%% \CheckSum{26}
% \iffalse (Comment)
%   This file contains a breif description of the T1R/zcm font family, 
%   the code for its font definition file, and the code the ecsubzcm 
%   package.
% \fi
% 
% \iffalse (Skip the driver code when DocInputting.)
%  (The driver code is still enclosed in a macrocode environment, just 
%  in case.)
%    \begin{macrocode}
%<*driver>
\documentclass{ltxdoc}
\newcommand\package[1]{\textsf{#1}}
\title{The \texttt{zcm} example font family}
\author{Lars Hellstr\"om%
  \thanks{E-mail: \texttt{Lars.Hellstrom@math.umu.se}}%
}
\begin{document}
\maketitle
\DocInput{t1rzcm.fdd}\Finale
\begin{thebibliography}{9}
\bibitem{ltoutenc}
  Johannes Braams, David Carlisle, Alan Jeffrey, Frank Mittelbach, 
  Chris Rowley, Rainer Sch\"opf: \texttt{ltoutenc.dtx} (part of the 
  \LaTeXe\ base distribution).
\end{thebibliography}
\end{document}
%</driver>
%    \end{macrocode}
% \fi
% 
% \section{The \texttt{zcm} font family and \texttt{reldemo.tex}}
% \label{zcm-family}
% %
% The \texttt{zcm} family of fonts consists of only two fonts and it is 
% meant to accompany the \package{relenc} package documentation. These 
% fonts are really just combinations of glyphs taken from other fonts, 
% primarily the Computer Modern fonts (hence the \texttt{cm}), but 
% there are also some glyphs which are taken from some \LaTeX\ symbol 
% fonts (\texttt{lasy10} and \texttt{lcircle10}).
% 
% The primary reason these fonts exist is that I felt I needed an example 
% of what can be done with the \package{relenc} package. As one really 
% cannot expect that people will have any font that is not either a 
% Computer Modern or a \LaTeX\ font, such an example has to be made 
% using these fonts. I am well aware that some of the glyphs look 
% terrible, but the \texttt{zcm} family is not intended to be used 
% for any serious typesetting.
% 
% The font family consists of two fonts: \texttt{zcmr8d} and 
% \texttt{zcmra}. The first of these is declared as 
% \texttt{T1R}\slash\texttt{zcm}\slash\texttt{m}\slash\texttt{n} and its 
% coding scheme is identical to that of the \texttt{T1} encoding. The 
% second is declared as \texttt{T1R}\slash\texttt{zcm}\slash
% \texttt{m}\slash\texttt{a} and its coding scheme deviates from that of 
% the \texttt{T1} encoding in four slots, which have been reassigned to 
% contain ligatures instead of accented letters.
% 
% A demonstration of these fonts is generated by typesetting 
% \texttt{reldemo.tex}; this document contains a font table listing the 
% contents of each slot, a demonstration of all the symbol commands, a 
% demonstration of the effects of applying the accenting commands to the 
% non-accented letters, and a comprehensive list of character pairs, for 
% both fonts. The reason I have put it in a separate file is (i) that 
% the \package{relenc} package will have to be installed before these 
% fonts can be viewed (the files needed are \texttt{relenc.sty}, 
% \texttt{t1renc.def}, and \texttt{t1rzcm.fd}) and (ii) that there 
% might be some problems connected to viewing these fonts.
% 
% To begin with, both fonts are virtual fonts and some DVI drivers cannot 
% handle these. If you only have such drivers, you should get one that 
% can (not just for the sake of the \package{relenc} package---virtual 
% fonts are in general neat to be able to use).
% 
% One of the fonts used to make these virtaul fonts---the 
% \texttt{lcircle10} font---occurs under two other names as well: 
% \texttt{circle10} and \texttt{lcirc10}. Unfortunately, one cannot 
% expect that there is more than one of these in any given \TeX\ ^^A
% installation. Thus you will get some problems if your installation 
% uses another name for this font. Some DVI drivers will translate the 
% name used in the virtual font to that of the font names which actually 
% occurs in the system, and in this case there is no problem, but if not 
% then you will have to intervene yourself.
% 
% The easiest way to do this is simply to rename a few virtual font 
% files, since there are such files accompanying the \package{relenc} 
% package for using the \texttt{lcircle10} font under any one of these 
% names. What you have to see too is that the ones which use the font 
% under the name on your system are the ones which are named 
% \texttt{zcmr8d.vf} and \texttt{zcmra.vf} respectively. The following 
% table shows what the file names are and which font it uses
% $$
%   \mbox{^^A
%     \begin{tabular}{cc}
%       Virtual font file&  \texttt{lcircle10} name used^^A
%         \\[-0.9\ht\strutbox]
%       \hrulefill&\hrulefill\\
%       \texttt{zcmr8d.vf}&   \texttt{lcricle10}\\
%       \texttt{zcmra.vf}&    \texttt{lcricle10}\\
%       \texttt{zcmr8d.vf2}&  \texttt{cricle10}\\
%       \texttt{zcmra.vf2}&   \texttt{cricle10}\\
%       \texttt{zcmr8d.vf3}&  \texttt{lcric10}\\
%       \texttt{zcmra.vf3}&   \texttt{lcric10}
%     \end{tabular}^^A
%   }
% $$
% Note that all the above files are virtual font files. The reason 
% only two have been given the correct suffix \texttt{.vf} is that there 
% really are no more than two fonts, so they should not take up any more 
% font name space than that either.
% 
% Finally, there is one other use for the \texttt{T1R}\slash
% \texttt{zcm}\slash\texttt{m}\slash\texttt{n} font---it is the final 
% substitution font in the \texttt{T1R} encoding. \LaTeX\ requires that 
% there is such a font, so it might as well be this one. This means that 
% you should see to that the files which are this font (\texttt{zcmr8d.tfm} 
% and \texttt{zcmr8d.vf}) are put in such locations that \TeX\ and its 
% helper programs (DVI drivers etc.) will find them if they are needed. 
% You should not need to move them before you typeset \texttt{reldemo.tex} 
% for the first time, however, as these fonts are initially in the same 
% directory as this and \TeX\ looks for files there first.
% 
% If you do have the \texttt{ec} family of fonts however, you may (quite 
% understandably) want to use one of them as final substitution font for 
% the \texttt{T1R} encoding instead. There is a package called 
% \package{ecsubzcm} that is installed with \package{relenc}. This 
% package declares the \texttt{zcm} family in encoding \texttt{T1R} and 
% \texttt{ecrm1000} under the encoding\slash family\slash series\slash 
% shape combination \texttt{T1R}\slash\texttt{zcm}\slash\texttt{m}\slash
% \texttt{n}. After loading this package, \LaTeX\ will not bother to 
% input the font definition file \texttt{t1rzcm.fd}, so the ``real'' 
% \texttt{zcm} fonts will not get involved.
% 
% \section{Implementation}
% \subsection{Font definition file}
%
% \StopEventually{}
%
% As is the custom, the file starts by announcing itself. 
%    \begin{macrocode}
%<*fd>
\ProvidesFile{t1rzcm.fd}[1999/01/19 Font definitions for T1R/zcm.]
%    \end{macrocode}
% 
% Then the family is declared. So far, there is nothing out of the 
% ordinary.
%    \begin{macrocode}
\DeclareFontFamily{T1R}{zcm}{}
%    \end{macrocode}
% 
% Next the shapes are declared. There is nothing strange about this 
% either.
%    \begin{macrocode}
\DeclareFontShape{T1R}{zcm}{m}{n}{
   <-> zcmr8d
}{}
%    \end{macrocode}
%    \begin{macrocode}
\DeclareFontShape{T1R}{zcm}{m}{a}{
   <-> zcmra
}{}
%    \end{macrocode}
% 
% That would be all in a normal font definition file. This file does 
% however go on with defining some variants of commands and 
% compositions, to compensate for the differences between the coding 
% scheme of the \texttt{zcmra} font and the default coding scheme.
% 
% Slot number 128 is used for a ligature instead of the default `\u{A}', 
% so this has to be compensated for. In this case it is done by making 
% another default definition of the |\u| command and defining all the 
% other compositions of that command again.
%    \begin{macrocode}
\DefineTextAccentVariant{\u}{T1R}{zcm}{}{a}{8}
\DefineTextVariantComposition{\u}{T1R}{zcm}{}{a}{G}{135}
\DefineTextVariantComposition{\u}{T1R}{zcm}{}{a}{a}{160}
\DefineTextVariantComposition{\u}{T1R}{zcm}{}{a}{g}{167}
%    \end{macrocode}
% It should be noted at this point that this font definition file is 
% not set up in the most efficient way. Normally, one would want to 
% minimize the number of variants that needs to be defined---something 
% which the above most certainly does not do---and one often achieves 
% this by trying to affect as few accenting commands as possible. The 
% four extra ligatures of the \texttt{zcmra} font could have been put in 
% slots 128, 135, 160, and 167---that would have made it possible to 
% get by with the single variant definition
%\begin{verbatim}
%   \DefineTextAccentVariant{\u}{T1R}{zcm}{}{a}{8}
%\end{verbatim}
% although a font designer who frequently use the |\u| command will 
% probably prefer to use slots for compositions of some other 
% command---but \texttt{zcmra} has been set up more to show what is 
% possible than what is optimal.
% 
% The same problem occurs with slot 131, which does not contain the 
% `\v{C}' glyph that the encoding-level composition of |\v| with |C| 
% assumes it does. Another solution to the problem is to give an 
% explicit definition of the composition at a lower level, as in
%    \begin{macrocode}
\DefineTextVariantCompositionCommand{\v}{T1R}{zcm}{}{a}{C}{%
   \add@accent{7}{C}%
}
%    \end{macrocode}
% |\add@accent| is standard \LaTeX\ and its definition can be found 
% in~\cite{ltoutenc}. This solution gets by using only two variants (the 
% \texttt{T1R}\slash\texttt{zcm}\slash\texttt{?}\slash\texttt{a} variant 
% of |\v|, and the compositon of that variant with |C|). Had instead 
% the first solution been used here, it would have required the code
%\begin{verbatim}
%\DefineTextAccentVariant{\v}{T1R}{zcm}{}{a}{7}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{D}{132}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{E}{133}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{L}{137}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{N}{140}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{R}{144}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{S}{146}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{T}{148}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{Z}{154}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{c}{163}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{d}{164}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{e}{165}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{l}{169}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{n}{172}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{r}{176}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{s}{178}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{t}{180}
%\DefineTextVariantComposition{\v}{T1R}{zcm}{}{a}{z}{186}
%\end{verbatim}
% which defines another 18 control sequences. The |\v| command sure has 
% many compositions, hasn't it?
% 
% Things are a bit different when the slot is used for a variant of a 
% composition, instead of a composition of a variant. In the former case, 
% there is a special command that can be used to extract the default 
% definition of the accenting command.
%    \begin{macrocode}
\DefineTextUncomposedVariant{\'}{T1R}{zcm}{}{a}{C}
%    \end{macrocode}
% 
% Finally, another example like |\v|.
%    \begin{macrocode}
\DefineTextVariantCompositionCommand{\k}{T1R}{zcm}{}{a}{a}%
   {a\llap{\char12\kern-0.07em}}
%</fd>
%    \end{macrocode}
% This definition demonstrates that there is absolutely no need to base 
% the definition of a composition on the default definition; using that 
% in this case would (i) be much longer, (ii) be unstable, as the default 
% definition of |\k| positions the accent incorrectly if not both the 
% height of the accent and the depth of the letter is zero or less, 
% and (iii) probably not kern particularly good (at least this definition 
% kerns like `a' to the left, the default does not kern at all).
% 
% 
% \subsection{The \package{ecsubzcm} package}
% 
%    \begin{macrocode}
%<*package>
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{ecsubzcm}[1999/01/19]
%    \end{macrocode}
%    \begin{macrocode}
\DeclareFontFamily{T1R}{zcm}{}
%    \end{macrocode}
%    \begin{macrocode}
\DeclareFontShape{T1R}{zcm}{m}{n}{
   <-> ecrm1000
}{}
%</package>
%    \end{macrocode}
\endinput