% \CheckSum{873}
% \iffalse meta-comment
%
% Copyright 1999 the fontinst maintenance team and any individual 
% authors listed elsewhere in this file.  All rights reserved.
% 
% This file is part of the fontinst system version 1.9.
% -----------------------------------------------------
% 
% It may be distributed under the terms of the LaTeX Project Public
% License, as described in lppl.txt in the base LaTeX distribution.
% Either version 1.0 or, at your option, any later version.
% 
%%% From file: fimapgen.dtx
%
%<*driver>
\documentclass{ltxdoc}
\usepackage{fisource}

\title{\texttt{fimapgen.dtx}}
\author{Lars Hellstr\"om}
\begin{document}
\maketitle

\DocInput{fimapgen.dtx}

\end{document}
%</driver>
% \fi
% 
% 
% \section{Generating map file fragments}
% \label{Sec:Mapfiles}
% \changes{1.904}{1999/06/15}{Completed rudimentary map file fragment 
%    generator, made it part of \texttt{finstmsc.sty}. (LH)}
% \newcommand\OzTeX{O\kern-.03em z\kern-.15em\TeX}
% 
% A \emph{map file} is a file which is used by some DVI driver to link 
% various kinds of font information to each other, as is needed for the 
% driver's operation. Examples of such files are the file 
% \texttt{psfonts.map} used by \texttt{dvips} and the config files of 
% \OzTeX. There are however many other such files around in the \TeX\ 
% world.
% 
% Not all of a map file need to be related to linking specific kinds of 
% font information to each other. \OzTeX\ config files can for example 
% be used to set the values of \TeX\ implementation parameters\footnote
% {The kind of things that were Pascal constants in the original \Web\ 
% sources for \TeX.} and there need not be any font-related information 
% at all in them. The important thing is however that there can be map 
% information in them---that information could be automatically written 
% by the routines described here. 
% 
% Since there may be other kinds of information in these files (and often 
% enough need to be for everthing to work right), the routines described 
% here will only generate map file \emph{fragments}. These fragments 
% will then have to be inserted in the final map files somehow, usually 
% through manual editing. The purpose of the routines described here is 
% only to save the user a good deal of (often quite boring) typing, not 
% to actually install everything where it needs to be.
% 
% \StopEventually{}
% 
% \begin{macro}{\mapfrags_subsystem}
%   This macro holds the name of the automatic map file fragments 
%   writer subsystem of \package{fontinst}, as it appears in error 
%   messages.
%    \begin{macrocode}
\def\mapfrags_subsystem{Map~fragments~writer}
%    \end{macrocode}
% \end{macro}
% 
% \subsection{Interface to main \package{fontinst}}
% \label{Ssec:interface}
% 
% The automatic generation of map file fragments is based on the two 
% commands |\storemapdata| and |\makemapentry|. Their respective 
% syntaxes are
% \begin{quote}
%   |\storemapdata|\marg{\TeX\ font name}\marg{source}^^A
%     \marg{transforms}\\
%   |\makemapentry|\marg{\TeX\ font name}
% \end{quote}
% 
% \DescribeMacro{\storemapdata}|\storemapdata| commands are written when 
% a metric file \meta{\TeX\ font name}|.mtx| is generated. The purpose 
% of these commands is to record where the data for that file came from, 
% and what was done to these data. The source of the data is specified 
% in the \meta{source} argument, which can contain one of
% \begin{quote}
%   |\fromafm|\marg{AFM name}\marg{PS name}\\
%   |\frompl|\marg{PL name}\\
%   |\frommtx|\marg{MTX name}\\
%   |\fromvpl|
% \end{quote}
% The only real difference between |\fromafm| and |\frompl| at this 
% stage is that the former specifies the PS name of the font, but the 
% latter do not. If you write a |\store|\-|map|\-|data| command yourself 
% and want to supply the PS name then you should use |\fromafm| even if 
% you took the font metrics from a PL.
% There is a important difference between |\fromvpl| and the first three 
% in that virtual fonts need no map file entry (and hence there should 
% not be any either). Besides some error checking, |\fromvpl| causes a 
% |\makemapentry| to do essentially nothing.
% 
% What was done to the data is specified by the \meta{transforms} 
% argument, which is a possibly empty sequence of commands, in which 
% each item is one of
% \begin{isyntax}
%   |\transformfont|\marg{x-scale}\marg{slant-scale}\\
%   |\reencodefont|\marg{etx}\\
%   |\reglyphfont|
% \end{isyntax}
% The order is interpreted so that the thing done first appear first in 
% the sequence. In normal cases there is at most one of each, and then 
% the order is not important. \meta{x-scale}, \meta{slant-scale}, and 
% \meta{y-scale} are the values of these variables used for the 
% transformation, as \TeX\ numbers. \meta{etx} is the name of the ETX 
% file used for the font reencoding.
% |\reglyphfont| is an error marker. It will not be encountered (but 
% it may well get stored in some table) unless a metric font transform 
% is applied to a font that has been reglyphed, which is illegal.
% 
% \changes{1.911}{1999/11/17}{\cs{storemapdata} commands are also 
%    written to metric files when they are generated. (LH)}
% In addition to being written to a transforms record file (if one is 
% open), |\storemapdata| commands are also written to the actual metric 
% file. This makes it possible to find out where the data for a file 
% comes from even if the file was made on a previous \package{fontinst} 
% run, but since it requires reading an additional file just to find one 
% command, it will be slower than if the |\storemapdata| appeared in a 
% transforms records file.
% 
% \DescribeMacro{\makemapentry}|\makemapentry| commands are written when 
% a VPL that uses or a ligfull PL for a font is generated. These 
% commands are the ones which actually cause the map file fragment 
% generator to write an entry, but entries are only written if they 
% haven't been written before. |\makemapentry| uses information that 
% was stored by a previous call to |\storemapdata|.
% 
% |\storemapdata| stores its arguments in one of the control sequences 
% \describecsfamily{Tf-\meta{font}}|\Tf-|\meta{font}, where \meta{font} 
% is the same thing as \meta{\TeX\ font name} above. |Tf| stands for 
% ``\TeX\ font''. The control sequences in this family are paramterless 
% macros whose replacement texts have the following form:
% \changes{1.914}{2000/05/30}{Contents of \cs{Tf-\meta{font}} control 
%    sequences changed to allow processing the same file of recorded 
%    transformations several times on the same run. (LH)}
% \begin{quote}
%   \marg{made}\marg{source}\marg{transforms}
% \end{quote}
% Here \meta{source} and \meta{transforms} are exactly as above. 
% \meta{made} is a number which describes the current status of this font. 
% If \meta{made} is even then the font has been defined but no entry for 
% it has subsequently been written to the map file, whereas if it is odd 
% then an entry for it has been written to the map file. If the value of 
% \meta{made} is less than |\process_generation| then the data in the 
% other two arguments is from a previous run and should be ignored.
% The |\Tf-|\meta{font} control sequences should always be set globally.
% 
% \begin{macro}{\process_generation}
% \begin{macro}{\process_generation_succ}
%   |\process_generation| is a counter which stores the number of the 
%   current ``entry generation''. It starts at 0 and is increased by 
%   two at each |\donedrivers|. |\process_generation_succ| is a macro 
%   which expands to a number one larger than that in |\process_generation|.
%   \multchanges{\cs{process_generation}\cs{process_generation_succ}}
%      {1.914}{2000/05/30}{Control sequences added. (LH)}
%    \begin{macrocode}
%<*map>
\newcount\process_generation
\process_generation=0
\def\process_generation_succ{1}
%</map>
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% \begin{macro}{\recordtransforms}
% \begin{macro}{\endrecordtransforms}
% \begin{macro}{\transform_record_file}
%   In main \package{fontinst}, the command
%   \begin{quote}
%     |\recordtransforms|\marg{filename}
%   \end{quote}
%   starts a block of code within which font transforms will be recorded 
%   in the file \meta{filename}. |\endrecordtransforms| ends such a block.
%    \begin{macrocode}
%<*pkg>
\def\recordtransforms#1{\open_pout\transform_record_file{#1}}
\def\endrecordtransforms{
   \close_pout\transform_record_file{Font~transformation~records}
}
\chardef\transform_record_file=\closed_stream
%</pkg>
%    \end{macrocode}
% \end{macro} \end{macro} \end{macro}
% 
% 
% \begin{macro}{\extract_font_generation}
%   The |\extract_font_generation| macro takes the name of a font and 
%   returns the \meta{made} component from the |\Tf-|\meta{font} macro 
%   for that font, or minus one if that macro hasn't been defined.
%   \changes{1.914}{2000/05/30}{Macro added. (LH)}
%    \begin{macrocode}
%<*map>
\def\extract_font_generation#1{
   \if_defined{Tf-#1}\then
      \expandafter\expandafter \expandafter\first_of_three
         \csname Tf-#1\endcsname
   \else
      \m@ne
   \fi
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\storemapdata}
%   There should not be two |\storemapdata| for the same font, hence 
%   the check below. (Note that a `font' in this case is an MTX file. 
%   It is quite possible (and legal) to generate the PL file for that 
%   MTX file more than once.)
%   \changes{1.927}{2004/07/12}{Improved wording of warning message 
%      and downgraded it to an info in the case when the two 
%      definitions are the same. (LH)}
%    \begin{macrocode}
\def\storemapdata#1#2#3{
   \expandafter\def \expandafter\a_macro
      \expandafter{ \expandafter{ \the\process_generation}{#2}{#3}}
   \ifnum \extract_font_generation{#1}<\process_generation \else
      \x_cs\ifx{Tf-#1}\a_macro 
         \fontinstinfo\mapfrags_subsystem
            {Repeated~definition~of~font~#1}
      \else
         \fontinstwarning\mapfrags_subsystem
            {Inconsistent~redefinition~of~font~#1}
      \fi
   \fi
   \x_cs\let{Tf-#1}=\a_macro
}
%</map>
%    \end{macrocode}
%   In main \package{fontinst}, |\storemapdata| should be a noop so 
%   that it can appear in metric files.
%    \begin{macrocode}
%<pkg>\let\storemapdata=\gobble_three
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\record_transform}
%   \changes{1.911}{1999/11/18}{\cs{storemapdata} lines are optionally 
%      written to the main output file as well. (LH)}
%   In main \package{fontinst}, the call
%   \begin{quote}
%     |\record_transform|\marg{TFM name}\marg{source}^^A
%        \marg{transforms}\marg{if}
%   \end{quote}
%   writes
%   \begin{quote}
%     |\storemapdata|\marg{TFM name}\marg{source}\marg{transforms}
%   \end{quote}
%   to the transformation recordings file (if font transforms are being 
%   recorded) and to the main output file (if the \meta{if} evaluates 
%   to true). Note that the caller of |\record_transform| must see to 
%   that macros in \meta{source} and \meta{transforms} are written 
%   correctly to the file (this is usually accomplished by adding 
%   |\string| in suitable places of these arguments during their 
%   construction).
%   
%    \begin{macrocode}
%<*pkg>
\def\record_transform#1#2#3#4{
   \ifnum \transform_record_file=\closed_stream \else
      \pout_line\transform_record_file{\string\storemapdata{#1}{#2}{#3}}
   \fi
   #4 \out_line{\string\storemapdata{#1}{#2}{#3}} \fi
}
%</pkg>
%    \end{macrocode}
% \end{macro}
% 
% 
% \begin{macro}{\transformfont}
%   \changes{1.913}{2000/03/11}{Third argument removed, since it isn't 
%      used anymore. This change is harmless, since the worst thing 
%      that can happen to this argument is that it is typeset. (LH)}
% \begin{macro}{\reencodefont}
% \begin{macro}{\reglyphfont}
%   These are initially |\relax|, so they can be |\edef|ed with safely.
%    \begin{macrocode}
%<*map>
\let\transformfont\x_relax
\let\reencodefont\x_relax
\let\reglyphfont\x_relax
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}
% 
% 
% \changes{1.914}{2000/05/30}{The total transform applied for a font is 
%    determined before the entry makers are called. (LH)}
% \begin{macro}{\makemapentry}
%   |\makemapentry| sets |\TeX_font_name|, checks if any map data have 
%   been stored for the font in question, and passes them on to 
%   |\make_map_entry| if they have; otherwise it raises an error. There 
%   is also a group which is begun and ended by |\makemapentry|, to stop 
%   values deduced for one entry to interfere with the deduction of values 
%   in the following.
%   \changes{1.911}{1999/11/20}{When map data are not known, try to 
%      get them from the MTX file before declaring the source unknown. 
%      (LH)}
%    \begin{macrocode}
\def\makemapentry#1{\begingroup
   \def\TeX_font_name{#1}
   \ifnum \extract_font_generation{#1}<\process_generation
      \if_file_exists{#1.mtx}\then
         \inputmtx{#1}
   \fi\fi
   \ifnum \extract_font_generation{#1}<\process_generation
      \from_unknown{#1}
      \x_cs\xdef{Tf-#1}{
         {\process_generation_succ}{\noexpand\from_unknown{#1}}{}
      }
   \else
      \expandafter\expandafter \expandafter\make_map_entry 
         \csname Tf-#1\endcsname
   \fi
   \endgroup
}
%    \end{macrocode}
%   
%   \begin{macro}{\make_map_entry}
%     |\make_map_entry| oversees the interpretation of the 
%     \meta{source} part of the map data, something which sets 
%     |\source_font_TeX_name| and possibly |\PS_font_name|. It also 
%     collects the transforms applied in |\font_transforms|, 
%     concatenates them, and calls a list macro |\entry_makers_list| which 
%     causes the actual entries to be written, and records in 
%     |\Tf-|\meta{\TeX\ font name} that the entries have been written.
%    \begin{macrocode}
\def\make_map_entry#1#2#3{
   \ifnum #1=\process_generation
      \def\font_transforms{#3}
      #2
      \_a_false
      \let\transformfont\concat_transformfont
      \let\reencodefont\concat_reencodefont
      \let\reglyphfont\_a_true
      \font_transforms
      \if_a_
         \fontinsterror\mapfrags_subsystem{
            \string\makemapentry\space for~reglyphed~font
         }{ No~entry~for~font~\TeX_font_name\space 
            can~be~written,\messagebreak
            since~it~had~been~reglyphed!~\error_help_a
         }
      \else
         \entry_makers_list
      \fi
      \expandafter\gdef \csname Tf-\TeX_font_name \expandafter\endcsname
         \expandafter{\expandafter{\process_generation_succ}{#2}{#3}}
   \fi
}
%</map>
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% 
% \begin{macro}{\record_usage}
%   In main \package{fontinst}, the call
%   \begin{quote}
%     |\record_usage|\marg{TFM name}
%   \end{quote}
%   writes
%   \begin{quote}
%     |\makemapentry|\marg{TFM name}
%   \end{quote}
%   to the transformation recordings file, if font transforms are being 
%   recorded. The |\record_usage| command is, roughly speaking, only used 
%   by |\installfont| and |\installrawfont|.
%    \begin{macrocode}
%<*pkg>
\def\record_usage#1{
   \ifnum \transform_record_file=\closed_stream \else
      \pout_line\transform_record_file{\string\makemapentry{#1}}
   \fi
}
%</pkg>
%    \end{macrocode}
% \end{macro}
% 
% 
% \begin{macro}{\fromafm}
%   |\fromafm| saves its two arguments in the suitable string macros.
%    \begin{macrocode}
%<*map>
\def\fromafm#1#2{
   \def\source_font_TeX_name{#1}
   \def\PS_font_name{#2}
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\frompl}
%   |\frompl| saves its argument in the suitable string macro.
%    \begin{macrocode}
\def\frompl#1{
   \def\source_font_TeX_name{#1}
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\frommtx}
%   This one is tricky, since it will have to work recursively, 
%   fetching data that were stored for some other font. If it cannot 
%   find those data in memory, then it tries to get them from the 
%   metric file itself.
%   \changes{1.911}{1999/11/17}{When map data are not known, try to 
%      get them from the MTX file before declaring the source unknown. 
%      (LH)}
%    \begin{macrocode}
\def\frommtx#1{%
   \ifnum \extract_font_generation{#1}<\process_generation
      \if_file_exists{#1.mtx}\then
         \inputmtx{#1}
   \fi\fi
   \ifnum \extract_font_generation{#1}<\process_generation
      \from_unknown{#1}
      \x_cs\xdef{Tf-#1}{
         {\the\process_generation}{\noexpand\from_unknown{#1}}{}
      }
   \else
      \expandafter\expandafter \expandafter\from_mtx
         \csname Tf-#1\endcsname
   \fi
}
%    \end{macrocode}
% \begin{macro}{\from_mtx}
%    \begin{macrocode}
\def\from_mtx#1#2#3{
   \edef\font_transforms{#3\font_transforms}
   #2
}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% \begin{macro}{\fromvpl}
%   The |\fromvpl| command checks if |\font_transforms| is empty. If it 
%   is then everything is fine, but no entry should be written for this 
%   font. If it isn't then someone has tried to make a transformation of 
%   a virtual font, which doesn't work.
%    \begin{macrocode}
\def\fromvpl{
   \ifx \empty_command\font_transforms \else
      \fontinsterror\mapfrags_subsystem{
         Font~is~virtual,~it~cannot~be~transformed}{
         No~entry~for~font~\TeX_font_name\space can~be~written.
         \messagebreak\error_help_a
      }
   \fi
   \let\maker_do\gobble_one
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\AssumeMetafont}
%   The |\AssumeMetafont| general settings command makes |\frompl| 
%   behave like |\fromvpl|.
%    \begin{macrocode}
\def\AssumeMetafont{
   \def\frompl{
      \ifx \empty_command\font_transforms \else
         \fontinsterror\mapfrags_subsystem{
            A~Metafont~cannot~be~transformed}{
            No~entry~for~font~\TeX_font_name\space can~be~written.
            \messagebreak\error_help_a
         }
      \fi
      \let\maker_do\gobble_one
   }
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\from_unknown}
%   This special value for \meta{source} is used for fonts that are 
%   referenced by some |\frommtx| but which have no |\storemapdata| 
%   themselves.
%    \begin{macrocode}
\def\from_unknown#1{
   \fontinstwarningnoline\mapfrags_subsystem{
      No~map~data~stored~for~font~#1.\messagebreak
      No~entry~for~\TeX_font_name\space will~be~written,\messagebreak
      due~to~insufficient~information}
   \includewarning\warn_unknown_source
   \let\maker_do\gobble_one
}
%    \end{macrocode}
% \end{macro}
% 
% 
% \begin{macro}{\font_transforms}
%   This macro is used to collect all transformations that have been 
%   applied to a font in, before they are concatenated.
%    \begin{macrocode}
\let\font_transforms\empty_command
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\xscale_factor}
% \begin{macro}{\slant_factor}
% \begin{macro}{\reencode_etx}
%   |\xscale_factor| and |\slant_factor| are dimens which the entry 
%   makers can inspect to check the amount of horizontal scaling and 
%   slanting should be applied to the current font. 1\,pt equals the 
%   factor~1. 
%   \begin{quote}
%     |\expandafter\lose_measure\the\xscale_factor|
%   \end{quote}
%   will produce the corresponding factor.
%   
%   |\reencode_etx| is a macro which contains the name of the (last) 
%   ETX file used to reencode the font; it is empty if the font hasn't 
%   been reencoded.
%   \multchanges{\cs{xscale_factor}\cs{slant_factor}\cs{reencode_etx}}
%      {1.914}{2000/05/30}{Control sequences added. (LH)}
%    \begin{macrocode}
\newdimen\xscale_factor  \newdimen\slant_factor
\xscale_factor=\p@       \slant_factor=\z@
\let\reencode_etx\empty_command
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}
% 
% \multchanges{\cs{concat_transformfont}\cs{concat_reencodefont}}
%    {1.914}{2000/05/30}{Macros added. (LH)}
% \begin{macro}{\concat_transformfont}
%   The |\concat_transformfont| macro is a definition of |\transformfont| 
%   which concatenates the transformation expressed by the arguments 
%   with the one in |\xscale_factor| and |\slant_factor|. 
%   Mathematically, it performs the multiplication
%   $$
%     \left( \begin{array}{cc} f(\#1)& f(\#2)\\ 0& 1 \end{array} \right)
%     \left( \begin{array}{cc} 
%        \mbox{\cs{xscale_factor}}& \mbox{\cs{slant_factor}} \\ 
%        0& 1 
%     \end{array} \right)
%   $$
%   where $f$ stands for |\make_factor|.
%    \begin{macrocode}
\def\concat_transformfont#1#2{
   \edef\a_macro{\make_factor{#1}}
   \xscale_factor=\a_macro\xscale_factor
   \slant_factor=\a_macro\slant_factor
   \advance \slant_factor \make_factor{#2}\p@
}
%    \end{macrocode}
% \end{macro}
% 
% 
% \begin{macro}{\concat_reencodefont}
%   The |\concat_reencodefont| macro is a definition of |\reencodefont| 
%   which concatenates the reencoding expressed by the argument with 
%   the one in |\reencode_etx|. Since reencoding ignores the previous 
%   encoding, concatenating is the same thing as remembering the last 
%   reencoding.
%    \begin{macrocode}
\def\concat_reencodefont#1{\def\reencode_etx{#1}}
%    \end{macrocode}
% \end{macro}
% 
% 
% \subsection{User interface}
% 
% The basic usage of the automatic map file fragment generator consists 
% of specifying for which driver(s) entries should be generated, 
% |\input|ing a file of recorded transformations generated by main 
% \package{fontinst}, and signaling that there isn't anything more to 
% write. This can be done with the commands
% \begin{quote}
%   |\adddriver|\marg{driver name}\marg{fragment file name}\\
%   \meta{possible additional \cs{adddriver} commands}\\
%   |\input |\meta{recorded transforms file}\\
%   |\donedrivers|\\
%   |\bye|
% \end{quote}
% It should however be noted that this is the \emph{basic} usage. The 
% map fragments that work for one \TeX\ system need not work for 
% another (even if the driver is the same), and therefore it is 
% necessary to make the whole process of writing map file fragments 
% configurable. A few examples of things you may have to inform the map 
% fragment writer about are (and these are for \package{dvips} alone; 
% that's the driver I know best):
% \begin{itemize}
%   \item
%     Is the font resident on the printer or must it be downloaded?
%   \item
%     If the font must be downloaded, what is the name of the file it 
%     is in? Here one must take into account not only the possibility 
%     that the font file might have to be shared with some other 
%     software (such as a GUI) and thus cannot be named according to 
%     the Berry scheme---even if it is named according to the Berry 
%     scheme one still has the question of its extension: \texttt{.pfa}, 
%     \texttt{.pfb}, or something else? For instances of Multiple Master 
%     fonts, you (at least sometimes) have to download more than one file.
%   \item
%     Again if the font must be downloaded, can/should it be partially 
%     downloaded?
%   \item
%     In case the font has been reencoded, what is the name of the file 
%     which defines this encoding, and by what name does that file make 
%     the encoding known to the postscript interpreter?
% \end{itemize}
% The mechanisms available for such configuration are described in 
% Subsection~\ref{Sssec:Config-interface}. 
% Note that map files for DVI viewers are on average more likely to need 
% various platform-specific information about the fonts than map files 
% for DVI printer drivers are, and hence once can expect that 
% generation of these will need more extensive configuration than that 
% for the printer drivers.
% 
% 
% \subsubsection{Interface for basic usage}
% 
% An \emph{entry maker} is a group of macros which write the entry for 
% the font currently under consideration to a map fragments file each 
% time they are called. The macro to call must have a name of the form 
% \describecsfamily{make_\meta{driver}}|\make_|\meta{driver} for 
% |\adddriver| to recognise it. Each entry maker has a separate output 
% file (opened using |\open_pout|) and the identifier connected to that 
% file is called \describecsfamily{output_\meta{driver}}\relax
% |\output_|\meta{driver}.
% 
% A list of all entry makers currently active is maintined in the macro 
% |\entry_makers_list|. Each item in this list has the form
% \begin{quote}
%   |\maker_do|\,|\make_|\meta{driver}
% \end{quote}
% |\maker_do| is usually |\relax|, but it does occationally get set to 
% other values.
% \par\bigskip
% 
% 
% \begin{macro}{\adddriver}
%   The |\adddriver| command adds the named driver to the list of 
%   drivers to write entries for and opens an output file where the 
%   entries for that particular driver will go. Repeated calls to 
%   |\adddriver| for the same driver have no effect.
%    \begin{macrocode}
\def\adddriver#1#2{
   \x_cs\ifx{make_#1}\x_relax
      \fontinsterror\mapfrags_subsystem
         {There~is~no~entry~maker~for~#1}\error_help_a
   \else
      \x_cs\ifx{output_#1}\x_relax \_a_true \else
         \x_cs\ifx{output_#1}\closed_stream \_a_true \else
            \_a_false
      \fi\fi
      \if_a_
         \x_cs\open_pout{output_#1}{#2}
         \expandafter\add_to \expandafter\entry_makers_list 
            \expandafter{ \expandafter\maker_do 
            \csname make_#1\endcsname}
      \fi
   \fi
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\entry_makers_list}
% \begin{macro}{\maker_do}
%    \begin{macrocode}
\let\entry_makers_list\empty_command
\let\maker_do\x_relax
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% \begin{macro}{\donedrivers}
%   The main function performed by the |\donedrivers| command is to 
%   close all the open output files. It might also print some warning 
%   messages.
%    \begin{macrocode}
\def\donedrivers{
   \def\maker_do##1{
      \x_cs\close_pout{output\expandafter\gobble_five\string##1}
         {Map~file~fragments}
   }
   \entry_makers_list
   \let\maker_do\x_relax
   \let\entry_makers_list\empty_command
   \errorstopmode
   \reportwarnings
   \advance \process_generation \thr@@
   \edef\process_generation_succ{\the\process_generation}
   \advance \process_generation \m@ne
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\gobble_five}
%    \begin{macrocode}
\def\gobble_five#1#2#3#4#5{}
%    \end{macrocode}
% \end{macro}
% 
% 
% It is appropriate that the map file writer writes a summary of the 
% kinds of risky things which happened when it is done writing data to 
% files. To simplify implementing such things, there is a command 
% \DescribeMacro{\includewarning}|\includewarning| that takes care of 
% the bookkeeping involved. After the call
% \begin{quote}
%   |\includewarning|\meta{command}
% \end{quote}
% the \meta{command} will be executed exactly once the next time 
% |\reportwarnings| is executed. The \meta{command} usually expands to 
% something like
% \begin{quote}
%   \small|\fontinstwarningnoline\mapfrags_subsystem{|\\
%   |   Check~the~output~file(s)--some~data~was~considered~uncertain}|
% \end{quote}
% 
% \begin{macro}{\warnings_list}
%   The |\warnings_list| macro contains a list of all warnings that 
%   should be made. It expands to a sequence of
%   \begin{quote}
%     |\warning_do|\meta{command}
%   \end{quote}
%   |\warnings_list| is always assigned globally.
%    \begin{macrocode}
\g_let\warnings_list=\empty_command
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\includewarning}
% \begin{macro}{\warning_do}
%   The |\includewarning| command adds an entry for its argument to the 
%   |\warnings_list| list, provided there wasn't already such an entry. 
%   |\includewarning| is based on the macro |\warning_do|, which does 
%   most of the bookkeeping for making sure the list contains at most 
%   one entry of each kind. |\warning_do| normally expects to be 
%   expanded in the context
%   \begin{quote}
%     |\warning_do|\meta{new command}\meta{old command}\meta{next}
%   \end{quote}
%   The \meta{new command} is the command that is being added to the 
%   list, and the \meta{old command} is a command that is already in the 
%   list. \meta{next} is the first token in the next item in the 
%   list---in most cases another |\warning_do|. If \meta{new command} 
%   and \meta{old command} are not equal, this should expand to
%   \begin{quote}
%     |\noexpand\warning_do|\,|\noexpand|\meta{old command}\,^^A
%     \meta{next}\,\meta{new command}
%   \end{quote}
%   If on the other hand they are equal, this should expand to
%   \begin{quote}
%     |\noexpand\warning_do|\,|\noexpand|\meta{old command}\,^^A
%     \meta{next}\,|\x_relax|
%   \end{quote}
%   The reason for this is that the last \meta{next} will not be a 
%   |\warning_do|, but an |\ifx| which tests whether a new item should 
%   be added to the list.
%    \begin{macrocode}
\def\warning_do#1#2#3{
   \noexpand\warning_do \noexpand#2
   \ifx #1#2
      \expandafter#3 \expandafter\x_relax
   \else
      \expandafter#3 \expandafter#1
   \fi
}
\def\includewarning#1{
   \xdef\warnings_list{
      \expandafter\swap_two \expandafter#1 \warnings_list
      \if_equal\x_relax\then \else
         \noexpand\warning_do \noexpand#1
      \fi
   }
}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% \begin{macro}{\reportwarnings}
%   The |\reportwarnings| command reports all the warnings and empties 
%   the |\warnings_list|.
%    \begin{macrocode}
\def\reportwarnings{
   \begingroup
      \let\warning_do=\x_relax
      \warnings_list
   \endgroup
   \g_let\warnings_list=\empty_command
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\warn_unknown_source}
% \begin{macro}{\warn_undecided_data}
% \begin{macro}{\warn_uncertain_data}
%   These macros are used to output warnings at the |\reportwarnings| at 
%   the end of |\donedrivers|.
%    \begin{macrocode}
\def\warn_unknown_source{
   \fontinstwarningnoline\mapfrags_subsystem{
      Some~font~is~missing~from~the~output~file(s),\messagebreak
      since~its~source~is~unknown}
}
\def\warn_undecided_data{
   \fontinstwarningnoline\mapfrags_subsystem{
      Check~the~output~file(s)--some~data~could~not~be~determined}
}
\def\warn_uncertain_data{
   \fontinstwarningnoline\mapfrags_subsystem{
      Check~the~output~file(s)--some~data~was~considered~uncertain}
}
%    \end{macrocode}
% \end{macro}\end{macro}\end{macro}
% 
% 
% 
% \subsubsection{Configuration interface}
% \label{Sssec:Config-interface}
% 
% To correctly format reencodings, the map file writer must know what 
% the ETX encodings correspond to. In the case of drivers which 
% generate postscript output, this information is stored in the 
% \describecsfamily{pse-\meta{etx}}|\pse-|\meta{etx} family of macros. 
% \meta{etx} is the name (suffix excluded) of the ETX file that the 
% information pertains to. The expansion of these macros are of the form
% \begin{quote}
%   \marg{postscript name}\marg{action}
% \end{quote}
% \meta{postscript name} is the name by which the encoding is known to 
% the postscript interpreter, and \meta{action} lists any additional 
% action that must be taken before the encoding can be used. So far the 
% only action known is \DescribeMacro{\download}|\download|\marg{file}, 
% which will cause code for downloading the file by the name \meta{file} 
% (suffix included) to be inserted in the output.
% 
% \begin{macro}{\declarepsencoding}
%   Data is entered in a |\pse-|\meta{etx} macro using the 
%   |\declare|\-|ps|\-|encoding| command. Its syntax is
%   \begin{quote}
%     |\declarepsencoding|\marg{etx}\marg{postscript name}\marg{action}
%   \end{quote}
%    \begin{macrocode}
\def\declarepsencoding#1#2#3{\x_cs\gdef{pse-#1}{{#2}{#3}}}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\download}
%   By default |\download| gobbles its argument. It should be redefined 
%   when that is not the desired effect.
%    \begin{macrocode}
\let\download=\gobble_one
%    \end{macrocode}
% \end{macro}
% 
% Some encodings seem to always be present, so they can be declared here.
%    \begin{macrocode}
\declarepsencoding{8r}{TeXBase1Encoding}{\download{8r.enc}}
\declarepsencoding{8a}{StandardEncoding}{}
%    \end{macrocode}
% \package{fontinst} must be told about other postscript encodings (if you 
% have them installed). The \texttt{finstmsc.rc} file is the right place 
% for these declarations.\relax
% \SortIndex{finstmsc.rc file}{\texttt{finstmsc.rc} file}
% 
% Next we have the cofiguration for fonts, which works in a similar 
% fashion. The main problem here seems to be to determine which files (if 
% any) should be downloaded to the printer, and this can be specified 
% using |\download| commands as for the encodings. The family 
% \describecsfamily{psf-\meta{PS font name}}|\psf-|\meta{PS font name} 
% of macros expand to a sequence of \meta{actions} as for the encodings. 
% If there is such a macro for a font then the instructions found there 
% should be followed.
% 
% It is recommended that the contents of a |\psf-|\meta{PS font name} 
% macro is executed before the map file entry is written, and that 
% commands like |\download| are temporarily redefined to build the text 
% for the entry, rather than having the |\write| in |\pout_line| expand 
% the contents of |\psf-|\meta{PS font name}.
% 
% \begin{macro}{\specifypsfont}
%   The |\specifypsfont| command is used as
%   \begin{quote}
%     |\specifypsfont|\marg{PS font name}\marg{actions}
%   \end{quote}
%   It can be used to specify the actions that should be done to make a 
%   Postscript font known to the printer, when the automatic guessing 
%   would not be right.
%    \begin{macrocode}
\def\specifypsfont#1#2{\x_cs\def{psf-#1}{#2}}
%    \end{macrocode}
% \end{macro}
% 
% Examples of cases where |\specifypsfont| would be needed are:
% \begin{itemize}
%   \item Fonts which are resident on the printer. In this case the 
%     \meta{actions} argument should be empty, e.g.
%     \begin{quote}
%       |\specifypsfont{Times-Roman}{}|
%     \end{quote}
%   \item Instances of multiple master fonts. In this case one must 
%     download both the multiple master font and the stub file that 
%     defines the instance.
%     
%     Subsection~10.6.1 in The \LaTeX\ graphics companion~\cite
%     {LaTeX-graph-comp} contains an example with an instance of the 
%     \texttt{MinionMM} multiple master font. Both the \TeX\ and 
%     (what is of interest here) the PS name for this instance is 
%     \texttt{zmnl8ac6}, the base multiple master font is stored in the 
%     file \texttt{MinionMM.pfb}, and the stub file is called 
%     \texttt{zmnl8ac6.pro}. The |\specifypsfont| command for this is
%     \begin{quote}
%       |\specifypsfont{zmnl8ac6}{%|\\
%       |   \download{MinionMM.pfb}\download{zmnl8ac6.pro}%|\\
%       |}|
%     \end{quote}
%   \item Fonts which do not fit any of the general naming schemes.
% \end{itemize}
% 
% 
% \begin{macro}{\AssumeLWFN}
%   This command makes \mbox{MacOS} \texttt{LWFN} style abbreviated 
%   Postscript font names the default for fonts that have no 
%   |\psf-| entry.
%    \begin{macrocode}
\def\AssumeLWFN{\let\get_PS_font_file\LWFN_get_PS_font_file}
%    \end{macrocode}
% \end{macro}
% 
% 
% 
% \subsection{Deducing values for the map file entries}
% 
% 
% \subsubsection{Basic principles}
% 
% The automatic generation of map file fragments mainly consists of 
% determining various text strings and writing these to a file as the 
% format of the map file being written requires. The complicated part is 
% usually to determine what these text strings should be, since the only 
% restriction imposed by the output format often is that the strings 
% should be written in the right order and with separating whitespace.
% 
% It is furthermore the case that some of these text strings seem to be 
% hard to deduce from the information primarily given in the command to 
% write the entry, but somewhat easier to deduce from some other deduced 
% text string. 
% 
% Therefore the following model seems appropriate. For each text string 
% that may need to be deduced, there is one macro which is used to store 
% the string (if it has been deduced) and one macro which can be called 
% to set the former macro to an appropriate value. Thus there is one 
% macro |\PS_font_name| which stores the postscript name for the font 
% currently in question and one macro 
% \describecsfamily{get_\meta{string name}}|\get_PS_font_name| which 
% determines the proper value for |\PS_font_name|. There is also a macro 
% \DescribeMacro{\unknown_str}|\unknown_str| to which all the 
% string storing macros should initially be |\let|, so that it can be 
% easily tested whether a string storing macro has been given its proper 
% value or not.
% 
% Typically, if |\PS_font_name| is used somewhere, one would first have 
% a piece of code that says
% \begin{quote}
%   \small
%   |\ifx\PS_font_name\unknown_str|\\
%   |   \get_PS_font_name|\\
%   |\fi|
% \end{quote}
% to ensure that it is known when it is used.
% 
% \begin{macro}{\unknown_str}
%   A suitable value for this macro seems to be |?????|.
%    \begin{macrocode}
\def\unknown_str{?????}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\clueless_str}
%   To further support this model, there is also a macro |\clueless_str| 
%   which a string storing macro should be |\let| equal to if its proper 
%   value could not be determined. This distinction is useful for the 
%   |\get_|\textellipsis\ macros, since if |\get_|$A$ can determine the 
%   correct value of $A$ from $B$, but also from $C$, then it helps if 
%   |\get_|$A$ can easily check whether it has previously turned out to 
%   be impossible to determine the value of $B$, because then it can 
%   simply deduce $A$ from $C$ instead.
%   
%    \begin{macrocode}
\edef\clueless_str{\unknown_str ?}
%    \end{macrocode}
% \end{macro}
% 
% An example of how |\clueless_str| should be used is the following 
% skeleton of a |\get_|$A$ macro:
% \begin{quote}\small
%   |\def\get_|$A$|{|\\
%   |   \ifx\unknown_str\|$B$| \get_|$B$| \fi|\\
%   |   \ifx\clueless_str\|$B$\\
%   |      \ifx\unknown_str\|$C$| \get_|$C$| \fi|\\
%   |      \ifx\clueless_str\|$C$\\
%   |         \let\|$A$|\clueless_str|\\
%   |      \else|\\
%   |         |\meta{Deduce $A$ from $C$}\\
%   |      \fi|\\
%   |   \else|\\
%   |      |\meta{Deduce $A$ from $B$}\\
%   |   \fi|\\
%   |}|
% \end{quote}
% 
% 
% \subsubsection{Implementation}
% 
% \begin{macro}{\TeX_font_name}
%   This is the name (as appearing in a DVI or VF file) of the font for 
%   which an entry should be made. It is set by |\makemapentry|, so no 
%   |\get_|\textellipsis\ macro is needed.
%    \begin{macrocode}
\let\TeX_font_name\unknown_str
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\source_font_TeX_name}
%   This is the name (as AFM or PL) of the font whose metrics were 
%   used by \package{fontinst}. It is set by |\fromafm| or |\frompl|, 
%   so no |\get_|\textellipsis\ macro is needed.
%    \begin{macrocode}
\let\source_font_TeX_name\unknown_str
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\PS_font_name}
%   This is the name (as FontName entry in an AFM or correspondingly) of 
%   the font in question.
%    \begin{macrocode}
\let\PS_font_name\unknown_str
%    \end{macrocode}
%   \begin{macro}{\get_PS_font_name}
%     I expect this to become one of the central macros in the map file 
%     generation (at least when entries are generated for postscript 
%     fonts), but for the moment it does the closest thing to nothing a 
%     |\get_|\textellipsis\ macro is allowed to do; it admits it hasn't 
%     got a clue about what the proper value is. 
%    \begin{macrocode}
\def\get_PS_font_name{\let\PS_font_name\clueless_str}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% \begin{macro}{\AssumeAMSBSYY}
% \begin{macro}{\AssumeBaKoMa}
%   These commands redefine |\get_PS_font_name| so that it returns the 
%   PS name this font would have if it was part of the AMS\slash 
%   Blue~Sky\slash Y\&Y and BaKoMa respectively distribution of the 
%   Computer Modern fonts---the \TeX\ font name in all upper case and 
%   all lower case respectively.
%    \begin{macrocode}
\def\AssumeAMSBSYY{\def\get_PS_font_name{
   \uppercase \expandafter{ \expandafter\def 
      \expandafter\PS_font_name \expandafter{ \source_font_TeX_name}
   }
}}
%    \end{macrocode}
%    \begin{macrocode}
\def\AssumeBaKoMa{\def\get_PS_font_name{
   \lowercase \expandafter{ \expandafter\def 
      \expandafter\PS_font_name \expandafter{ \source_font_TeX_name}
   }
}}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% 
% \begin{macro}{\PS_font_file}
%   This is the name of the file (suffix included) in which the PS font 
%   is expected to be found.
%    \begin{macrocode}
\let\PS_font_file\unknown_str
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\get_PS_font_file}
% \begin{macro}{\normal_get_PS_font_file}
% \begin{fistring}{PSfontsuffix}
%   The macro |\normal_get_PS_font_file| is (hardly surprisingly) the 
%   normal |\get_PS_font_file|. It simply uses |\source_font_TeX_name| 
%   plus the suffix specified by the |PSfontsuffix| string.
%    \begin{macrocode}
\resetstr{PSfontsuffix}{.pfa}
\def\normal_get_PS_font_file{
   \edef\PS_font_file{\source_font_TeX_name\str{PSfontsuffix}}
}
\let\get_PS_font_file=\normal_get_PS_font_file
%    \end{macrocode}
% \end{fistring}\end{macro}\end{macro}
% 
% \begin{macro}{\LWFN_get_PS_font_file}
% \begin{macro}{\abbreviate_PS_font_name}
%   In MacOS, Postscript fonts file names are usually abbreviated forms of 
%   the Postscript font names, formed using the so called 
%   \(5+3+3+\cdots\) rule---keep the first five letters of the first 
%   subword, keep the first three letters of all following subwords. The 
%   |\LWFN_get_PS_font_file| macro uses this scheme if the Postscript 
%   name for the font is known, otherwise it calls the 
%   |\normal_get_PS_font_file|. The LWFN in the macro name is the type 
%   code for such files.
%   
%   The algorithm is based on using |\aftergroup| to construct the 
%   wanted |\def| statement, only |\aftergroup|ing the letters that are 
%   not to be removed in the abbreviation. |\a_count| is used as a 
%   counter of how many more letters in the current subword should be 
%   kept.
%    \begin{macrocode}
\def\LWFN_get_PS_font_file{
   \ifx \PS_font_name\unknown_str \get_PS_font_name \fi
   \ifx \PS_font_name\clueless_str
      \normal_get_PS_font_file
      \includewarning\warn_uncertain_data
   \else
      \begingroup
         \aftergroup\def \aftergroup\PS_font_file
         \aftergroup{
         \a_count=4~
         \expandafter\expandafter \expandafter\aftergroup
            \expandafter\swap_two \expandafter\abbreviate_PS_font_name 
            \PS_font_name \x_relax
         \aftergroup}
      \endgroup
   \fi
}
%    \end{macrocode}
%    \begin{macrocode}
\def\abbreviate_PS_font_name#1{
   \ifx \x_relax#1 \else
      \ifnum \uccode`#1=`#1
         \a_count=2
         \aftergroup#1
      \else\ifx -#1
         \a_count=\z@
      \else\ifnum \a_count>\z@
         \advance \a_count \m@ne
         \aftergroup#1
      \fi\fi\fi
      \expandafter\abbreviate_PS_font_name
   \fi
}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% 
% 
% \subsection{Driver makers}
% 
% This subsection contains the definitions of macros that makes up the 
% driver makers.
% 
% 
% \subsubsection{The \texttt{debug} driver}
% 
% The \texttt{debug} driver maker doesn't really generate entries for 
% any DVI driver map file, it just prints the data that was available. 
% It is mainly intended for debugging purposes, but it might also serve 
% as a basic model for other driver makers.
% 
% \begin{macro}{\make_debug}
%    \begin{macrocode}
\def\make_debug{
   \pout_line\output_debug{Driver~data~for~font~\TeX_font_name:}
   \pout_lline\output_debug{Source~font~TeX~name:~\source_font_TeX_name}
   \ifx \reencode_etx\empty_command \else
      \pout_lline\output_debug{Font~reencoded~using~\reencode_etx.etx.}
   \fi
   \ifdim \xscale_factor=\p@ \else
      \pout_lline\output_debug{Font~x-scaled~by~
         \expandafter\lose_measure\the\xscale_factor.
      }
   \fi
   \ifdim \slant_factor=\z@ \else
      \pout_lline\output_debug{Font~slanted~by~
         \expandafter\lose_measure\the\slant_factor.
      }
   \fi
   \debug_values_hook
}
%    \end{macrocode}
% \end{macro}
% 
% 
% \begin{macro}{\debug_value}
%   The |\debug_value| macro can be used to print the name and contents 
%   of an arbitrary value macro in the |debug| driver. It is called with 
%   the value macro as argument, e.g.
%   \begin{quote}
%      |\debug_value\PS_font_name|
%   \end{quote}
%   
%    \begin{macrocode}
\def\debug_value#1{
   \ifx #1\unknown_str
      \csname get_ \expandafter\gobble_one \string#1 \endcsname
   \fi
   \pout_lline\output_debug{\string#1:~#1}
   \ifx #1\clueless_str \includewarning\warn_undecided_data \fi
}
%    \end{macrocode}
% \end{macro}
% 
% \begin{macro}{\debugvalue}
% \begin{macro}{\debug_values_hook}
%   The |\debugvalue| command is a user level interface for adding 
%   value macros to the list of those that are displayed by the 
%   \texttt{debug} driver. The argument is the name of the value in 
%   question, e.g.
%   \begin{quote}
%      |\debugvalue{PS_font_name}|
%   \end{quote}
%   Note that the name given to |\debugvalue| is not the control 
%   sequence in which the name is stored.
%    \begin{macrocode}
\def\debugvalue#1{
   \expandafter\add_to \expandafter\debug_values_hook
   \expandafter{ \expandafter\debug_value \csname#1\endcsname}
}
%    \end{macrocode}
%    \begin{macrocode}
\let\debug_values_hook\empty_command
\debugvalue{PS_font_name}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% 
% \subsubsection{The \texttt{dvips} driver}
% 
% \changes{1.912}{2000/02/19}{\texttt{dvips} mapfile fragments writer 
%    added. (LH)}
% Before constructing an entry for a \package{dvips} mapfile, it should 
% be sorted out how such an entry should look. The \package{dvips} 
% manual says
% \begin{quotation}
%   The parsing of the \texttt{psfonts.map} file should be explained to 
%   eliminate all confusion.  If a line is empty or begins with a space, 
%   asterisk, semicolon, or hash mark, it is ignored.  Each remaining 
%   line is separated into words, where words are separated by spaces or 
%   tabs.  If a word begins with a double quote, it extends until the 
%   next double quote or the end of the line.  If a word starts with a 
%   less than character, it is treated as a font header file (or a 
%   downloaded PostScript font).  There can be more than one such header 
%   for a given font.  If a word starts with a double quote, it is a 
%   special instruction for generating that font.  Otherwise it is a 
%   name.  The first such name is always the name \TeX\ uses for the 
%   font and is also the name of the raw \texttt{tfm} file.  If there is 
%   another name word, that name is used as the PostScript name; if 
%   there is only one name word, it is used for both the \TeX\ name and 
%   the PostScript name.
% \end{quotation}
% 
% A \package{fontinst}-generated map file entry for the \texttt{dvips} 
% driver has the following structure:
% \begin{isyntax}
%   \meta{\TeX{} font name} \meta{PS font name} \meta{downloads}
%     \meta{font transformations}
% \end{isyntax}
% \meta{\TeX{} font name} is simply the value of |\TeX_font_name| and 
% \meta{PS font name} is simply the value of |\PS_font_name|. 
% \meta{downloads} is a possibly empty sequence in which each item 
% has the form
% \begin{quote}
%   \meta{prefix}\meta{filename}
% \end{quote}
% The \meta{prefix} values I've came across are empty,\footnote{I think 
% this is only used for files that \package{dvips} should ignore, but 
% which certain other programs that read the same \texttt{psfonts.map} 
% need.} |<|, |<<|, and |<[|. Currently |<| is always used. 
% \meta{filename} is a filename with suffix. \meta{font transformations} 
% is either empty or has the form
% \begin{quote}
%   |"| \meta{Postscript code} |"|
% \end{quote}
% 
% Should support for the |<<| or |<[| prefixes be needed, then this 
% should be done by adding some new variant of the |\download| 
% command---|\fullldownload|, maybe---rather than adding the extra 
% character to the \meta{filename}. To simplify matters for other drivers, 
% such new variants should by default expand to |\download|, rather than 
% |\gobble_one|.
% 
% 
% \begin{macro}{\downloads_list}
% \begin{macro}{\append_download}
%   The |\downloads_list| is a token list register which is especially 
%   used for accumulating |\download| commands. Each driver maker which 
%   uses it should begin by emptying it.
%   \begin{quote}
%     |\append_download|\marg{arg}
%   \end{quote}
%   appends
%   \begin{quote}
%     |\download|\marg{arg}
%   \end{quote}
%   to |\downloads_list|.
%    \begin{macrocode}
\newtoks\downloads_list
\def\append_download#1{
   \downloads_list=\expandafter{ \the\downloads_list \download{#1} }
}
%    \end{macrocode}
% \end{macro}\end{macro}
% 
% 
% \begin{macro}{\make_dvips}
%   This macro gathers the information for a \texttt{dvips} driver entry 
%   and writes it to the corresponding output file. As a \texttt{dvips} 
%   mapfile entry is on one line, the entire entry is written at once. 
%   The \meta{font transformations} is collected as explicit text in the 
%   macro |\postscript_code|. The \meta{downloads} is collected as a 
%   sequence of |\download| commands in the |\downloads_list| token 
%   register.
%    \begin{macrocode}
\def\make_dvips{
   \downloads_list={}
   \let\postscript_code\empty_command
   \let\download\append_download
   \ifx \reencode_etx\empty_command \else
      \if_undefined{pse-\reencode_etx}\then
         \etxtoenc{\reencode_etx}{\reencode_etx}
      \fi
      \expandafter\expandafter \expandafter\second_of_two
         \csname pse-\reencode_etx\endcsname
      \edef\postscript_code{\postscript_code\space
         \expandafter\expandafter \expandafter\first_of_two
            \csname pse-\reencode_etx\endcsname
         \space ReEncodeFont
      }
   \fi
   \ifdim \xscale_factor=\p@ \else
      \edef\postscript_code{\postscript_code
         \space\expandafter\lose_measure\the\xscale_factor
         \space ExtendFont
      }
   \fi
   \ifdim \slant_factor=\z@ \else
      \edef\postscript_code{\postscript_code
         \space\expandafter\lose_measure\the\slant_factor
         \space SlantFont
      }
   \fi
%    \end{macrocode}
%   After constructing the \meta{Postscript code} and having appended 
%   the necessary download (if any) for that code, the next problem is 
%   to determine the actual \meta{PS font name} and append the downloads 
%   needed to actually define the font to the Postscript interpreter. If 
%   there is no special entry for this font in the |\psf-|\meta{PS font 
%   name} table, or if its \meta{PS font name} is unknown, then it is 
%   assumed that exactly one file should be downloaded. As the name of 
%   that file is taken the value of |\PS_font_file|.
%    \begin{macrocode}
   \ifx \PS_font_name\unknown_str \get_PS_font_name \fi
   \ifx \PS_font_name\clueless_str
      \includewarning\warn_undecided_data
      \_a_true
   \else
      \if_undefined{psf-\PS_font_name}\then
         \_a_true
      \else
         \csname psf-\PS_font_name \endcsname
         \_a_false
   \fi\fi
   \if_a_
      \ifx \PS_font_file\unknown_str \get_PS_font_file \fi
      \append_download{\PS_font_file}
      \ifx \PS_font_file\clueless_str
         \includewarning\warn_undecided_data
      \fi
   \fi
%    \end{macrocode}
%   Finally, the entire entry is written to the file. The point with 
%   expanding past an empty command is that \TeX\ in a |\write| normally 
%   jumps past the expansion of a |\the|\meta{token list register} 
%   without expanding it further, but this effect can be prevented by 
%   expanding the |\the| with an |\expandafter|.
%    \begin{macrocode}
   \def\download##1{~<##1}
   \pout_line\output_dvips{
      \TeX_font_name\space\PS_font_name
      \expandafter\empty_command \the\downloads_list
      \ifx \postscript_code\empty_command \else
         \space"\postscript_code\space"
      \fi
   }
}
%    \end{macrocode}
% \end{macro}
% 
% 
% 
% \subsubsection{The \texttt{dvipdfm} driver}
% 
% \changes{1.912}{2000/02/22}{\texttt{dvipdfm} mapfile fragments writer 
%    added. (LH)}
% 
% A mapfile entry for the \texttt{dvipdfm} driver has the following 
% structure:
% \begin{isyntax}
%   \meta{\TeX{} font name} \meta{encoding} \meta{PS font}
%     \meta{options}
% \end{isyntax}
% \meta{\TeX{} font name} is simply the value of |\TeX_font_name|. 
% \meta{encoding} is the name of the encoding file which should be used 
% to reencode the font, or \texttt{default} if there is none. \meta{PS 
% font} is the value of |\PS_font_name| for the standard 35 fonts 
% (i.e., fonts which will not be included in the PDF generated), but for 
% other fonts it is the name of the file which contains the 
% font.\footnote{The documentation seems to say that \texttt{dvipdfm} 
% can only understand fonts in PFB format; I have chosen to ignore this 
% potential problem.} \meta{options}, finally, is a possibly empty 
% sequence of space-separated options. Each option is one of the 
% following
% \begin{quote}
%   |-e |\meta{number}\\
%   |-s |\meta{number}\\
%   |-r|
% \end{quote}
% The |-e| and |-s| options extend and slant by the given amounts. The 
% |-r| option is a workaround for some Acrobat bugs; it is currently not 
% generated by \package{fontinst}.
% 
% \begin{macro}{\make_dvipdfm}
%   This macro gathers the information for a \texttt{dvipdfm} driver entry 
%   and writes it to the corresponding output file. As a \texttt{dvipdfm} 
%   mapfile entry is on one line, the entire entry is written at once. 
%   The \meta{options} text is collected as explicit text in the 
%   macro |\options_text|. The \meta{downloads} is collected as a 
%   sequence of |\download| commands in the |\downloads_list| token 
%   register.
%    \begin{macrocode}
\def\make_dvipdfm{
   \def\font_encoding{default}
   \ifx \reencode_etx\empty_command \else
      \if_undefined{pse-\reencode_etx}\then
         \etxtoenc{\reencode_etx}{\reencode_etx}
      \fi
      \def\download##1{\def\font_encoding{##1}}
      \expandafter\expandafter \expandafter\second_of_two
         \csname pse-\reencode_etx\endcsname
   \fi
   \let\options_text\empty_command
   \ifdim \xscale_factor=\p@ \else
      \edef\options_text{\options_text\space 
         -e~\expandafter\lose_measure\the\xscale_factor
      }
   \fi
   \ifdim \slant_factor=\z@ \else
      \edef\options_text{\options_text\space 
         -s~\expandafter\lose_measure\the\slant_factor
      }
   \fi
%    \end{macrocode}
%   After constructing the \meta{options} and having determined 
%   \meta{encoding}, the next problem is to determine the actual 
%   \meta{PS font}, which will be put in |\a_macro|. If there is no 
%   special entry for this font in the |\psf-|\meta{PS font name} table, 
%   or if its \meta{PS font name} is unknown, then it is assumed that 
%   exactly one file should be downloaded. As the name of that file is 
%   taken the value of |\PS_font_file|.
%    \begin{macrocode}
   \ifx \PS_font_name\unknown_str \get_PS_font_name \fi
   \if_or \if_equal\PS_font_name\clueless_str \or_else
      \if_undefined{psf-\PS_font_name}
   \then
      \ifx \PS_font_file\unknown_str \get_PS_font_file \fi
      \ifx \PS_font_file\clueless_str
         \includewarning\warn_undecided_data
      \fi
      \let\a_macro=\PS_font_file
   \else
      \let\a_macro=\PS_font_name
      \def\download##1{\def\a_macro{##1}}
      \csname psf-\PS_font_name \endcsname
   \fi
%    \end{macrocode}
%   Finally, the entire entry is written to the file.
%    \begin{macrocode}
   \pout_line\output_dvipdfm{
      \TeX_font_name\space\font_encoding\space\a_macro
      \options_text
   }
}
%    \end{macrocode}
% \end{macro}
% 
% 
% \subsubsection{The \texttt{pltotf} ``driver''}
% \changes{1.915}{2000/06/27}{\texttt{pltotf} ``driver'' support 
%    added. (LH)}
% 
% It can sometimes be hard to determine which of all the PL files that 
% \package{fontinst} creates need to be converted to TFM files. In most 
% cases no \texttt{8a}-encoded PLs need to be converted as they aren't 
% used as base fonts or installed in an FD file, but to automatically 
% exclude them isn't a trivial task (even though it probably could be 
% done by a regular expression filter for fonts named according to the 
% \texttt{fontname} scheme). There furthermore seems to be some systems 
% on which it for various reasons isn't easy to convert all PLs in a 
% directory. The \texttt{pltotf} ``driver'' support is meant to help with 
% both these problems, as the ``map file'' it creates really is a shell 
% script (batch file) for converting precisely those PL files that need 
% a map file entry to TFM format. I believe the shell script will work 
% both for UNIX and DOS systems.
% 
% \begin{macro}{\make_pltotf}
% \begin{fistring}{TFMfileprefix}
%   |\make_pltotf| writes a \package{PLtoTF} command for converting the 
%   current font's PL file to a TFM file. If set, the string 
%   \texttt{TFMfileprefix} will be prepended to the TFM file name---this 
%   could be used for putting the TFMs in some directory other than the 
%   current.
%    \begin{macrocode}
\def\make_pltotf{
   \pout_line\output_pltotf{pltotf~\TeX_font_name.pl~
      \ifisstr{TFMfileprefix}\then \str{TFMfileprefix}\fi
      \TeX_font_name.tfm
   }
}
%    \end{macrocode}
% \end{fistring}\end{macro}
% 
% 
%    \begin{macrocode}
%</map>
%    \end{macrocode}
% \Finale
\endinput

