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+%%% ====================================================================
+%%% @LaTeX-file{
+%%% author = "Scott Pakin",
+%%% version = "2.1",
+%%% date = "13 September 2015",
+%%% time = "23:06:32 MDT",
+%%% filename = "dtxtut.tex",
+%%% checksum = "38789 2107 7734 71546"
+%%% email = "scott+dtx@pakin.org (Internet)",
+%%% codetable = "ISO/ASCII",
+%%% keywords = "LaTeX, packages, .ins files, .dtx files,
+%%% literate programming",
+%%% supported = "yes",
+%%% abstract = "This tutorial is intended for advanced
+%%% LaTeX 2e users who want to learn how to
+%%% create .ins and .dtx files for distributing
+%%% their homebrewed classes and style files.",
+%%% docstring = "The checksum field above contains a CRC-16
+%%% checksum as the first value, followed by
+%%% the equivalent of the standard UNIX wc
+%%% (word count) utility output of lines,
+%%% words, and characters. This is produced by
+%%% Robert Solovay's checksum utility. This file
+%%% header was produced with the help of Nelson
+%%% Beebe's filehdr utility. Both checksum and
+%%% filehdr are available from CTAN
+%%% (http://www.ctan.org)."
+%%%
+%%% }
+%%% ====================================================================
+
+\documentclass[11pt]{ltxguide}
+\usepackage{varioref}
+\usepackage{makeidx}
+\usepackage{alltt}
+\usepackage{tocbibind}
+\usepackage[bookmarksopen]{hyperref}
+\usepackage{hyperxmp}
+
+% Define this document's metadata.
+\title{How to Package Your \LaTeX{} Package}
+\author{Scott Pakin \texttt{<scott+dtx@pakin.org>}}
+\date{13 September 2015}
+\hypersetup{%
+ pdftitle={How to Package Your LaTeX Package},
+ pdfauthor={Scott Pakin},
+ pdfcontactemail={scott+dtx@pakin.org},
+ pdfcontacturl={http://www.pakin.org/\xmptilde scott},
+ pdfsubject={Writing .ins and .dtx files for LaTeX},
+ pdfkeywords={LaTeX package documentation, literate programming, typesetting, installer files},
+ pdfcaptionwriter={Scott Pakin},
+ pdfcopyright={Copyright (C) 2015 Scott Pakin},
+ pdflicenseurl={http://latex-project.org/lppl/},
+ pdflang={en-US}
+}
+
+% Define a term.
+\newcommand{\defn}[2][X]{%
+ \ifx#1X
+ \emph{#2}\index{#2}%
+ \else
+ \emph{#2}\index{#1}%
+ \fi
+}
+
+% Make a version of \dots that allows a subsequent line break.
+\newcommand{\dotsbrk}{\dots\linebreak[0]}
+
+% If we have url.sty loaded, use that for formatting URLs.
+\ifx\url\undefined
+\else
+ \let\URL=\url
+\fi
+
+% Define formatting for various packages.
+\newcommand{\DOC}{\textsf{Doc}\index{Doc@\textsf{Doc}}}
+\newcommand{\ds}{\textsf{DocStrip}\index{DocStrip@\textsf{DocStrip}}}
+\newcommand{\svrb}{\texttt{shortvrb}\index{shortvrb@\texttt{shortvrb}}}
+
+% Customize varioref's messages.
+\def\reftextbefore{on the preceding page}
+\def\reftextfacebefore{on the preceding page}
+\def\reftextcurrent{above} % We promise not to make any forward references.
+
+% Define some macros to help automate indexing.
+\makeindex
+{\catcode`\|=0 \catcode`\\=12
+ |gdef|bslash{\}}
+\newcommand{\defmacro}[1]{% % Define a macro.
+ \texttt{\bslash#1}%
+ \index{#1@\texttt{\string\bslash{}#1}}%
+}
+\newcommand{\usemacro}[1]{% % Use a macro.
+ \texttt{\bslash#1}%
+ \index{#1@\texttt{\string\bslash{}#1}}%
+}
+\newcommand{\indexmacro}[1]{% % Index a macro (no display).
+ \index{#1@\texttt{\string\bslash{}#1}}%
+}
+{\catcode`\|=12 % Same as \indexmacro, but
+ \gdef\indexmacroBegin#1{% % for ranges of text
+ \index{#1@\texttt{\string\bslash{}#1}|(}%
+ }
+ \gdef\indexmacroEnd#1{%
+ \index{#1@\texttt{\string\bslash{}#1}|)}%
+ }
+}
+\newcommand{\defthing}[1]{% % Define a non-macro thing.
+ \texttt{#1}%
+ \index{#1@\texttt{#1}}%
+}
+\newcommand{\usething}[1]{% % Use a non-macro thing.
+ \texttt{#1}%
+ \index{#1@\texttt{#1}}%
+}
+\newcommand{\indexthing}[1]{% % Index a non-macro thing.
+ \index{#1@\texttt{#1}}%
+}
+{\catcode`\|=12 % Same as \indexthing, but
+ \gdef\indexthingBegin#1{% % for ranges of text
+ \index{#1@\texttt{#1}|(}%
+ }
+ \gdef\indexthingEnd#1{%
+ \index{#1@\texttt{#1}|)}%
+ }
+}
+
+% Define shortcuts to index commonly used terms.
+\newcommand{\insfile}{%
+ \texttt{.ins}\index{installer file}}
+\newcommand{\dtxfile}{%
+ \texttt{.dtx}\index{documented LaTeX file@documented \string\LaTeX{} file}}
+\newcommand{\styfile}{%
+ \texttt{.sty}\index{style file}}
+\newcommand{\clsfile}{%
+ \texttt{.cls}\index{class file}}
+\newcommand{\CTAN}{%
+ CTAN\index{Comprehensive \string\TeX{} Archive Network}}
+\newcommand{\swiftexel}{%
+ \texttt{swiftex.el}\index{swiftex.el@\texttt{swiftex.el}}}
+\newcommand{\Emacs}{%
+ Emacs\index{Emacs}}
+\newcommand{\latex}[1][\LaTeX]{%
+ #1\index{LaTeX@\LaTeX}}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{document}
+\sloppy
+\maketitle
+
+\begin{abstract}
+ This tutorial is intended for advanced \latex[\LaTeXe]{} users who
+ want to learn how to create \insfile{} and \dtxfile{} files for
+ distributing their homebrewed classes and style files.
+\end{abstract}
+
+
+\section{Introduction}
+
+\paragraph{Requirements}
+We assume that you already know how to \emph{program} in \latex\@.
+That is, you should know how to use \usemacro{newcommand},
+\usemacro{newenvironment}, and preferably a smidgen of \TeX\@. You
+should also be familiar with ``\clsguide'', which is available from
+\CTAN{} (\URL{http://www.ctan.org}) and comes with most
+\latex[\LaTeXe]{} distributions in a file called |clsguide.dvi|.
+Finally, you should know how to install packages\index{package} that
+are shipped as a \dtxfile{} file plus a \insfile{} file.
+
+\index{package|(}
+\paragraph{Terminology}
+A \defn[style file]{style \textnormal{(\styfile{})} file} is primarily a
+collection of macro and environment definitions. One or more style
+files (\eg a main style file that \usemacro{input}s or
+\usemacro{RequirePackage}s multiple helper files) is called a
+\defn{package}. Packages are loaded into a document with
+\usemacro{usepackage}|{<main .sty file>}|\index{style file}. In the
+rest of this document, we use the notation ``\m{package}'' to
+represent the name of your package.
+\index{package|)}
+
+\paragraph{Motivation}
+The important parts of a package\index{package} are the code, the
+documentation of the code, and the user documentation. Using the
+\DOC{} and \ds{} programs, it's possible to combine all three of these
+into a single, \defn[documented LaTeX file@documented \string\LaTeX{}
+file]{documented \LaTeX \textnormal{(\dtxfile{})} file}. The primary
+advantage of a \dtxfile{} file is that it enables you to use arbitrary
+\latex{} constructs to comment\index{comments} your code. Hence,
+macros, environments, code stanzas, variables, and so forth can be
+explained using tables, figures, mathematics, and font changes. Code
+can be organized into sections using \latex's sectioning commands.
+\index{indexing|(}
+\DOC{} even facilitates generating a unified index that indexes both
+macro definitions (in the \latex{} code) and macro descriptions (in
+the user documentation).
+\index{indexing|)}
+This emphasis on writing verbose, nicely typeset
+comments\index{comments} for code---essentially treating a program as
+a book that describes a set of algorithms---is known as \defn{literate
+programming}~\cite{Knuth1984:literate} and has been in use since the
+early days of \TeX.
+
+This tutorial will teach you how to write basic \dtxfile{} files and
+the \insfile{} files that manipulate them. Although there is much
+overlap with chapter~14 of \emph{The \latex{}
+Companion}~\cite{Goossens1994:companion}, this document is structured
+as a step-by-step tutorial, while \emph{The \latex{} Companion} is
+more reference-like. Furthermore, this tutorial shows how to write a
+single file that serves as both documentation and driver file, which
+is a more typical usage of the \DOC{} system than using separate
+files.
+
+
+\index{installer file|(}
+
+\section{The \texttt{.ins} file}
+\label{sec:ins-file}
+
+The first step in preparing a package for distribution is to write an
+\defn[installer file]{installer \textnormal{(\insfile{})} file}. An
+installer file extracts the code from a \dtxfile{} file, uses \ds{} to
+strip off the comments\index{comments} and documentation, and outputs
+a \styfile{} file. The good news is that a \insfile{} file is
+typically fairly short and doesn't change significantly from one
+package\index{package} to another.
+
+\index{license|(}
+\insfile{} files usually start with comments\index{comments}
+specifying the copyright\index{copyright} and license information:
+
+\begin{verbatim}
+ %%
+ %% Copyright (C) <year> by <your name>
+ %%
+ %% This file 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.
+ %%
+\end{verbatim}
+
+\noindent
+\index{package|(}
+The \latex{} Project Public License\index{LaTeX Project Public
+License@\LaTeX{} Project Public License} (LPPL) is the license under
+which most packages---and \latex{} itself---are distributed. Of
+course, you can release your package under any license you want; the
+LPPL is merely the most common license for \latex{} packages. The
+LPPL specifies that a user can do whatever he wants with your
+package---including sell it and give you nothing in return. The only
+restrictions are that he must give you credit for your work, and he
+must change the name of the package if he modifies anything to avoid
+versioning confusion.
+\index{package|)}
+\index{license|)}
+\index{LPPL|see{\LaTeX{} Project Public License}}
+
+The next step is to load \ds:
+
+\begin{verbatim}
+ \input docstrip.tex
+\end{verbatim}
+
+
+\indexmacroBegin{keepsilent} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{keepsilent}
+\end{decl}
+
+By default, \ds{} gives a line-by-line account of its activity. These
+messages aren't terribly useful, so most people turn them off:
+
+\begin{verbatim}
+ \keepsilent
+\end{verbatim}
+
+\indexmacroEnd{keepsilent} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{usedir} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{usedir} \arg{directory}
+\end{decl}
+
+A system administrator can specify the base directory under which all
+\TeX-related files should be installed, \eg |/usr/share/texmf|. (See
+``\usemacro{BaseDirectory}'' in the \ds{} manual.) The \insfile{}
+file specifies where its files should be installed relative to that.
+The following is typical:
+
+\begin{verbatim}
+ \usedir{tex/latex/<package>}
+\end{verbatim}
+
+\indexmacroEnd{usedir} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{preamble} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{endpreamble}
+
+\begin{decl}
+ \defmacro{preamble} \\
+ \m{text} \\
+ \defmacro{endpreamble}
+\end{decl}
+
+\index{comments|(}
+The next step is to specify a \defn{preamble}, which is a block of
+commentary that will be written to the top of every generated file:
+
+\begin{verbatim}
+ \preamble
+
+ This is a generated file.
+
+ Copyright (C) <year> by <your name>
+
+ This file 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.
+
+ \endpreamble
+\end{verbatim}
+
+\index{comments|)}
+
+\noindent
+The preceding preamble would cause |<package>.sty|\index{style file}
+to begin as follows:
+
+\begin{verbatim}
+ %%
+ %% This is file `<package>.sty',
+ %% generated with the docstrip utility.
+ %%
+ %% The original source files were:
+ %%
+ %% <package>.dtx (with options: `package')
+ %%
+ %% This is a generated file.
+ %%
+ %% Copyright (C) <year> by <your name>
+ %%
+ %% This file 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.
+ %%
+\end{verbatim}
+
+\indexmacroEnd{endpreamble}
+\indexmacroEnd{preamble} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{generate} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{file}
+\indexmacroBegin{from}
+
+\begin{decl}
+ \defmacro{generate}
+ |{|\defmacro{file} |{<style-file>}|
+ |{|\defmacro{from} |{<dtx-file>}| |{<tag>}}}|
+\end{decl}
+
+We now reach the most important part of a \insfile{} file: the
+specification of what files to generate from the \dtxfile{} file. The
+following tells \ds{} to generate |<package>.sty|\index{style file}
+from |<package>.dtx| by extracting only those parts marked as
+``|package|'' in the \dtxfile{} file. (Marking parts of a \dtxfile{}
+file is described in Section~\ref{sec:dtx-file}.)
+
+\label{code:generate}
+\begin{verbatim}
+ \generate{\file{<package>.sty}{\from{<package>.dtx}{package}}}
+\end{verbatim}%
+\index{style file}
+
+\noindent
+\usemacro{generate} can extract any number of files from a given
+\dtxfile{} file. It can even extract a single file from multiple
+\dtxfile{} files. See the \ds{} manual for details.
+
+\indexmacroEnd{from}
+\indexmacroEnd{file}
+\indexmacroEnd{generate} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{Msg} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{Msg} \arg{text}
+\end{decl}
+
+The next part of a \insfile{} file consists of commands to output a
+message to the user, telling him what files need to be installed and
+reminding him how to produce the user documentation. The following
+set of \usemacro{Msg} commands is typical:
+
+\begin{verbatim}
+ \obeyspaces
+ \Msg{****************************************************}
+ \Msg{* *}
+ \Msg{* To finish the installation you have to move the *}
+ \Msg{* following file into a directory searched by TeX: *}
+ \Msg{* *}
+ \Msg{* <package>.sty *}
+ \Msg{* *}
+ \Msg{* To produce the documentation run the file *}
+ \Msg{* <package>.dtx through LaTeX. *}
+ \Msg{* *}
+ \Msg{* Happy TeXing! *}
+ \Msg{* *}
+ \Msg{****************************************************}
+\end{verbatim}%
+\index{style file}%
+
+\indexmacroEnd{Msg} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+Note the use of \usemacro{obeyspaces} to inhibit \TeX{} from
+collapsing multiple spaces into one.
+
+
+\indexmacroBegin{endbatchfile} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \usemacro{endbatchfile}
+\end{decl}
+
+Finally, we tell \ds{} that we've reached the end of the \insfile{} file:
+
+\begin{verbatim}
+ \endbatchfile
+\end{verbatim}
+
+\indexmacroEnd{endbatchfile} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+Appendix~\ref{sec:skeleton-ins-file-style} lists a complete, skeleton
+\insfile{} file. Appendix~\ref{sec:skeleton-ins-file-class} is
+similar but contains slight modifications intended to produce a class
+(\clsfile) file instead of a style (\styfile) file.
+
+\index{installer file|)}
+\index{documented LaTeX file@documented \LaTeX{} file|(}
+
+
+\section{The \texttt{.dtx} file}
+\label{sec:dtx-file}
+
+\index{package|(}
+A \dtxfile{} file contains both the commented source code and the user
+documentation for the package. Running a \dtxfile{} file through
+|latex| typesets the user documentation, which usually also includes a
+nicely typeset version of the commented\index{comments} source code.
+\index{package|)}
+
+Due to some \DOC{} trickery, a \dtxfile{} file is actually evaluated
+\emph{twice}. The first time, only a small piece of \latex{} driver
+code is evaluated. The second time, \emph{comments}\index{comments}
+in the \dtxfile{} file are evaluated, as if there were no ``|%|''
+preceding them. This can lead to a good deal of confusion when
+writing \dtxfile{} files and occasionally leads to some awkward
+constructions. Fortunately, once the basic structure of a \dtxfile{} file
+is in place, filling in the code is fairly straightforward.
+
+
+\subsection{Prologue}
+
+\index{comments|(}
+
+\dtxfile{} files generally begin with a copyright\index{copyright} and
+license\index{license} comment:
+
+\begin{verbatim}
+ % \iffalse meta-comment
+ %
+ % Copyright (C) <year> by <your name>
+ %
+ % This file 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.
+ %
+ % \fi
+\end{verbatim}
+
+\index{comments|)}
+
+\noindent
+The \usemacro{iffalse} and |\fi| are needed because the second time
+the \dtxfile{} file is processed, |%| characters at the beginning of lines
+are ignored. To prevent the
+copyright\index{copyright}/license\index{license} from being evaluated
+as \latex{} code, we have to surround it with
+\usemacro{iffalse}\dotsbrk|\fi|. Adding ``\usething{meta-comment}''
+after ``\usemacro{iffalse}'' is nothing more than a convention for
+indicating that the comment\index{comments} is intended to be read by
+a human, not by \DOC{}, \ds{}, or \latex.
+
+\indexmacroBegin{NeedsTeXFormat} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{ProvidesPackage}
+
+\begin{decl}
+ \defmacro{NeedsTeXFormat} \arg{format-name} \oarg{release-date} \\
+ \defmacro{ProvidesPackage} \arg{package-name} \oarg{release-info}
+\end{decl}
+
+The next few lines are also surrounded by
+\usemacro{iffalse}\dotsbrk|\fi| so as not to be processed by |latex|
+on the second pass through the \dtxfile{} file. However, these lines are
+intended not for a human reader, but for \ds{} (hence, no
+``\usething{meta-comment}''):
+
+\label{code:ProvidesPackage}
+\begin{verbatim}
+ % \iffalse
+ %<<package>>\NeedsTeXFormat{LaTeX2e}[2005/12/01]
+ %<<package>>\ProvidesPackage{<package>}
+ %<<package>> [<YYYY>/<MM>/<DD> v<version> <description>]
+ %
+\end{verbatim}%
+\indexmacro{NeedsTeXFormat}%
+\indexmacro{ProvidesPackage}
+
+\noindent
+(We'll encounter the |\fi| shortly.)
+
+Remember the \usemacro{generate} line in the \insfile{} file
+(page~\pageref{code:generate})? It ended with the tag ``|package|''.
+This tells \ds{} to write lines that begin with ``|%<<package>>|'' to
+the \styfile{} file, stripping off the ``|%<<package>>|'' in the
+process. Hence, our \styfile{} file will begin with the following:
+
+\begin{verbatim}
+ \NeedsTeXFormat{LaTeX2e}[2005/12/01]
+ \ProvidesPackage{<package>}
+ [<YYYY>/<MM>/<DD> v<version> <description>]
+\end{verbatim}%
+\indexmacro{NeedsTeXFormat}%
+\indexmacro{ProvidesPackage}
+
+\noindent
+For example:
+
+\begin{verbatim}
+ \NeedsTeXFormat{LaTeX2e}[2005/12/01]
+ \ProvidesPackage{skeleton}
+ [2002/03/25 v1.0 .dtx skeleton file]
+\end{verbatim}%
+\label{code:ProvidesPackage-example}%
+\indexmacro{NeedsTeXFormat}%
+\indexmacro{ProvidesPackage}
+
+\noindent
+\index{package|(}
+The \usemacro{NeedsTeXFormat} line ensures that the package won't run
+under a version of \latex[\LaTeXe]{} older than what the package was
+tested with. The date and version strings in the
+\usemacro{ProvidesPackage} line are used by \DOC{} to set the
+\usemacro{filedate} and \usemacro{fileversion} macros. Note the
+date\index{date format} format; \emph{YYYY/MM/DD} is used throughout
+\latex[\LaTeXe]{} and should be used in your packages as well.
+\index{package|)}
+
+\indexmacroEnd{ProvidesPackage}
+\indexmacroEnd{NeedsTeXFormat} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{EnableCrossrefs} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{CodelineIndex}
+\indexmacroBegin{RecordChanges}
+\indexmacroBegin{DocInput}
+
+\begin{decl}
+ \defmacro{EnableCrossrefs} \\
+ \defmacro{CodelineIndex} \\
+ \defmacro{RecordChanges} \\
+ \defmacro{DocInput} \arg{filename} \label{desc:CodelineIndex}
+\end{decl}
+
+Next comes the only part of the \dtxfile{} file that isn't commented out
+(\ie doesn't begin each line with |%|):
+
+\begin{verbatim}
+ %<<*driver>>
+ \documentclass{ltxdoc}
+ \usepackage{<package>}
+ \EnableCrossrefs
+ \CodelineIndex
+ \RecordChanges
+ \begin{document}
+ \DocInput{<package>.dtx}
+ \end{document}
+ %<</driver>>
+ % \fi
+\end{verbatim}
+
+The preceding code stanza is what |latex| evaluates on its first pass
+through the \dtxfile{} file. We'll now examine that stanza line-by-line:
+
+\begin{enumerate}
+ \item Putting code between ``|%<<*driver>>|'' and ``|%<</driver>>|''
+ is a \ds{} shorthand for prefixing each line with ``|%<<driver>>|''.
+ This demarcates the \DOC{} driver\index{driver code} code.
+
+ \item The \usemacro{documentclass} should almost always be
+ \usething{ltxdoc}, as that loads \DOC{} and provides a few useful
+ macros for formatting program documentation.
+
+\index{package|(}
+ \item You should always \usemacro{usepackage} your package. If you
+ don't, \DOC{} won't see the package's \usemacro{ProvidesPackage}
+ line and won't know how to set \usemacro{filedate} and
+ \usemacro{fileversion} (see page~\pageref{code:GetFileInfo}). This
+ is also where you should \usemacro{usepackage} any other packages
+ needed to typeset the user documentation.
+\index{package|)}
+
+ \item \usemacro{EnableCrossrefs} tells \DOC{} that you want it to
+ construct an index for your code---normally a good idea. The
+ alternative is \usemacro{DisableCrossrefs}, which speeds up
+ processing by a negligible amount.
+
+ \item \usemacro{CodelineIndex} tells \DOC{} that the index should
+ refer to program line numbers instead of page numbers. (The
+ alternative is \usemacro{PageIndex}.) \usemacro{CodelineIndex}
+ makes index entries easier to find at the expense of making the
+ index less self-consistent (because descriptions of macros and
+ environments are always indexed by page number). The index does,
+ however, begin with a note of explanation.
+
+ \item \label{item:RecordChanges} On page~\pageref{code:changes},
+ we'll see how to log the changes made in each revision of the
+ package\index{package}. \usemacro{RecordChanges} tells \DOC{} that
+ it should keep and aggregate the log entries.
+
+ \item There should be only one command between the
+ |\begin{document}| and |\end{document}|: a \usemacro{DocInput} call
+ with which the \dtxfile{} file inputs itself. This enables a master
+ file to \usemacro{DocInput} multiple files in order to produce a
+ single document that covers more than one package\index{package} but
+ contains a unified index\index{indexing}. Master documentation
+ files are described~\vpageref{sec:master-files}.
+\end{enumerate}
+
+\indexmacroEnd{DocInput}
+\indexmacroEnd{RecordChanges}
+\indexmacroEnd{CodelineIndex}
+\indexmacroEnd{EnableCrossrefs} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{OnlyDescription} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{OnlyDescription} \label{desc:OnlyDescription}
+\end{decl}
+
+Another command that sometimes appears in the preamble (\ie before the
+|\begin{document}|) is \usemacro{OnlyDescription}, which tells \DOC{}
+to typeset only the user documentation, not the package\index{package}
+code/comments\index{comments}. It's usually best to omit
+\usemacro{OnlyDescription} (or add it commented out). A user can
+always add it manually or even enable \usemacro{OnlyDescription} for
+\emph{all} \dtxfile{} files by adding the following to his
+\defthing{ltxdoc.cfg} file:
+
+\begin{verbatim}
+ \AtBeginDocument{\OnlyDescription}
+\end{verbatim}%
+\indexmacro{AtBeginDocument}
+
+\indexmacroEnd{OnlyDescription} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\bigskip
+The remainder of this section covers |latex|'s second pass through the
+\dtxfile{} file. Consequently, all subsequent examples are prefixed
+with percent signs.
+
+\indexmacroBegin{CheckSum} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\index{checksumming|(}
+
+\begin{decl}
+ \defmacro{CheckSum} \arg{number} \label{decl:CheckSum}
+\end{decl}
+
+\DOC{} supports a very simplistic form of document checksumming, to
+help ensure that a package\index{package} didn't get corrupted in
+transport. \DOC{} merely counts the number of backslashes that occur
+in the code. If the number matches the checksum, \DOC{} gives a
+success message:
+
+\begin{verbatim}
+ *******************
+ * Checksum passed *
+ *******************
+\end{verbatim}
+
+\noindent
+Otherwise, it says what the correct checksum should be:
+
+\begin{verbatim}
+ ! Package doc Error: Checksum not passed (<incorrect><<>><correct>).
+\end{verbatim}%
+\indexthing{Checksum not passed}
+
+\noindent
+To specify the checksum in a \dtxfile{} file, merely add a \usemacro{CheckSum}
+statement:
+
+\begin{verbatim}
+ % \CheckSum{<number>}
+\end{verbatim}
+
+\noindent
+If \m{number} is~|0|, or if the \dtxfile{} file lacks a
+\usemacro{CheckSum} line entirely, then \DOC{} outputs the following
+warning message:
+
+\begin{verbatim}
+ **********************************
+ * This macro file has no checksum!
+ * The checksum should be <number>!
+ **********************************
+\end{verbatim}
+
+\noindent
+During code development it is convenient to specify |\CheckSum{0}| so
+you don't receive an error message every time you run |latex|. But
+don't forget to replace ``|0|'' with the correct number before
+releasing your package\index{package}!
+
+\index{checksumming|)}
+\indexmacroEnd{CheckSum} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{CharacterTable} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{CharacterTable} \arg{text}
+\end{decl}
+
+The second mechanism that \DOC{} uses to ensure that a \dtxfile{} file
+is uncorrupted is a character table. If you put the following command
+verbatim into your \dtxfile{} file, then \DOC{} will ensure that no
+unexpected character translation took place in transport:\footnote{The
+character table is commonly prefixed with double percent signs so that
+it gets written to the \texttt{.sty}\index{style file} file. This
+seems unnecessary and is therefore shown here with single percent
+signs.}
+
+\begin{verbatim}
+ % \CharacterTable
+ % {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+ % Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+ % Digits \0\1\2\3\4\5\6\7\8\9
+ % Exclamation \! Double quote \" Hash (number) \#
+ % Dollar \$ Percent \% Ampersand \&
+ % Acute accent \' Left paren \( Right paren \)
+ % Asterisk \* Plus \+ Comma \,
+ % Minus \- Point \. Solidus \/
+ % Colon \: Semicolon \; Less than \<<
+ % Equals \= Greater than \>> Question mark \?
+ % Commercial at \@ Left bracket \[ Backslash \\
+ % Right bracket \] Circumflex \^ Underscore \_
+ % Grave accent \` Left brace \{ Vertical bar \|
+ % Right brace \} Tilde \~}
+\end{verbatim}
+
+\noindent
+A success message looks like this:
+
+\begin{verbatim}
+ ***************************
+ * Character table correct *
+ ***************************
+\end{verbatim}
+
+\noindent
+and an error message looks like this:
+
+\begin{verbatim}
+ ! Package doc Error: Character table corrupted.
+\end{verbatim}%
+\indexthing{Character table corrupted}
+
+\indexmacroEnd{CharacterTable} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{changes} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ \defmacro{changes} \arg{version} \arg{date} \arg{description}
+ \label{code:changes}
+\end{decl}
+
+\index{package|(}
+
+On page~\pageref{item:RecordChanges} we learned that \DOC{} has a
+mechanism for recording changes to the package. The command is
+``|\changes{<version>}{<date>}{<description>}|'', and it's common to
+use \usemacro{changes} for the initial version of the package to log
+the package's creation date:
+
+\index{package|)}
+
+\begin{verbatim}
+ % \changes{v1.0}{2002/03/25}{Initial version}
+\end{verbatim}
+
+One nice feature of the \usemacro{changes} command is that it knows
+whether it was used internally to a macro/environment definition. As
+Figure~\ref{fig:change-history} shows, top-level changes are prefixed
+with ``General:'', and internal changes are prefixed with the name of
+the enclosing macro or environment.
+
+\begin{figure}[htbp]
+ \centering
+ \index{change history}
+ \fbox{%
+ \begin{minipage}[t]{0.75\textwidth}
+ {\normalfont\Large\bfseries Change History\vskip 2.3ex plus 0.2ex}
+ v1.0 \\
+ \hspace*{2em} General: Top-level comment \dotfill 1 \\
+ v1.2j \\
+ \hspace*{2em} \texttt{myMacro}: Internal macro comment \dotfill 5
+ \end{minipage}%
+ }%
+ \caption{Sample change history}
+ \label{fig:change-history}
+\end{figure}
+
+\indexmacroEnd{changes} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{GetFileInfo} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{filedate}
+\indexmacroBegin{fileversion}
+\indexmacroBegin{fileinfo}
+
+\begin{decl}
+ \defmacro{GetFileInfo} \arg{style-file} \label{code:GetFileInfo} \\[1ex]
+ \defmacro{filedate} \\
+ \defmacro{fileversion} \\
+ \defmacro{fileinfo}
+\end{decl}
+
+Next, we tell \DOC{} to parse the \usemacro{ProvidesPackage} command
+(page~\pageref{code:ProvidesPackage}), calling the three components of
+\usemacro{ProvidesPackage}'s argument, respectively,
+``\usemacro{filedate}'', ``\usemacro{fileversion}'', and
+``\usemacro{fileinfo}'':
+
+\begin{verbatim}
+ % \GetFileInfo{<package>.sty}
+\end{verbatim}%
+\index{style file}%
+\indexmacro{GetFileInfo}
+
+\noindent
+For instance, the \usemacro{ProvidesPackage} example
+shown~\vpageref{code:ProvidesPackage-example} would be parsed as
+follows:
+
+| |%
+\begin{tabular}{@{}l@{\qquad$\equiv$\qquad}l@{}}
+ \usemacro{filedate} & 2002/03/25 \\
+ \usemacro{fileversion} & v1.0 \\
+ \usemacro{fileinfo} & .dtx skeleton file
+\end{tabular}
+
+\indexmacroEnd{fileinfo}
+\indexmacroEnd{fileversion}
+\indexmacroEnd{filedate}
+\indexmacroEnd{GetFileInfo} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{DoNotIndex} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\index{indexing|(}
+
+\begin{decl}
+ \defmacro{DoNotIndex} \arg{macro-name \textnormal{, \dots}}
+\end{decl}
+
+When producing an index, \DOC{} normally indexes \emph{every} control
+sequence (\ie backslashed word or symbol) in the code. The problem
+with this level of automation is that many control sequences are
+uninteresting from the perspective of understanding the code. For
+example, a reader probably doesn't want to see every location where
+|\if| is used---or |\the| or |\let| or |\begin| or any of numerous
+other control sequences.
+
+As its name implies, the \usemacro{DoNotIndex} command gives \DOC{} a
+list of control\index{control sequences} sequences that should not be
+indexed. \usemacro{DoNotIndex} can be used any number of times, and
+it accepts any number of control\index{control sequences} sequence
+names per invocation:
+
+\begin{verbatim}
+ % \DoNotIndex{\#,\$,\%,\&,\@,\\,\{,\},\^,\_,\~,\ }
+ % \DoNotIndex{\@ne}
+ % \DoNotIndex{\advance,\begingroup,\catcode,\closein}
+ % \DoNotIndex{\closeout,\day,\def,\edef,\else,\empty,\endgroup}
+\end{verbatim}
+\centerline{$\vdots$}
+
+\index{indexing|)}
+\indexmacroEnd{DoNotIndex} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\subsection{User documentation}
+
+We can finally start writing the user documentation. A typical
+beginning looks like this:
+
+\begin{verbatim}
+ % \title{The \textsf{<package>} package\thanks{This document
+ % corresponds to \textsf{<package>}~\fileversion,
+ % dated~\filedate.}}
+ % \author{<your name> \\ \texttt{<your e-mail address>}}
+ %
+ % \maketitle
+\end{verbatim}%
+\indexmacro{title}
+\indexmacro{author}
+\indexmacro{maketitle}
+
+\noindent
+\index{package|(}
+The title can certainly be more creative, but note that it's common
+for package names to be typeset with \usemacro{textsf} and for
+\usemacro{thanks} to be used to specify the package version and date.
+This yields one of the advantages of literate\index{literate
+programming} programming: Whenever you change the package version (the
+optional second argument to \usemacro{ProvidesPackage}), the user
+documentation is updated accordingly. Of course, you still have to
+ensure manually that the user documentation accurately describes the
+updated package.
+\index{package|)}
+
+Write the user documentation as you would any \latex{} document,
+except that you have to precede each line with a ``|%|''. Note that
+the \usething{ltxdoc} document class is derived from |article|, so the
+top-level sectioning command is \usemacro{section}, not
+\usemacro{chapter}.
+
+
+\indexmacroBegin{DescribeMacro} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{DescribeEnv}
+
+\begin{decl}
+ \defmacro{DescribeMacro} \arg{macro} \\
+ \defmacro{DescribeEnv} \arg{environment}
+\end{decl}
+
+\DOC{} provides a couple of commands to help format user
+documentation. If you include
+``|\DescribeMacro{<macro>}|''\footnote{``\m{macro}'' should include
+the backslash.} within a paragraph, \DOC{} will stick ``\m{macro}'' in
+the margin to make it easy for a reader to see. \DOC{} will also add
+\m{macro} to the index and format the corresponding page number to
+indicate that this is where the macro is described (as opposed to the
+place in the source code where the macro is defined).
+
+\usemacro{DescribeEnv} is the analogous command for describing an
+environment. Both \usemacro{DescribeMacro} and \usemacro{DescribeEnv}
+can be used multiple times within a paragraph.
+
+\indexmacroEnd{DescribeEnv}
+\indexmacroEnd{DescribeMacro} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexmacroBegin{marg} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{oarg}
+\indexmacroBegin{parg}
+\indexmacroBegin{meta}
+
+\begin{decl}
+ \defmacro{marg} \arg{argument} \\
+ \defmacro{oarg} \arg{argument} \\
+ \defmacro{parg} \arg{argument} \\
+ \defmacro{meta} \arg{text}
+\end{decl}
+
+The \usething{ltxdoc} document class provides three commands to help
+typeset macro and environment syntax
+(Table~\ref{tbl:argument-formatting}). \usemacro{marg} formats
+mandatory arguments, \usemacro{oarg} formats optional arguments, and
+\usemacro{parg} formats picture arguments. All three of these utilize
+\usemacro{meta} to typeset the argument proper. \usemacro{meta} is
+also useful on its own. For example, ``\texttt{This needs a}
+|\meta{dimen}|.'' is typeset as ``This needs a \m{dimen}.''
+
+\begin{table}[htbp]
+ \centering
+ \caption{Argument-formatting commands}
+ \label{tbl:argument-formatting}
+ \begin{tabular}{@{}ll@{}}
+ \hline
+ \multicolumn{1}{@{}c}{Command} &
+ \multicolumn{1}{c@{}}{Result} \\
+ \hline
+ \usemacro{marg}|{text}| & |{<text>}| \\
+ \usemacro{oarg}|{text}| & |[<text>]| \\
+ \usemacro{parg}|{text}| & |(<text>)| \\
+ \hline
+ \end{tabular}
+\end{table}
+
+In addition to those commands, \DOC{} facilitates the typesetting of
+macro descriptions by automatically loading the \svrb{}
+package\index{package}. \svrb{} lets you use \verb+|+\dots\verb+|+
+as a convenient shorthand for |\verb|\verb+|+\dots\verb+|+. For
+instance, ``\verb+|\mymacro|+ |\oarg{pos}| |\marg{width}|
+|\marg{text}|'' is typeset as follows:
+
+\begin{verbatim}
+ \mymacro [<pos>] {<width>} {<text>}
+\end{verbatim}
+
+\noindent
+Like \usemacro{verb}, the \verb+|+\dots\verb+|+ shorthand does not
+work within \usemacro{footnote} or other fragile macros.
+
+\indexmacroEnd{meta}
+\indexmacroEnd{parg}
+\indexmacroEnd{oarg}
+\indexmacroEnd{marg} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\subsection{Code and commentary}
+
+\indexmacroBegin{StopEventually} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexmacroBegin{Finale}
+
+\begin{decl}
+ \defmacro{StopEventually} |{<text>}| \\
+ \defmacro{Finale}
+\end{decl}
+
+The package's\index{package} source code is delineated by putting it
+between \usemacro{StopEventually} and \usemacro{Finale}. Note that
+\usemacro{CheckSum} (page~\pageref{decl:CheckSum}) applies only to the
+package's\index{package} source code. \usemacro{StopEventually} takes
+an argument, which is a block of text to typeset after the code. If
+\usemacro{OnlyDescription} (page~\pageref{desc:OnlyDescription}) is
+specified, then nothing after the \usemacro{StopEventually} will be
+output---including text that follows \usemacro{Finale}.
+\usemacro{StopEventually}'s \m{text} parameter is therefore the
+mechanism for providing a piece of text that should be output
+regardless of whether or not a code listing is typeset. It commonly
+includes a bibliography section and/or one or more of the following
+commands.
+
+\indexmacroEnd{Finale}
+\indexmacroEnd{StopEventually} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\begin{decl}
+ \defmacro{PrintChanges} \\
+ \defmacro{PrintIndex}
+\end{decl}
+
+\indexmacroBegin{PrintChanges} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\index{change history|(}
+
+\usemacro{PrintChanges} produces an unnumbered section called ``Change
+History''. (See Figure~\vref{fig:change-history}). The Change
+History section aggregates all of the \usemacro{changes} commands in
+the \dtxfile{} file into a single list of per-version modifications.
+This makes it easy to keep track of what changed from version to
+version.
+
+\usemacro{PrintChanges} uses \latex's glossary mechanism. Running
+|latex| on |<package>.dtx| produces change-history data in
+|<package>.glo|. To produce the actual change history
+(|<package>.gls|), the user should run the \usething{makeindex}
+program as follows:
+
+\begin{verbatim}
+ makeindex -s gglo.ist -o <package>.gls <package>.glo
+\end{verbatim}
+
+\index{change history|)}
+\indexmacroEnd{PrintChanges} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\indexmacroBegin{PrintIndex} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\index{indexing|(}
+
+\usemacro{PrintIndex} produces an unnumbered section called ``Index''.
+The index automatically includes entries for all macros and
+environments that are used, defined, or described in the document.
+All environments are additionally listed under ``environments''.
+Table~\ref{tbl:index-formatting} illustrates the way that various
+entries are formatted. In that table, ``27'' refers to a page number,
+and ``123'' refers to a line number.\footnote{If
+\texttt{\string\CodelineIndex} (page~\pageref{desc:CodelineIndex})
+were not used then ``123'' would refer to a page number.} Note that
+macro/environment definitions and uses are included in the index only
+if the document includes a code listing (\ie
+\usemacro{OnlyDescription} was not specified).
+
+\begin{table}[htbp]
+ \centering
+ \caption{Formatting of entries in the index}
+ \label{tbl:index-formatting}
+ \begin{tabular}{@{}llp{6cm}@{}}
+ \hline
+ Item & Function & Formatting in index \\
+ \hline
+ Macro & Used & |\myMacro| \dotfill~123 \\
+ Macro & Defined & |\myMacro| \dotfill~\underline{123} \\
+ Macro & Described & |\myMacro| \dotfill~\textit{27} \\
+ Environment & Defined & |myEnv| (environment) \dotfill~\underline{123} \\
+ Environment & Described & |myEnv| (environment) \dotfill~\textit{27} \\
+ \multicolumn{2}{@{}l}{Other (\ie an explicit \texttt{\string\index})}
+ & myItem \dotfill~27 \\
+ \hline
+ \end{tabular}
+\end{table}
+
+The default formatting for an explicit \usemacro{index} command uses a
+roman page number. This leads to confusion, as roman page numbers
+otherwise indicate line numbers in the package source code. The
+solution is to specify ``|usage|'' formatting to the \usemacro{index}
+command:
+
+\begin{verbatim}
+ \index{explicit indexing|usage}
+\end{verbatim}
+
+Running |latex| on |<package>.dtx| produces index data in
+|<package>.idx|. To produce the actual index (|<package>.ind|), the
+user should run the \usething{makeindex} program as follows:
+
+\begin{verbatim}
+ makeindex -s gind.ist -o <package>.ind <package>.idx
+\end{verbatim}
+
+A code index is a nice ``value added'' made possible by
+literate\index{literate programming} programming. It requires
+virtually no extra effort and greatly helps code maintainers to find
+macro definitions and see what other macros a package\index{package}
+depends upon.
+
+\index{indexing|)}
+\indexmacroEnd{PrintIndex} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexthingBegin{macrocode} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\begin{decl}
+ |\begin{macrocode}| \\
+ \m{code} \\
+ |\end{macrocode}|
+\end{decl}
+
+Code fragments listed between |\begin{macrocode}| and
+|\end{macrocode}| are extracted verbatim into the \styfile{} file.
+When typeset, the code fragments are shown with a running line counter
+to make it easy to refer to a specific line. Here are some key points
+to remember about the \usething{macrocode} environment:
+
+\begin{enumerate}
+ \item There must be \emph{exactly} four spaces between the ``|%|''
+ and the ``|\begin{macrocode}|'' or ``|\end{macrocode}|''.
+ Otherwise, \DOC{} won't detect the end of the code
+ fragment.\footnote{Trivia: Only the
+ \texttt{\string\end\string{macrocode\string}} needs this precise
+ spacing and then, only for typesetting the documentation.
+ Nevertheless, it's good practice to use
+ ``\texttt{\%\textvisiblespace\textvisiblespace\textvisiblespace\textvisiblespace}''
+ for the \texttt{\string\begin\string{macrocode\string}}, as well.}
+
+ \item The lines of code within
+ |\begin{macrocode}|\dotsbrk|\end{macrocode}| should not begin with
+ ``|%|''. The code gets written exactly as it is to the \insfile{}
+ file, with no |%|-stripping.
+\end{enumerate}
+
+The following is a sample code fragment. It happens to be a complete
+macro definition, but this is not necessary; any fragment of \latex{}
+code can appear within a \usething{macrocode} environment.
+
+\label{code:mymacro}
+\begin{verbatim}
+ % \begin{macrocode}
+ \newcommand{\mymacro}{This is
+ a \LaTeX{} macro.}
+ % \end{macrocode}
+\end{verbatim}
+
+\noindent
+\DOC{} formats the preceding code fragment as follows:
+
+\begin{tabbing}
+| |\={\tiny 9} \=\kill
+ \> {\tiny 1} \> |\newcommand{\mymacro}{This is| \\
+ \> {\tiny 2} \> | a \LaTeX{} macro.}|
+\end{tabbing}
+
+\noindent
+Note that line numbers are unique across the entire program (as
+opposed to being reset at the top of each page). If
+\usemacro{PrintIndex} is used in the \dtxfile{} file containing the
+preceding definition of |\mymacro|, the index will automatically
+include entries for |\newcommand|, |\mymacro|, and |\LaTeX|, unless
+any of these are \usemacro{DoNotIndex}'ed.
+
+\indexthingEnd{macrocode} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+\indexthingBegin{macro} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\indexthingBegin{environment}
+
+\begin{decl}
+ |\begin{macro}{<macro>}| \\
+ \qquad $\vdots$ \\
+ |\end{macro}| \\
+ \\
+ |\begin{environment}{<environment>}| \\
+ \qquad $\vdots$ \\
+ |\end{environment}| \\
+\end{decl}
+
+The \usething{macro} and \usething{environment} environments are used
+to delineate a complete macro or environment definition.
+\usething{macro}/\usething{environment} environments generally contain
+one or more \usething{macrocode} environments interspersed with code
+documentation. The following is a more complete version of the
+\usething{macrocode} example shown~\vpageref{code:mymacro}.
+
+\begin{verbatim}
+ % \begin{macro}{\mymacro}
+ % We define a trivial macro, |\mymacro|, to illustrate
+ % the use of the |macro| environment.
+ % \begin{macrocode}
+ \newcommand{\mymacro}{This is
+ a \LaTeX{} macro.}
+ % \end{macrocode}
+ % \end{macro}
+\end{verbatim}
+
+\noindent
+The typeset version is shown below:
+
+\begin{tabbing}
+| \mymacro|\qquad\={\tiny 9} \= \kill
+| \mymacro| \> We define a trivial macro, |\mymacro|, to illustrate the \\
+ \> use of the \usething{macro} environment. \\
+ \> {\tiny 1} \> |\newcommand{\mymacro}{This is| \\
+ \> {\tiny 2} \> | a \LaTeX{} macro.}|
+\end{tabbing}
+
+\DOC{} typesets the macro/environment name in the margin for increased
+visibility. \DOC{} also adds the appropriate entries to the index.
+(See Table~\vref{tbl:index-formatting} for examples of how these
+entries are formatted.) Note that
+|\begin{macro}|\dotsbrk|\end{macro}| is not required to indicate a
+macro definition. It can also be used to indicate definitions of
+\latex{} datatypes, such as counters, lengths, and boxes:
+
+\begin{verbatim}
+ % \begin{macro}{myCounter}
+ % This is an example of using the |macro| environment to format
+ % something other than a macro.
+ % \begin{macrocode}
+ \newcounter{myCounter}
+ % \end{macrocode}
+ % \end{macro}
+\end{verbatim}%
+\indexthing{macrocode}
+
+\usething{macro} and \usething{environment} environments can be
+nested. This capability is useful not only for macros that define
+other macros, but also when defining a group of related datatypes that
+share a description:
+
+\begin{verbatim}
+ % \begin{macro}{\thingheight}
+ % \begin{macro}{\thingwidth}
+ % \begin{macro}{\thingdepth}
+ % These lengths keep track of the dimensions of our |\thing|
+ % box. (Actually, we're just trying to show how to nest
+ % |macro| environments.)
+ % \begin{macrocode}
+ \newlength{\thingheight}
+ \newlength{\thingwidth}
+ \newlength{\thingdepth}
+ % \end{macrocode}
+ % \end{macro}
+ % \end{macro}
+ % \end{macro}
+\end{verbatim}%
+\indexthing{macro}%
+\indexthing{macrocode}
+
+\noindent
+Descriptionless \usething{macro} environments should generally be
+avoided, as the formatting is a little ugly; the macro name appears on
+its own line, to the left of an ``empty'' description, but the code
+doesn't start until the next line.
+
+There can be multiple \usething{macrocode} environments within a
+|\begin{macro}|\dotsbrk|\end{macro}| or
+|\begin{environment}|\dotsbrk|\end{environment}| block.
+\index{comments|(} This is the mechanism by which code can be
+commented internally to a macro/environment. (It's considered bad
+style to use ``|%|'' for comments within a \usething{macrocode}
+block.) Here's an example of the way that a nontrivial macro might be
+commented:
+
+\begin{verbatim}
+ % \begin{macro}{\complexMacro}
+ % Pretend that this is a very complex macro that needs
+ % to have its various pieces documented.
+ % \begin{macrocode}
+ \newcommand{\complexMacro}{%
+ % \end{macrocode}
+ % Initialize all of our counters to zero.
+ % \begin{macrocode}
+ \setcounter{count@i}{0}%
+ \setcounter{count@ii}{0}%
+ \setcounter{count@iii}{0}%
+ \setcounter{count@iv}{0}%
+ % \end{macrocode}
+ % Do some really complicated processing.
+ % \begin{macrocode}
+\end{verbatim}%
+\indexthing{macrocode}
+| |$\vdots$
+\begin{verbatim}
+ % \end{macrocode}
+ % We're all finished now.
+ % \begin{macrocode}
+ }
+ % \end{macrocode}
+ % \end{macro}
+\end{verbatim}%
+\indexthing{macrocode}
+
+\indexthingEnd{environment}
+\indexthingEnd{macro} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\index{comments|)}
+
+Appendix~\ref{sec:skeleton-dtx-file-style} lists a complete, skeleton
+\dtxfile{} file that encapsulates a \styfile{} file and its
+documentation.
+
+\index{class file|(}
+
+\paragraph{Class files}
+The procedure to produce a class file from a \dtxfile{} file is far
+less straightforward than the procedure to produce a style file. The
+problem is that \usemacro{DocInput} relies on the
+|\usepackage{|\m{package}|}| line (more precisely, the
+\usemacro{ProvidesPackage} line within \m{package}|.sty|) to set the
+\usemacro{fileversion} and \usemacro{filedate} macros. However, a
+class file can't be loaded with |\usepackage|. Nor can we simply load
+it with |\documentclass{|\m{package}|}| because only one class can be
+loaded per document and we need that class to be \usething{ltxdoc}.
+
+The solution is to use \usemacro{ProvidesFile} to make the file
+version and date available to the \dtxfile{} file.
+Appendix~\ref{sec:skeleton-dtx-file-class} lists a complete, skeleton
+\dtxfile{} file that encapsulates a \clsfile{} file and its
+documentation. It resembles the skeleton file shown in
+Appendix~\ref{sec:skeleton-dtx-file-style} but has a differently
+structured header section.
+
+\index{class file|)}
+
+
+\index{documented LaTeX file@documented \LaTeX{} file|)}
+
+
+\section{Tips, tricks, and recommendations}
+
+\begin{itemize}
+ \item Write lots of good documentation! It really helps others
+ understand your code and the package\index{package} as a whole.
+
+ \item If you believe the \latex{} community at large would be
+ interested in your package then you should upload it to \CTAN{} at
+ \URL{http://www.ctan.org/upload}. As a central repository of all
+ things \TeX-related, \CTAN{} makes it easier for others to find your
+ \latex{} package than if it were located on your personal home page.
+
+\index{documentation, prebuilt PDF|(}
+ \item When distributing your package, be sure to include a
+ |README|\index{README file@\texttt{README} file} file describing
+ what your package does as well as \emph{prebuilt} documentation,
+ preferably as a PDF file. Prebuilt documentation saves users the
+ bother of having to download your package, install it, and build the
+ documentation before even knowing what the package is supposed to do
+ or if it meets their needs.
+\index{documentation, prebuilt PDF|)}
+
+ \item Use \latex's sectioning commands to organize the code and
+ clarify its structure (\eg |\subsection{|\texttt{Initialization
+ macros}|}|, |\subsection{|\texttt{Helper functions}|}|,
+ |\subsection{|\texttt{Exported macros and environments}|}|,~\dots).
+
+\index{comments|(}
+
+ \item Although commentary really belongs only in the typeset
+ documentation, it is also possible to write comments that are
+ visible only in the \styfile{} file, in both the typeset
+ documentation and the \styfile{} file, or only in the \dtxfile{}
+ source. Table~\ref{tbl:comment-visibility} shows how to control
+ comment visibility.
+
+\index{comments|)}
+
+ \begin{table}[hbp]
+ \centering
+ \caption{Comment visibility}
+ \label{tbl:comment-visibility}
+ \newcommand{\yes}{Y}%
+ \newcommand{\no}{N}%
+ \index{style file}%
+ \index{comments}%
+ \begin{tabular}{@{}ccl@{}}
+ \hline
+ Appears & Appears \\
+ in docs & in \styfile{} & \raisebox{1.5ex}[0pt]{Mechanism} \\
+ \hline
+
+ \no & \no & |% ^^A <comment>| \\[2ex]
+
+ \no & \yes & |% \iffalse| \\
+ & & |%% <comment>| \\
+ & & |% \fi| \\[2ex]
+
+ \yes & \no & |% <comment>| \\[2ex]
+
+ \yes & \yes & |%% <comment>| \\
+ \hline
+ \end{tabular}
+ \end{table}
+
+ \item All lines between |<<*package>>| and |<</package>>|, except
+ those within a \usething{macrocode} environment, should begin with
+ ``|%|''. Don't use any blank lines; these would get written to the
+ \styfile{} file (and oughtn't).
+
+
+\index{package|(}
+\index{"@@\texttt{"@}!in macro names|(}
+ \item It is good practice for \latex{} programs to use ``|@|''
+ within the names of macros, lengths, counters, etc.\ that are
+ declared globally, but intended to be used only internally to the
+ package. This prevents a user from corrupting package state by
+ inadvertently redefining package internals.\footnote{Within a
+ \LaTeX{} document, ``|@|'' is set to category code~12 (``other''),
+ not category code~11 (``letter''), so the user can't easily define
+ or use a macro with ``|@|'' in its name.} Another good practice is
+ to prefix all global names that are internal to the package with the
+ name of the package (\eg ``|\<package>@thing|'' instead of
+ ``|\@thing|'' or---even worse---just ``|\thing|''). This helps
+ avoid inter-package naming conflicts. Finally, because decimal
+ digits are not normally allowed in macro names, it is common to use
+ roman\index{roman numerals} numerals instead, for example: |\arg@i|,
+ |\arg@ii|, |\arg@iii|, |\arg@iv|, etc.
+\index{"@@\texttt{"@}!in macro names|)}
+\index{package|)}
+
+ \item You can use \usemacro{index} in the normal way to index things
+ other than macros and environments.
+
+ \item Because macro names can be long, consider using the
+ \defthing{idxlayout} package to reduce the number of columns in
+ the index. (It provides control over other aspects of index
+ formatting, as well.)
+
+ \item If you use \Emacs{} as your text editor, try out \swiftexel's
+ |doctex-mode|\index{doctex-mode@\texttt{doctex-mode}}, an \Emacs{}
+ mode designed specifically for writing \dtxfile{} files.
+ \swiftexel{} is available from \CTAN{}.
+
+ As a more primitive alternative, look up \Emacs's |string-rectangle|
+ and |kill-rectangle| commands. These help a great deal with adding
+ and removing a ``|%|'' at the beginning of every line in a region.
+
+ \item Be sure to read ``The \ds{} Program'' and ``The \DOC{} and
+ \svrb{} Packages'', the documentation for \ds{} and \DOC{},
+ respectively (provided in \dtxfile{} format, of course). These
+ explain how to do more advanced things with \insfile{} and
+ \dtxfile{} files than this tutorial covered. Some advanced topics
+ include the following:
+
+ \begin{itemize} \item Extracting multiple \styfile{}
+ files from a single \dtxfile{} file.
+
+ \item Putting different preambles in different
+ \styfile{} files.
+
+ \item Extracting something other than a \styfile{} file (\eg a
+ configuration file or a Perl script) from a \dtxfile{} file.
+
+ \item Changing the formatting of the typeset documentation.
+ \end{itemize}
+\end{itemize}
+
+
+\section{Advanced packaging techniques}
+
+This section describes various bits of wizardry that can be
+accomplished with \DOC{} and \ds. Few packages require these
+techniques but they are included here for convenient reference.
+
+\subsection{Master documentation files}
+\label{sec:master-files}
+
+\DOC{} supports ``master'' documentation files that typeset multiple
+\dtxfile{} files. The advantage is that a set of related \dtxfile{}
+files can be typeset with continuous section numbering and a single,
+unified index. In fact, the \latex[\LaTeXe]{} source code itself is
+typeset using a master document (|source2e.tex|) that includes all of
+the myriad \dtxfile{} files that comprise \latex[\LaTeXe].
+
+To help produce master documents, the \usething{ltxdoc} class
+provides a command called ``\usemacro{DocInclude}''.
+\usething{ltxdoc}'s \usemacro{DocInclude} is much like \DOC's
+\usemacro{DocInput}---it even uses it internally---but has the
+following additional features.
+
+ \begin{itemize}
+ \item \usemacro{PrintIndex} is automatically handled properly.
+
+ \item Every \usemacro{DocInclude}'d file is given a title page.
+
+ \item \usemacro{tableofcontents} works as expected. \dtxfile{}
+ filenames are used as ``chapter'' names.
+ \end{itemize}
+
+\noindent
+Note that \usemacro{DocInclude}, unlike \usemacro{DocInput}, assumes
+a \dtxfile{} extension.
+
+Appendix~\ref{sec:skeleton-master-file} presents a master-document
+skeleton that uses \usemacro{DocInclude} to typeset |<file1>.dtx|,
+|<file2>.dtx|, and |<file3>.dtx| as a single document. If you prefer
+a more manual approach (\eg if you dislike \usemacro{DocInclude}'s
+per-file title pages), you can still use \usemacro{DocInput}.
+\index{indexing|(}
+Just make sure to redefine \usemacro{PrintIndex} to do nothing;
+otherwise, each file will get its own index. After all of the
+\dtxfile{} files have been typeset, call the original
+\usemacro{PrintIndex} command to print a unified index:
+
+\begin{verbatim}
+ \begin{document}
+ \let\origPrintIndex=\PrintIndex \let\PrintIndex=\relax
+ \DocInput{<file1>.dtx}
+ \DocInput{<file2>.dtx}
+ \DocInput{<file3>.dtx}
+ \origPrintIndex
+ \end{document}
+\end{verbatim}%
+\indexmacro{PrintIndex}%
+\indexmacro{DocInput}
+
+\index{indexing|)}
+
+\subsection{Single-file package distributions}
+\label{sec:single-file}
+
+Although \latex{} packages are typically distributed as both
+a~\insfile{} and a \dtxfile{} file, it is possible to distribute a
+package as a single file. The trick is to include the entire
+\insfile{} at the top of the \dtxfile{} file, right after the
+|%<package>| lines:
+
+\begin{alltt}
+ %\string<*batchfile\string>
+ \string\begingroup
+ \(\vdots\)
+ <Entire contents of the {\normalfont\texttt{.ins}} file>
+ \(\vdots\)
+ \string\endgroup
+ %\string</batchfile\string>
+\end{alltt}
+
+\noindent
+Omit the \usemacro{endbatchfile} to allow \latex{} to continue on with
+the rest of the \dtxfile{} file. Also, to avoid the ``\texttt{File}
+\m{sty-file} \texttt{already exists on the system. Overwrite it?
+[y/n]}'' message you can put ``\usemacro{askforoverwritefalse}''
+before the first \usemacro{generate} command. (This will
+automatically overwrite the existing \styfile{} file. Wrapping the
+\usemacro{generate} command(s) within
+``\usemacro{IfFileExists}|{|\m{sty-file}|}{}{|\dots|}|'' will suppress
+the overwriting.) You should also move the \styfile{} installation
+instructions to the end of the \dtxfile{} file so they don't scroll
+off the user's screen. You'll need to use \usemacro{typeout} as
+\usemacro{Msg} won't be defined:
+
+\begin{verbatim}
+ % \Finale
+ %
+ % \typeout{**************************************************}
+ % \typeout{*}
+ % \typeout{* To finish the installation you have to move the}
+ % \typeout{* following file into a directory searched by TeX:}
+ % \typeout{*}
+ % \typeout{* \space\space skeleton.sty}
+ % \typeout{*}
+ % \typeout{* Documentation is in skeleton.dvi.}
+ % \typeout{*}
+ % \typeout{* Happy TeXing!}
+ % \typeout{**************************************************}
+ \endinput
+\end{verbatim}
+
+
+\subsection{Class and style files with shared versioning information}
+
+Some packages contain both a \clsfile{} and \styfile{} file. It may
+be desirable to have these extracted from the same \insfile{} file and
+share the same versioning string. The \ds{} documentation explains
+how to extract multiple files from a single \usemacro{generate} call:
+
+\begin{verbatim}
+ \generate{\file{<package>.cls}{\from{<package>.dtx}{class}}
+ \file{<package>.sty}{\from{<package>.dtx}{package}}}
+\end{verbatim}
+
+Using a single versioning string for both the \clsfile{} and
+\styfile{} files can be accomplished by changing the following lines
+in the \dtxfile{} file shown in
+Appendix~\ref{sec:skeleton-dtx-file-class}:
+
+\begin{verbatim}
+ %<<class>>\NeedsTeXFormat{LaTeX2e}[2005/12/01]
+ %<<class>>\ProvidesClass{<package>}
+ %<<*class>>
+ [<YYYY>/<MM>/<DD> v<version> <brief description>]
+ %<</class>>
+\end{verbatim}
+
+The replacement code specifies which lines belong to the class file
+and which belong to the style file:
+
+\begin{verbatim}
+ %<<class|package>>\NeedsTeXFormat{LaTeX2e}[2005/12/01]
+ %<<class>>\ProvidesClass{<package>}
+ %<<package>>\ProvidesPackage{<package>}
+ %<<*class|package>>
+ [<YYYY>/<MM>/<DD> v<version> <brief description>]
+ %<</class|package>>
+\end{verbatim}
+
+\subsection{Gallery of advanced packaging techniques}
+
+See the \dtxfile\ gallery on
+\CTAN\ \URL{https://www.ctan.org/tex-archive/info/dtxgallery} for
+examples of various packaging possibilities, including the following:
+
+\begin{itemize}
+ \item single-file package distributions (cf.~Section~\ref{sec:single-file})
+
+ \item conditional code inclusion (cf.~Table~\ref{tbl:comment-visibility})
+
+ \item rearranging code for presentation in the documentation
+\end{itemize}
+
+
+\appendix
+
+\section{Skeleton files}
+
+This section contains complete skeletons of the types of files
+discussed in the rest of the document. These skeletons can be used as
+templates for creating your own packages.\index{package}
+
+\index{installer file|(}
+
+\subsection{A skeleton \texttt{.ins} file to generate a \texttt{.sty} file}
+\label{sec:skeleton-ins-file-style}
+
+\begin{verbatim}
+%%
+%% Copyright (C) <year> by <your name>
+%%
+%% This file 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.
+%%
+
+\input docstrip.tex
+\keepsilent
+
+\usedir{tex/latex/<package>}
+
+\preamble
+
+This is a generated file.
+
+Copyright (C) <year> by <your name>
+
+This file 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.
+
+\endpreamble
+
+\generate{\file{<package>.sty}{\from{<package>.dtx}{package}}}
+
+\Msg{*********************************************************}
+\Msg{*}
+\Msg{* To finish the installation you have to move the}
+\Msg{* following file into a directory searched by TeX:}
+\Msg{*}
+\Msg{* \space\space <package>.sty}
+\Msg{*}
+\Msg{* To produce the documentation run the file <package>.dtx}
+\Msg{* through LaTeX.}
+\Msg{*}
+\Msg{* Happy TeXing!}
+\Msg{*********************************************************}
+
+\endbatchfile
+\end{verbatim}
+
+
+\subsection{A skeleton \texttt{.ins} file to generate a \texttt{.cls} file}
+\label{sec:skeleton-ins-file-class}
+
+\begin{verbatim}
+%%
+%% Copyright (C) <year> by <your name>
+%%
+%% This file 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.
+%%
+
+\input docstrip.tex
+\keepsilent
+
+\usedir{tex/latex/<package>}
+
+\preamble
+
+This is a generated file.
+
+Copyright (C) <year> by <your name>
+
+This file 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.
+
+\endpreamble
+
+\generate{\file{<package>.cls}{\from{<package>.dtx}{class}}}
+
+\Msg{*********************************************************}
+\Msg{*}
+\Msg{* To finish the installation you have to move the}
+\Msg{* following file into a directory searched by TeX:}
+\Msg{*}
+\Msg{* \space\space <package>.cls}
+\Msg{*}
+\Msg{* To produce the documentation run the file <class>.dtx}
+\Msg{* through LaTeX.}
+\Msg{*}
+\Msg{* Happy TeXing!}
+\Msg{*********************************************************}
+
+\endbatchfile
+\end{verbatim}
+
+\index{installer file|)}
+\index{documented LaTeX file@documented \LaTeX{} file|(}
+
+
+\subsection{A skeleton \texttt{.dtx} file to generate a \texttt{.sty} file}
+\label{sec:skeleton-dtx-file-style}
+
+\begin{verbatim}
+% \iffalse meta-comment
+%
+% Copyright (C) <year> by <your name>
+% -----------------------------------
+%
+% This file 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.
+%
+% \fi
+%
+% \iffalse
+%<<package>>\NeedsTeXFormat{LaTeX2e}[2005/12/01]
+%<<package>>\ProvidesPackage{<package>}
+%<<package>> [<YYYY>/<MM>/<DD> v<version> <brief description>]
+%
+%<<*driver>>
+\documentclass{ltxdoc}
+\usepackage{<package>}
+\EnableCrossrefs
+\CodelineIndex
+\RecordChanges
+\begin{document}
+ \DocInput{<package>.dtx}
+\end{document}
+%<</driver>>
+% \fi
+%
+% \CheckSum{0}
+%
+% \CharacterTable
+% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+% Digits \0\1\2\3\4\5\6\7\8\9
+% Exclamation \! Double quote \" Hash (number) \#
+% Dollar \$ Percent \% Ampersand \&
+% Acute accent \' Left paren \( Right paren \)
+% Asterisk \* Plus \+ Comma \,
+% Minus \- Point \. Solidus \/
+% Colon \: Semicolon \; Less than \<<
+% Equals \= Greater than \>> Question mark \?
+% Commercial at \@ Left bracket \[ Backslash \\
+% Right bracket \] Circumflex \^ Underscore \_
+% Grave accent \` Left brace \{ Vertical bar \|
+% Right brace \} Tilde \~}
+%
+%
+% \changes{v1.0}{<YYYY>/<MM>/<DD>}{Initial version}
+%
+% \GetFileInfo{<package>.sty}
+%
+% \DoNotIndex{<list of control sequences>}
+%
+% \title{The \textsf{<package>} package\thanks{This document
+% corresponds to \textsf{<package>}~\fileversion,
+% dated \filedate.}}
+% \author{<your name> \\ \texttt{<your e-mail address>}}
+%
+% \maketitle
+%
+% \begin{abstract}
+% Put text here.
+% \end{abstract}
+%
+% \section{Introduction}
+%
+% Put text here.
+%
+% \section{Usage}
+%
+% \DescribeMacro{\YOURMACRO}
+% Put description of |\YOURMACRO| here.
+%
+% \DescribeEnv{YOURENV}
+% Put description of |YOURENV| here.
+%
+% \StopEventually{\PrintIndex}
+%
+% \section{Implementation}
+%
+% \begin{macro}{\YOURMACRO}
+% Put explanation of |\YOURMACRO|'s implementation here.
+% \begin{macrocode}
+\newcommand{\YOURMACRO}{}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{environment}{YOURENV}
+% Put explanation of |YOURENV|'s implementation here.
+% \begin{macrocode}
+\newenvironment{YOURENV}{}{}
+% \end{macrocode}
+% \end{environment}
+%
+% \Finale
+\endinput
+\end{verbatim}
+
+
+\subsection{A skeleton \texttt{.dtx} file to generate a \texttt{.cls} file}
+\label{sec:skeleton-dtx-file-class}
+
+\begin{verbatim}
+% \iffalse meta-comment
+%
+% Copyright (C) <year> by <your name>
+% -----------------------------------
+%
+% This file 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.
+%
+% \fi
+%
+% \iffalse
+%<<*driver>>
+\ProvidesFile{<package>.dtx}
+%<</driver>>
+%<<class>>\NeedsTeXFormat{LaTeX2e}[2005/12/01]
+%<<class>>\ProvidesClass{<package>}
+%<<*class>>
+ [<YYYY>/<MM>/<DD> v<version> <brief description>]
+%<</class>>
+%
+%<<*driver>>
+\documentclass{ltxdoc}
+\EnableCrossrefs
+\CodelineIndex
+\RecordChanges
+\begin{document}
+ \DocInput{<package>.dtx}
+\end{document}
+%<</driver>>
+% \fi
+%
+% \CheckSum{0}
+%
+% \CharacterTable
+% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+% Digits \0\1\2\3\4\5\6\7\8\9
+% Exclamation \! Double quote \" Hash (number) \#
+% Dollar \$ Percent \% Ampersand \&
+% Acute accent \' Left paren \( Right paren \)
+% Asterisk \* Plus \+ Comma \,
+% Minus \- Point \. Solidus \/
+% Colon \: Semicolon \; Less than \<<
+% Equals \= Greater than \>> Question mark \?
+% Commercial at \@ Left bracket \[ Backslash \\
+% Right bracket \] Circumflex \^ Underscore \_
+% Grave accent \` Left brace \{ Vertical bar \|
+% Right brace \} Tilde \~}
+%
+%
+% \changes{v1.0}{<YYYY>/<MM>/<DD>}{Initial version}
+%
+% \GetFileInfo{<package>.dtx}
+%
+% \DoNotIndex{<list of control sequences>}
+%
+% \title{The \textsf{<package>} class\thanks{This document
+% corresponds to \textsf{<package>}~\fileversion,
+% dated \filedate.}}
+% \author{<your name> \\ \texttt{<your e-mail address>}}
+%
+% \maketitle
+%
+% \begin{abstract}
+% Put text here.
+% \end{abstract}
+%
+% \section{Introduction}
+%
+% Put text here.
+%
+% \section{Usage}
+%
+% \DescribeMacro{\YOURMACRO}
+% Put description of |\YOURMACRO| here.
+%
+% \DescribeEnv{YOURENV}
+% Put description of |YOURENV| here.
+%
+% \StopEventually{\PrintIndex}
+%
+% \section{Implementation}
+%
+% \begin{macro}{\YOURMACRO}
+% Put explanation of |\YOURMACRO|'s implementation here.
+% \begin{macrocode}
+\newcommand{\YOURMACRO}{}
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{environment}{YOURENV}
+% Put explanation of |YOURENV|'s implementation here.
+% \begin{macrocode}
+\newenvironment{YOURENV}{}{}
+% \end{macrocode}
+% \end{environment}
+%
+% \Finale
+\endinput
+\end{verbatim}
+
+\index{documented LaTeX file@documented \LaTeX{} file|)}
+
+\subsection{A skeleton master-document file (\texttt{.tex})}
+\label{sec:skeleton-master-file}
+
+\begin{verbatim}
+\documentclass{ltxdoc}
+\usepackage{<file1>}
+\usepackage{<file2>}
+\usepackage{<file3>}
+
+\title{<title>}
+\author{<you>}
+
+\EnableCrossrefs
+\CodelineIndex
+\RecordChanges
+
+\begin{document}
+ \maketitle
+
+ \begin{abstract}
+ <abstract>
+ \end{abstract}
+
+ \tableofcontents
+
+ \DocInclude{<file1>}
+ \DocInclude{<file2>}
+ \DocInclude{<file3>}
+\end{document}
+\end{verbatim}
+
+
+% The following was generated by BibTeX and slightly touched up by hand.
+\vfill
+\begin{thebibliography}{1}
+ \bibitem{Goossens1994:companion}
+ Michel Goossens, Frank Mittelbach, and Alexander Samarin.
+ \newblock \emph{The {\LaTeX} Companion}.
+ \newblock Addison~Wesley, Reading, Massachusetts, October~1, 1994.
+ \newblock ISBN~\mbox{0-201-54199-8}.
+
+ \bibitem{Knuth1984:literate}
+ Donald~E. Knuth.
+ \newblock Literate programming.
+ \newblock \emph{The Computer Journal}, 27(2):97--111, May 1984.
+ \newblock British Computer Society. Available from
+ \URL{http://www.literateprogramming.com/knuthweb.pdf}.
+\end{thebibliography}
+
+% Print an index.
+\index{sty@\texttt{.sty}|see{style file}}
+\index{cls@\texttt{.cls}|see{class file}}
+\index{ins@\texttt{.ins}|see{installer file}}
+\index{dtx@\texttt{.dtx}|see{documented \LaTeX{} file}}
+\index{CTAN|see{Comprehensive \TeX{} Archive Network}}
+\printindex
+
+\end{document}