% \iffalse
% Copyright (C) 2004 TeX Users Group.
% 
%    This program is free software; you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation; either version 2 of the License, or
%    (at your option) any later version.
%
%    This program is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with this program; if not, write to the Free Software
%    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
%
%<*driver>
\ProvidesFile{pracjourn.dtx}
%</driver>
%<class>\NeedsTeXFormat{LaTeX2e}[1999/12/01]
%<class>\ProvidesClass{pracjourn}
%<*class>
    [2005/08/22 v0.4e PracTeX Journal Class]
%</class>
%
%<*driver>
\documentclass{ltxdoc}
\usepackage{hyperref,multicol}
\EnableCrossrefs
\CodelineIndex
\RecordChanges
\begin{document}
  \DocInput{pracjourn.dtx}
\end{document}
%</driver>
%
% \fi
%
% \CheckSum{601}
%
%
% \changes{v0.0}{2004/10/03}{KB: Initial version}
% \changes{v0.2}{2004/11/13}{KB: Palatino, no date printing}
% \changes{v0.3}{2005/01/03}{AO: Add \cmd\TPJissue, \cmd\TPJrevision, \cmd\TPJcopyright}
% \changes{v0.3}{2005/01/03}{AO: Rewrite using \LaTeXe{} idioms}
% \changes{v0.3a}{2005/01/03}{AO: changes to \cmd\TPJissue, \cmd\TPJrevision, \cmd\TPJcopyright}
% \changes{v0.3b}{2005/01/07}{AO: change \cmd\evensidemargin}
%
%
% \newcommand\pkg[1]{\texttt{#1}}
%
%
% \GetFileInfo{pracjourn.dtx}
%
% \DoNotIndex{\if}
%
% \title{%
%  The \textsf{pracjourn} class%
%  \thanks{%
%   This document corresponds to \textsf{pracjourn}~\fileversion, dated \filedate.
%  }%
% }
% \author{%
%  Karl Berry \\
%  Arthur Ogawa\\
%  Will Robertson\\
%  Correspondence to: \texttt{pracjourn@tug.org}%
% }
%
% \maketitle
%
% \begin{abstract}
%   For articles in The Prac\TeX\ Journal, \url{http://tug.org/pracjourn}.
% \end{abstract}
%
% \makeatletter
% \def\@dotsep{1000}
% \setcounter{tocdepth}{2}
% \setlength\columnseprule{0.4pt}
% \renewcommand\tableofcontents{\relax
%   \begin{multicols}{2}[\section*{\contentsname}]\relax
%     \@starttoc{toc}\relax
%   \end{multicols}}
% \makeatother
% \tableofcontents
% 
% \section{Introduction}
%
% The \pkg{pracjourn} \LaTeX{} document class is to be used for
% articles written for the The Prac\TeX\ Journal,
% \url{http://tug.org/pracjourn}.  The source for the document class
% resides at \url{http://tug.org/pracjourn/dtx}. (WR: why isn't it at
% CTAN?)
%
% \section{Usage}
%
% To use this document class, proceed as per the \pkg{article}
% document class, with the following emendments.
% \begin{itemize}
% 
% \item Refer to the sample document for context:\\
%   \url{http:www.tug.org/PracJourn/dtx/pjsample.tex}.
% 
% \item Issue a |\documentclass{pracjourn}| command in
%   the preamble of your document. No class options are necessary.
%
% \item This document class requires packages \pkg{mathpazo}, (or if
%   not found, \pkg{palatino}), \pkg{textcomp}, \pkg{color}, and \pkg{hyperref}. These
%   are all available in a reasonably up-to-date \TeX\ distribution.
% \end{itemize}
%
% \subsection{Formatting}
% 
% \begin{itemize}
%
% \item Page metrics should be correct for printing on either A4 or
%   letter size paper. The type size is 12/15.5 Palatino. 
%
% \item Except in exceptional circumstances, please refrain from 
%   using typefaces other than those defined by this class.
%
% \end{itemize}
%
% \subsection{Author/article metadata}
%
% All author and article information must be defined before the \cmd\maketitle\
% command. Preferably even before \verb|\begin{document}| would be good.
% 
% \begin{itemize}
%
% \item The \cmd\author, \cmd\title, and \cmd\abstract\ commands are used to
%   define those pieces of metadata about the article, and are mandatory.
%
%   \begin{itemize}
%   \item Note that the \cmd\abstract\ is a plain old command, 
%     \emph{not} an environment.
%
%   \item Should you have a reason for not having an abstract,
%     this may be signified by declaring \cmd\noabstract\ instead.
%   \end{itemize}
%
% \item It is optional to specify a copyright and/or license declaration, 
%   to be typeset in the footer of the first page, with the \cmd\license\
%   command.\footnote{The \cmd\TPJcopyright\ command, which used to provide this
%   functionality is still provided for backwards compatibility.}
%
% \item Additional author information may be specified, to be typeset appropriately,
%   with the following commands: \cmd\email, \cmd\website, and \cmd\address.
%   
%   \begin{itemize}
%   \item If the \pkg{switcheml} package is installed somewhere that
%     \TeX\ will find it, it is loaded for the purpose of obfuscating
%     the typeset email address. This is done to prevent harvesting by
%     spammers, but if the package cannot be found the email address
%     will by typeset as a hyperlink. 
%
%   \item Should you wish to typeset your
%     email address as a hyperlink (that is, theoretically harvestable
%     by spammers) despite having \pkg{switcheml} installed, you may
%     simply include the command \cmd\hyperlinkemail\ anywhere before
%     \cmd\maketitle.
%   \end{itemize}
% \end{itemize}
%
% \subsubsection{Adding more author/article information}
%
% As previously
% mentioned, this class provides the \cmd\email, \cmd\website, and \cmd\address\
% macros for typesetting that information in the header block. These commands are defined 
% in the source code of the class file with the following:\footnote{\cmd\typesetemail\ 
%   is an internal command defined by either \cmd\hyperlinkemail\ or \cmd\obfuscateemail.}
% \begin{quote}
%   |\addinfo{Address}|\\
%   |\addinfo[\typesetemail]{Email}|\\
%   |\addinfo[\url]{Website}|
%  \end{quote}
% Additional blocks my be added on a per-article basis in the same manner.
%
% To be specific, the \cmd\addinfo\ command takes one mandatory argument,
% which is the title of the item to be added to the list, and one optional
% argument, which is used to define the formatting of the block.
%
% This command will then define the macro used to input the additional information
% by taking the lowercase of the title of the information and turning it into
% a \TeX\ macro. This creates some obvious limitations on the name of the information
% blocks that can be created---if this upsets you, write me.
%
% If you don't like the ordering of the information blocks or you wish to edit
% the formatting for some reason, the \cmd\clearinfo\ command allows you to start
% fresh and redefine the address, email, and website information blocks however you may wish.
%
% \subsection{TPJ internal commands}
%
% \begin{itemize}
% 
% \item Two commands are to be used at the direction of the Prac\TeX\
%   production team: \cmd\TPJrevision\ and \cmd\TPJissue. These
%   commands typeset information in the header of the first page
%   relating to the revision number (or date) of the article and the
%   issue number of the journal.
%
%   Below this information is a hyperlink to send email comments to
%   the relevant mailing list. If \cmd\TPJissue\ is declared, then the
%   article is presumed to be in its publication form; emails are directed
%   to the public \url{pracjourn@tug.org} mailing list. If the
%   \cmd\TPJissue\ has \emph{not} been specifed, then the article is
%   still in its revision stage and the link directs emails to the
%   closed Prac\TeX\ journal production mailing list, intended for
%   article reviewers only.
% 
% \item This document class creates a file \verb+_rev.tex+ in the
%   current directory (if a \cmd\TPJrevision{} statement is present)
%   and reads a file \verb+_iss.tex+, if present.  Please keep a
%   separate directory for each article you develop for TPJ.
% 
% \end{itemize}
%
% \subsection{Logos}
%
% The following logos and abbreviations are defined for your
% convenience: \cmd\TeX, \cmd\LaTeX, \cmd\LaTeXe, \cmd\BibTeX,
% \cmd\MF, \cmd\MP\ (METAFONT and METAPOST, typeset in their own
% font), \cmd\ConTeXt, \cmd\pdfTeX, \cmd\pdfLaTeX, \cmd\PracTeX,
% \cmd\TPJ\ (`The Prac\TeX\ Journal').
%
% \StopEventually{\clearpage\PrintChanges\clearpage\PrintIndex}
%
% \section{History}
%
% The first revision of this class was written by Karl Berry.
% KB: Gratefully based on the \texttt{dtxtut} skeleton.
%
% Revised by Arthur Ogawa, 2004/01/03, to include new features, per
% Lance Carnes, as follows:
%
% \begin{enumerate}
% \item Define an \cmd\articleID{} macro which typesets the article
%   identification in a block somewhere on the first page of the
%   article, and which can be used to identify the article/revision
%   date for reader comments.  E.g. if this appears in the article
%   source file:
% \begin{verbatim}
% \author{A.U. Thor}
% \title{Pracjourn Sample}
% \TPJissue{TPJ Vol 1 No 1, 2005-1-15}
% \TPJrevision{2005-2-12}%
% \TPJcopyright{\textcopyright\ 2005 TeX Users Group}
% \end{verbatim}
%   it will become a block of text typeset on the first page of the
%   article.  See
%   e.g. \url{http://www.ams.org/bull/2004-41-04/S0273-0979-04-01032-8/S0273-0979-04-01032-8.pdf}
%
% \item Write the information from the argument of the
%   \cmd\articleID{} macro into a file called \verb+_id.tex+.  Put
%   this file in the same directory as the source file, and overwrite
%   any previous files of the same name.
%
% \item Define a \cmd\TPJcopyright{} macro which will print a
%   copyright notice at the bottom of the first page.
%   E.g. \cmd\TPJcopyright\verb+{2005 TeX Users Group}+ will produce
%   ``\copyright2005 TeX Users Group'' in the page footer of the title
%   page.
%
% \item The page measures should work with both Letter and A4 paper
%   sizes.
% \end{enumerate}
%
% Revised again by Will Robertson, mid-2005, to implement a couple of
% extra things.
% \begin{itemize}
%
% \item The \cmd\maketitle\ has been redesigned with additional
%   author information. \cmd\email, \cmd\address,
%   \cmd\website, and \cmd\abstract\ are now also supported. Further
%   information may be added in the same style.
%
% \item Appropriate some various style files to remove dependancies on
%   \pkg{mflogo} and \pkg{texnames}. In addition, the various
%   \cmd\TeX\ logos were tuned to look better in the Palatino
%   typeface.
%
% \item The hyperref package is loaded and set up to colour various
%   hyperlinks.
%
% \item Document divisions have been un-boldened, just for a change.
%
% \end{itemize}
%
% \section{Implementation}
%
% \subsection{Base class and default options}
%
% Use \LaTeX's \pkg{article} class, but at a bigger default type size.
%
% KB: 12pt seems a little too big, 11pt seems a little too small.
% Implementing 11.5pt is not obvious.
%
% \changes{v0.3}{2004/01/03}{AO: Override the default option list of
%   \pkg{article.cls}}
%
% If the document instance calls for options that conflict with the
% following choices, then the document wins.  However our default
% option list is not the same as those of \pkg{article.cls}.
%    \begin{macrocode}
\let\ExecuteOptions@ltx\ExecuteOptions
\def\ExecuteOptions#1{%
 \ExecuteOptions@ltx{letterpaper,12pt,oneside,onecolumn,final}%
}%
\LoadClassWithOptions{article}
\let\ExecuteOptions\ExecuteOptions@ltx
%    \end{macrocode}
%
% \subsection{Metrics}
%
% Default leading (from \texttt{classes.dtx}) for 11pt is 13.6pt
% leading, for 12pt is 14.5pt.  We want more---this factor gives us
% 12pt type on 15.5pt leading.
%    \begin{macrocode}
\linespread{1.069}
%    \end{macrocode}
% 
% Change the text width to something that works for both A4 and
% Letter paper, as well as possible.
%
% xx The vertical dimensions need to be changed as well, perhaps
% for a 9in text height, taking account of the headline and
% footline.
%    \begin{macrocode}
\setlength\textwidth{432pt}
\setlength\oddsidemargin{18pt}% xx depend on letter/a4
\setlength\evensidemargin{18pt}
%    \end{macrocode}
%
% \subsection{Package loading}
%
% Palatino, including math (sc option for true small caps, not in TL
% 2003).  Try for \pkg{mathpazo}; if not available use \pkg{palatino}.
%
% \changes{v0.3}{2004/01/03}{AO: rewrite using \cs{IfFileExists} idiom.}
% \changes{v0.4e}{2005/08/22}{WR: requires the textcomp package.}
%
% The \pkg{textcomp} package is loaded in order to provide a nice looking copyright logo, amongst other things.
%
%    \begin{macrocode}
\IfFileExists{mathpazo.sty}
             {\RequirePackage{mathpazo}}
             {\RequirePackage{palatino}}
\RequirePackage{textcomp}             
%    \end{macrocode}
% \pkg{hyperref} is used for creating live hyperlinks, as well as
% providing \cmd\url\ for typesetting URLs easily. All hyperlinks
% are coloured in a dark shade of blue.
%    \begin{macrocode}
\RequirePackage{color,hyperref}
\definecolor{refcolor}{rgb}{0,0.2,0.6}
\hypersetup{bookmarks,colorlinks,breaklinks,
            linkcolor=refcolor,citecolor=refcolor,
            filecolor=refcolor,urlcolor=refcolor}
%    \end{macrocode}
% If the \pkg{switcheml} package is installed in the author's
% system, use it to obfuscate their email address by default. Otherwise, just
% use a hyperlink. The commands to do this are defined in a later section.
%
% An author may specify \cmd\hyperlinkemail\ explicitly
% should they not care to obfuscate their email address even with the \pkg{switcheml}
% package installed.
%    \begin{macrocode}
\IfFileExists{switcheml.sty}
             {\RequirePackage{switcheml}
              \AtBeginDocument{\@ifx@undefined{\typesetemail}{\obfuscateemail}{}}}
             {\AtBeginDocument{\@ifx@undefined{\typesetemail}{\hyperlinkemail}{}}}
%    \end{macrocode}
%
%
% \subsection{Amendments from \pkg{article}}
%
% \begin{macro}{\maketitle}
% Printing the date of the last \TeX\ run in the title block does
% not seem warranted---if someone reprocesses the document with no
% changes, we wouldn't want the date to change.
%
% xx use rcs.sty or something?
%
% xx include bibtex id?
%
% \changes{v0.3}{2004/01/03}{AO: reproduce entire definition from
%   \texttt{article.cls}, with modifications.}
% \changes{v0.3}{2004/01/03}{AO: \cmd\thispagestyle{titlepage}. Do
%   not empty out \cmd\@author, \cmd\@title, etc.}
% \changes{v0.4b}{2005/06/26}{WR: removed some twocolumn conditional code.}
% \changes{v0.4b}{2005/06/26}{WR: added check for an abstract}
%    \begin{macrocode}
\renewcommand\maketitle{\par
  \iftpj@noabstract\else
    \@ifx@undefined{\tpj@info@Abstract}
      {\ClassError{pracjourn}
        {Please specify an \string\abstract\space before \string\maketitle}
        {It is a PracTeX Journal requirement to include an abstract.   \MessageBreak 
                                                                       \MessageBreak
         If you have exceptional reasons for not having one in this    \MessageBreak
         article, write \string\noabstract\space somewhere before \string\maketitle.}}{}
  \fi
  \begingroup
    \renewcommand\thefootnote{\@fnsymbol\c@footnote}%
    \def\@makefnmark{\rlap{\@textsuperscript{\normalfont\@thefnmark}}}%
    \long\def\@makefntext##1{\parindent 1em\noindent
            \hb@xt@1.8em{%
                \hss\@textsuperscript{\normalfont\@thefnmark}}##1}%
    \newpage
    \global\@topnum\z@   % Prevents figures from going at top of page.
    \@maketitle
    \thispagestyle{titlepage}\@thanks
  \endgroup
  \setcounter{footnote}{0}%
  \global\let\thanks\relax
  \global\let\maketitle\relax
  \global\let\@maketitle\relax
% \global\let\@thanks\@empty
% \global\let\@author\@empty
% \global\let\@date\@empty
% \global\let\@title\@empty
  \global\let\title\relax
  \global\let\author\relax
  \global\let\date\relax
  \global\let\and\relax
}%
%    \end{macrocode}
% \end{macro}
%
%
%
% \begin{macro}{\@maketitle}
%
% \changes{v0.4a}{2005/06/13}{WR: various changes to accommodate extras.}
%    \begin{macrocode}
\def\@maketitle{%
  \newpage
  \null
  \write@ID@aux\read@issue
  \vspace{1.5em}
  \begin{flushleft}
    \let\footnote\thanks
    \begingroup\LARGE \@title  \par\endgroup
    \vspace{2ex}%
    \begingroup\large \@author \par\endgroup
  \end{flushleft}
%    \end{macrocode}
% This is where the extra author information is typeset. As various
% pieces of information are defined, they fill up the \cmd{\tpj@optional@author@info}
% macro, which is subsequently used here as per the definition of the author.
%    \begin{macrocode}
  \tpj@optional@author@info
  \iftpj@noabstract\else
    \vspace{2ex}%
    \tpj@info@container{Abstract}
  \fi}
%    \end{macrocode}
% \end{macro}
%
%
% \subsubsection{Formatting changes}
%
% Remove bold from the all the section headings, just for something a
% little different. This is verbatim from \texttt{article.cls} with a
% bunch of \cmd\bfseries's omitted.
%
%    \begin{macrocode}
\renewcommand\section{\@startsection {section}{1}{\z@}%
                                     {-3.5ex \@plus -1ex \@minus -.2ex}%
                                     {2.3ex \@plus.2ex}%
                                     {\normalfont\Large}}
\renewcommand\subsection{\@startsection{subsection}{2}{\z@}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {1.5ex \@plus .2ex}%
                                     {\normalfont\large}}
\renewcommand\subsubsection{\@startsection{subsubsection}{3}{\z@}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {1.5ex \@plus .2ex}%
                                     {\normalfont\normalsize}}
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}%
                                     {3.25ex \@plus1ex \@minus.2ex}%
                                     {-1em}%
                                     {\normalfont\normalsize\itshape}}
\renewcommand\subparagraph{\@startsection{subparagraph}{5}{\parindent}%
                                     {3.25ex \@plus1ex \@minus .2ex}%
                                     {-1em}%
                                     {\normalfont\normalsize\itshape}}
%    \end{macrocode}
%
%
% \subsection{TPJ additions}
%
% \subsubsection{Boolean logic}
%
% \begin{macro}{\@ifx@empty}
% \begin{macro}{\@ifx@undefined}
% \begin{macro}{\@ifeof}
%   The following three procedures implement part of the boolean logic
%   facility, an expansion-only calculating engine.
%    \begin{macrocode}
\def\@ifx@empty#1{% Implicit #2#3
  \ifx#1\@empty
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi}%
\def\@ifx@undefined#1{% Implicit #2#3
  \ifx#1\@undefined
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi}%
\def\@ifeof#1{% Implicit #2#3
 \ifeof#1
   \expandafter\@firstoftwo
 \else
   \expandafter\@secondoftwo
 \fi}%
\def\boolean@true#1{\let#1\@firstoftwo}%
\def\boolean@false#1{\let#1\@secondoftwo}%
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
%
% \subsubsection{Titlepage pagestyle}
%
% \begin{macro}{\ps@titlepage}
% The \cmd{\ps@titlepage} procedure effects a page style
% called \texttt{titlepage}, which applies only to the title page.
% The \cmd{\titlepage@head} procedure sets type in the page header,
% \cmd{\titlepage@foot} in the page footer.
%
% \changes{v0.3}{2004/01/03}{AO: add page header and footer to title page} 
%    \begin{macrocode}
\def\ps@titlepage{%
  \def\@oddhead{\titlepage@head\hfil}%
  \let\@evenhead\@oddhead
  \def\@oddfoot{\hfil\titlepage@foot}%
  \let\@evenfoot\@oddfoot}%
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\titlepage@head}
%
% This is the text block before the article title. Changes depending
% on the production stage, and includes an email link to send
% comments on the article. In the review phase, this links to
% \url{pracjourn-prod@tug.org}, the closed Prac\TeX\ production
% mailing list. Once published, the link points at
% \url{pracjourn@tug.org} for public discussion.
%
% \changes{v0.4b}{2005/06/26}{WR: More conditional text.}
% \changes{v0.4b}{2005/06/26}{WR: Added hyperref link to email article
%   comments for both reviewers and readers.}
% \changes{v0.4c}{2005/06/27}{WR: Tweaked conditionals; revision date is important even after publication!}
% \changes{v0.4c}{2005/06/27}{WR: Added error check for \cmd\TPJrevision\ defined without \cmd\TPJissue.}
% \changes{v0.4d}{2005/07/17}{WR: Make the header \cmd\small.}
% \changes{v0.4e}{2005/07/17}{WR: Removed email comments links.}
%    \begin{macrocode}
\def\titlepage@head{\small
  \vtop{%
    \baselineskip1.2em
    \halign{%
     ##\unskip\hfil\cr
     \relax\@ifx@empty\@TPJissue{For submission to \TPJ}
                                {\TPJ\cr\@TPJissue}\cr
     \relax\@ifx@empty\@TPJissue
       {\@ifx@empty\@TPJrevision
          {Draft of \today}
          {Article revision \@TPJrevision
%            \cr
%           \tpj@compose@mailto
%             {pracjourn-prod@tug.org}
%             {Review comments on \@author's article, rev. \@TPJrevision}
%             {Send review comments to the \PracTeX\ production mailing list}
          }\cr
       }%
       {\@ifx@empty\@TPJrevision
          {\ClassError{pracjourn}
            {\string\TPJrevision\space must be defined if 
             \string\TPJissue\space is also}
            {It is a requirement for PracTeX Journal articles to contain\MessageBreak
             revision information for version tracking. Please input this\MessageBreak
             information, or omit \protect\TPJissue.}}
          {Article revision \@TPJrevision}
        \cr
%        \tpj@compose@mailto{pracjourn@tug.org}
%                           {Comments on \@author's article}
%                           {Comment on this article}
        \cr}}}}%
%    \end{macrocode}
% \end{macro}
%
% Email subjects should look like "comment on 2005-2-robertson Rev. 2005-03-25"
% for consistency with the online links that serve the same purpose. For now, too bad.
%
% \begin{macro}{\titlepage@foot}
% To typeset the optional copyright declaration by the author.
%
% \changes{v0.4d}{2005/07/17}{Removed \cmd\copyright\ from the copyright 
%   notice and put the whole thing in a lowered \cmd\vbox\ to allow multi-line declarations.}
%    \begin{macrocode}
\def\titlepage@foot{%
  \@ifx@empty\@TPJcopyright{}{%
    \lower\baselineskip\hbox{\vbox{%
      \raggedleft\small\@TPJcopyright}}}}%
%    \end{macrocode}
% \end{macro}
%
%
% \subsubsection{Additional author/article information}
%
% \begin{macro}{\addinfo}
%
% This command defines a new block of information to be typeset
% in the title block of the document. For every new item, a new
% \cmd{\tpj@info@container} is appended to \cmd{\tpj@optional@author@info}, which
% is called in \cmd{\@maketitle}.
%
% \changes{v0.4d}{2005/07/30}{WR: Name change to user-space.}
%    \begin{macrocode}
\newcommand\addinfo[2][]{%
  \tpj@define@info@block[#1]{#2}%
  \g@addto@macro\tpj@optional@author@info{\tpj@info@container[#1]{#2}}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\tpj@define@info@block}
%   \changes{v0.4a}{2005/06/13}{WR: Implemented for new \cmd{\@maketitle}.}
% This macro actually does the work of \cmd\addinfo. 
% It takes the name of a piece of info to be typeset in the
% title block of the article. The name of the info is lowercased to
% create a control sequence for the user to input this data. E.g.,
% \cs{addinfo{Abstract}} will create a control sequence
% \cmd\abstract\ which saves its argument inside \cmd{\tpj@info@Abstract}.
%
% All commands are defined \cmd\long\ so that paragraphs are
% allowed. This is much easier than
% |\begin{abstract}...\end{abstract}| contortions
% (cf. \texttt{ltugboat.cls}).
%    \begin{macrocode}
\newcommand\tpj@define@info@block[2][]{%
  \lowercase{\expandafter\long\expandafter\def\csname#2\endcsname}%
  ##1{\expandafter\def\csname tpj@info@#2\endcsname{##1}}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\clearinfo}
% If the \cmd{\tpj@optional@author@info} macro needs to be cleared for some reason,\footnotemark
% the \cmd\clearinfo\ command will come quite in handy. This command is also used to
% initialise the macro in question.
% \footnotetext{The only reason I can think of to do this is to re-arrange the order of
%   the items in the title block of the article.}
% \changes{v0.4d}{2005/07/30}{WR: Implemented to allow for re-definition of standard information blocks.}
%    \begin{macrocode}
\newcommand\clearinfo{\let\tpj@optional@author@info\@empty}
\clearinfo
%    \end{macrocode}
% \end{macro}
%
% \paragraph{Optional fields}
%
% These are the default information blocks.
% \cmd\typesetemail\ is defined by one of either \cmd\hyperlinkemail\ or \cmd\obfuscateemail.
%
%    \begin{macrocode}
\addinfo{Address}
\addinfo[\typesetemail]{Email}
\addinfo[\url]{Website}
%    \end{macrocode}
%
% \paragraph{Abstract} We bypass \cmd\addinfo\ 
% so that the abstract info block is not added 
% to the \cmd{\tpj@optional@author@info} macro.
%
% The abstract block itself is called directly in \cmd{\@maketitle}.
%
%    \begin{macrocode}
\tpj@define@info@block{Abstract}
%    \end{macrocode}
%
% \begin{macro}{\noabstract}
% However, the abstract may indeed be suppressed if that is the author's wish.
% \changes{v0.4d}{2005/07/25}{WR: Implemented to turn off the abstract.}
%    \begin{macrocode}
\newif\iftpj@noabstract
\newcommand\noabstract{\tpj@noabstracttrue}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\endabstract}
% If an abstract environment is used, give an error. Maybe I should
% just support the environment, instead.
%    \begin{macrocode}
\def\endabstract{%
  \ClassError{pracjourn}
   {Please input the abstract with \string\abstract{...}, before \string\maketitle}
   {Instead of the \string\begin{abstract}...\string\end{abstract} \MessageBreak 
    environment, use \string\abstract{...}. Paragraphs are allowed!\MessageBreak 
                                                                   \MessageBreak 
    Because the abstract is typeset with the title block,          \MessageBreak 
    it must be input before the \string\maketitle\space command.}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\TPJissue}
% \begin{macro}{\TPJrevision}
% \begin{macro}{\TPJcopyright}
%
% \changes{v0.3}{2004/01/03}{AO: add commands specifying issue,
%   revision, copyright.} 
%
% The three user-level commands
% \cmd\TPJissue, \cmd\TPJrevision, and \cmd\TPJcopyright{} specify
% the issue, the revision, and the copyright information of the
% document.
%
% Since these commands are like \cmd\author{} and \cmd\title, one
% might wish to disable them upon executing the \cmd\titlepage{}
% procedure. But we do not.
%
% If the document has a \cmd\TPJrevision{} statement, the title page
% header contains ``Rev. YY-MM-DD'', otherwise it bears the current
% date.
%
% If the document lacks a \cmd\TPJcopyright{} statement, the title
% page footer contains nothing.
%    \begin{macrocode}
\newcommand{\TPJissue}[1]{\gdef\@TPJissue{#1}}%
\newcommand{\TPJrevision}[1]{\gdef\@TPJrevision{#1}}%
\newcommand{\TPJcopyright}[1]{\gdef\@TPJcopyright{#1}}%
\let\@TPJissue\@empty
\let\@TPJrevision\@empty
\let\@TPJcopyright\@empty
%    \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
%
% \begin{macro}{\license}
%
% For consistency with the other user commands of this class, \cmd\license\
% is defined as an alias of \cmd\TPJcopyright.
%
% \changes{v0.4d}{2005/07/30}{WR: name change from \cmd\TPJcopyright\
%   for consistency with other commands.}
%
%    \begin{macrocode}
\let\license\TPJcopyright
%    \end{macrocode}
%
% \end{macro}
%
% \begin{macro}{\tpj@info@container}
% This is the macro that typesets the optional author info for
% fields defined as above. It splits it all up in minipages, in a
% smaller font and with more compressed leading than the main
% document text. It takes the name of the info as a mandatory
% argument, which is used to typeset the info label as well as
% retrieve the actual data from the |\tpj@info@#1| macro (see
% \cmd{\addinfo}).
%
% An optional argument is used as a hook to typeset the info data in
% the equivalent form |#1{#2}|.
%
% For example, to typeset the info defined by the author in the
% \cmd\abstract\ (recall, this is set up due to a corresponding
% |\addinfo{Abstract}|---see above), input
% |\tpj@info@container{Abstract}|. To typeset it, say, in italics,
% it would be possible to write
% |\tpj@info@container[\textit]{Abstract}|.
%
% \changes{v0.4a}{2005/06/13}{Implemented for new \cmd\@maketitle.}
% \changes{v0.4d}{2005/06/29}{Warn if a title block command is used after \cmd\maketitle.}
%
%    \begin{macrocode}
\newcommand\tpj@info@container[2][]{%
%    \end{macrocode}
% After \cmd\maketitle, redefine the info command to return an error.
%    \begin{macrocode}
  \lowercase{\expandafter\gdef\csname#2\endcsname}%
    {\ClassError{pracjourn}{#2 must be defined BEFORE \string\maketitle}{}}
%    \end{macrocode}
% Now, we typeset the info block, but only if the info has actually been specified by the author.
%    \begin{macrocode}
  \expandafter\ifx\csname tpj@info@#2\endcsname\relax\else
    \noindent\null\hfill\small
%    \end{macrocode}
% On the left, right-aligned sans serif item label, e.g., `Abstract':
%    \begin{macrocode}
    \begin{minipage}[t]{0.1\textwidth}
      \noindent\hfill\sffamily#2%
    \end{minipage}\hfill
%    \end{macrocode}
% On the right, the content, defined by, e.g., \cmd\abstract:
%    \begin{macrocode}
    \begin{minipage}[t]{0.85\textwidth}
      \linespread{1.0}\selectfont
      \setlength\parindent{1.5em}%
      \noindent\ignorespaces
      \expandafter#1\expandafter{\csname tpj@info@#2\endcsname}
    \end{minipage}\par
  \fi}
%    \end{macrocode}
% \end{macro}
%
% \subsubsection{Email \& hyperlink macros}
%
% \begin{macro}{\typesetemail}
%
% We define the macro \cmd\typesetemail\ to be used for self-explanatory purposes.
% The class contains methods to define it in one of two ways.
%
% \begin{macro}{\hyperlinkemail}
% 
% The \cmd\hyperlinkemail\ command defines \cmd\typesetemail\ to use the \pkg{hyperref}
% package's facilities to create a hyperlink email address in the output document.
%
% \begin{macro}{\obfuscateemail}
% 
% The \cmd\obfuscateemail\ command defines \cmd\typesetemail\ to use the \pkg{switcheml}
% package's facilities to create a machine-obfuscated email address in the output 
% document.\footnote{The \pkg{switcheml} package defines, among a couple of other things, a macro for
% typesetting email addresses that obfuscates their representation in the PDF file,
% ensuring protection against harvesting email addresses from web-public
% PDF documents.}
%
%    \begin{macrocode}
\newcommand\obfuscateemail{%
  \def\typesetemail##1{\ttfamily\switchemail{##1}}}
\newcommand\hyperlinkemail{%
  \def\typesetemail##1{\ttfamily\tpj@compose@mailto{##1}{Re: PracTeX Journal article}{##1}}}
%    \end{macrocode}  
% \end{macro}\end{macro}\end{macro}
%
% \begin{macro}{\tpj@compose@mailto}
%
% This macro takes three arguments to typeset a mailto email
% hyperlink. The |#1| takes the email address, |#2| takes the
% default subject of the email, and |#3| is the text to appear in
% the output as the hyperlink.
%
% All spaces in the hyperlink source are converted to |%20| to
% accommodate Mac~OS~X's PDF reader; this isn't necessary for Adobe
% Reader. Oh well.
%
% \changes{v0.4b}{2005/06/26}{Implemented; creates a workable mailto
%   hyperlink.}
%
%    \begin{macrocode}
\newcommand\tpj@compose@mailto[3]{%
  \edef\@tempa{mailto:#1?subject=#2 }%
  \edef\@tempb{\expandafter\html@spaces\@tempa\@empty}%
  \href{\@tempb}{#3}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\html@spaces}
% \changes{v0.4b}{2005/06/25}{Implemented to overcome the mailto
%   problems in Mac~OS~X's PDF reader.}  

% This macro takes a string and (hopefully) converts all spaces (or
% is it all whitespace?) to `\%20', creating a string that can be
% used for encoding the subject of the email comments hyperlink in
% \cmd{\titlepage@head}. Using \cmd\catcode, we remove the comment
% ability of the \verb|%| character, making it a normal letter.
% (This code was heavily influenced by the \LaTeX\ kernel's
% \cmd{\zap@space} command.)
%    \begin{macrocode}
\catcode`\%=11
\def\html@spaces#1 #2{#1%20\ifx#2\@empty\else\expandafter\html@spaces\fi#2} 
\catcode`\%=14
%    \end{macrocode}
% \end{macro}
%
%
%
% \subsubsection{Logos}
%
% \changes{v0.4a}{2005/06/05}{WR: Incorporated code from \pkg{texnames}
%   and \pkg{mflogo}.}
%
% The \pkg{texnames} and \pkg{mflogo} packages have been incorporated
% into the class in order to remove the dependence on external
% packages and to tune the logos for Palatino. First, here are the
% relevant parts\footnote{No-one still refers to AMSTeX and SLITeX and
%   so on, right?} of \texttt{texnames.sty}, v1.10, tuned for Palatino
% and adapted to use \cs{textsc} where appropriate:
%    \begin{macrocode}
\def\TeX{T\kern-.15em\lower.5ex\hbox{E}\kern-.07em X\spacefactor1000\relax}
\def\LaTeX{L\kern-.35em\raise.3ex\hbox{\textsc a}\kern-.15em\TeX}
\def\LaTeXe{\LaTeX2$_{\textstyle\varepsilon}$}
\def\BibTeX{B{\textsc i\kern-.025em \textsc b}\kern-.08em\TeX}
%    \end{macrocode}
% And now \texttt{mflogo.sty}, unchanged in its entirety:
%    \begin{macrocode}
\DeclareRobustCommand\logofamily{%
  \not@math@alphabet\logofamily\relax
  \fontencoding{U}\fontfamily{logo}\selectfont}
\DeclareTextFontCommand{\textlogo}{\logofamily}
\def\MF{\textlogo{META}\@dischyph\textlogo{FONT}\@}
\def\MP{\textlogo{META}\@dischyph\textlogo{POST}\@}
%    \end{macrocode}
% Now some new definitions. Despite the fact that it makes no
% difference with the main font used for this class, I define
% \cs{pdfTeX} with some italic correction to set a good
% precedent. Compare Computer Modern with and without:
% {\usefont{OT1}{cmr}{m}{n}pdf\/\TeX}
% vs.~{\usefont{OT1}{cmr}{m}{n}pdf\TeX}; I find the former more
% attractive because the ascender of the `f' doesn't collide.
%    \begin{macrocode}
\newcommand\ConTeXt{C\kern-.03em on\-\kern-.10em\TeX\kern-0.04em t}%
\newcommand\pdfTeX{pdf\/\TeX}
\newcommand\pdfLaTeX{pdf\/\LaTeX}
\newcommand\PracTeX{Prac\kern-0.08em\TeX}
\newcommand\TPJ{The \PracTeX\ Journal}
%    \end{macrocode}
%
% \subsubsection{Version tracking}
%
% \begin{macro}{\write@ID@aux}
% \changes{v0.3}{2004/01/03}{AO: add ID file}
% Establish an auxiliary file, \verb+_id.tex+, for TPJ tracking information.
% 
%    \begin{macrocode}
\def\write@ID@aux{%
 \@ifx@empty\@TPJrevision{}{%
  \begingroup
   \let\thanks\@gobble
   \immediate\openout\ID@aux _rev.tex
%  \immediate\write\ID@aux{\@percentchar\space 
%    This file generated by the pracjourn document class}%
   \immediate\write\ID@aux{\@TPJrevision}%
   \immediate\closeout\ID@aux
  \endgroup
 }%
}%
\newwrite\ID@aux
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\read@iss@aux}
% \changes{v0.3}{2004/01/03}{AO: read the "issue" file}
% 
% FIXME: Check if \cmd\@TPJissue{} has been assigned already.
%    \begin{macrocode}
\def\read@issue{%
 \openin\@inputcheck _iss.tex
 \@ifeof\@inputcheck{}{%
  \read\@inputcheck to\@TPJissue
  \global\let\@TPJissue\@TPJissue}%
 \closein\@inputcheck}
%    \end{macrocode}
% \end{macro}
%
% \subsubsection{Miscellaneous}
%
% \begin{macro}{\set@pdfpage}
%   \changes{v0.3}{2004/01/03}{AO: add commands setting pdftex's page
%     metrics from LaTeX's} 
%
% The PDF\TeX{} parameters \cmd\pdfpagewidth{} and
% \cmd\pdfpageheight determine the
% CropBox/BleedBox/TrimBox/ArtBox. The procedure \cmd\setpdfpage{}
% sets them to the values of the \LaTeX{} \cmd\paperwidth{} and
% \cmd\paperheight.  If PDF\TeX{} is not the engine, nothing is
% done.
%
% We arrange for the procedure to be executed at Begin Document
% time.
%    \begin{macrocode}
\def\set@pdfpage{%
 \@ifx@undefined\pdfoutput{}{%
  \pdfpagewidth =\paperwidth
  \pdfpageheight=\paperheight
  \relax}}
\AtBeginDocument{\set@pdfpage}
%    \end{macrocode}
% \end{macro}
%
% \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         \~}
%
% \Finale
\endinput