,}
                  \l__exsheets_tmpa_tl
                \textit { \seq_use:Nn \l__exsheets_tmpa_seq {,~} }
              }
          }
      }
  }

\exsheets_deprecate_cs:Npnn \DebugExSheets #1
  {the~ option~ debug}
  { \keys_set:nn {exsheets} { debug = #1 } }

% ----------------------------------------------------------------------------
% include random/selected questions from a file:
\cs_new_protected:Npn \exsheets_file_input_if_exist:n #1
  { \file_if_exist:nT {#1} { \file_input:n {#1} } }
\cs_new_protected:Npn \exsheets_file_input_if_exist:nF #1#2
  { \file_if_exist:nTF {#1} { \file_input:n {#1} } {#2} }

\cs_new_protected:Npn \exsheets_prop_count:N #1
  {
    \__exsheets_prop_count:NN #1 \l__exsheets_tmpa_int
    \int_use:N \l__exsheets_tmpa_int
  }

\cs_new_protected:Npn \__exsheets_prop_count:NN #1#2
  {
    \int_zero:N #2
    \prop_map_inline:Nn #1
      { \int_incr:N #2 }
  }

\NewDocumentCommand \includequestions { om }
  {
    \group_begin:
      \IfNoValueF {#1}
        { \keys_set:nn { exsheets / include } {#1} }
      \exsheets_include_questions:n {#2}
    \group_end:
  }

\cs_new_protected:Npn \exsheets_include_questions:n #1
  {
    \bool_set_true:N \l__exsheets_select_questions_bool
    \clist_gclear:N \questionsincludedlast
    \seq_set_split:Nnn \l__exsheets_tmpa_seq { , } {#1}
    \seq_map_inline:Nn \l__exsheets_tmpa_seq
      {
        \bool_set_true:N \l__exsheets_questions_deactivate_bool
        \int_set_eq:NN
          \l__exsheets_questions_set_int
          \g__exsheets_questions_used_int
        \int_set_eq:NN
          \l__exsheets_tmpc_int
          \g__exsheets_questions_id_int
        \int_gzero:N \g__exsheets_select_random_int
        \exsheets_file_input_if_exist:nF {##1}
          { \msg_error:nnn {exsheets} {file-not-found} {##1} }
        \__exsheets_prop_count:NN
          \g__exsheets_included_questions_prop
          \l__exsheets_tmpa_int
        \bool_if:NT \l__exsheets_questions_debug_bool
          {
            \exsheets_debug_box:nn
              { \linewidth }
              {
                The~file~ ` \texttt { \tl_to_str:n {##1} } ' ~contains~
                \exsheets_prop_count:N \g__exsheets_included_questions_prop
                \c_space_tl questions~with~the~following~IDs:\par
                \cs_set_protected:Npn \__exsheets_list_comma:
                  { \cs_set:Npn \__exsheets_list_comma: { ,~ } }
                \prop_map_inline:Nn \g__exsheets_included_questions_prop
                  { \__exsheets_list_comma: ####2 }
              }
          }
        \bool_set_false:N \l__exsheets_questions_deactivate_bool
        \int_set_eq:NN    \l__exsheets_tmpd_int \g__exsheets_questions_id_int
        \int_gset_eq:NN   \g__exsheets_questions_id_int \l__exsheets_tmpc_int
        \bool_if:NT \l__exsheets_include_questions_no_duplicates_bool
          {
            \seq_map_inline:Nn \g_exsheets_included_questions_seq
              { \clist_put_right:Nn \l__exsheets_exclude_id_clist {####1} }
          }
        \__exsheets_select_question_random:n {##1}
        \exsheets_file_input_if_exist:n {##1}
        \int_gset_eq:NN   \g__exsheets_questions_id_int \l__exsheets_tmpd_int
        \prop_gclear:N    \g__exsheets_included_questions_prop
        \clist_clear:N    \l__exsheets_include_id_clist
        \clist_clear:N    \l__exsheets_exclude_id_clist
        \int_gzero:N      \g__exsheets_selection_number_int
        % \seq_show:N \g_exsheets_included_questions_seq
      }
    \bool_set_false:N \l__exsheets_select_questions_bool
  }

% options:
%  - IDs=&lt;list of IDs&gt;
%  - all=true|false    % default when no option is given
%  - random=&lt;num&gt;
%  - exclude=&lt;list of IDs&gt;
\keys_define:nn { exsheets / include }
  {
    all     .bool_set:N  = \l__exsheets_include_all_bool ,
    IDs     .code:n      =
      \bool_set_false:N \l__exsheets_include_all_bool
      \bool_set_false:N \l__exsheets_include_random_bool
      \bool_set_true:N  \l__exsheets_include_by_id_bool
      \clist_set:Nn \l__exsheets_include_id_clist {#1} ,
    % the `exclude' option does _not_ set \l__exsheets_include_random_bool ,
    % \l__exsheets_include_by_id_bool or \l__exsheets_include_all_bool so
    % it can be combined with the other options:
    exclude .clist_set:N = \l__exsheets_exclude_id_clist ,
    random  .code:n      =
      \bool_set_false:N \l__exsheets_include_all_bool
      \bool_set_true:N  \l__exsheets_include_random_bool
      \bool_set_false:N \l__exsheets_include_by_id_bool
      \int_set:Nn \l__exsheets_include_random_int {#1} ,
    no-duplicates .bool_set:N = \l__exsheets_include_questions_no_duplicates_bool
  }

\cs_new_protected:Npn \__exsheets_select_question:n #1
  {
    \bool_if:NTF \l__exsheets_select_questions_bool
      {
        \bool_if:NTF \l__exsheets_questions_deactivate_bool
          {
            \bool_if:NT \l__exsheets_questions_use_bool
              {
                \int_gincr:N \g__exsheets_selection_number_int
                \bool_if:NTF \l__exsheets_include_random_bool
                  {
                    \prop_gput:Nxn \g__exsheets_included_questions_prop
                      { \int_use:N \g__exsheets_selection_number_int } {#1}
                  }
                  {
                    \prop_gput:Nxn \g__exsheets_included_questions_prop
                      { \int_use:N \g__exsheets_questions_id_int } {#1}
                  }
              }
          }
          {
            \int_gincr:N \g__exsheets_questions_id_int
            \bool_if:NTF \l__exsheets_include_random_bool
              {
                \int_gincr:N \g__exsheets_select_random_int
                \int_set_eq:NN \l__exsheets_tmpa_int \g__exsheets_select_random_int
%                 ID: \int_use:N \g__exsheets_questions_id_int ,~
%                 set: \int_use:N \l__exsheets_questions_set_int ,~
%                 selection: \int_use:N \g__exsheets_selection_number_int ,~
%                 tmpa: \int_use:N \l__exsheets_tmpa_int \par
              }
              {
                \int_set_eq:NN
                  \l__exsheets_tmpa_int
                  \g__exsheets_questions_id_int
              }
            \prop_get:NxN \g__exsheets_included_questions_prop
              { \int_use:N \l__exsheets_tmpa_int }
              \l__exsheets_tmpa_tl
            \__exsheets_select_question_by_id:V \l__exsheets_tmpa_tl
          }
      }
      {
        \__exsheets_use_question:n {#1}
      }
  }
\cs_generate_variant:Nn \__exsheets_select_question:n { V }

\cs_new_protected:Npn \__exsheets_select_question_by_id:n #1
  {
    \bool_if:NTF \l__exsheets_include_all_bool
      {% parsing list of excluded IDs
        \clist_if_in:NnTF
          \l__exsheets_exclude_id_clist
          {#1}
          { \bool_gset_false:N  \g__exsheets_questions_use_bool }
          {
            \bool_gset_true:N \g__exsheets_questions_use_bool
            \clist_gput_right:Nn \questionsincludedlast {#1}
            \seq_gput_right:Nn \g_exsheets_included_questions_seq {#1}
            \__exsheets_use_question:n {#1}
          }
      }
      {% parsing list of included IDs
        \clist_if_in:NnTF
          \l__exsheets_include_id_clist
          {#1}
          {
            \clist_if_in:NnTF
              \l__exsheets_exclude_id_clist
              {#1}
              { \bool_gset_false:N \g__exsheets_questions_use_bool }
              {
                \bool_gset_true:N  \g__exsheets_questions_use_bool
                \clist_gput_right:Nn \questionsincludedlast {#1}
                \seq_gput_right:Nn \g_exsheets_included_questions_seq {#1}
                \__exsheets_use_question:n {#1}
                % \exsheets_if_current_question_is_used:T
                %   { \__exsheets_mark_as_used:n {#1} }
                % \prop_gput:NnV \g__exsheets_questions_id_prop
                %   {#1}
                %   \g__exsheets_questions_id_int
              }
          }
          { \bool_gset_false:N \g__exsheets_questions_use_bool }
      }
  }
\cs_generate_variant:Nn \__exsheets_select_question_by_id:n { V }

\cs_new_protected:Npn \__exsheets_use_question:n #1
  {
    \exsheets_if_current_question_is_used:T
      { \__exsheets_mark_as_used:n {#1} }
    \prop_gput:NnV \g__exsheets_questions_id_prop
      {#1}
      \g__exsheets_questions_id_int
  }

% TODO: poor efficiency -- there should be no need to map through
% \l__exsheets_class_prop *two* times
\cs_new_protected:Npn \__exsheets_select_question_random:n #1
  {
    \bool_if:NT \l__exsheets_include_random_bool
      {
        % number of question in file:
        \__exsheets_prop_count:NN
          \g__exsheets_included_questions_prop
          \l__exsheets_tmpa_int
        % number of selectable questions in file:
        \int_zero:N \l__exsheets_tmpb_int
        \prop_map_inline:Nn \g__exsheets_included_questions_prop
          {
            \prop_map_inline:Nn \l__exsheets_class_prop
              {
                \bool_if:cT { g__exsheets_use_####1_bool }
                  {
                    \bool_set_true:N \l__exsheets_use_selection_bool
                    \prop_get:cnNT { g__exsheets_questions_####2_prop } {##1}
                      \l__exsheets_tmpa_tl
                      {
                        \prop_if_in:cVT { g__exsheets_####1_active_prop }
                          \l__exsheets_tmpa_tl
                          { \int_incr:N \l__exsheets_tmpb_int }
                      }
                  }
              }
          }
        \int_compare:nTF { \l__exsheets_include_random_int &gt;= \l__exsheets_tmpa_int }
          {
            % not enough questions available:
            \msg_warning:nnxxx {exsheets} {random-file}
              { \int_use:N \l__exsheets_include_random_int }
              {#1}
              { \int_use:N \l__exsheets_tmpa_int }
            \bool_set_true:N \l__exsheets_include_all_bool
          }
          {
            \bool_if:nTF
              {
                \int_compare_p:n
                  { \l__exsheets_include_random_int &gt;= \l__exsheets_tmpb_int }
                  &amp;&amp;
                \l__exsheets_use_selection_bool
              }
              {
                % not enough questions selectable:
                \msg_warning:nnxxxx {exsheets} {random-selectable}
                  { \int_use:N \l__exsheets_include_random_int }
                  {#1}
                  { \int_use:N \l__exsheets_tmpa_int }
                  { \int_use:N \l__exsheets_tmpb_int }
                \bool_set_true:N \l__exsheets_include_all_bool
              }
              {
                \int_zero:N \l__exsheets_tmpb_int
                \int_do_while:nn
                  { \l__exsheets_tmpb_int &lt; \l__exsheets_include_random_int }
                  {
                    \pgfmathparse { random(\int_use:N \l__exsheets_tmpa_int) }
                    \tl_set_eq:NN \l__exsheets_tmpa_tl \pgfmathresult
                    \prop_get:NVN \g__exsheets_included_questions_prop
                      \l__exsheets_tmpa_tl
                      \l__exsheets_tmpb_tl
                    \clist_if_in:NVF \l__exsheets_include_id_clist \l__exsheets_tmpb_tl
                      {
                        \tl_clear:N \l__exsheets_include_id_tl
                        \prop_map_inline:Nn \l__exsheets_class_prop
                          {
                            \prop_get:cVNT { g__exsheets_questions_##2_prop }
                              \l__exsheets_tmpa_tl \l__exsheets_tmpc_tl
                              {
                                \bool_if:cT { g__exsheets_use_##1_bool }
                                  {
                                    \prop_if_in:cVTF { g__exsheets_##1_active_prop }
                                      \l__exsheets_tmpc_tl
                                      { \tl_put_right:Nn \l__exsheets_include_id_tl {y} }
                                      { \tl_put_right:Nn \l__exsheets_include_id_tl {n} }
                                  }
                              }
                          }
                        \bool_set_true:N \l__exsheets_tmpa_bool
                        \clist_if_in:NVT
                          \l__exsheets_exclude_id_clist
                          \l__exsheets_tmpb_tl
                          { \bool_set_false:N \l__exsheets_tmpa_bool }
                        \seq_if_in:NnT
                          \g_exsheets_included_questions_seq
                          \l__exsheets_tmpb_tl
                          { \bool_set_false:N \l__exsheets_tmpa_bool }
                        \tl_if_in:NnT \l__exsheets_include_id_tl {n}
                          { \bool_set_false:N \l__exsheets_tmpa_bool }
                        \bool_if:NT \l__exsheets_tmpa_bool
                        % \tl_if_in:NnF \l__exsheets_include_id_tl { n }
                        %   {
                        %     \clist_if_in:NVF
                        %       \l__exsheets_exclude_id_clist
                        %       \l__exsheets_tmpb_tl
                              {
                                \clist_put_right:NV
                                  \l__exsheets_include_id_clist
                                  \l__exsheets_tmpb_tl
                                \int_incr:N \l__exsheets_tmpb_int
                              }
                         %  }
                      }
                  }
              }
          }
      }
  }
% \cs_generate_variant:Nn \clist_if_in_p:Nn {NV}
% \cs_generate_variant:Nn \seq_if_in_p:Nn   {NV}

\NewDocumentCommand \PrintIfIncludeActiveTF { mm }
  { \bool_if:NTF \l__exsheets_questions_deactivate_bool {#2} {#1} }

\NewDocumentCommand \PrintIfIncludeActiveT { }
  { \bool_if:NF \l__exsheets_questions_deactivate_bool }

\NewDocumentCommand \PrintIfIncludeActiveF { }
  { \bool_if:NT \l__exsheets_questions_deactivate_bool }

% ----------------------------------------------------------------------------
% die 'solution' Umgebung:
\cs_new_protected:Npn \__exsheets_save_solution:n #1
  {
    % save for later use
    \bool_if:NTF \l__exsheets_include_all_bool
      { \int_set:Nn \l__exsheets_tmpe_int { \g__exsheets_questions_id_int -1 } }
      { \int_set_eq:NN \l__exsheets_tmpe_int \g__exsheets_questions_id_int }
    \prop_gput:Nxn \g__exsheets_solutions_content_prop
      { \int_use:N \g__exsheets_questions_id_int }
      {#1}
    \prop_gput:NxV \g__exsheets_solutions_questions_id_prop
      { \int_use:N \g__exsheets_questions_id_int }
      \g__exsheets_questions_current_id_tl
    \prop_gput:NxV \g__exsheets_solutions_names_prop
      { \int_use:N \g__exsheets_questions_id_int }
      \l__exsheets_solutions_name_tl
    \prop_gput:NxV \g__exsheets_solutions_counter_prop
      { \int_use:N \g__exsheets_questions_id_int }
      \l__exsheets_qu_counter_pattern_tl
    % print here
    \exsheets_if_current_question_is_used:T
      {
        \bool_if:NT \l__exsheets_solutions_print_bool
          {
            \int_set:Nn \l_exsheets_counter_qu_int { \arabic {question} }
            \__exsheets_get_sectioning_numbers:
            \__exsheets_print_solution:VVn
              \g__exsheets_questions_current_id_tl
              \l__exsheets_solutions_name_tl
              {#1}
          }
      }
  }
\cs_generate_variant:Nn \__exsheets_save_solution:n { V }

\NewEnviron { __exsheets_solution_internal: }
  {
    \bool_if:nT
      { \g__exsheets_questions_use_bool &amp;&amp; \l__exsheets_solutions_use_bool }
      { \__exsheets_save_solution:V \BODY }
  }

\newenvironment {__exsheets_solution:} [1]
  {
    \tl_clear:N \l__exsheets_use_solution_tl
    % \prop_show:N \l__exsheets_class_prop
    \prop_map_inline:Nn \l__exsheets_class_prop
      {
        \use:c {__exsheets_solutions_use_##1:}
        \bool_if:nTF
          {
            \l__exsheets_solutions_use_bool
            &amp;&amp;
            (
              !\bool_if_p:c {g__exsheets_use_##1_bool}
                ||
              \bool_if_p:c {l__exsheets_##2_active_bool}
            )
          }
          { \tl_put_right:Nn \l__exsheets_use_solution_tl {y} }
          { \tl_put_right:Nn \l__exsheets_use_solution_tl {n} }
      }
    % verwende, wenn ein Ja dabei war:
    \tl_if_in:NnT \l__exsheets_use_solution_tl {y}
      { \bool_set_true:N \l__exsheets_solutions_use_bool }
    \bool_if:NT \l__exsheets_questions_deactivate_bool
      { \bool_set_false:N \l__exsheets_solutions_use_bool }
    \bool_if:NT \l__exsheets_solutions_use_bool
      {
        \bool_set_true:N \l__exsheets_inside_solution_bool
        \IfNoValueF {#1} { \keys_set:nn {exsheets/solution} {#1} }
      }
    \tl_if_blank:VT \l__exsheets_solution_heading_instance_tl
      {
        \tl_set_eq:NN
          \l__exsheets_solution_heading_instance_tl
          \l__exsheets_heading_instance_tl
      }
    \__exsheets_solution_internal:
  }
  { \end__exsheets_solution_internal: }

\cs_new_protected:Npn \__exsheets_solutions_name:nnn #1#2#3
  {
    \tl_if_blank:VT \l__exsheets_solution_heading_instance_tl
      {
        \tl_set_eq:NN
          \l__exsheets_solution_heading_instance_tl
          \l__exsheets_heading_instance_tl
      }
    \exsheets_use_heading:Vnnnnn
      \l__exsheets_solution_heading_instance_tl
      {#2} {#1} { 0 } { 0 } {#3}
  }
\cs_generate_variant:Nn \__exsheets_solutions_name:nnn { VV , VVV }

\cs_new:Npn \exsheets_solutions_name_style:n #1
  { \l_exsheets_solutions_name_style_tl #1 }

% ----------------------------------------------------------------------------
% print solutions:
% save section / chapter counter:
\cs_new_protected:Npn \__exsheets_exlabel:n #1
  {
    \@bsphack
      \exsheets_write_to_aux_x:n
        {
          \token_to_str:N \newlabel { exse:#1 }
            { { \arabic {section} } { \thepage } }
        }
      \cs_if_exist:NT \thechapter
        {
          \exsheets_write_to_aux_x:n
            {
              \token_to_str:N \newlabel { exch:#1 }
                { { \arabic {chapter} } { \thepage } }
            }
        }
    \@esphack
  }

% user command:
\cs_new_eq:NN \exlabel \__exsheets_exlabel:n

% adapt \label, maybe do this _after_ BeginDocument:
\bool_if:NT \l__exsheets_solutions_by_ref_bool
  {
    \cs_new_eq:NN \__exsheets_saved_label:n \label
    \cs_set:Npn \label #1
      { \__exsheets_saved_label:n {#1} \__exsheets_exlabel:n {#1} }
  }

% this is like \ref from latex.ltx
\cs_new:Npn \__exsheets_exref:n #1
  {
    \cs_if_exist:cTF { r@#1 }
     { \__exsheets_exref_aux:n {#1} }
     {
       1\relax
       \protect\G@refundefinedtrue
       \@latex@warning{exlabel `#1' on page \thepage \space undefined}%
     }
  }

\cs_new:Npn \__exsheets_exref_aux:n #1
  { \exp_after:wN \exp_after:wN \exp_after:wN \use_i:nn \cs:w r@#1 \cs_end: }

\cs_new_eq:NN \exref \__exsheets_exref:n

% user command:
\NewDocumentCommand \printsolutions { O{all} }
  { \exsheets_print_solutions:n {#1} }

% internal command:
\cs_new_protected:Npn \exsheets_print_solutions:n #1
  {
    \group_begin:
      \bool_set_true:N \l__exsheets_solutions_print_bool
      \bool_set_true:N \l__exsheets_inside_solution_bool
      \cs_set:Npn \S ##1 { \exref { exse:##1 } }
      \cs_set:Npn \C ##1 { \exref { exch:##1 } }
      \keys_set:nn { exsheets / exsheets_print_solutions } {#1}
    \group_end:
  }

\keys_define:nn {exsheets}
  {
    exsheets_print_solutions           .choice: ,
    exsheets_print_solutions / section .code:n    =
      { \exsheets_print_solutions_section:n {#1} } ,
    exsheets_print_solutions / chapter .code:n    =
      { \exsheets_print_solutions_chapter:n {#1} } ,
    exsheets_print_solutions / all     .code:n    =
      { \exsheets_print_solutions_all: } ,
    exsheets_print_solutions / byID    .code:n    =
      { \exsheets_print_solutions_byID:n {#1} }
  }

\cs_new_protected:Npn \__exsheets_get_sectioning_numbers:
  {
    \cs_if_exist:NT \chapter
      { \int_set:Nn \l__exsheets_counter_ch_int { \arabic {chapter} } }
    \int_set:Nn \l__exsheets_counter_sec_int { \arabic {section} }
    \int_set:Nn \l_exsheets_counter_qu_int   { \arabic {question} }
  }

% #1: numeric ID
% #2: condition
\cs_new_protected:Npn \__exsheets_print_solution_if:nn #1#2
  {
    \bool_if:nT
      { #2 &amp;&amp; \prop_if_in_p:Nn \g__exsheets_solutions_questions_id_prop {#1} }
      {
        \prop_get:NnN \g__exsheets_solutions_names_prop
          {#1} \l__exsheets_tmpa_tl
        \prop_get:NnN \g__exsheets_solutions_content_prop
          {#1} \l__exsheets_tmpb_tl
        \prop_get:NnN \g__exsheets_solutions_questions_id_prop
          {#1} \l__exsheets_tmpc_tl
        \prop_get:NnN \g__exsheets_solutions_counter_prop
          {#1} \l__exsheets_tmpd_tl
        \group_begin:
          \tl_set_eq:NN \CurrentQuestionID \l__exsheets_tmpc_tl
          \__exsheets_sectioning_hook:nV {ch}
            \l__exsheets_new_chapter_hook_tl
          \__exsheets_sectioning_hook:nV {sec}
            \l__exsheets_new_section_hook_tl
        \group_end:
        \__exsheets_print_solution:VVV
          \l__exsheets_tmpc_tl
          \l__exsheets_tmpa_tl
          \l__exsheets_tmpb_tl
      }
  }

% print by section:
\cs_new_protected:Npn \exsheets_print_solutions_section:n #1
  {
    \tl_if_blank:nTF {#1}
      {
        \prop_map_inline:Nn \g_exsheets_question_identification_prop
          {
            \__exsheets_print_solutions_section:nnn
              {##1}
              {##2}
              { \arabic{section} }
          }
      }
      {
        \clist_map_inline:nn {#1}
          { \__exsheets_print_solutions_by_section:w ##1-- \q_stop }
      }
  }

\cs_new_protected:Npn \__exsheets_print_solutions_by_section:w #1-#2-#3 \q_stop
  {
    % wenn #3=-, dann range-Input
    \tl_if_eq:nnTF {#3} { - }
      {
        \int_zero:N \l__exsheets_tmpa_int
        \int_set:Nn \l__exsheets_tmpb_int { 10000 }
        \tl_if_blank:nF {#1} { \int_set:Nn \l__exsheets_tmpa_int {#1} }
        \tl_if_blank:nF {#2} { \int_set:Nn \l__exsheets_tmpb_int {#2} }
        \int_do_while:nn { \l__exsheets_tmpa_int &lt;= \l__exsheets_tmpb_int }
          {
            \prop_map_inline:Nn \g_exsheets_question_identification_prop
              {
                \__exsheets_print_solutions_section:nnn
                  {##1} {##2} { \l__exsheets_tmpa_int }
              }
            \int_incr:N \l__exsheets_tmpa_int
          }
      }
      {
        \prop_map_inline:Nn \g_exsheets_question_identification_prop
          { \__exsheets_print_solutions_section:nnn {##1} {##2} {#1} }
      }
  }

\cs_new_protected:Npn \__exsheets_print_solutions_section:nnn #1#2#3
  {
    \__exsheets_read_number:w #2 \q_stop
    \__exsheets_print_solution_if:nn {#1}
      { \int_compare_p:n { \l__exsheets_counter_sec_int = #3 } }
  }

% print by chapter:
\cs_new_protected:Npn \exsheets_print_solutions_chapter:n #1
  {
    \tl_if_blank:nTF {#1}
      {
        \prop_map_inline:Nn \g_exsheets_question_identification_prop
          {
            \__exsheets_print_solutions_chapter:nnn {##1} {##2}
              { \arabic{chapter} }
          }
      }
      {
        \clist_map_inline:nn {#1}
          { \__exsheets_print_solutions_by_chapter:w ##1-- \q_stop }
      }
  }

\cs_new_protected:Npn \__exsheets_print_solutions_by_chapter:w #1-#2-#3 \q_stop
  {
    % wenn #3=-, dann range-Input
    \tl_if_eq:nnTF {#3} { - }
      {
        \int_zero:N \l__exsheets_tmpa_int
        \int_set:Nn \l__exsheets_tmpb_int { 10000 }
        \tl_if_blank:nF {#1} { \int_set:Nn \l__exsheets_tmpa_int {#1} }
        \tl_if_blank:nF {#2} { \int_set:Nn \l__exsheets_tmpb_int {#2} }
        \int_do_while:nn { \l__exsheets_tmpa_int &lt;= \l__exsheets_tmpb_int }
          {
            \prop_map_inline:Nn \g_exsheets_question_identification_prop
              {
                \__exsheets_print_solutions_chapter:nnn
                  {##1}
                  {##2}
                  { \l__exsheets_tmpa_int }
              }
            \int_incr:N \l__exsheets_tmpa_int
          }
      }
      {
        \prop_map_inline:Nn \g_exsheets_question_identification_prop
          { \__exsheets_print_solutions_chapter:nnn {##1} {##2} {#1} }
      }
  }

\cs_new_protected:Npn \__exsheets_print_solutions_chapter:nnn #1#2#3
  {
    \__exsheets_read_number:w #2 \q_stop
    \__exsheets_print_solution_if:nn {#1}
      { \int_compare_p:n { \l__exsheets_counter_ch_int = #3 } }
  }

% print all:
\cs_new_protected:Npn \exsheets_print_solutions_all:
  {
    \prop_map_function:NN \g_exsheets_question_identification_prop
      \__exsheets_print_solutions_all:nn
    % \prop_show:N \g_exsheets_question_identification_prop
  }

\cs_new:Npn \__exsheets_sectioning_hook:nn #1#2
  {
    \bool_if:nT {
      !\int_compare_p:n
        {
          \use:c { l__exsheets_current_#1_int }
            =
          \use:c { l__exsheets_counter_#1_int }
        }
      % &amp;&amp;
      % !\int_compare_p:n
      %   { \use:c { l__exsheets_counter_#1_int } = 0 }
    }
    {#2}
  }
\cs_generate_variant:Nn \__exsheets_sectioning_hook:nn { nV }

\cs_new_protected:Npn \__exsheets_print_solutions_all:nn #1#2
  { \exsheets_print_solutions_if:nnn { \c_true_bool } {#1} {#2} }

% #1: condition
% #2: numeric question ID
% #3: question number string (stored in \g_exsheets_question_identification_prop)
% use function in a wrapper which in turn is fed to
%    \prop_map_function:NN \g_exsheets_question_identification_prop 
\cs_new_protected:Npn \exsheets_print_solutions_if:nnn #1#2#3
  {
    \prop_if_in:NnT \g__exsheets_solutions_names_prop {#2}
      {
        \int_set_eq:NN
          \l__exsheets_current_sec_int
          \l__exsheets_counter_sec_int
        \int_set_eq:NN
          \l__exsheets_current_ch_int
          \l__exsheets_counter_ch_int
        \__exsheets_read_number:w #3 \q_stop
        \__exsheets_print_solution_if:nn {#2} {#1}
      }
  }
\cs_generate_variant:Nn \exsheets_print_solutions_if:nnn {nnV}

% print by ID:
\seq_new:N \l__exsheets_solutions_byID_seq
\cs_new_protected:Npn \exsheets_print_solutions_byID:n #1
  {
    \seq_set_split:Nnn \l__exsheets_solutions_byID_seq { , } {#1}
    \seq_clear:N \l__exsheets_tmpa_seq
    \seq_map_inline:Nn \l__exsheets_solutions_byID_seq
      {
        \prop_get:NnN \g__exsheets_questions_id_prop
          {##1} \l__exsheets_tmpa_tl
        \seq_put_right:NV \l__exsheets_tmpa_seq \l__exsheets_tmpa_tl
      }
    \bool_if:NT \l__exsheets_print_byID_sorted_bool
      {
        \seq_sort:Nn \l__exsheets_tmpa_seq
          {
            \int_compare:nNnTF {##1} &gt; {##2}
              { \sort_return_swapped: }
              { \sort_return_same: }
          }
      }
    \seq_map_inline:Nn \l__exsheets_tmpa_seq
      {
        \prop_get:NnNT \g_exsheets_question_identification_prop {##1}
          \l__exsheets_tmpa_tl
          {
            \exsheets_print_solutions_if:nnV 
              { \c_true_bool }
              {##1}
              \l__exsheets_tmpa_tl
          }
      }
  }

\cs_new_protected:Npn \__exsheets_read_number:w #1-#2-#3 \q_stop
  {
    \int_zero:N \l__exsheets_counter_ch_int
    \int_zero:N \l__exsheets_counter_sec_int
    \int_zero:N \l_exsheets_counter_qu_int
    \tl_if_in:nnF {#1} { @@@ }
      {
        \tl_if_blank:nF {#1}
          { \int_set:Nn \l__exsheets_counter_ch_int {#1} }
      }
    \int_set:Nn \l__exsheets_counter_sec_int {#2}
    \int_set:Nn \l_exsheets_counter_qu_int {#3}
  }

\cs_new_protected:Npn \exsheets_solutions_print_name:nnn #1#2#3
  {
    \tl_set_rescan:Nnn \l__exsheets_tmpa_tl
      { \char_set_catcode_letter:N \@ } {#1}
    \tl_if_in:nnTF {#1} { @@@ }
      { \__exsheets_solutions_name:nnn { } {#2} {#3} }
      { \__exsheets_solutions_name:nnn {#1} {#2} {#3} }
    \tex_penalty:D 10000 \scan_stop:
  }
\cs_generate_variant:Nn \exsheets_solutions_print_name:nnn { V , VVV }

\cs_new:Npn \__exsheets_surround_with:nnn #1#2#3 { #2#1#3 }
\cs_generate_variant:Nn \__exsheets_surround_with:nnn { nVV }

% think about the interface with \exsheetsprintsolution a bit more, especially
% about the placement of the hooks!

% #1: ID
% #2: name
% #3: body
\cs_new_protected:Npn \__exsheets_print_solution:nnn #1#2#3
  {
    \group_begin:
      \tl_set:Nn \CurrentQuestionID {#1}
      \tl_set:Nx \l__exsheets_tmpa_tl { \exsheets_question_number:n {#1} }
      \__exsheets_surround_with:nVV
        {
          \exp_args:Nnx
          \exsheetsprintsolution
            { \exsheets_solutions_print_name:Vnn \l__exsheets_tmpa_tl {#2} {#1} }
            {
              \exp_not:V \l__exsheets_solutions_pre_body_hook_tl
              \exp_not:n {#3}
              \exp_not:V \l__exsheets_solutions_post_body_hook_tl
            }
        }
        \l__exsheets_solutions_pre_hook_tl
        \l__exsheets_solutions_post_hook_tl
      \exsheets_add_space:N \l__exsheets_solutions_skip_below_dim
    \group_end:
  }
\cs_generate_variant:Nn \__exsheets_print_solution:nnn { VV , VVV }

% a user command to be redefined as needed; must have two mandatory arguments!
% #1: heading
% #2: body
\cs_new:Npn \exsheetsprintsolution #1#2 { #1#2 }

\cs_new:Npn \PrintSolutionsTF
  { \bool_if:NTF \l__exsheets_solutions_print_bool }
\cs_new:Npn \PrintSolutionsT
  { \bool_if:NT \l__exsheets_solutions_print_bool }
\cs_new:Npn \PrintSolutionsF
  { \bool_if:NF \l__exsheets_solutions_print_bool }

\keys_define:nn { exsheets / solution }
  {
    headings        .tl_set:N   = \l__exsheets_solution_heading_instance_tl ,
    print           .choice: ,
    print / true    .code:n     =
      {
        \bool_set_true:N  \l__exsheets_solutions_print_bool
        \bool_set_false:N \l__exsheets_solutions_print_section_bool
        \bool_set_false:N \l__exsheets_solutions_print_chapter_bool
        \bool_set_false:N \l__exsheets_solutions_print_all_bool
      } ,
    print / false   .code:n     =
      {
        \bool_set_false:N \l__exsheets_solutions_print_bool
      } ,
    print           .default:n  = true ,
    name            .tl_set:N   = \l__exsheets_solutions_name_tl ,
    sorted          .bool_set:N = \l__exsheets_print_byID_sorted_bool ,
    skip-below      .dim_set:N  = \l__exsheets_solutions_skip_below_dim ,
    no-skip-below   .bool_set:N = \l__exsheets_no_skip_after_bool ,
    pre-body-hook   .tl_set:N   = \l__exsheets_solutions_pre_body_hook_tl ,
    post-body-hook  .tl_set:N   = \l__exsheets_solutions_post_body_hook_tl ,
    pre-hook        .tl_set:N   = \l__exsheets_solutions_pre_hook_tl ,
    post-hook       .tl_set:N   = \l__exsheets_solutions_post_hook_tl
  }

% ----------------------------------------------------------------------------
% create question/solution pairs
\cs_new_protected:Npn \__exsheets_new_qu_sol_pair:nnnnnn #1#2#3#4#5#6
  {
    \NewDocumentEnvironment {#1} { O{}G{} }
      { \keys_set:nn {exsheets} {#3} \__exsheets_question: {#2,##1} {##2} }
      { \end__exsheets_question: }
    \NewDocumentEnvironment {#4} { O{} }
      { \keys_set:nn {exsheets} {#6} \__exsheets_solution: {#5,##1} }
      { \end__exsheets_solution: }
  }

\cs_new_protected:Npn \__exsheets_renew_qu_sol_pair:nnnnnn #1#2#3#4#5#6
  {
    \RenewDocumentEnvironment {#1} { O{}G{} }
      { \keys_set:nn {exsheets} {#3} \__exsheets_question: {#2,##1} {##2} }
      { \end__exsheets_question: }
    \RenewDocumentEnvironment {#4} { O{} }
      { \keys_set:nn {exsheets} {#6} \__exsheets_solution: {#5,##1} }
      { \end__exsheets_solution: }
  }

\NewDocumentCommand \NewQuSolPair { mO{}O{}mO{}O{} }
  { \__exsheets_new_qu_sol_pair:nnnnnn {#1} {#2} {#3} {#4} {#5} {#6} }
\@onlypreamble \NewQuSolPair

\NewDocumentCommand \RenewQuSolPair { mO{}O{}mO{}O{} }
  { \__exsheets_renew_qu_sol_pair:nnnnnn {#1} {#2} {#3} {#4} {#5} {#6} }
\@onlypreamble \RenewQuSolPair

% ----------------------------------------------------------------------------
% the `tasks' list
\RequirePackage {tasks} [2014/07/03]
\AddCounterPattern* [tasks] {question} {qu}
\ReadCounterFrom    [tasks] {question} \l_exsheets_counter_qu_int

% ----------------------------------------------------------------------------
% the \blank{&lt;words&gt;} command
\RequirePackage {ulem} \normalem

\cs_new:Npn \exsheets_write_blank:n #1 {#1}
\cs_set_eq:NN \exsheets_write_blank:n \uline

\keys_define:nn { exsheets / blank }
  {
    style          .choice: ,
    style / line   .code:n =
      \cs_set_eq:NN \exsheets_write_blank:n \uline ,
    style / wave   .code:n =
      \cs_set_eq:NN \exsheets_write_blank:n \uwave ,
    style / dline  .code:n =
      \cs_set_eq:NN \exsheets_write_blank:n \uuline ,
    style / dotted .code:n =
      \cs_set_eq:NN \exsheets_write_blank:n \dotuline ,
    style / dashed .code:n =
      \cs_set_eq:NN \exsheets_write_blank:n \dashuline ,
    scale          .tl_set:N = \l__exsheets_blank_scale_tl ,
    width          .code:n =
      {
        \bool_set_true:N \l__exsheets_blank_width_bool
        \dim_set:Nn \l__exsheets_blank_dim {#1}
      } ,
    linespread     .code:n =
      \bool_set_true:N \l__exsheets_blank_linespread_bool
      \tl_set:Nn \l__exsheets_blank_linespread_tl {#1} ,
    line-increment .dim_set:N =
      \l__exsheets_blank_line_increment_dim ,
    line-increment .initial:n = 1pt ,
    line-minimum-length .dim_set:N =
      \l__exsheets_blank_line_minimum_length_dim ,
    line-minimum-length .initial:n = 2em
  }

\NewDocumentCommand \blank { som }
  {
    \group_begin:
      \IfNoValueF {#2} { \keys_set:nn { exsheets / blank } {#2} }
      \mode_if_vertical:TF
        {
          \IfBooleanF {#1} { \noindent }
          \exsheets_blank:n {#3}
          \IfBooleanF {#1}
            {
              \bool_if:NT \l__exsheets_blank_linespread_bool
                { \linespread { \l__exsheets_blank_linespread_tl } \selectfont }
              \par
            }
        }
        { \exsheets_blank:n {#3} }
    \group_end:
  }

\cs_new_protected:Npn \exsheets_blank:n #1
  {
    \box_clear:N \l__exsheets_blank_box
    \mode_if_math:TF
      { \hbox_set:Nn \l__exsheets_blank_box { $ \m@th \mathpalette{}{#1} $ } }
      { \hbox_set:Nn \l__exsheets_blank_box {#1} }
    \bool_if:NTF \l__exsheets_inside_solution_bool
      { \exsheets_write_blank:n {#1} }
      {
        \bool_if:NTF \l__exsheets_blank_width_bool
          { \__exsheets_blank_skip:V \l__exsheets_blank_dim }
          {
            \__exsheets_blank_skip:n
              { \box_wd:N \l__exsheets_blank_box }
          }
      }
  }
  
\cs_new_protected:Npn \__exsheets_blank_skip:n #1
  {
    \bool_if:NTF \l__exsheets_blank_width_bool
      { \dim_set:Nn \l__exsheets_tmpa_dim {#1} }
      {
        \fp_set:Nn \l__exsheets_tmpa_fp
          { \dim_to_fp:n {#1} * \l__exsheets_blank_scale_tl }
        \dim_set:Nn \l__exsheets_tmpa_dim { \fp_to_dim:N \l__exsheets_tmpa_fp }
      }
    \dim_compare:nTF
      { \l__exsheets_tmpa_dim &gt; \l__exsheets_blank_line_minimum_length_dim }
      {
        \mode_if_math:TF
          { \exsheets_write_blank:n { \skip_horizontal:N \l__exsheets_tmpa_dim } }
          {
            \dim_do_while:nn { \l__exsheets_tmpa_dim &gt; \c_zero_dim }
              {
                \tex_penalty:D \hyphenpenalty
                \dim_compare:nTF
                  { \l__exsheets_tmpa_dim &lt; \l__exsheets_blank_line_increment_dim }
                  { \exsheets_write_blank:n { \skip_horizontal:N \l__exsheets_tmpa_dim } }
                  {
                    \exsheets_write_blank:n
                      { \skip_horizontal:N \l__exsheets_blank_line_increment_dim }
                  }
                \dim_sub:Nn \l__exsheets_tmpa_dim { \l__exsheets_blank_line_increment_dim }
              }
          }
      }
      { \exsheets_write_blank:n { \skip_horizontal:N \l__exsheets_tmpa_dim } }
  }
\cs_generate_variant:Nn \__exsheets_blank_skip:n { V }

% the following code from Heiko Oberdieck in d.c.t.t served as inspiration
% and basis for the \blank command:
% https://groups.google.com/d/msg/de.comp.text.tex/fZLwraH04jE/o1RSdFXjGuIJ
% 
% \makeatletter
% \newcommand*{\luecke}{%
%   \begingroup
%     \setlength{\dimen@}{6cm}%
%     \ifdim\dimen@&gt;2em %
%       \underline{\hspace{1em}}%
%       \advance\dimen@ by -2em\relax
%       \@whiledim\dimen@&gt;0pt\do{%
%         \penalty\hyphenpenalty
%         \ifdim\dimen@&lt;1pt %
%           \underline{\hspace{\dimen@}}%
%         \else
%           \underline{\hspace{1pt}}%
%         \fi
%         \advance\dimen@ by -1pt %
%       }%
%       \underline{\hspace{1em}}%
%     \else
%       \underline{\hspace{\dimen@}}%
%     \fi
%   \endgroup
%   \xspace
% }
% \makeatother

% ----------------------------------------------------------------------------
% \examspace
% insert space for a student to answer a question
\cs_new_protected:Npn \__exsheets_examspace:nn #1#2
  {
    \par
    \tex_penalty:D -100 \scan_stop:
    \dim_set:Nn \l__exsheets_tmpa_dim {#2}
    \dim_set:Nn \l__exsheets_tmpb_dim { \pagegoal - \pagetotal - \baselineskip }
    \dim_compare:nTF { \l__exsheets_tmpa_dim &gt; \l__exsheets_tmpb_dim }
      {
        \dim_compare:nT { \l__exsheets_tmpb_dim &gt; 0pt } { \vfil }
        \break
        \IfBooleanF {#1}
          {
            \dim_sub:Nn \l__exsheets_tmpa_dim { \l__exsheets_tmpb_dim }
            \vspace* { \l__exsheets_tmpa_dim }
          }
      }
      { \skip_vertical:N \l__exsheets_tmpa_dim }
  }
\NewDocumentCommand \examspace { sm }
  { \__exsheets_examspace:nn {#1} {#2} }

% ----------------------------------------------------------------------------
% SETUP
\NewDocumentCommand \SetupExSheets { o +m }
  {
    \IfNoValueTF {#1}
      { \keys_set:nn {exsheets} {#2} }
      { \keys_set:nn { exsheets / #1 } {#2} }
  }

% ----------------------------------------------------------------------------
% default definitions:
% question / solution pair:
\NewQuSolPair {question} {solution}

% properties:
% \DeclareQuestionProperty{number}
\DeclareQuestionProperty {counter}
\DeclareQuestionProperty {subtitle}
\DeclareQuestionProperty {question-body}
\DeclareQuestionProperty {points}
\DeclareQuestionProperty {bonus-points}
\bool_if:NT \l__exsheets_auto_label_bool
  {
    \DeclareQuestionProperty {ref}
    \DeclareQuestionProperty {pageref}
  }

% classes:
\DeclareQuestionClass {class} {classes}
\DeclareQuestionClass {topic} {topics}

% ----------------------------------------------------------------------------
% Sprachanpassungen
\RequirePackage {translations}
% translation for the exercises
\DeclareTranslationFallback     {exsheets-exercise-name} {Exercise}
\DeclareTranslation {English}   {exsheets-exercise-name} {Exercise}
\DeclareTranslation {British}   {exsheets-exercise-name} {Exercise}
\DeclareTranslation {American}  {exsheets-exercise-name} {Exercise}
\DeclareTranslation {French}    {exsheets-exercise-name} {Exercice}
\DeclareTranslation {German}    {exsheets-exercise-name} {\"Ubung}
\DeclareTranslation {Italian}   {exsheets-exercise-name} {Esercizio}
\DeclareTranslation {Spanish}   {exsheets-exercise-name} {Ejercicio}
\DeclareTranslation {Catalan}   {exsheets-exercise-name} {Exercici}
\DeclareTranslation {Turkish}   {exsheets-exercise-name} {Egzersiz}
\DeclareTranslation {Croatian}  {exsheets-exercise-name} {Primjer}
\DeclareTranslation {Hungarian} {exsheets-exercise-name} {Gyakorol}
\DeclareTranslation {Danish}    {exsheets-exercise-name} {Opgave}
\DeclareTranslation {Norsk}     {exsheets-exercise-name} {Oppgave}
\DeclareTranslation {Portuges}  {exsheets-exercise-name} {Exerc\'\i cio}
% translation for the question
\DeclareTranslationFallback     {exsheets-question-name} {Question}
\DeclareTranslation {English}   {exsheets-question-name} {Question}
\DeclareTranslation {British}   {exsheets-question-name} {Question}
\DeclareTranslation {American}  {exsheets-question-name} {Question}
\DeclareTranslation {French}    {exsheets-question-name} {Question}
\DeclareTranslation {German}    {exsheets-question-name} {Aufgabe}
\DeclareTranslation {Italian}   {exsheets-question-name} {Questione}
\DeclareTranslation {Spanish}   {exsheets-question-name} {Pregunta}
\DeclareTranslation {Catalan}   {exsheets-question-name} {Q\"uesti\'o}
\DeclareTranslation {Turkish}   {exsheets-question-name} {Soru}
\DeclareTranslation {Croatian}  {exsheets-question-name} {Zadatak}
\DeclareTranslation {Hungarian} {exsheets-question-name} {Feladat}
\DeclareTranslation {Danish}    {exsheets-question-name} {Opgave}
\DeclareTranslation {Norsk}     {exsheets-question-name} {Oppgave}
\DeclareTranslation {Portuges}  {exsheets-question-name} {Quest\~ao}
% translation for the solutions
\DeclareTranslationFallback     {exsheets-solution-name} {Solution}
\DeclareTranslation {English}   {exsheets-solution-name} {Solution}
\DeclareTranslation {British}   {exsheets-solution-name} {Solution}
\DeclareTranslation {American}  {exsheets-solution-name} {Solution}
\DeclareTranslation {French}    {exsheets-solution-name} {Solution}
\DeclareTranslation {German}    {exsheets-solution-name} {L\"osung}
\DeclareTranslation {Italian}   {exsheets-solution-name} {Soluzione}
\DeclareTranslation {Spanish}   {exsheets-solution-name} {Soluci\'on}
\DeclareTranslation {Catalan}   {exsheets-solution-name} {Soluci\'o}
\DeclareTranslation {Turkish}   {exsheets-solution-name} {\c C\"oz\"um}
\DeclareTranslation {Croatian}  {exsheets-solution-name} {Rje\v{s}enje}
\DeclareTranslation {Hungarian} {exsheets-solution-name} {Megold\'{a}s}
\DeclareTranslation {Danish}    {exsheets-solution-name} {L\o sning}
\DeclareTranslation {Norsk}     {exsheets-solution-name} {L\o sning}
\DeclareTranslation {Portuges}  {exsheets-solution-name} {Solu\c c\~ao}
% the actual translating
\tl_set:Nn \l__exsheets_exercise_name_tl
  { \GetTranslation {exsheets-exercise-name} }
\tl_set:Nn \l__exsheets_questions_name_tl
  { \GetTranslation {exsheets-question-name} }
\tl_set:Nn \l__exsheets_solutions_name_tl
  { \GetTranslation {exsheets-solution-name} }


% ----------------------------------------------------------------------------
% save total points in .aux file to make it available for \allpoints anywhere
\AtEndDocument
  {
    \exsheets_write_to_aux_x:n
      {
        \exp_not:N \exsheets@sum@of@points
          { \fp_eval:n { \g__exsheets_points_sum_fp } }^^J
        \exp_not:N \exsheets@sum@of@bonus
          { \fp_eval:n { \g__exsheets_bonus_sum_fp } }^^J
        \exp_not:N \gdef \exp_not:N \numberofquestions
          { \int_use:N \g__exsheets_questions_used_int }
        % \exsheets@number@of@questions
        %   { \int_to_arabic:V \g__exsheets_questions_id_int }
      }
  }

% ----------------------------------------------------------------------------
% load custom configuration
\file_if_exist:nT {exsheets_configurations.cfg}
  {
    \AtBeginDocument
      {
        \msg_info:nn {exsheets} {loading-configurations}
        \file_input:n {exsheets_configurations.cfg}
      }
  }

\file_input_stop:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
HISTORY:
2011/11/23 v0.1pre     - first upload to bitbucket and all changes until
                         considered stable enough/ready to be called
                         0.1alpha. There'll be no further descriptions until
                         then.
2012/06/08 v0.1alpha   - first hopefully stable version
2012/06/11 v0.1alpha-a - added headings instances, slightly rewritten
                         `exercises-tasks' object and `tasks' environment
2012/06/11 v0.1alpha-b - added `multiplechoice' instance and `load-tasks'
                         option 
2012/06/12 v0.1alpha-c - renamed from `exercises' into `ExSheets'
2012/06/15 v0.1alpha-d - added more flexible solution printing method
2012/06/15 v0.1beta    - filled in some blanks in the documentation, now we
                         need some testing!
2012/09/07 v0.1beta-a  - adjustments to the updated l3kernel
2012/09/08 v0.1beta-b  - sort solutions printed with the `byID' key
2012/09/16 v0.1beta-c  - renamed option `questions-counter-format' into
                         `counter-format'
2012/09/19 v0.1beta-d  - added `topic' key, provide \includequestions with
                         options `all' and `IDs'
2012/09/24 v0.1beta-e  - added question properties and improved random
                         question selection
2012/09/27 v0.1        - added two headings instances, new option
                         `headings-format' 
                       - small changes in the definition of the
                         `exsheets-headings' object
                       - preliminary version of totoc options. Unfortunatly
                         \exsheets@recover@number is not expandable =&gt; no
                         hyperref support
2012/09/30 v0.2beta    - version numbering gone crazy! this will now stay
                         0.2beta until upload to CTAN (v0.2)
                       - integrated packages `translations' and `cntformats':
                         trnslt: provide expandable version of `translator's
                           \translate
                         cntfmts: outsourced previous counter formatting
                           commands; should now be usable in other packages,
                           too, and simplified definitions in `ExSheets'
                       - thanks to `translations' and `cntformats' the `totoc'
                         option now works with `hyperref'
2012/10/05 v0.2        - removed \sumpoints and moved the functionality to
                         \totalpoints*
                       - changed meaning of \addpoints* and moved former
                         functionality to \points
                       - added bonus point functionality including \addbonus,
                         \bonus, \bonussum, \pointssum, \currentpointssum,
                         \currentbonussum
                       - added grades distribution
2012/10/05 v0.2a       - resolved bug in saving and recovering question number
                         using \exsheets@save@number and \QuestionNumber
2012/10/08 v0.2b       - improved the reference to chapter/solution numbers
                         in \printsolutions
                       - resolved bug in \printsolutions introduced in the
                         last update
                       - upload to CTAN

2012/10/23 v0.3        - bugfix in \exref
                       - new: \NewQuSolPair, \RenewQuSolPair, \examspace
2012/10/24 v0.3a       - fix of headings when followed by a list
                       - changed syntax of {tasks} list to resemble the real
                         lists like enumerate
2012/10/26 v0.3b       - small fix to the {tasks} environment, \NewTasks,
                         \RenewTasks, resolve stupid bug:
                         \ckeckedchoicebox =&gt; \checkedchoicebox
2012/11/08 v0.4        - compatibility with KOMA-Script's `parskip' option:
                         now no unwanted skip and no overfull hbox is produced
                       - env {task} now supports inner environments
2012/12/02 v0.5        - added \CurrentQuestionID
2012/12/06 v0.5a       - bug fix: solutions had wrong numbers with
                         counter-format=se.qu and [print] option
2012/12/18 v0.6        - variations, Hungarian translations, corrected
                         Catalanian translations
2012/12/23 v0.6a       - bug fix: labels and items of {tasks} weren't joined
                         at their baselines
2013/01/06 v0.6b       - bug fix: ID counting fixed in \includequestions
2013/01/19 v0.7        - extracted `tasks' environment into standalone
                         package; this also lead to a slightly new syntax and
                         a few new options for it
                       - changed internals for random selection of questions:
                         uses `pgf' instead of `lcg' and seems to be more
                         reliable than before
2013/01/21 v0.7a       - added option `auto-label' and questions key `label',
                         also added question properties `ref' and `pageref'
2013/02/17 v0.7b       - bug fix: question selection by ID now works again
2013/03/10 v0.8        - \prop_length =&gt; \exsheets_prop_count
                       - define unexpandable internal commands protected
                       - translations basic dictionaries for English, German,
                         French and Spanish
                       - new \includequestions option `exclude'
                       - new way of handling the `class' of questions:
                         instead of hard-coded `classes' and `topics'
                         individual groups like e.g. `difficulties' can be
                         chosen; `classes' and `topics' are still provided for
                         backwards compatibility; this introduces the new
                         command \DeclareQuestionClass
                       - minor changes to the debugging information layout
                       - bug fix in number saving mechanism
                       - \includequestions[random=&lt;num&gt;] now obeys class
                         as done with \SetupExSheets{use-topics={foo,bar}}
                       - new macro \questionsincludedlast
2013/04/04 v0.8a       - added Portuguese translations
2013/04/07 v0.9        - protected internal commands where appropriate
                       - added possibility to set general options with
                         \NewQuSolPair and \RenewQuSolPair
2013/04/08 v0.9a       - added headings instance `empty'
2013/04/18 v0.9b       - fixed erroneous behaviour of \includequestions when
                         used more than once
                       - added hook \l__exsheets_heading_points_post_hook_tl
2013/04/21 v0.9c       - bug fix: \ForEachQuestion seems to work correctly
                         again
2013/04/25 v0.9d       - bug fix: \includequestions works correctly when used
                         multiple times together with ordinary instances of
                         the {question} environment
                       - bug fix: points/parse=false correctly disables
                         parsing points again
                       - bug fix: \addpoints didn't add to the question
                         property
                       - new option `points/format'
                       - \blank now works in math mode, it doesn't do
                         linebreaks there if `ulem' doesn't allow them (which
                         it doesn't)
2013/05/01 v0.9e       - corrected erroneous behaviour of \examspace
2013/05/26 v0.9f       - fixed incorrectly placed links when the `totoc'
                         option is enabled and questions/solutions are at the
                         top of a new page because there wasn't enough place
                         left at the page before
2013/05/30 v0.9g       - obey \if@filesw
2013/06/28 v0.9h       - cleaner internal use of
                         \exsheets_set_question_properties:n
2013/07/17 v0.9i       - made \g__exsheets_total_bonus_fp and
                         \g__exsheets_total_points_fp public
                       - removed `translations' from the bundle
2013/10/11 v0.10       - require `translations' like any other package
                       - added `exsheets-listings' package
                       - added Norwegian translations
                       - changed horizontal spaces declared as `1ex' into
                         `.3333em' in the declarations of the headings
                         instances
                       - added subtitles
2013/11/07 v0.10a      - fix bug in loading headings of questions;  when
                         included from an external file sometimes the wrong ID
                         has been passed to the headings
2013/11/20 v0.11       - \GetQuestionClass{}
                       - \PrintQuestionClass(TF)
2013/12/02 v0.12       - fix issue with \CurrentQuestionID
                       - new options `label-format', `label-cmd', `ref-cmd'
                         and `pageref-cmd' for `auto-label' options that
                         allow specification of labelling command and thus
                         compatibility with packages like `cleveref'
                       - write question properties to aux file so they can be
                         retrieved before the corresponding question is
                         printed
                       - make \GetQuestionProperty expandable
                       - new syntax feature in points argument: a leading
                         bang prevents the points from being added to the sum
                         of points
                       - added possibility for
                         https://bitbucket.org/cgnieder/exsheets/issue/15
                       - added \IfQuestionSubtitle(TF)
                       - added `subtitle' property
                       - dropped `color' option
2013/12/08 v0.12a      - changed details in the printing mechanism of the
                         points which seems to be more consistent
                       - fix bug introduced in the last update: subtitles work
                         again
2013/12/27 v0.12b      - ensure that points are not parsed if a leading bang
                         is inserted
                       - fix bug in parsing the points
2014/05/11 v0.13       - new options:
                         * chapter-hook
                         * section-hook
                         These options provide hooks to add code in the list
                         of solutions (when printed with \printsolutions[all])
                         when solutions from a new section or chapter are
                         printed
2014/05/11 v0.13a      - bug fix: solutions get the counter-format that's
                         active when the corresponding `solution' environment
                         is placed in the source
2014/06/27 v0.14       - new command: \ExSheetsHeading
                       - \__exsheets_use_heading:nnnnnn =&gt;
                         \exsheets_use_heading:nnnnnn
                       - new options `question/pre-hook' and
                         `question/post-hook'
                       - new pre-defined property `question-body'
                       - new pre-defined property `bonus-points'
                       - new pre-defined property `counter'
                       - new option `question/save-to-aux'
                       - \ForEachQuestion, \numberofquestions and
                         \iflastquestion are now available before any
                         questions have been typeset
2014/07/20 v0.15       - remove `tasks' from the bundle and into a package of
                         its own
                       - remove `cntformats' from the bundle and into a package of
                         its own
                       - drop options `load-headings' and `load-tasks'
                       - new command \IfQuestionPropertyTF
2014/09/14 v0.16       - fix `subtitle-format' option
                       - allow that the format given in `headings-format' and
                         `subtitle-format' can end with a command needing an
                         argument
                       - add options `solution/pre-hook',
                         `solution/post-hook', `solution/pre-body-hook' and
                         `solution/post-body-hook' (this adds a possibility
                         for issue #21)
                       - add options `question/pre-body-hook' and
                         `question/post-body-hook'
                       - add internal interface for the printing of solutions
                         ( \__exsheets_print_solution:nnnn )
                       - fix issue #22
                       - fix issue #23
                       - use only one version number for the whole bundle
2014/10/14 v0.17       - new option `use-saved-counter-format'
2015/02/09 v0.18       - added correct Danish translations - thanks to Jonas
                         Nyrup
                       - introduce \exsheetsprintsolution, see
                         http://tex.stackexchange.com/q/227078/ for motivation
                       - change test in \exsheets_h_or_vspace:N to something
                         more reliable and meaningful
                       - new option `no-skip-below'
2015/05/06 v0.18a      - fix bug in points mechanism
                       - singular points name is now only used for exactly 1
                         point
                       - a few cosmetic changes to the points function
                         definitions
2015/07/04 v0.19       - add http://tex.stackexchange.com/q/222814
                       - allow begin and end of pseudo-environments as hooks
                         to the question an solution environments
2015/11/18 v0.20       - add tagging feature
                       - new: \DeclareExSheetsHeadingContainer
2016/01/26 v0.21       - give error message when \includequestions tries to
                         load a file which can't be found (issue)
                       - \exsheets_print_solutions_if:nnn
                       - \l__exsheets_counter_qu_int =&gt;
                         \l_exsheets_counter_qu_int
                       - \g__exsheets_question_number_prop =&gt;
                         \g_exsheets_question_identification_prop
                       - make question properties accessable when question is
                         not printed
2016/01/26 v0.21a      - remove deprecated \prop_get:Nn (=&gt; \prop_item:Nn)
2016/02/01 v0.21b      - fix annoying bug in \exsheets_print_solutions_if:nnn
2016/03/21 v0.21c      - use question property `counter' for retrieving the
                         counter patterns in solution's headings (this
                         resolves http://tex.stackexchange.com/q/299898)
                       - remove option `use-saved-counter-format': solutions
                         should always have the same number pattern as the
                         corresponding questions
2016/08/14 v0.21d      - fix issue #32
2016/09/07 v0.21e      - fix issue #29
                       - fix issue #35
                       - fix issue #36
2016/09/17 v0.21f      - make \exsheets_question_number:n an alias of
                         \exsheets_get_question_property:nn {counter}; this
                         also makes \QuestionNumber an alias of
                         \GetQuestionProperty {counter}
2016/10/25 v0.21g      - smaller steps when creating the blank lines
2016/11/28 v0.21h      - bug in \exsheets@used@id fixed
2017/02/08 v0.21i      - adapt to l3sort integration into l3kernel
2019/09/27 v0.21j      - fix bug #44

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% TODO:
- solve the problem using verbatim material in questions and solutions
  (difficult)
- allow for different kinds of problems/solutions using an independant counter
  (not trivial)
- points/decimal-marker, points/frac (?), points/format (?,im interface)
- points: swedish style
- \examspace inside {tasks} =&gt; possible? (\pagegoal-\pagetotal) gives wrong
  values here
- remove doubled points name if total points are unknown
</pre></body></html>