path: root/Master/texmf-dist/doc/latex/tikz-cd/tikz-cd-doc.tex

% Copyright 2011 by Florêncio Neves
%
% This file may be distributed and/or modified
%
% 1. under the LaTeX Project Public License and/or
% 2. under the GNU Public License.
%
% The preamble of this file contains parts of the files
% pgfmanual-en-main.tex and pgfmanual-en-macros.tex of the pgf package,
% copyright 2006 by Till Tantau and distributed under LPPL and/or GNU
% GPL.

\documentclass{ltxdoc}

        \def\xcolorversion{2.00}

        \usepackage[version=latest]{pgf}

        \usepackage{xkeyval,calc,listings,tikz,fp}

        \usepackage{hyperref}
        \hypersetup{%
          colorlinks=true,	% use true to enable colors below:
          linkcolor=blue,%red,
          filecolor=blue,%magenta,
          pagecolor=blue,%red,
          urlcolor=blue,%cyan,
          citecolor=blue,
          pdfborder=0 0 0,
        }

        % We need lots of libraries...
        \usetikzlibrary{
          arrows,
          calc,
          fit,
          patterns,
          plotmarks,
          shapes.geometric,
          shapes.misc,
          shapes.symbols,
          shapes.arrows,
          shapes.callouts,
          shapes.multipart,
          shapes.gates.logic.US,
          shapes.gates.logic.IEC,
          circuits.logic.US,
          circuits.logic.IEC,
          circuits.logic.CDH,
          circuits.ee.IEC,
          datavisualization,
          datavisualization.formats.functions,
          er,
          automata,
          backgrounds,
          chains,
          topaths,
          trees,
          petri,
          mindmap,
          matrix,
          calendar,
          folding,
          fadings,
          shadings,
          spy,
          through,
          turtle,
          positioning,
          scopes,
          decorations.fractals,
          decorations.shapes,
          decorations.text,
          decorations.pathmorphing,
          decorations.pathreplacing,
          decorations.footprints,
          decorations.markings,
          shadows,
          lindenmayersystems,
          intersections,
          fixedpointarithmetic,
          fpu,
          svg.path,
          external,
        }

        \iffalse
        % \iftrue
        \tikzexternalize[
        mode=list only,export=true,% simply skips EVERY picture -> good for debugging the text.
        ]
        {pgfmanual}

        \tikzifexternalizing{%
          \pgfkeys{/pdflinks/codeexample links=false}%
        }{}%
        \fi


        \usepackage[a4paper,left=2.25cm,right=2.25cm,top=2.5cm,bottom=2.5cm,nohead]{geometry}
        \usepackage{amsmath,amssymb}
        \usepackage{xxcolor}
        \usepackage{pifont}
        \usepackage{makeidx}
        \usepackage[latin1]{inputenc}
        \usepackage{amsmath}

        \graphicspath{{../../images/}}              % TODOsp: under windows this would go up 2 directories, but the file is only one directory up
        % \makeindex

        \providecommand\href[2]{\texttt{#1}}
        \providecommand\hypertarget[2]{\texttt{#1}}
        \providecommand\hyperlink[2]{\texttt{#1}}


        \colorlet{examplefill}{yellow!80!black}
        \definecolor{graphicbackground}{rgb}{0.96,0.96,0.8}
        \definecolor{codebackground}{rgb}{0.8,0.8,1}

        \newenvironment{pgfmanualentry}{\list{}{\leftmargin=2em\itemindent-\leftmargin\def\makelabel##1{\hss##1}}}{\endlist}
        \newcommand\pgfmanualentryheadline[1]{\itemsep=0pt\parskip=0pt\item\strut{#1}\par\topsep=0pt}
        \newcommand\pgfmanualbody{\parskip3pt}



        \newenvironment{pgflayout}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{\texttt{\string\pgfpagesuselayout\char`\{\declare{#1}\char`\}}\oarg{options}}
            \index{#1@\protect\texttt{#1} layout}%
            \index{Page layouts!#1@\protect\texttt{#1}}%
            \pgfmanualpdflabel{#1}{}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }


        \newenvironment{command}[1]{
          \begin{pgfmanualentry}
            \extractcommand#1\@@
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \newenvironment{commandlist}[1]{%
          \begin{pgfmanualentry}
            \foreach \xx in {#1} {%
              \expandafter\extractcommand\xx\@@
            }%
            \pgfmanualbody
          }{%
          \end{pgfmanualentry}
        }%

        % \begin{internallist}[register]{\pgf@xa}
        % \end{internallist}
        % 
        % \begin{internallist}[register]{\pgf@xa,\pgf@xb}
        % \end{internallist}
        \newenvironment{internallist}[2][register]{%
          \begin{pgfmanualentry}
            \foreach \xx in {#2} {%
              \expandafter\extractinternalcommand\expandafter{\xx}{#1}%
            }%
            \pgfmanualbody
          }{%
          \end{pgfmanualentry}
        }%
        \def\extractinternalcommand#1#2{%
          \pgfmanualentryheadline{Internal #2 \declare{\texttt{\string#1}}}%
          \removeats{#1}%
          \index{Internals!\strippedat @\protect\myprintocmmand{\strippedat}}%
          \index{\strippedat @\protect\myprintocmmand{\strippedat}}%
          \pgfmanualpdflabel{\textbackslash\strippedat}{}%
        }

        %% MW: START MATH MACROS
        \def\mvar#1{{\ifmmode\textrm{\textit{#1}}\else\rmfamily\textit{#1}\fi}}

        \makeatletter

        \def\extractmathfunctionname#1{\extractmathfunctionname@#1(,)\tmpa\tmpb}
        \def\extractmathfunctionname@#1(#2)#3\tmpb{\def\mathname{#1}}

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          \def\mathdefaultname{#1}
          \extractmathfunctionname{#1}
          \edef\mathurl{{math:\mathname}}\expandafter\hypertarget\expandafter{\mathurl}{}%
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{\texttt{#1}}%
            \index{\mathname @\protect\texttt{\mathname} math function}%
            \index{Math functions!\mathname @\protect\texttt{\mathname}}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\pgfmanualemptytext{}
        \def\pgfmanualvbarvbar{\char`\|\char`\|}

        \newenvironment{math-operator}[4][]{%
          \begin{pgfmanualentry}
            \csname math#3operator\endcsname{#2}{#4}
            \def\mathtest{#4}%
            \ifx\mathtest\pgfmanualemptytext%
            \def\mathtype{(#3 operator)}
            \else%
            \def\mathtype{(#3 operator; uses the \texttt{#4} function)}
            \fi%
            \pgfmanualentryheadline{\mathexample\hfill\mathtype}%
            \def\mathtest{#1}%
            \ifx\mathtest\pgfmanualemptytext%
            \index{#2@\protect\texttt{#2} #3 math operator}%  
            \index{Math operators!#2@\protect\texttt{#2}}%
            \fi%
            \pgfmanualbody
          }
          {\end{pgfmanualentry}}

        \newenvironment{math-operators}[5][]{%
          \begin{pgfmanualentry}
            \csname math#4operator\endcsname{#2}{#3}
            \def\mathtest{#5}%
            \ifx\mathtest\pgfmanualemptytext%
            \def\mathtype{(#4 operators)}
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            \def\mathtype{(#4 operators; use the \texttt{#5} function)}
            \fi%
            \pgfmanualentryheadline{\mathexample\hfill\mathtype}%
            \def\mathtest{#1}%
            \ifx\mathtest\pgfmanualemptytext%
            \index{#2#3@\protect\texttt{#2\protect\ #3} #4 math operators}% 
            \index{Math operators!#2#3@\protect\texttt{#2\protect\ #3}}%
            \fi%
            \pgfmanualbody
          }
          {\end{pgfmanualentry}}

        \def\mathinfixoperator#1#2{%
          \def\mathoperator{\texttt{#1}}%
          \def\mathexample{\mvar{x}\space\texttt{#1}\space\mvar{y}}%
        }

        \def\mathprefixoperator#1#2{%
          \def\mathoperator{\texttt{#1}}%
          \def\mathexample{\texttt{#1}\mvar{x}}%
        }

        \def\mathpostfixoperator#1#2{%
          \def\mathoperator{\texttt{#1}}
          \def\mathexample{\mvar{x}\texttt{#1}}%
        }

        \def\mathgroupoperator#1#2{%
          \def\mathoperator{\texttt{#1\ #2}}%
          \def\mathexample{\texttt{#1}\mvar{x}\texttt{#2}}%
        }

        \expandafter\let\csname matharray accessoperator\endcsname=\mathgroupoperator
        \expandafter\let\csname matharrayoperator\endcsname=\mathgroupoperator

        \def\mathconditionaloperator#1#2{%
          \def\mathoperator{#1\space#2}
          \def\mathexample{\mvar{x}\ \texttt{#1}\ \mvar{y}\ {\texttt{#2}}\ \mvar{z}}
        }

        \newcommand\mathcommand[1][\mathdefaultname]{%
          \expandafter\makemathcommand#1(\empty)\stop%
          \expandafter\extractcommand\mathcommandname\@@%
          \medskip
        }
        \makeatletter

        \def\makemathcommand#1(#2)#3\stop{%
          \expandafter\def\expandafter\mathcommandname\expandafter{\csname pgfmath#1\endcsname}%
          \ifx#2\empty%
          \else%
          \@makemathcommand#2,\stop,
          \fi}
        \def\@makemathcommand#1,{%
          \ifx#1\stop%
          \else%
          \expandafter\def\expandafter\mathcommandname\expandafter{\mathcommandname{\ttfamily\char`\{#1\char`\}}}%
          \expandafter\@makemathcommand%
          \fi}
        \makeatother

        \def\calcname{\textsc{calc}}
        %% MW: END MATH MACROS


        \def\extractcommand#1#2\@@{%
          \pgfmanualentryheadline{\declare{\texttt{\string#1}}#2}%
          \removeats{#1}%
          \index{\strippedat @\protect\myprintocmmand{\strippedat}}
          \pgfmanualpdflabel{\textbackslash\strippedat}{}%
        }


        % \begin{environment}{{name}\marg{arguments}}
        \renewenvironment{environment}[1]{
          \begin{pgfmanualentry}
            \extractenvironement#1\@@
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\extractenvironement#1#2\@@{%
          \pgfmanualentryheadline{{\ttfamily\char`\\begin\char`\{\declare{#1}\char`\}}#2}%
          \pgfmanualentryheadline{{\ttfamily\ \ }\meta{environment contents}}%
          \pgfmanualentryheadline{{\ttfamily\char`\\end\char`\{\declare{#1}\char`\}}}%
          \index{#1@\protect\texttt{#1} environment}%
          \index{Environments!#1@\protect\texttt{#1}}
          \pgfmanualpdflabel{#1}{}%
        }


        \newenvironment{plainenvironment}[1]{
          \begin{pgfmanualentry}
            \extractplainenvironement#1\@@
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\extractplainenvironement#1#2\@@{%
          \pgfmanualentryheadline{{\ttfamily\declare{\char`\\#1}}#2}%
          \pgfmanualentryheadline{{\ttfamily\ \ }\meta{environment contents}}%
          \pgfmanualentryheadline{{\ttfamily\declare{\char`\\end#1}}}%
          \index{#1@\protect\texttt{#1} environment}%
          \index{Environments!#1@\protect\texttt{#1}}%
        }


        \newenvironment{contextenvironment}[1]{
          \begin{pgfmanualentry}
            \extractcontextenvironement#1\@@
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\extractcontextenvironement#1#2\@@{%
          \pgfmanualentryheadline{{\ttfamily\declare{\char`\\start#1}}#2}%
          \pgfmanualentryheadline{{\ttfamily\ \ }\meta{environment contents}}%
          \pgfmanualentryheadline{{\ttfamily\declare{\char`\\stop#1}}}%
          \index{#1@\protect\texttt{#1} environment}%
          \index{Environments!#1@\protect\texttt{#1}}}


        \newenvironment{shape}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Shape {\ttfamily\declare{#1}}}%
            \index{#1@\protect\texttt{#1} shape}%
            \index{Shapes!#1@\protect\texttt{#1}}
            \pgfmanualpdflabel{#1}{}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \newenvironment{shading}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Shading {\ttfamily\declare{#1}}}%
            \index{#1@\protect\texttt{#1} shading}%
            \index{Shadings!#1@\protect\texttt{#1}}
            \pgfmanualpdflabel{#1}{}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }


        \newenvironment{dataformat}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Format {\ttfamily\declare{#1}}}%
            \index{#1@\protect\texttt{#1} format}%
            \index{Formats!#1@\protect\texttt{#1}}
            \pgfmanualpdflabel{#1}{}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \newenvironment{handler}[1]{
          \begin{pgfmanualentry}
            \extracthandler#1\@nil%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\gobble#1{}
        \def\extracthandler#1#2\@nil{%
          \pgfmanualentryheadline{Key handler \meta{key}{\ttfamily/\declare{#1}}#2}%
          \index{\gobble#1@\protect\texttt{#1} handler}%
          \index{Key handlers!#1@\protect\texttt{#1}}
          \pgfmanualpdflabel{/handlers/#1}%
        }


        \makeatletter


        \newenvironment{stylekey}[1]{
          \begin{pgfmanualentry}
            \def\extrakeytext{style, }
            \extractkey#1\@nil%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        \def\choicesep{$\vert$}%
        \def\choicearg#1{\texttt{#1}}

        \newif\iffirstchoice

        % \mchoice{choice1,choice2,choice3}
        \newcommand\mchoice[1]{%
          \begingroup
          \firstchoicetrue
          \foreach \mchoice@ in {#1} {%
            \iffirstchoice
            \global\firstchoicefalse
            \else
            \choicesep
            \fi
            \choicearg{\mchoice@}%
          }%
          \endgroup
        }%

        % \begin{key}{/path/x=value}
        %   \begin{key}{/path/x=value (initially XXX)}
        %     \begin{key}{/path/x=value (default XXX)}
        \newenvironment{key}[1]{
          \begin{pgfmanualentry}
            \def\extrakeytext{}
            % \def\altpath{\emph{\color{gray}or}}%
            \extractkey#1\@nil%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }

        % \insertpathifneeded{a key}{/pgf} -> assign mykey={/pgf/a key}
        % \insertpathifneeded{/tikz/a key}{/pgf} -> assign mykey={/tikz/a key}
        % 
        % #1: the key
        % #2: a default path (or empty)
        \def\insertpathifneeded#1#2{%
          \def\insertpathifneeded@@{#2}%
          \ifx\insertpathifneeded@@\empty
          \def\mykey{#1}%
          \else
          \insertpathifneeded@#2\@nil
          \ifpgfutil@in@
          \def\mykey{#2/#1}%
          \else
          \def\mykey{#1}%
          \fi
          \fi
        }%
        \def\insertpathifneeded@#1#2\@nil{%
          \def\insertpathifneeded@@{#1}%
          \def\insertpathifneeded@@@{/}%
          \ifx\insertpathifneeded@@\insertpathifneeded@@@
          \pgfutil@in@true
          \else
          \pgfutil@in@false
          \fi
        }%

        % \begin{keylist}[default path]
        %   {/path/option 1=value,/path/option 2=value2}
        % \end{keylist}
        \newenvironment{keylist}[2][]{%
          \begin{pgfmanualentry}
            \def\extrakeytext{}%
            \foreach \xx in {#2} {%
              \expandafter\insertpathifneeded\expandafter{\xx}{#1}%
              \expandafter\extractkey\mykey\@nil%
            }%
            \pgfmanualbody
          }{%
          \end{pgfmanualentry}
        }%

        \def\extractkey#1\@nil{%
          \pgfutil@in@={#1}%
          \ifpgfutil@in@%
          \extractkeyequal#1\@nil
          \else%
          \pgfutil@in@{(initial}{#1}%
          \ifpgfutil@in@%
          \extractequalinitial#1\@nil%
          \else
          \pgfmanualentryheadline{{\ttfamily\declare{#1}}\hfill(\extrakeytext no value)}%
          \def\mykey{#1}%
          \def\mypath{}%
          \def\myname{}%
          \firsttimetrue%
          \decompose#1/\nil%
          \fi
          \fi%
        }

        \def\extractkeyequal#1=#2\@nil{%
          \pgfutil@in@{(default}{#2}%
          \ifpgfutil@in@%
          \extractdefault{#1}#2\@nil%
          \else%
          \pgfutil@in@{(initial}{#2}%
          \ifpgfutil@in@%
          \extractinitial{#1}#2\@nil%
          \else
          \pgfmanualentryheadline{{\ttfamily\declare{#1}=}#2\hfill(\extrakeytext no default)}%
          \fi%
          \fi%
          \def\mykey{#1}%
          \def\mypath{}%
          \def\myname{}%
          \firsttimetrue%
          \decompose#1/\nil%
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        \def\extractdefault#1#2(default #3)\@nil{%
          \pgfmanualentryheadline{{\ttfamily\declare{#1}\opt{=}}\opt{#2}\hfill (\extrakeytext default {\ttfamily#3})}%
        }

        \def\extractinitial#1#2(initially #3)\@nil{%
          \pgfmanualentryheadline{{\ttfamily\declare{#1}=}#2\hfill (\extrakeytext no default, initially {\ttfamily#3})}%
        }

        \def\extractequalinitial#1 (initially #2)\@nil{%
          \pgfmanualentryheadline{{\ttfamily\declare{#1}}\hfill (\extrakeytext initially {\ttfamily#2})}%
          \def\mykey{#1}%
          \def\mypath{}%
          \def\myname{}%
          \firsttimetrue%
          \decompose#1/\nil%
        }

        % Introduces a key alias '/#1/<name of current key>'
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        \def\keyalias#1{\vspace{-3pt}\item{\small alias {\ttfamily/#1/\myname}}\vspace{-2pt}\par
          \pgfmanualpdflabel{/#1/\myname}{}%
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        \makeatother

        \def\decompose/#1/#2\nil{%
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          \ifx\test\empty%
          % aha.
          \index{#1@\protect\texttt{#1} key}%
          \index{\mypath#1@\protect\texttt{#1}}%
          \def\myname{#1}%
          \else%
          \iffirsttime
          \begingroup	
          % also make a pdf link anchor with full key path.
          \def\hyperlabelwithoutslash##1/\nil{%
            \pgfmanualpdflabel{##1}{}%
          }%
          \hyperlabelwithoutslash/#1/#2\nil
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          \def\firsttime{}
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          \pgfmanualentryheadline{Method \declare{\ttfamily #1}\texttt(#2\texttt) \hfill(predefined for all classes)}
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            \index{Class #1@Class \protect\texttt{#1}}%
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          \pgfmanualentryheadline{Method \declare{\ttfamily #1}\texttt(#2\texttt)}
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          \index{#1@\protect\texttt{#1} method}%
          \index{Methods!#1@\protect\texttt{#1}}
          \index{Class \currentclass!#1@\protect\texttt{#1}}%
          \pgfmanualpdflabel{#1}{}%
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        \newenvironment{attribute}[1]{
          \begin{pgfmanualentry}
            \extractattribute#1\@nil
            \pgfmanualbody
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          \pgfmanualentryheadline{Private attribute \declare{\ttfamily #1} \hfill (initially empty)}
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          \pgfmanualentryheadline{Private attribute \declare{\ttfamily #1} \hfill (initially {\ttfamily #2})}
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          \index{#1@\protect\texttt{#1} attribute}%
          \index{Attributes!#1@\protect\texttt{#1}}
          \index{Class \currentclass!#1@\protect\texttt{#1}}%
          \pgfmanualpdflabel{#1}{}%
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        \newenvironment{predefinednode}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Predefined node {\ttfamily\declare{#1}}}%
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          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Coordinate system {\ttfamily\declare{#1}}}%
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          \begin{pgfmanualentry}
            \pgfmanualentryheadline{Snake {\ttfamily\declare{#1}}}%
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          \begin{pgfmanualentry}
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            \ifx\pgfmanualtest\@empty%
            \index{#2@\protect\texttt{#2} (data visualization)}%
            \index{Data visualization!#2@\protect\texttt{#2}}%
            \pgfmanualpdflabel{#2}{}%
            \fi%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }
        \makeatother

        \def\extractcommand#1#2\@@{%
          \pgfmanualentryheadline{\declare{\texttt{\string#1}}#2}%
          \removeats{#1}%
          \index{\strippedat @\protect\myprintocmmand{\strippedat}}
          \pgfmanualpdflabel{\textbackslash\strippedat}{}%
        }

        \def\doublebs{\texttt{\char`\\\char`\\}}


        \newenvironment{package}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{{\ttfamily\char`\\usepackage\char`\{\declare{#1}\char`\}\space\space \char`\%\space\space  \LaTeX}}
            \index{#1@\protect\texttt{#1} package}%
            \index{Packages and files!#1@\protect\texttt{#1}}%
            \pgfmanualentryheadline{{\ttfamily\char`\\input \declare{#1}.tex\space\space\space \char`\%\space\space  plain \TeX}}
            \pgfmanualentryheadline{{\ttfamily\char`\\usemodule[\declare{#1}]\space\space \char`\%\space\space  Con\TeX t}}
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }


        \newenvironment{pgfmodule}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{{\ttfamily\char`\\usepgfmodule\char`\{\declare{#1}\char`\}\space\space\space
                \char`\%\space\space  \LaTeX\space and plain \TeX\space and pure pgf}}
            \index{#1@\protect\texttt{#1} module}%
            \index{Modules!#1@\protect\texttt{#1}}%
            \pgfmanualentryheadline{{\ttfamily\char`\\usepgfmodule[\declare{#1}]\space\space \char`\%\space\space  Con\TeX t\space and pure pgf}}
            \pgfmanualbody
            \pgfmanualpdflabel{#1}{}%
          }
          {
          \end{pgfmanualentry}
        }

        \newenvironment{pgflibrary}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{{\ttfamily\char`\\usepgflibrary\char`\{\declare{#1}\char`\}\space\space\space
                \char`\%\space\space  \LaTeX\space and plain \TeX\space and pure pgf}}
            \index{#1@\protect\texttt{#1} library}%
            \index{Libraries!#1@\protect\texttt{#1}}%
            \pgfmanualentryheadline{{\ttfamily\char`\\usepgflibrary[\declare{#1}]\space\space \char`\%\space\space  Con\TeX t\space and pure pgf}}
            \pgfmanualentryheadline{{\ttfamily\char`\\usetikzlibrary\char`\{\declare{#1}\char`\}\space\space
                \char`\%\space\space  \LaTeX\space and plain \TeX\space when using \tikzname}}
            \pgfmanualentryheadline{{\ttfamily\char`\\usetikzlibrary[\declare{#1}]\space
                \char`\%\space\space  Con\TeX t\space when using \tikzname}}
            \pgfmanualbody
            \pgfmanualpdflabel{#1}{}%
          }
          {
          \end{pgfmanualentry}
        }

        \newenvironment{tikzlibrary}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{{\ttfamily\char`\\usetikzlibrary\char`\{\declare{#1}\char`\}\space\space \char`\%\space\space  \LaTeX\space and plain \TeX}}
            \index{#1@\protect\texttt{#1} library}%
            \index{Libraries!#1@\protect\texttt{#1}}%
            \pgfmanualentryheadline{{\ttfamily\char`\\usetikzlibrary[\declare{#1}]\space \char`\%\space\space Con\TeX t}}
            \pgfmanualbody
            \pgfmanualpdflabel{#1}{}%
          }
          {
          \end{pgfmanualentry}
        }



        \newenvironment{filedescription}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{File {\ttfamily\declare{#1}}}%
            \index{#1@\protect\texttt{#1} file}%
            \index{Packages and files!#1@\protect\texttt{#1}}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }


        \newenvironment{packageoption}[1]{
          \begin{pgfmanualentry}
            \pgfmanualentryheadline{{\ttfamily\char`\\usepackage[\declare{#1}]\char`\{pgf\char`\}}}
            \index{#1@\protect\texttt{#1} package option}%
            \index{Package options for \textsc{pgf}!#1@\protect\texttt{#1}}%
            \pgfmanualbody
          }
          {
          \end{pgfmanualentry}
        }



        \newcommand\opt[1]{{\color{black!50!green}#1}}
        \newcommand\ooarg[1]{{\ttfamily[}\meta{#1}{\ttfamily]}}

        \def\opt{\afterassignment\pgfmanualopt\let\next=}
        \def\pgfmanualopt{\ifx\next\bgroup\bgroup\color{black!50!green}\else{\color{black!50!green}\next}\fi}



        \def\beamer{\textsc{beamer}}
        \def\pdf{\textsc{pdf}}
        \def\eps{\texttt{eps}}
        \def\pgfname{\textsc{pgf}}
        \def\tikzname{Ti\emph{k}Z}
        \def\pstricks{\textsc{pstricks}}
        \def\prosper{\textsc{prosper}}
        \def\seminar{\textsc{seminar}}
        \def\texpower{\textsc{texpower}}
        \def\foils{\textsc{foils}}

        {
          \makeatletter
          \global\let\myempty=\@empty
          \global\let\mygobble=\@gobble
          \catcode`\@=12
          \gdef\getridofats#1@#2\relax{%
            \def\getridtest{#2}%
            \ifx\getridtest\myempty%
            \expandafter\def\expandafter\strippedat\expandafter{\strippedat#1}
            \else%
            \expandafter\def\expandafter\strippedat\expandafter{\strippedat#1\protect\printanat}
            \getridofats#2\relax%
            \fi%
          }

          \gdef\removeats#1{%
            \let\strippedat\myempty%
            \edef\strippedtext{\stripcommand#1}%
            \expandafter\getridofats\strippedtext @\relax%
          }

          \gdef\stripcommand#1{\expandafter\mygobble\string#1}
        }

        \def\printanat{\char`\@}

        \def\declare{\afterassignment\pgfmanualdeclare\let\next=}
        \def\pgfmanualdeclare{\ifx\next\bgroup\bgroup\color{red!75!black}\else{\color{red!75!black}\next}\fi}


        \let\textoken=\command
        \let\endtextoken=\endcommand

        \def\myprintocmmand#1{\texttt{\char`\\#1}}

        \def\example{\par\smallskip\noindent\textit{Example: }}
        \def\themeauthor{\par\smallskip\noindent\textit{Theme author: }}


        \def\indexoption#1{%
          \index{#1@\protect\texttt{#1} option}%
          \index{Graphic options and styles!#1@\protect\texttt{#1}}%
        }

        \def\itemcalendaroption#1{\item \declare{\texttt{#1}}%
          \index{#1@\protect\texttt{#1} date test}%
          \index{Date tests!#1@\protect\texttt{#1}}%
        }



        \def\class#1{\list{}{\leftmargin=2em\itemindent-\leftmargin\def\makelabel##1{\hss##1}}%
          \extractclass#1@\par\topsep=0pt}
        \def\endclass{\endlist}
        \def\extractclass#1#2@{%
        \item{{{\ttfamily\char`\\documentclass}#2{\ttfamily\char`\{\declare{#1}\char`\}}}}%
          \index{#1@\protect\texttt{#1} class}%
          \index{Classes!#1@\protect\texttt{#1}}}

        \def\partname{Part}

        \makeatletter
        \def\index@prologue{\section*{Index}\addcontentsline{toc}{section}{Index}
          This index only contains automatically generated entries. A good
          index should also contain carefully selected keywords. This index is
          not a good index.
          \bigskip
        }
        \c@IndexColumns=2
        \def\theindex{\@restonecoltrue
          \columnseprule \z@  \columnsep 29\p@
          \twocolumn[\index@prologue]%
          \parindent -30pt
          \columnsep 15pt
          \parskip 0pt plus 1pt
          \leftskip 30pt
          \rightskip 0pt plus 2cm
          \small
          \def\@idxitem{\par}%
          \let\item\@idxitem \ignorespaces}
        \def\endtheindex{\onecolumn}
        \def\noindexing{\let\index=\@gobble}



        \newcommand\symarrow[1]{
          \index{#1@\protect\texttt{#1} arrow tip}%
          \index{Arrow tips!#1@\protect\texttt{#1}}
          \texttt{#1}& yields thick  
          \begin{tikzpicture}[arrows={#1-#1},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture} and thin
          \begin{tikzpicture}[arrows={#1-#1},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}
        }
        \newcommand\symarrowdouble[1]{
          \index{#1@\protect\texttt{#1} arrow tip}%
          \index{Arrow tips!#1@\protect\texttt{#1}}
          \texttt{#1}& yields thick  
          \begin{tikzpicture}[arrows={#1-#1},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}
          and thin
          \begin{tikzpicture}[arrows={#1-#1},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}, double 
          \begin{tikzpicture}[arrows={#1-#1},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw[double,double equal sign distance] (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture} and 
          \begin{tikzpicture}[arrows={#1-#1},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw[double,double equal sign distance] (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}
        }

        \newcommand\sarrow[2]{
          \index{#1@\protect\texttt{#1} arrow tip}%
          \index{Arrow tips!#1@\protect\texttt{#1}}
          \index{#2@\protect\texttt{#2} arrow tip}%
          \index{Arrow tips!#2@\protect\texttt{#2}}
          \texttt{#1-#2}& yields thick  
          \begin{tikzpicture}[arrows={#1-#2},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture} and thin
          \begin{tikzpicture}[arrows={#1-#2},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}
        }

        \newcommand\sarrowdouble[2]{
          \index{#1@\protect\texttt{#1} arrow tip}%
          \index{Arrow tips!#1@\protect\texttt{#1}}
          \index{#2@\protect\texttt{#2} arrow tip}%
          \index{Arrow tips!#2@\protect\texttt{#2}}
          \texttt{#1-#2}& yields thick  
          \begin{tikzpicture}[arrows={#1-#2},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture} and thin
          \begin{tikzpicture}[arrows={#1-#2},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}, double 
          \begin{tikzpicture}[arrows={#1-#2},thick,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw[double,double equal sign distance] (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture} and 
          \begin{tikzpicture}[arrows={#1-#2},thin,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1cm,2ex);
            \draw[double,double equal sign distance] (0pt,.5ex) -- (1cm,.5ex);
          \end{tikzpicture}
        }

        \newcommand\carrow[1]{
          \index{#1@\protect\texttt{#1} arrow tip}%
          \index{Arrow tips!#1@\protect\texttt{#1}}
          \texttt{#1}& yields for line width 1ex
          \begin{tikzpicture}[arrows={#1-#1},line width=1ex,baseline]
            \useasboundingbox (0pt,-0.5ex) rectangle (1.5cm,2ex);
            \draw (0pt,.5ex) -- (1.5cm,.5ex);
          \end{tikzpicture}
        }
        \def\myvbar{\char`\|}
        \newcommand\plotmarkentry[1]{%
          \index{#1@\protect\texttt{#1} plot mark}%
          \index{Plot marks!#1@\protect\texttt{#1}}
          \texttt{\char`\\pgfuseplotmark\char`\{\declare{#1}\char`\}} &
          \tikz\draw[color=black!25] plot[mark=#1,mark options={fill=examplefill,draw=black}] coordinates{(0,0) (.5,0.2) (1,0) (1.5,0.2)};\\
        }
        \newcommand\plotmarkentrytikz[1]{%
          \index{#1@\protect\texttt{#1} plot mark}%
          \index{Plot marks!#1@\protect\texttt{#1}}
          \texttt{mark=\declare{#1}} & \tikz\draw[color=black!25]
          plot[mark=#1,mark options={fill=examplefill,draw=black}] 
          coordinates {(0,0) (.5,0.2) (1,0) (1.5,0.2)};\\
        }



        \ifx\scantokens\@undefined
        \PackageError{pgfmanual-macros}{You need to use extended latex
          (elatex) or (pdfelatex) to process this document}{}
        \fi

        \begingroup
        \catcode`|=0
        \catcode`[= 1
        \catcode`]=2
        \catcode`\{=12
        \catcode `\}=12
        \catcode`\\=12 |gdef|find@example#1\end{codeexample}[|endofcodeexample[#1]]
        |endgroup

        % define \returntospace.
        % 
        % It should define NEWLINE as {}, spaces and tabs as \space.
        \begingroup
        \catcode`\^=7
        \catcode`\^^M=13
        \catcode`\^^I=13
        \catcode`\ =13%
        \gdef\returntospace{\catcode`\ =13\def {\space}\catcode`\^^I=13\def^^I{\space}}
        \gdef\showreturn{\show^^M}
        \endgroup

        \begingroup
        \catcode`\%=13
        \catcode`\^^M=13
        \gdef\commenthandler{\catcode`\%=13\def%{\@gobble@till@return}}
          \gdef\@gobble@till@return#1^^M{}
          \gdef\@gobble@till@return@ignore#1^^M{\ignorespaces}
          \gdef\typesetcomment{\catcode`\%=13\def%{\@typeset@till@return}}
            \gdef\@typeset@till@return#1^^M{{\def%{\char`\%}\textsl{\char`\%#1}}\par}
                \endgroup

        % Define tab-implementation functions
        % \codeexample@tabinit@replacementchars@
        % and
        % \codeexample@tabinit@catcode@
        % 
        % They should ONLY be used in case that tab replacement is active.
        % 
        % This here is merely a preparation step.
        % 
        % Idea:
        % \codeexample@tabinit@catcode@ will make TAB active
        % and
        % \codeexample@tabinit@replacementchars@ will insert as many spaces as
        % /codeexample/tabsize contains.
        {
          \catcode`\^^I=13
          % ATTENTION: do NOT use tabs in these definitions!!
          \gdef\codeexample@tabinit@replacementchars@{%
            \begingroup
            \count0=\pgfkeysvalueof{/codeexample/tabsize}\relax
            \toks0={}%
            \loop
            \ifnum\count0>0
            \advance\count0 by-1
            \toks0=\expandafter{\the\toks0\ }%
            \repeat
            \xdef\codeexample@tabinit@replacementchars@@{\the\toks0}%
            \endgroup
            \let^^I=\codeexample@tabinit@replacementchars@@
          }%
          \gdef\codeexample@tabinit@catcode@{\catcode`\^^I=13}%
        }%

        % Called after any options have been set. It assigns
        % \codeexample@tabinit@catcode
        % and
        % \codeexample@tabinit@replacementchars
        % which are used inside of 
        % \begin{codeexample}
        %   ...
        % \end{codeexample}
        % 
        % \codeexample@tabinit@catcode  is either \relax or it makes tab
        % active.
        % 
        % \codeexample@tabinit@replacementchars is either \relax or it inserts
        % a proper replacement sequence for tabs (as many spaces as
        % configured)
        \def\codeexample@tabinit{%
          \ifnum\pgfkeysvalueof{/codeexample/tabsize}=0\relax
          \let\codeexample@tabinit@replacementchars=\relax
          \let\codeexample@tabinit@catcode=\relax
          \else
          \let\codeexample@tabinit@catcode=\codeexample@tabinit@catcode@
          \let\codeexample@tabinit@replacementchars=\codeexample@tabinit@replacementchars@
          \fi
        }

        \pgfqkeys{/codeexample}{%
          width/.code=	{\setlength\codeexamplewidth{#1}},
          graphic/.code=	{\colorlet{graphicbackground}{#1}},
          code/.code=	{\colorlet{codebackground}{#1}},
          execute code/.is if=code@execute,
          code only/.code=	{\code@executefalse},
          pre/.store in=\code@pre,
          post/.store in=\code@post,
          % #1 is the *complete* environment contents as it shall be
          % typeset. In particular, the catcodes are NOT the normal ones.
          typeset listing/.code=	{#1},
          render instead/.store in=\code@render,
          vbox/.code=	{\def\code@pre{\vbox\bgroup\setlength{\hsize}{\linewidth-6pt}}\def\code@post{\egroup}},
          ignorespaces/.code=	{\let\@gobble@till@return=\@gobble@till@return@ignore},
          leave comments/.code=	{\def\code@catcode@hook{\catcode`\%=12}\let\commenthandler=\relax\let\typesetcomment=\relax},
          tabsize/.initial=0,% FIXME : this here is merely used for indentation. It is just a TAB REPLACEMENT.
          every codeexample/.style={width=4cm+7pt},
        }

        \let\code@pre\pgfutil@empty
        \let\code@post\pgfutil@empty
        \let\code@render\pgfutil@empty
        \def\code@catcode@hook{}

        \newdimen\codeexamplewidth
        \newif\ifcode@execute
        \newbox\codeexamplebox
        \def\codeexample[#1]{%
          \begingroup%
          \code@executetrue
          \pgfqkeys{/codeexample}{every codeexample,#1}%
          \codeexample@tabinit% assigns \codeexample@tabinit@[catcode,replacementchars]
          \parindent0pt
          \begingroup%
          \par%
          \medskip%
          \let\do\@makeother%
          \dospecials%
          \obeylines%
          \@vobeyspaces%
          \catcode`\%=13%
          \catcode`\^^M=13%
          \code@catcode@hook%
          \codeexample@tabinit@catcode
          \relax%
          \find@example}
        \def\endofcodeexample#1{%
          \endgroup%
          \ifcode@execute%
          \setbox\codeexamplebox=\hbox{%
            \ifx\code@render\pgfutil@empty%
            {%
              {%
                \returntospace%
                \commenthandler%
                \xdef\code@temp{#1}% removes returns and comments
              }%
              \catcode`\^^M=9%
              \colorbox{graphicbackground}{\color{black}\ignorespaces%
                \code@pre\expandafter\scantokens\expandafter{\code@temp\ignorespaces}\code@post\ignorespaces}%
            }%
            \else%
            \colorbox{graphicbackground}{\color{black}\ignorespaces%
              \code@render}%
            \fi%
          }%
          \ifdim\wd\codeexamplebox>\codeexamplewidth%
          \def\code@start{\par}%
          \def\code@flushstart{}\def\code@flushend{}%
          \def\code@mid{\parskip2pt\par\noindent}%
          \def\code@width{\linewidth-6pt}%
          \def\code@end{}%
          \else%
          \def\code@start{%
            \linewidth=\textwidth%
            \parshape \@ne 0pt \linewidth
            \leavevmode%
            \hbox\bgroup}%
          \def\code@flushstart{\hfill}%
          \def\code@flushend{\hbox{}}%
          \def\code@mid{\hskip6pt}%
          \def\code@width{\linewidth-12pt-\codeexamplewidth}%
          \def\code@end{\egroup}%
          \fi%
          \code@start%
          \noindent%
          \begin{minipage}[t]{\codeexamplewidth}\raggedright
            \hrule width0pt%
            \footnotesize\vskip-1em%
            \code@flushstart\box\codeexamplebox\code@flushend%
            \vskip-1ex
            \leavevmode%
          \end{minipage}%
          \else%
          \def\code@mid{\par}
          \def\code@width{\linewidth-6pt}
          \def\code@end{}
          \fi%
          \code@mid%  
          \colorbox{codebackground}{%
            \begin{minipage}[t]{\code@width}%
              {%
                \let\do\@makeother
                \dospecials
                \frenchspacing\@vobeyspaces
                \normalfont\ttfamily\footnotesize
                \typesetcomment%
                \codeexample@tabinit@replacementchars
                \@tempswafalse
                \def\par{%
                  \if@tempswa
                  \leavevmode \null \@@par\penalty\interlinepenalty
                  \else
                  \@tempswatrue
                  \ifhmode\@@par\penalty\interlinepenalty\fi
                  \fi}%
                \obeylines
                \everypar \expandafter{\the\everypar \unpenalty}%
                \pgfkeysvalueof{/codeexample/typeset listing/.@cmd}{#1}\pgfeov
              }
            \end{minipage}}%
          \code@end%
          \par%
          \medskip
        \end{codeexample}
      }

      \def\endcodeexample{\endgroup}


      \makeatother

      \usepackage{pgfmanual}

      \makeatletter
      % \pgfautoxrefs will be defined by 'make dist'
      \pgfutil@ifundefined{pgfautoxrefs}{%
	\def\pgfmanualpdflabel#1#2{#2}% NO-OP
	\def\pgfmanualpdfref#1#2{#2}%
	\pgfkeys{
          /pdflinks/codeexample links=false,% DISABLED.
	}%
      }{}
      \makeatother


      \makeatletter
      \renewcommand*\l@subsection{\@dottedtocline{2}{1.5em}{2.8em}}
      \renewcommand*\l@subsubsection{\@dottedtocline{3}{4.3em}{3.2em}}
      \makeatother

      % \includeonly{pgfmanual-en-library-profiler}

      % Global styles:
      \tikzset{
        every plot/.style={prefix=plots/pgf-},
        shape example/.style={
          color=black!30,
          draw,
          fill=yellow!30,
          line width=.5cm,
          inner xsep=2.5cm,
          inner ysep=0.5cm}
      }

\usepackage{tikz-cd}
\usepackage{multicol,longtable}

\hypersetup{pdftitle={The tikz-cd package},
            pdfauthor={Florêncio Neves},
            pdfkeywords={commutative diagrams, latex, tikz, pgf},
            colorlinks
           }
           
\title{The \texttt{tikz-cd} package}
\author{\normalsize Florêncio Neves\footnote{\emph{E-mail:} \href{mailto:florencioneves@gmail.com}{\texttt{florencioneves@gmail.com}}}}
\date{\normalsize Version 0.2a, of December 9, 2011}

\tikzset{commutative diagrams/background color=graphicbackground}

\newcommand{\displayarrow}[2][]{\texttt{#2} & yelds \tikz[baseline=-2.5pt] \draw[#2-#2, line width=0.0929ex, #1] (0,0) -- (1,0);}
\newcommand{\displayarrowstyle}[2][]{\texttt{#2} #1 & yelds \tikz[baseline=-2.5pt] \draw[commutative diagrams/.cd, #2] (0,0) -- (0.6,0);}

\begin{document}
\maketitle

The general-purpose drawing package Ti\emph{k}Z can be used to typeset
commutative diagrams and other kinds of mathematical pictures,
generating high-quality results (see for example \cite{lenders} or
\cite{milne}).  This package facilitates the creation of such diagrams
by providing a convenient set of macros and reasonable default
settings.  Familiarity with Ti\emph{k}Z is helpful, but not necessary,
as the examples contained here cover the most often encountered
situations.

This package also includes an arrow tip library that match closely the
arrows present in the Computer Modern typeface.

\textsc{pgf} version 2.10 is required.

\tableofcontents

\section{Basic usage}
\label{sec:basic-usage}

Commutative diagrams are created with the |tikzcd| environment.  Its
content describes a matrix, like the |\matrix| command in \tikzname{}
or the |align| environment in \LaTeX.  Everything is typeset in math
mode, but you will probably want use \texttt{tikzcd} inside an
|equation| environment or inside |\[| \dots |\]|, so that the diagram is
placed on a new line and centered.

\subsection{Inserting arrows}
\label{sec:inserting-arrows}

Inside the |tikzcd| environment, the command |\arrow| is provided to
produce arrows.  In its simplest form, it takes one argument, a string
containing the characters |r|, |l|, |u| or |d|, standing for right, left,
up and down, that determine the arrow target.  A label can be
placed on an arrow by providing a second argument.
\begin{codeexample}[]
  \begin{tikzcd}
    A \arrow{rd} \arrow{r}{\phi} & B \\
                                 & C
  \end{tikzcd}
\end{codeexample}

You can control the behavior of the arrow by placing an argument
inside square braces before the direction parameter.  It may contain
any option that can be passed to \tikzname{}'s
|\path| command.  Similarly, a label can be modified by an argument in
square braces right before it.  It may contain anything that can be
passed to \tikzname's |node| operator.
\begin{codeexample}[]
\begin{tikzcd}
  A \arrow{r}{\psi} \arrow[color=red]{d}
        & B \arrow{d}[color=red]{\psi} \\
  C \arrow[color=red]{r}[color=blue]{\eta}
        & D
\end{tikzcd}
\end{codeexample}

An arrow can actually have an arbitrary number of labels, each one
specified by juxtaposing |{|\meta{text}|}| or
|[|\meta{options}|]{|\meta{text}|}| to the |\arrow| command.

\begin{codeexample}[]
\begin{tikzcd}
  A \arrow{r}[near start]{\phi}[swap]{\psi}[near end]{\eta} & B    
\end{tikzcd}
\end{codeexample}

To save some typing, the command |\ar| is provided as a shorthand to
|\arrow|.  There are also commands |\rar|, |\lar|, |\uar|, |\dar|,
|\urar|, |\ular|, |\drar| and |\dlar| that act like |\arrow{r}|,
|\arrow{l}|, \dots, |\arrow{ur}|, and so forth.  They can take an optional
argument in square braces to modify the arrow, followed by label
specifiers of the form |{|\meta{text}|}| or
|[|\meta{options}|]{|\meta{text}|}|.
Thus, the diagram above can be rewritten as follows.
\begin{codeexample}[]
\begin{tikzcd}
  A \rar{\psi} \dar[color=red]
        & B \dar[][color=red]{\psi} \\
  C \rar[color=red][color=blue]{\eta}
        & D
\end{tikzcd}
\end{codeexample}

We provide one more example, reproduced from X\raisebox{-0.3ex}{Y}-pic
user's guide.

\begin{codeexample}[]
\begin{tikzcd}
  T
  \arrow[bend left]{drr}{x}
  \arrow[bend right]{ddr}{y}
  \arrow[dotted]{dr}[description]{(x,y)} & & \\
      & X \times_Z Y \arrow{r}{p} \arrow{d}{q} & X \arrow{d}{f} \\
      & Y \arrow{r}{g}                         & Z
\end{tikzcd}
\end{codeexample}

\subsection{Changing arrow tips}
\label{sec:changing-arrow-tips}

For each arrow-producing command present in \AmS-\LaTeX, there is a
corresponding option (without a ``|\|'') that can be passed to
|\arrow| to produce that kind of arrow.  Notice the use of
|hookrightarrow| and |dashrightarrow| in the example below.

\begin{codeexample}[]
  \begin{tikzcd}
    X \arrow[hookrightarrow]{r} \arrow[dashrightarrow]{rd}
      & \bar{X} \arrow{d}\\
      & Y
  \end{tikzcd}
\end{codeexample}

Of course, a similar effect could be achieved by directly using
\tikzname's arrow tip selection scheme (e.g., using the option
|right hook->|).  However, the method more above is more appropriate, as it
abstracts the choice of an actual arrow tip design (see also the key
\texttt{commutative diagrams/arrow style} below), and is probably also
better from the mnemonic standpoint.

The following list shows all arrow styles available.

{\tikzset{commutative diagrams/.cd, background color=white}
  \begin{quote}
    \begin{tabular}{ll}
      \displayarrowstyle{rightarrow}\\
      \displayarrowstyle{Rightarrow}\\
      \displayarrowstyle{leftarrow}\\
      \displayarrowstyle{Leftarrow}\\
      \displayarrowstyle{leftrightarrow}\\
      \displayarrowstyle{Leftrightarrow}\\
      \displayarrowstyle{equals}\\
      \displayarrowstyle[(or \texttt{maps to})]{mapsto}\\
      \displayarrowstyle[(or \texttt{hook})]{hookrightarrow}\\
      \displayarrowstyle{hookleftarrow}\\
      \displayarrowstyle{rightharpoonup}\\
      \displayarrowstyle{rightharpoondown}\\
      \displayarrowstyle{leftharpoonup}\\
      \displayarrowstyle{leftharpoondown}\\
      \displayarrowstyle[(or \texttt{dashed})]{dashrightarrow}\\
      \displayarrowstyle{dashleftarrow}\\
      \displayarrowstyle[(or \texttt{tail})]{rightarrowtail}\\
      \displayarrowstyle{leftarrowtail}\\
      \displayarrowstyle[(or \texttt{two heads})]{twoheadrightarrow}\\
      \displayarrowstyle{twoheadleftarrow}\\
      \displayarrowstyle[(or \texttt{squiggly})]{rightsquigarrow}\\
      \displayarrowstyle{leftsquigarrow}\\
      \displayarrowstyle{leftrightsquigarrow}
    \end{tabular}
  \end{quote}
}

Some of the styles above have two names.  In these cases, the second
one behaves a little differently from the first, in that it can be
superimposed with other arrow styles.

\begin{codeexample}[]
\begin{tikzcd}
  A \arrow[tail, two heads, dashed]{r} & B
\end{tikzcd}
\end{codeexample}


\section{Controlling the appearance of diagrams}
\label{sec:chang-appe-diagr}

This section lists all customization keys defined by this package.
Options can be made take effect in different scopes:
\begin{enumerate}
\item Globally, using the command |\tikzset|.  This can be done in the
  document preamble, or in the body, to affect all diagrams
  appearing next.
\item For the current diagram, by placing options in the optional
  argument to the |tikzcd| environment.  Such options are applied to
  the |tikzpicture| environment generated by |tikzcd| (cf.\ \S\ref{sec:intern-arrow-comm}).  Thus you can,
  for instance, use the |execute at end picuture| option in this
  situation to have arbitrary \tikzname{} code executed after a
  diagram is drawn.
\item For the current arrow or label, by placing options in one of the
  optional arguments of |\arrow|.
\end{enumerate}

Of course, not all options make sense in all contexts.  For example,
setting |row sep=1cm| globally with |\tikzset| will have no effect on
diagrams, since the |row sep| option is re-set at the beginning of
each diagram.  To make all diagrams have |row sep| set to 1\,cm, you
can use
\begin{quote}
  |\tikzset{commutative diagrams/row sep/normal=1cm}|,
\end{quote}
as detailed below.

All keys provided by this package are located in the path
|/tikz/commutative diagrams|.  Methods 2.\ and 3.\ above will search
in this path by default.  If a key is not found there, an attempt is
made to find it in |/tikz|, which is what you would expect.  When
using method 1., it is convenient to change the default search path by using
\begin{quote}
  |\tikzset{commutative diagrams/.cd, |\meta{options}|}|.
\end{quote}

\subsection{General options}
\label{sec:general-options}

\begin{stylekey}{/tikz/commutative diagrams/every diagram}
  This style is applied to every |tikzcd| environment.  Initially, it
  contains the following:
\begin{codeexample}[code only]
/tikz/commutative diagrams/.cd,
/tikz/text height=1.5ex,
/tikz/text depth=0.25ex,
/tikz/baseline=0pt,
row sep=normal,
column sep=normal
\end{codeexample}

The options |text height| and |text depth| are set to ensure arrows
between nodes in the same row are drawn horizontally, as discussed in
\cite{lenders}.  The |baseline=0pt| setting is used to make equation
numbers be placed correctly.

\end{stylekey}

\begin{key}{/tikz/commutative diagrams/diagrams=\meta{options}}
  This key appends \meta{options} to the style
  |/tikz/commutative diagrams/every diagram|.
\end{key}

\begin{key}{/tikz/commutative diagrams/row sep=\meta{size} (initially normal)}
  This key acts as a ``frontend'' to \tikzname's |/tikz/row sep| key.  If
  the key
  \begin{quote}
    |/tikz/commutative diagrams/row sep/|\meta{size}
  \end{quote}
stores a
  \meta{value}, then it is read and |/tikz/row sep|=\meta{value} is
  set.  If the key above is not initialized, then \meta{size} is
  presumably a dimension, and |/tikz/row sep|=\meta{size} is set.

  The values of \meta{size} initially available, and their values, are
  the following:
  \begin{center}
    \begin{tabular}{cccccc}
      |tiny| & |small| & |scriptsize| & |normal| & |large| & |huge| \\
      1.25\,ex & 2.5\,ex   & 3.75\,ex       & 5\,ex      & 7.5\,ex   & 10\,ex
    \end{tabular}
  \end{center}
\end{key}

  To change, say, the |normal| size (which is applied by default) to 1\,cm, you
  can use the code
\begin{quote}
|\tikzset{commutative diagrams/row sep/normal=1cm}|.
\end{quote}
  You can also create new sizes, but |pgfkeys| requires new keys to be
  explicitly initialized.  For example, to create a size |my size|, meaning
  1\,cm, you should use
\begin{quote}
|\tikzset{commutative diagrams/row sep/my size/.initial=1cm}|.
\end{quote}

\begin{key}{/tikz/commutative diagrams/column sep=\meta{size} (initially normal)}
  This works analogously to the |row sep| key above.  The sizes available
  initially are the following:
  \begin{center}
    \begin{tabular}{cccccc}
      |tiny| & |small| & |scriptsize| & |normal| & |large| & |huge| \\
      1.5\,ex & 3\,ex   & 4.5\,ex       & 6\,ex      & 9\,ex   & 12\,ex
    \end{tabular}
  \end{center}
\end{key}

In the examples below, the triangular diagrams would look too wide or
too tall if the column or row separation were not set appropriately.

\begin{codeexample}[]
\begin{tikzcd}[column sep=small]
                         & A \arrow{dl}\arrow{dr} & \\
  B \arrow{rr}           &                        & C 
\end{tikzcd}
\end{codeexample}

\begin{codeexample}[]
\begin{tikzcd}[row sep=tiny]
                         & B \arrow{dd}             \\
  A \arrow{ur}\arrow{dr} &                          \\
                         & C
\end{tikzcd}
  
\end{codeexample}

\begin{key}{/tikz/commutative diagrams/math mode=\meta{boolean}
    (initially true)}
  This keys determines whether the contents of a diagram is typeset in
  math mode or not.  If set globally or diagram-wise, it affects both
  the diagram entries and arrow labels.  If used with |\arrow|, it affect
  only its labels.
\end{key}

\begin{key}{/tikz/commutative diagrams/background color=\meta{color} (initially white)}
  This key stores the name of a color, and is read by 
  styles that fill the background, such as |description| and |crossing over|.
  It does not cause the background to painted.
\end{key}

\subsection{Options for arrows}
\label{sec:options-arrows}

Besides the options and styles provided by this package, there are
several options defined by \tikzname{} that are useful for arrows, such
as |dashed|, |dotted| and its relatives, |line width=|\meta{dimension}, |color=|\meta{color},
|bend right|, |bend left|, |in=|\meta{angle}, |out=|\meta{angle},
|loop|, etc.  See \pgfname{} manual~\cite{pgfman}.

\begin{stylekey}{/tikz/commutative diagrams/every arrow}
  This style is applied to every |\arrow|.  Initially, it contains the
  following:
\begin{codeexample}[code only]
/tikz/commutative diagrams/.cd,
/tikz/draw,
/tikz/commutative diagrams/default arrow
\end{codeexample}

Initially, the style |default arrow| is a synonym to |rightarrow|.
\end{stylekey}

\begin{key}{/tikz/commutative diagrams/arrows=\meta{options}}
  This key appends \meta{options} to the style
  |/tikz/commutative diagrams/every arrow|.
\end{key}

\begin{key}{/tikz/commutative diagrams/arrow style=\meta{style} (initially computer
    modern)}
  Setting this key causes the several arrow-tip-specifying styles
  listed on \S\ref{sec:changing-arrow-tips} to be (re)defined.  In
  particular, it makes the style
  |/tikz/commutative diagrams/default arrow|,
    which is automatically applied to every arrow, to be defined.
  Currently, \meta{style} can be one of |computer modern| or |tikz|.  The |tikz| style uses the arrow tips defined in \tikzname's |arrows|
  library, and it honors the option |/tikz/>|.

  The |computer modern| style sets the parameter |/tikz/line width| in
  accordance to the current font size.  The |tikz| arrow style,
  however, does not change it, allowing you to directly control the
  thickness of arrows.
\end{key}

If you are using a font different from Computer Modern, you may find
better results by selecting the |tikz| arrow style, setting |/tikz/>| to
the value that best matches your font, and adjusting |/tikz/line width|
if necessary.  The following example, if not particularly elegant,
should be instructive.

\begin{codeexample}[]
\tikzset{
  commutative diagrams/.cd,
  arrow style=tikz,
  diagrams={>=open triangle 45, line width=1pt}}
  
\begin{tikzcd}
  A \arrow{r} \arrow{d} & B \arrow{d}\\
  C \arrow{r}           & D
\end{tikzcd}
\end{codeexample}

\begin{key}{/tikz/commutative diagrams/start anchor=\meta{anchor}
    (default \normalfont empty)}
  This style specifies at which anchor of the current node an arrow
  should start.  The default behavior is not to specify an anchor,
  causing the arrow to start at the point in the boundary of the
  current node closest to the destination, as explained in
  \pgfname{} manual~\cite{pgfman}.
\end{key}

\begin{key}{/tikz/commutative diagrams/end anchor=\meta{anchor}
    (default \normalfont empty)}
  This style works analogously, but refers to the target node of the arrow.
\end{key}

Some of the possible values for \meta{anchor} are shown below.

  \begin{center}
    \begin{tikzpicture}
      \node[name=s,shape=rectangle,shape example] {\Huge Rectangle\vrule
        width 1pt height 2cm}; \foreach \anchor/\placement in {north
        west/above left, north/above, north east/above right,
        west/left, center/above, east/right, mid west/right,
        mid/above, mid east/left, base west/left, base/below, base
        east/right, south west/below left, south/below, south
        east/below right, text/left, 10/right, 130/above}
      \draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
      node[\placement] {\scriptsize\texttt{\anchor}};
    \end{tikzpicture}
  \end{center}

The picture below illustrates the use of |end anchor| and
|start anchor|.

\begin{codeexample}[]
\begin{tikzcd}
  A \rar[start anchor=north east, end anchor=north west]{\psi}
    \rar[start anchor=south east, end anchor=south west,swap]{\phi}
  & B
\end{tikzcd}
\end{codeexample}

\begin{stylekey}{/tikz/commutative diagrams/crossing over}
  This style makes a thicker line, with color
  |/tikz/commutative diagrams/background color|, to be drawn under the
  current arrow, simulating the effect of its passing over other
  arrows.

\begin{codeexample}[]
\begin{tikzcd}
  A \arrow{dr} & B \arrow[crossing over]{dl} \\
  C            & D
\end{tikzcd}
\end{codeexample}
\end{stylekey}

Note that, since arrows are drawn in the order they are read, some
arrows may need to run ``backwards'' to achieve the desired result.
The following picture, from \cite{lenders}, illustrates this.

\begin{codeexample}[]
\begin{tikzcd}[row sep=scriptsize, column sep=scriptsize]
  & f^* E_V \arrow{dl}\arrow{rr}\arrow{dd} & & E_V \arrow{dl}\arrow{dd} \\
  f^* E \arrow[crossing over]{rr}\arrow{dd} & & E \\
  & U \arrow{dl}\arrow{rr} &  & V \arrow{dl} \\
  M \arrow{rr} & & N\arrow[crossing over, leftarrow]{uu} \\
\end{tikzcd}
\end{codeexample}
  
\begin{key}{/tikz/commutative diagram/crossing over clearance=\meta{dimension}
    (initially 6pt)}
  This key specifies the width of the background-colored line drawn
  under a |crossing over| arrow.
\end{key}


\subsection{Options for labels}
\label{sec:options-labels}

Besides the options provided by this package and listed below, there
are many options provided by \tikzname{} that are useful for
labels, such as  |above|, |below|, |left|,
|right|, |swap| (which makes the label be placed in the opposite side
to the default), |sloped|, |pos=|\meta{fraction}, |near start|,
|near end|, |inner sep=|\meta{dimension}, |font=|\meta{font
  command}, |text width=|\meta{dimension}, etc.  See \pgfname{} manual~\cite{pgfman}.

\begin{stylekey}{/tikz/commutative diagrams/every label}
  This style works as if it were applied to the optional argument
  corresponding to each label attached to an arrow.  Initially is set
  to the following:

\begin{codeexample}[code only]
/tikz/commutative diagrams/.cd,
/tikz/auto,
/tikz/font=\scriptsize,
/tikz/inner sep=0.5ex,
/tikz/text height=,
/tikz/text depth=
\end{codeexample}

The style |/tikz/auto| makes the label be placed to the left of the
arrow, understanding ``front'' as the direction the arrow points at.
The dimension |/tikz/inner sep| controls the distance between the
arrow and the label.  The options |text height| and |text depth| are
reset here because they are set picture-wise by the |every diagram|
style.
\end{stylekey}

\begin{key}{/tikz/commutative diagrams/labels=\meta{options}}
  This key appends \meta{options} to the style
  |/tikz/commutative diagrams/every label|.
\end{key}

\begin{stylekey}{/tikz/commutative diagrams/description}
  This style causes the label to be placed on the arrow, with the
  background filled.

\begin{codeexample}[]
\begin{tikzcd}
  A \arrow{r}[description]{\phi} & B
\end{tikzcd}
\end{codeexample}
\end{stylekey}

\begin{key}{/tikz/commutative diagrams/description
    clearance=\meta{dimension} (initially 1.5pt)}
  This key determines the size of the border around a label when the
  |description| style above is applied.  Its value is used to set the
  key |/tikz/inner sep|.
\end{key}

\section{Further possibilities}
\label{sec:further}

This sections provides further details on the functioning of
this package, with the aim of showing how a more or less arbitrary use of
\tikzname{} features can be made inside it.

\subsection{Internals of \texttt{tikzcd} and the arrow commands}
\label{sec:intern-arrow-comm}

The |tikzcd| environment works by substituting code of the form
\begin{quote}
  |\begin{tikzcd}[|\meta{options}|]|
    \meta{contents}
  |\end{tikzcd}|
\end{quote}
with roughly the following:
\begin{quote}
  |\begin{tikzpicture}[commutative diagrams/every diagram,|
    \meta{options}|]|\\
  |  \matrix[matrix of |[|math|]| nodes] {|\\
  |    |\meta{contents} |\\|\\
  |  };|\\
  |  |\meta{paths}\\
  |\end{tikzpicture}|
\end{quote}

Note that the next-row command |\\| for the last row is inserted by
|tikzcd|, and therefore does not need to be present in
\meta{contents}.  The |\matrix| is supplied the option \texttt{matrix
  of nodes} or \texttt{matrix of math nodes} as specified by the
option \texttt{commutative diagrams/math mode}.  Also, not shown above
are a number of initialization procedures, such as defining the
commands |\arrow|, |\ar|, |\rar|, |\lar|, |\dar|, |\uar|, |\urar|,
|\ular|, |\drar|, |\dlar|.

The command |\arrow[|\meta{options}|]{|\meta{direction}|}| does
nothing at the point it is inserted, and causes the following code to
be added to \meta{paths}:
\begin{quote}
  |\path[commutative diagrams/every arrow, |\meta{options}|] (|%
  \meta{current node}|) to |\meta{labels}| (|\meta{target~node}|);|
\end{quote}

Here, \meta{current node} is the node corresponding to the matrix cell
where the command |\arrow| is, and \meta{target node} is determined by
\meta{direction} as explained in \S\ref{sec:inserting-arrows}.  The
abbreviated commands |\rar|, |\dar|, etc., generate the same kind of
code.

Initially, \meta{labels} is the empty string.  A label specifier of
the form |{|\meta{label text}|}| or |[|\meta{label
  options}|]{|\meta{label text}|}| immediately following the
\meta{direction} argument or a previous label specifier causes the
string
\begin{quote}
  |node [commutative diagrams/every label, |\meta{label options}|] {|[|$|]\meta{label text}[|$|]|}|
\end{quote}
to be appended to \meta{labels}.  Dollars signs surround \meta{label
  text} depending on the setting \texttt{commutative diagrams/math
  mode}.  For the abbreviated form |\rar| (and similarly for |\dar|,
|\lar|, etc.), the following are valid usages:
\begin{quote}
  |\rar{|\meta{label text}|}|\meta{more labels},\\
  |\rar[|\meta{options}|]{|\meta{label text}|}|\meta{more labels}, or\\
  |\rar[|\meta{options}|][|\meta{label options}|]{|\meta{label
      text}|}|\meta{more labels}.
\end{quote}
Their effects are entirely analogous.

\subsection{Tweaking \texttt{to} paths}
\label{sec:tweaking-to-paths}

Recall that the |to| path operation used in the paths created by
|\arrow| can take a number of options, as described in \S{}14.14
and \S{}51 of the \pgfname{} manual~\cite{pgfman}.  In particular, the
option |/tikz/to path| determines the path that is actually drawn, and
can be used to do all sorts of tweaking.

\begin{codeexample}[]
\begin{tikzcd}
  A \arrow[dashed, to path=|- (\tikztotarget)]{dr}
    \arrow[to path={..controls +(1.5,0.5) and +(-1,0.8).. (\tikztotarget)}]{dr}
    & \\
    & B \arrow[loop right]{}
\end{tikzcd}
\end{codeexample}

In the next example, empty labels are used to create nodes for later
reference, and in the third |\arrow| command the |to path| key is used
in a way that, in the terminology of the previous section,
\meta{current node} and \meta{target node} are completely ignored.
\begin{codeexample}[]
\begin{tikzcd}
  A \arrow[bend left=50]{r}[name=U,below]{}
    \arrow[bend right=50]{r}[name=D]{} &
  B \arrow[Rightarrow,to path=(U) -- (D)]{}
\end{tikzcd}
\end{codeexample}

\subsection{Drawing diagrams directly with Ti\emph{k}Z}
\label{sec:draw-diagr-directly}

If the tools provided by this package prove not flexible enough for
some application, you can use the methods described in \cite{lenders}
and \cite{milne} to draw diagrams directly with \tikzname.  In this
case, you can still use the styles provided here in order to achieve
uniformity with diagrams drawn with |tikzcd|.  The pictures below show
how this can be done (the second one is adapted from \cite{milne}).

\begin{codeexample}[]
\begin{tikzpicture}[commutative diagrams/every diagram]
  \matrix[matrix of math nodes, name=m] {
    X & \bar X \\
      & Y      \\};
  \path[commutative diagrams/.cd, every arrow, every label]
    (m-1-1) edge[commutative diagrams/hook] (m-1-2)
            edge[commutative diagrams/dashed] (m-2-2)
    (m-1-2) edge (m-2-2);
\end{tikzpicture}
\end{codeexample}


\begin{codeexample}[]
\begin{tikzpicture}[commutative diagrams/every diagram]
  \node (P0) at (90:2.8cm) {$X\otimes (Y\otimes (Z\otimes T))$};
  \node (P1) at (90+72:2.5cm) {$X\otimes ((Y\otimes Z)\otimes T))$} ;
  \node (P2) at (90+2*72:2.5cm) {\makebox[5ex][r]{$(X\otimes (Y\otimes Z))\otimes T$}};
  \node (P3) at (90+3*72:2.5cm) {\makebox[5ex][l]{$((X\otimes Y)\otimes Z)\otimes T$}};
  \node (P4) at (90+4*72:2.5cm) {$(X\otimes Y)\otimes (Z\otimes T)$};

  \path[commutative diagrams/.cd, every arrow, every label]
    (P0) edge node[swap] {$1\otimes\phi$} (P1)
    (P1) edge node[swap] {$\phi$} (P2)
    (P2) edge node {$\phi\otimes 1$} (P3)
    (P4) edge node {$\phi$} (P3)
    (P0) edge node {$\phi$} (P4);
\end{tikzpicture}
\end{codeexample}

\section{Computer Modern arrow tips}
\label{sec:comp-modern-arrow}

The naming scheme of the Computer Modern-like arrow tips provided by
this package parallels that of \pgfname's |arrows| library, documented
in \S{}23 of \pgfname{} manual~\cite{pgfman}.  To match the Computer Modern
typeface at size 10\,pt, line width should be set to 0.4\,pt; for
larger font sizes, scale this parameter accordingly, or use the esoteric
figure 0.0929\,ex.

Notice that by using the mechanism explained in
\S\ref{sec:changing-arrow-tips}, it is not necessary, and in fact not
advisable, to directly use the arrow tips listed in this section
when creating diagrams with |tikzcd|.

Incidentally, \tikzname's original |to| arrow tip seems to be based on
the pre-1992 version of Computer Modern which, in spite of the
author's wish \cite{knuth}, can still be found in many systems.
\TeX{}Live, for instance, distributed the old version up until 2007 or
2008.  Therefore, an up-to-date \TeX{} distribution may be necessary
to get matching arrows in formulas and diagrams.

\begin{description}
\item[Basic arrow tips]\ \\
\begin{tabular}{ll}
  \displayarrow{cm to}\\
  \displayarrow{cm to reversed}\\
  \displayarrow[line width=0.66pt]{cm bold to} (with a line 50\% thicker)\\
  \texttt{cm \char`\|} & yelds \tikz[baseline=-2.5pt] \draw[cm |-cm |, line width=0.0929ex] (0,0) -- (1,0);\\
  \displayarrow{cm o}\\
  \displayarrow{cm *}\\
  \displayarrow{cm cap}\\
\end{tabular}

\item[Arrow tips for double lines]\ \\
\begin{tabular}{ll}
  \displayarrow[/tikz/double distance=3.643\pgflinewidth]{cm implies}\\
  \displayarrow[/tikz/double distance=3.643\pgflinewidth]{cm implies cap}
\end{tabular}

\item[Hooks]\ \\
\begin{tabular}{ll}
  \displayarrow{cm left hook}\\
  \displayarrow{cm right hook}\\
\end{tabular}


\item[Double arrow tips]\ \\
\begin{tabular}{ll}
  \displayarrow{cm double to}\\
  \displayarrow{cm double to reversed}\\
\end{tabular}

\item[Partial arrow tips]\ \\
\begin{tabular}{ll}
  \displayarrow{cm left to}\\
  \displayarrow{cm left to reversed}\\
  \displayarrow{cm right to}\\
  \displayarrow{cm right to reversed}\\
\end{tabular}
\end{description}

% \section{Some examples}
% \label{sec:some-examples}


% \begin{codeexample}[]
%   \begin{tikzcd}[row sep=small]
%     H^i(A) \rar & H^i(B) \rar & H^i(C) \arrow[out=0, in=180]{dll}\\
%     H^{i+1}(A) \rar & H^{i+1}(B) \rar & H^{i+1}(C)
%   \end{tikzcd}
% \end{codeexample}

\section{Change history}
\label{sec:change-history}

\begin{description}
\item[Version 0.2a] (December 2011)
  \begin{itemize}
  \item Option |/tikz/commutative diagrams/path operation| removed
    in favor of direct use of |/tikz/to path|.
  \item Double lines with |tikz| arrow style now use \texttt{double
      equal sign distance}.
  \end{itemize}
\item[Version 0.2] (October 2011) Several changes.
\item[Version 0.1] (September 2011) Preliminary release. 
\end{description}

\begin{thebibliography}{9}
\bibitem{knuth}
  Donald Knuth,
  \emph{Important message to all users of \TeX}.
  Available at \url{http://www-cs-staff.stanford.edu/~uno/cm.html}
\bibitem{lenders}
  Felix Lenders,
  \emph{Commutative diagrams using TikZ}.
  Available at \url{http://www.felixl.de/commu.pdf}.
\bibitem{milne}
  James Milne,
  \emph{Guide to commutative diagrams}.
  Available at \url{http://www.jmilne.org/not/CDGuide.html}.
\bibitem{pgfman}
  Till Tantau,
  \emph{The \tikzname{} and \pgfname{} packages:  Manual for version 2.10}.
  Available at \url{http://sourceforge.net/projects/pgf}.
\end{thebibliography}

\end{document}

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