From f41a5d46017f730e9586332f28744912872326f5 Mon Sep 17 00:00:00 2001
From: Norbert Preining <norbert@preining.info>
Date: Sat, 28 Sep 2019 03:00:42 +0000
Subject: CTAN sync 201909280300

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-% $Id: faq-bits+pieces.tex,v 1.32 2014/01/28 18:17:36 rf10 Exp rf10 $
-
-\section{Bits and pieces of \AllTeX{}}
-
-\Question[Q-dvi]{What is a \acro{DVI} file?}
-
-`\acro{DVI}' is supposed to be an acronym for
-\acro{D}e\acro{V}ice-\acro{I}ndependent, meaning that the file may be
-processed for printing or viewing on most kinds of typographic output
-device or display.
-
-A \acro{DVI} file (that is, a file with the type or extension
-\extension{dvi}) is the main output file of ``original'' \tex{} (later
-\tex{}-like systems, such as \Qref*{\pdftex{}}{Q-whatpdftex} may use
-other formats).
-
-A \acro{DVI} file contains all the information that is needed for
-printing or previewing, except for the actual bitmaps or outlines of
-fonts, and any material to be introduced by means of % !line break
-\Qref*{\csx{special} commands}{Q-specials}.  Characters in the
-\acro{DVI} file (representing glyphs for printing or display) appear
-in an encoding determined in the document.
-
-Any \TeX{} input file should produce the same \acro{DVI} file
-regardless of which implementation of \TeX{} is used to produce it.
-
-An \acro{DVI} file may be processed by a \Qref*{DVI driver}{Q-driver}
-to produce further output designed specifically for a particular
-printer, or for output in another format (for distribution), or it may
-be used by a previewer for display on a computer screen.
-
-Note that \Qref*{\xetex{}}{Q-xetex} (released some time after
-\pdftex{}) uses an ``extended \acro{DVI} format'' (\acro{XDV}) to send
-its output to a close-coupled \Qref*{\acro{DVI} driver}{Q-driver},
-\ProgName{xdvipdfmx}.
-
-The canonical reference for the structure of a \acro{DVI} file is the
-source of Knuth's program \ProgName{dvitype} (whose original purpose,
-as its name implies, was to view the content of a \acro{DVI} file).
-A partially complete ``standard'' for the way they should be
-processed may offer further enlightenment.
-\begin{ctanrefs}
-\item[\nothtml{rmfamily}DVI processing standard]\CTANref{dvistd}
-\item[dvitype]\CTANref{dvitype}
-\end{ctanrefs}
-\LastEdit{2013-03-15}
-
-\Question[Q-driver]{What is a \acro{DVI} driver?}
-
-A \acro{DVI} driver is a program that takes as input a
-\Qref*{\acro{DVI} file}{Q-dvi}
-and (usually) produces a file in a format that something \emph{other}
-than a \TeX{}-related program can process.
-
-A driver may be designed for producing output for printing (e.g.,
-\PS{}), for later processing (e.g., \PS{} for inclusion in a later
-document), or for document exchange (e.g., \acro{PDF}).
-
-As well as the \acro{DVI} file, the driver typically also needs font
-information.  Font information may be held as bitmaps or as outlines,
-or simply as a set of pointers into the fonts that a printer itself
-provides.  Each driver will expect the font information in a particular
-form.
-
-For more information on the forms of font information, see
-\Qref[questions]{\acro{PK} files}{Q-pk},
-% ! line break
-\Qref[]{\acro{TFM} files}{Q-tfm},
-\Qref[]{virtual fonts}{Q-virtualfonts}
-and \Qref[]{Using \PS{} fonts with \TeX{}}{Q-usepsfont}.
-\LastEdit{2011-10-10}
-
-\Question[Q-pk]{What are \acro{PK} files?}
-
-\acro{PK} files (packed raster) are the canonical form of \tex{} font
-bitmaps.  The output from \Qref*{\MF{}}{Q-useMF} includes a generic
-font (\acro{GF}) file and the utility \ProgName{gftopk} produces a
-\acro{PK} file from that.
-
-There are potentially a lot of \acro{PK} files, as one
-is needed for each font: that is for each magnification of each
-design (point) size for each weight for each font in each family.
-
-Further, since the \acro{PK} files for one printer do not necessarily
-work well for another, the whole set needs to be duplicated for each
-printer type at a site.
-
-While this menagerie of bitmaps can (in principle) provide fonts that
-are closely matched to the capabilities of each printer, the size of
-the collection (and the resulting difficulty of maintaining it) has
-been a potent driver to the move towards outline fonts such as
-\Qref*{Adobe Type 1 fonts}{Q-adobetypen}.
-\LastEdit{2012-10-20}
-
-\Question[Q-tfm]{What are \acro{TFM} files?}
-
-\acro{TFM} is an acronym for `\TeX{} Font Metrics'; \acro{TFM} files hold
-information about the sizes of the characters of the font in question,
-and about ligatures and kerns within that font.  One \acro{TFM} file is
-needed for each font used by \TeX{}, that is for each design (point)
-size for each weight for each family; each \acro{TFM} file serves for all
-magnifications of `its' font, so that there are (typically) fewer
-\acro{TFM} files than there are \Qref*{\acro{PK}}{Q-pk} files.  \TeX{},
-\LaTeX{}, etc.,\@
-themselves need only know about the sizes of characters and their
-interactions with each other, but not what characters look like.  By
-contrast, \acro{TFM} files are not, in principle, needed by the
-\acro{DVI} driver, which only needs to know about the glyphs that each
-character selects, so as to print or display them.
-
-Note that TrueType and OpenType fonts contain the necessary metrics,
-so that \Qref{\xetex{}}{Q-xetex} and \Qref{\luatex{}}{Q-luatex}, using
-such fonts, have no need of \acro{TFM} files.  A corollary of this is
-that setting up fonts for use by these engines is far \emph{easier}.
-\LastEdit{2012-10-20}
-
-\Question[Q-virtualfonts]{What are virtual fonts?}
-
-Virtual fonts provide a means of collecting bits and pieces together
-to make the glyphs of a font: the bits and pieces may be glyphs from
-``other'' fonts, rules and other ``basic'' typesetting commands, and
-the positioning information that specifies how everything comes
-together.
-
-An early instance of something like virtual fonts for \TeX{} was
-implemented by David Fuchs to use an unusual printer.  However, for
-practical purposes for the rest of us, virtual fonts date from when Knuth
-specified a format and wrote some support software, in 1989 (he
-published an % ! line break
-\href{http://tug.org/TUGboat/tb11-1/tb27knut.pdf}{article in \textsl{TUGboat}}
-at the time; a plain text copy is available on \acro{CTAN}).
-
-Virtual fonts provide a way of telling \TeX{} about something more
-complicated than just a one-to-one character mapping.  \TeX{} reads a
-\acro{TFM} file of the font, just as before, but the \acro{DVI}
-processor will read the \acro{VF} and use its content to specify how
-each glyph is to be processed.
-
-The virtual font may contain commands:
-\begin{itemize}
-\item to `open' one or more (real) fonts for subsequent use,
-\item to remap a glyph from one of the (real) fonts for use in the
-  virtual font,
-\item to build up a more complicated effect (using \acro{DVI} commands).
-\end{itemize}
-
-% !this has to be generated as a new paragraph by the translator, so
-% leave the blank line in place
-In practice, the most common use of virtual fonts is to remap
-Adobe Type 1 fonts (see \Qref[question]{font metrics}{Q-metrics}),
-though there has also been useful useful work building `fake' maths
-fonts (by bundling glyphs from several fonts into a single virtual
-font).  Virtual Computer Modern fonts, making a % ! line break
-\Qref*{Cork encoded}{Q-ECfonts} font from Knuth's originals by using
-remapping and fragments of \acro{DVI} for single-glyph `accented
-characters', were the first ``Type~1 format'' Cork-encoded Computer
-Modern fonts available.
-
-Virtual fonts are normally created in a single \acro{ASCII} \acro{VPL}
-(Virtual Property List) file, which includes two sets of information.
-The \ProgName{vptovf} utility will use the \acro{VPL} file to create
-the binary \acro{TFM} and \acro{VF} files.
-
-A ``how-to'' document, explaining how to generate a \acro{VPL},
-describes the endless hours of fun that may be had, doing the job by
-hand.  Despite the pleasures to be had, the commonest way (nowadays)
-of generating an \acro{VPL} file is to use the 
-\ProgName{fontinst} package, which is described in more detail
-\htmlonly{together with the discussion of}
-\Qref[in answer]{\PS{} font metrics}{Q-metrics}.
-\Package{Qdtexvpl} is another utility for creating ad-hoc virtual
-fonts (it uses \TeX{} to parse a description of the virtual font, and
-\ProgName{qdtexvpl} itself processes the resulting \acro{DVI} file).
-\begin{ctanrefs}
-\item[fontinst]\CTANref{fontinst}
-\item[\nothtml{\rmfamily}Knuth on virtual fonts]\CTANref{vf-knuth}
-\item[\nothtml{\rmfamily}Virtual fonts ``how to'']\CTANref{vf-howto}
-\item[qdtexvpl]\CTANref{qdtexvpl}
-\end{ctanrefs}
-\LastEdit{2012-10-20}
-
-\Question[Q-whatmacros]{What are (\TeX{}) macros}
-
-\TeX{} is a \emph{macro processor}: this is a computer-science-y term
-meaning ``text expander'' (more or less); \TeX{} typesets text as it
-goes along, but \emph{expands} each macro it finds.  \TeX{}'s macros
-may include instructions to \TeX{} itself, on top of the simple text
-generation one might expect.
-
-Macros are a \emph{good thing}, since they allow the user to
-manipulate documents according to context.  For example, the macro
-\csx{TeX} is usually defined to produce ``TEX'' with the `E' lowered
-(the original idea was Knuth's),
-but in these \acro{FAQ}s the default definition of the macro is
-overridden, and it simply expands to the letters ``TeX''.  (\emph{You}
-may not think this a good thing, but the author of the macros has his
-reasons~-- see \Qref[question]{\TeX{}-related logos}{Q-logos}.)
-
-Macro names are conventionally built from a \texttt{\textbackslash }
-followed by a sequence of letters, which may be upper or lower case
-(as in \csx{TeX}, mentioned above).  They may also be % ! line break
-\texttt{\textbackslash \meta{any single character}}, which allows all
-sorts of oddities (many built in to most \TeX{} macro sets, all the
-way up from the apparently simple `\csx{ }' meaning ``insert a space
-here'').
-
-Macro programming can be a complicated business, but at their very
-simplest they need little introduction~--- you'll hardly need to be
-told that:
-\begin{quote}
-\begin{verbatim}
-\def\foo{bar}
-\end{verbatim}
-\end{quote}
-replaces each instance of \csx{foo} with the text ``bar''.  The
-command \csx{def} is \plaintex{} syntax for defining commands;
-\LaTeX{} offers a macro \csx{newcommand} that goes some way towards
-protecting users from themselves, but basically does the same thing:
-\begin{quote}
-\begin{verbatim}
-\newcommand{\foo}{bar}
-\end{verbatim}
-\end{quote}
-Macros may have ``arguments'' , which are used to substitute for marked
-bits of the macro expansion:
-\begin{quote}
-\begin{verbatim}
-\def\foo#1{This is a #1 bar}
-...
-\foo{2/4}.
-\end{verbatim}
-\end{quote}
-which produces:
-\begin{quote}
-  This is a 2/4 bar.
-\end{quote}
-or, in \LaTeX{} speak:
-\begin{quote}
-\begin{verbatim}
-\newcommand{\foo}[1]{This is a #1 bar}
-...
-\foo{3/4}.
-\end{verbatim}
-\end{quote}
-which produces:
-\begin{quote}
-  This is 3/4 bar.
-\end{quote}
-(\latex{} users waltz through life, perhaps?)
-
-You will have noticed that the arguments, above, were enclosed in
-braces (\texttt{\obracesymbol{}\dots{}\cbracesymbol{}}); this is the
-normal way of typing arguments, though \TeX{} is enormously flexible,
-and you may find all sorts of other ways of passing arguments (if you
-stick with it).
-
-Macro writing can get very complicated, very quickly.  If you are a
-beginner \AllTeX{} programmer, you are well advised to read something
-along the lines of the \Qref*{\TeX{}book}{Q-tex-books}; once you're under
-way, \Qref*{\TeX{} by Topic}{Q-ol-books} is possibly a more satisfactory
-choice.  Rather a lot of the answers in these \acro{FAQ}s tell you
-about various issues of how to write macros.
-\LastEdit{2011-10-12}
-
-\Question[Q-specials]{\csx{special} commands}
-
-\TeX{} provides the means to express things that device drivers can
-do, but about which \TeX{} itself knows nothing.  For example, \TeX{}
-itself knows nothing about how to include \PS{} figures into
-documents, or how to set the colour of printed text; but some device
-drivers do.
-
-Instructions for such things are introduced to your document by means
-of \csx{special} commands; all that \TeX{} does with these commands is
-to expand their 
-arguments and then pass the command to the \acro{DVI} file.  In most
-cases, there are macro packages provided (often with the driver) that
-provide a human-friendly interface to the \csx{special}; for example,
-there's little point including a figure if you leave no gap for it in
-your text, and changing colour proves to be a particularly fraught
-operation that requires real wizardry.  \LaTeXe{}
-has standard graphics and colour packages that make figure inclusion,
-rotation and scaling, and colour typesetting relatively
-straightforward, despite the rather daunting \csx{special} commands
-involved.  (\CONTeXT{} provides similar support, though not by way of
-packages.)
-
-The allowable arguments of \csx{special} depend on the device driver
-you're using.  Apart from the examples above, there are \csx{special}
-commands in the em\TeX{} drivers (e.g., \ProgName{dvihplj}, \ProgName{dviscr},
-\emph{etc}.)~that will draw lines at arbitrary orientations, and
-commands in \ProgName{dvitoln03} that permit the page to be set in
-landscape orientation.
-
-Note that \csx{special} behaves rather differently in \PDFTeX{}, since
-there is no device driver around.  There \emph{is} a concept of
-\acro{PDF} specials, but in most cases \csx{special} will provoke a
-warning when used in \PDFTeX{}.
-\LastEdit{2011-10-15}
-
-\Question[Q-write]{Writing (text) files from \tex{}}
-
-\TeX{} allows you to write to output files from within your document.
-The facility is handy in many circumstances, but it is vital for
-several of the things \latex{} (and indeed almost any higher-level
-\tex{}-based macro package) does for you.
-
-The basic uses of writing to an external file are ``obvious''~---
-remembering titles of sections for a table of contents, remembering
-label names and corresponding section or figure numbers, all for a
-later run of your document.  However, the ``non-obvious'' thing is
-easy to forget: that page numbers, in \tex{}, are slippery beasts, and
-have to be captured with some care.  The trick is that \csx{write}
-operations are only executed as the page is sent to the \acro{DVI}
-or \acro{PDF} file.  Thus, if you arrange that your page-number macro
-(\csx{thepage}, in \latex{}) is not expanded until the page is
-written, then the number written is correct, since that time is where
-\tex{} guarantees the page number tallies with the page being sent
-out.
-
-Now, there are times when you want to write something straight away:
-for example, to interact with the user.  \TeX{} captures that
-requirement, too, with the primitive command \csx{immediate}:
-\begin{quote}
-\begin{verbatim}
-\immediate\write\terminal{I'm waiting...}
-\end{verbatim}
-\end{quote}
-writes a ``computer-irritates-user'' message, to the terminal.
-
-Which brings us to the reason for that \csx{terminal}.  \TeX{} can
-``\csx{write}'' up to 16 streams simultaneously, and that argument to
-\csx{write} says which is to be used.  Macro packages provide the
-means of allocating streams for your use: \plaintex{} provides a macro
-\csx{newwrite} (used as ``\csx{newwrite}\csx{streamname}'', which sets
-\csx{streamname} as the stream number).  In fact, \csx{terminal} (or
-its equivalent) is the first output stream ever set up (in most macro
-packages): it is never attached to a file, and if \tex{} is asked to
-write to \emph{any} stream that isn't attached to a file it will send
-the output to the terminal (and the log).
-\LastEdit{2011-10-15}
-
-\Question[Q-spawnprog]{Spawning programs from \AllTeX{}: \csx{write18}}
-
-The \tex{} \Qref*{\csx{write} primitive instruction}{Q-write} is used
-to write to different file `streams'; TeX refers to each open file by
-a number, not by a file name (although most of the time we hide this).
-Originally, \tex{} would write to a file connected to a stream
-numbered 0--15.  More recently, a special ``stream 18'' has been
-implemented: it is not writing to a file, but rather tells TeX to ask
-the operating system to do something.  To run a command, we put it as
-the argument to \csx{write18}.  So to run the \progname{epstopdf}
-utility on a file with name stored as \csx{epsfilename}, we would
-write:
-\begin{quote}
-\begin{verbatim}
-\write18{epstopdf \epsfilename}
-\end{verbatim}
-\end{quote}
-When using something like the \Package{epstopdf} package, the `stream'
-write operation is hidden away and you don't need to worry about the
-exact way it's done.
-
-However, there is a security issue. If you download some \alltex{} code from
-the Internet, can you be sure that there is not some command in it
-(perhaps in a hidden way) to do stuff that might be harmful to your
-computer (let's say: delete everything on the hard disk!)?  In the
-face of this problem, both \miktex{} and \tex{}~Live have, for some
-time, disabled \csx{write18} by default.  To turn the facility on,
-both distributions support an additional argument when starting \tex{}
-from the command shell:
-\begin{quote}
-\begin{verbatim}
-(pdf)(la)tex --shell-escape <file>
-\end{verbatim}
-\end{quote}
-The problem with this is that many people use \alltex{} via a graphical
-editor, so to use \csx{write18} for a file the editor's settings must
-be changed.  Of course, the settings need restoring after the file is
-processed: you defeat the point of the original protection, that way.
-
-The latest \miktex{} (version 2.9), and recent \tex{}~Live (from the
-2010 release) get
-around this by having a special ``limited'' version of \csx{write18}
-enabled `out of the box'.  The idea is to allow only a pre-set list of
-commands (for example, \BibTeX{}, \progname{epstopdf}, \tex{} itself,
-and so on).  Those on the list are regarded as safe enough to allow,
-whereas anything else (for example deleting files) still needs to be
-authorised by the user. This seems to be a good balance: most people
-most of the time will not need to worry about \csx{write18} at all,
-but it will be available for things like \Package{epstopdf}.
-
-Note that the \tex{} system may tell you that the mechanism is in use:
-\begin{wideversion}
-\begin{quote}
-\begin{verbatim}
-This is pdfTeX, Version 3.1415926-1.40.11 (TeX Live 2010)
- restricted \write18 enabled.
-\end{verbatim}
-\end{quote}
-\end{wideversion}
-\begin{narrowversion}
-\begin{quote}
-\begin{verbatim}
-This is pdfTeX, Version 3.1415926-1.40.11
-                              (TeX Live 2010)
- restricted \write18 enabled.
-\end{verbatim}
-\end{quote}
-\end{narrowversion}
-when it starts.
-\begin{ctanrefs}
-\item[epstopdf.sty]Distributed with Heiko Oberdiek's packages
-  \CTANref{oberdiek}[epstopdf-pkg]
-\end{ctanrefs}
-\LastEdit{2012-12-03}
-
-\Question[Q-hyphen]{How does hyphenation work in \TeX{}?}
-
-Everyone knows what hyphenation is: we see it in most books we read,
-and (if we're alert) will spot occasional ridiculous mis-hyphenation
-(at one time, British newspapers were a fertile source).
-
-Hyphenation styles are culturally-determined, and the same language
-may be hyphenated differently in different countries~--- for example,
-British and American styles of hyphenation of English are very
-different.  As a result, a typesetting system that is not restricted
-to a single language at a single locale needs to be able to change its
-hyphenation rules from time to time.
-
-\TeX{} uses a pretty good system for hyphenation (originally designed
-by Frank Liang~--- you may view his % ! line break
-\href{http://tug.org/docs/liang/}{Ph.D.\ thesis} online) and while
-it's capable of missing ``sensible'' hyphenation points, it seldom
-selects grossly wrong ones.  The
-algorithm matches candidates for hyphenation against a set of
-``hyphenation patterns''.  The candidates for hyphenation must be
-sequences of letters (or other single characters that \TeX{} may be
-persuaded to think of as letters).  Non-letters interrupt hyphenation;
-this applies to \TeX{}'s \csx{accent} primitive (as in `syst\`eme')
-just as much as the exclamation in`syst!eme'.
-
-(Hyphenation takes place on the characters ``sent to the printer''.
-The problem with \csx{accent} is avoided~---in \latex{}~--- by the use
-of the \Package{fontenc} package, as discussed in % ! line break
-``\Qref*{Accented words aren t hyphenated}{Q-hyphenaccents}''.)
-
-Sets of hyphenation patterns are usually derived from analysis of
-a list of valid hyphenations (the process of derivation, using a tool
-called \Package{patgen}, is not ordinarily a sport to be played by
-ordinary mortals).
-
-The patterns for the languages a \TeX{} system is going to deal with
-may only be loaded when the system is installed.  To change the set of
-hyphenation patterns recognised by a \tex{}-based or \xetex{} system,
-a \Qref*{partial reinstallation}{Q-newlang} is necessary (note that 
-\Qref*{\luatex{}}{Q-luatex} relaxes this constraint).
-
-\TeX{} provides two ``user-level'' commands for control of
-hyphenation: \csx{language} (which selects a hyphenation style), and
-\csx{hyphenation} (which gives explicit instructions to the hyphenation
-engine, overriding the effect of the patterns).
-
-The ordinary \LaTeX{} user need not worry about \csx{language}, since
-it is very thoroughly managed by the \Package{babel} package; use of
-\csx{hyphenation} is discussed in
-\begin{wideversion}
-  the context of
-\end{wideversion}
-% beware line wrap
-\Qref[question]{hyphenation failure}{Q-nohyph}.
-\LastEdit{2012-12-03}
-
-\Question[Q-clsvpkg]{What are \LaTeX{} classes and packages?}
-
-\latex{} aims to be a general-purpose document processor.  Such an aim
-could be achieved by a selection of instructions which would enable
-users to use \tex{} primitives, but such a procedure is considered too
-inflexible (and probably too daunting for ordinary users).  Thus the
-designers of \latex{} created a model which offered an
-\emph{abstraction} of the design of documents.  Obviously, not all
-documents can look the same (even with the defocussed eye of
-abstraction), so the model uses \emph{classes} of document.  Base
-\latex{} offers five classes of document: \Class{book},
-\Class{report}, \Class{article} and \Class{letter}.
-For each class, \latex{} provides a \emph{class file}; the user
-arranges to use it via a \csx{documentclass} command at the top of the
-document.  So a document starting
-\begin{quote}
-  \cmdinvoke{documentclass}{article}
-\end{quote}
-may be called ``an \emph{article} document''.
-
-This is a good scheme, but it has a glaring flaw: the actual
-typographical designs provided by the \latex{} class files aren't
-widely liked.  The way around this is to \emph{refine} the class.  To
-refine a class, a programmer may write a new class file that loads an
-existing class, and then does its own thing with the document design.
-
-If the user finds such a refined class, all is well, but if not, the
-common way is to load a \emph{package} (or several).
-
-The \latex{} distribution, itself, provides rather few package files,
-but there are lots of them, by a wide variety of authors, to be found
-on the archives.  Several packages are designed just to adjust the
-design of a document~--- using such packages achieves what the
-programmer might have achieved by refining the class.
-
-Other packages provide new facilities: for example, the
-\Package{graphics} package (actually provided as part of any \latex{}
-distribution) allows the user to load externally-provided graphics
-into a document, and the \Package{hyperref} package enables the user
-to construct hyper-references within a document.
-
-On disc, class and package files only appear different by virtue of
-their name ``extension''~--- class files are called \File{*.cls} while
-package files are called \File{*.sty}.  Thus we find that the \LaTeX{}
-standard \Class{article} class is represented on disc by a file called
-\File{article.cls}, while the \Package{hyperref} package is
-represented on disc by a file called \File{hyperref.sty}.
-
-The class vs.~package distinction was not clear in \LaTeXo{}~---
-everything was called a style (``document style'' or ``document style
-option'').  It doesn't really matter that the nomenclature has
-changed: the important requirement is to understand what other people
-are talking about.
-\LastEdit{2013-10-21}
-
-\Question[Q-whatenv]{What are \latex{} ``environments''}
-
-While \tex{} makes direct provision for commands, \latex{} adds a
-concept of ``environment''; environments perform an action on a block
-(of something or other) rather than than just doing something at one
-place in your document.
-
-A totally trivial environment could change the font in use for a chunk
-of text, as
-\begin{quote}
-\begin{verbatim}
-\newenvironment{monoblock}%
-  {\ttfamily}%
-  {}
-\end{verbatim}
-\end{quote}
-which defines a \environment{monoblock} which may be used as
-\begin{quote}
-\begin{verbatim}
-\begin{monoblock}
-  some text set in monospace
-\end{monoblock}
-\end{verbatim}
-\end{quote}
-which will look like:
-\begin{quote}
-  \texttt{some text set in monospace}
-\end{quote}
-so it is a particularly simple example.  A rather complicated
-environment is introduced by \cmdinvoke{begin}{document}; it looks
-simple, but needs all sorts of special \tex{} code to make it work
-`transparently'; most environments are more elaborate than
-\environment{monoblock} and \emph{much} simpler than
-\environment{document}.
-
-An environment puts its content inside a \tex{} \emph{group}, so that
-commands used inside the environment don't `leak out'~--- the
-\environment{monoblock} environment, above, restricts its effect to
-its own contents (the stuff between the \cmdinvoke{begin}{monoblock}
-and \cmdinvoke{end}{monoblock}), which is just what you need for this
-sort of thing.
-
-So that's ``simple'' environments; the \environment{monoblock}, above
-doesn't actually gain us much over
-\begin{quote}
-\begin{verbatim}
-{\ttfamily some text set in monospace}
-\end{verbatim}
-\end{quote}
-though in fact many useful environments are just as simple (to look
-at).  Some, such as \environment{verbatim}, look simple but are
-actually very tricky inside.
-
-\latex{} also allows arguments to an environment:
-\begin{quote}
-\begin{verbatim}
-\newenvironment{fontblock}[1]%
-  {#1\selectfont}%
-  {}
-\end{verbatim}
-\end{quote}
-and use of \environment{fontblock} as:
-\begin{quote}
-\begin{verbatim}
-\begin{fontblock}{\ttfamily}
-\end{verbatim}
-\end{quote}
-would produce the same effect as the \environment{monoblock}
-environment.
-
-Environments may also have optional arguments, in much the same way as
-commands:
-\begin{quote}
-\begin{verbatim}
-\newenvironment{normaltext}[1][\itshape]%
-  {#1}%
-  {}
-\end{verbatim}
-\end{quote}
-which will ordinarily set its body in italic, but
-\begin{quote}
-\begin{verbatim}
-\begin{normaltext}[\ttfamily]
-  ...
-\end{normaltext}
-\end{verbatim}
-\end{quote}
-will observe its optional argument, and behave the same as the
-\environment{monoblock} we started with.
-
-Note that an environments argument(s) (mandatory or optional) are
-\emph{not} passed to the `\csx{end}' text of the environment~--- that
-is specified as a macro with no arguments, so that
-\begin{quote}
-\begin{verbatim}
-\newenvironment{normaltext}[1][\itshape]%
-  {#1}%
-  {\typeout{what was #1, again?}
-\end{verbatim}
-\end{quote}
-produces an error message
-\begin{quote}
-\begin{verbatim}
-! Illegal parameter number in definition of \endnormaltext.
-\end{verbatim}
-\end{quote}
-So, if you need to pass an environment argument to the end-code, you
-have to wrap it in a macro of its own:
-\begin{quote}
-\begin{verbatim}
-\newenvironment{normaltext}[1][Intro]%
-  {#1%
-   \newcommand{\foo}{#1}}%
-  {\typeout{what was \foo{}, again?}
-\end{verbatim}
-\end{quote}
-\LastEdit*{2013-02-20}
-
-\Question[Q-dtx]{Documented \LaTeX{} sources (\extension{dtx} files)}
-
-\LaTeXe{}, and many contributed \latex{} macro packages, are written
-in a \Qref*{literate programming style}{Q-lit}, with source and
-documentation in the
-same file.  This format in fact originated before the
-days of the \LaTeX{} project as one of the ``Mainz'' series of
-packages.  A documented source file conventionally has the suffix
-\extension{dtx}, and will normally be `stripped' before use with
-\LaTeX{}; an installation (\extension{ins}) file is normally provided,
-to automate this process of removing comments for speed of loading.
-If the \extension{ins} file is available, you may process \emph{it}
-with \latex{} to produce the package (and, often, auxiliary files).
-
-Output should look something like:
-\begin{quote}
-\begin{verbatim}
-Generating file(s) ./foo.sty 
-
-Processing file foo.dtx (package) -> foo.sty
-File foo.dtx ended by \endinput.
-Lines  processed: 2336
-Comments removed: 1336
-Comments  passed: 2
-Codelines passed: 972
-\end{verbatim}
-\end{quote}
-The lines ``\texttt{Processing \dots{}\ ended by \csx{endinput}}'' may
-be repeated if the \extension{dtx} file provides more than one
-`unpacked' file.
-
-To read the comments ``as a document'', you can run \LaTeX{} on the
-\extension{dtx} file to produce a nicely formatted version of the
-documented code.  (Most \latex{} packages on \ctan{}, nowadays, already
-have \acro{PDF} of the result of processing the \extension{dtx} file,
-as ``documentation''.)
-
-Several packages may be included in one \extension{dtx} file, with
-conditional sections, and there are facilities for indexes of macros,
-etc.  All of this m\'elange is sorted out by directives in the
-\extension{ins} file; conventional indexing utilities may be necessary
-for ``full'' output.
-
-Anyone may write \extension{dtx} files; the format is explained in
-\Qref*{The \LaTeX{} Companion}{Q-latex-books}, and a tutorial is available
-from \acro{CTAN} (which comes with skeleton \extension{dtx} and
-\extension{ins} files).
-
-Composition of \extension{dtx} files is supported in \ProgName{emacs} by
-\Qref*{\acro{AUC}-\TeX{}}{Q-editors}.
-
-The (unix-based) script \ProgName{dtxgen} generates a proforma basic
-\extension{dtx} file, which could be useful when starting a new
-project.
-
-Another route to an \extension{dtx} file is to write the
-documentation and the code separately, and then to combine them using
-the \ProgName{makedtx} system.  This technique has particular value in
-that the documentation file can be used separately to generate
-\acro{HTML} output; it is often quite difficult to make % ! line break
-\Qref*{\LaTeX{} to \acro{HTML} conversion}{Q-LaTeX2HTML} tools deal
-with \extension{dtx} files, since they use an unusual class file.
-
-The \ProgName{sty2dtx} system goes one step further: it attempts to
-create a \extension{dtx} file from a `normal' \extension{sty} file
-with comments.  It works well, in some circumstances, but can become
-confused by comments that aspire to ``structure'' (e.g., tabular
-material, as in many older packages' file headers).
-
-The \extension{dtx} files are not used by \LaTeX{} after they have been
-processed to produce \extension{sty} or \extension{cls} (or whatever)
-files.  They need not be kept with the working system; however, for
-many packages the \extension{dtx} file is the primary source of
-documentation, so you may want to keep \extension{dtx} files elsewhere.
-
-An interesting sideline to the story of \extension{dtx} files is the
-\Package{docmfp} package, which extends the model of the \Package{doc}
-package to
-\begin{flatversion}
-  \MF{} and \MP{} (\Qref[see questions]{}{Q-MF} and \Qref[\nothtml]{}{Q-MP})
-\end{flatversion}
-\begin{hyperversion}
-  \Qref{\MF{}}{Q-MF} and \Qref{\MP{}}{Q-MP},
-\end{hyperversion}
-thus permitting documented distribution of bundles containing code for
-\MF{} and \MP{} together with related \LaTeX{} code.
-\begin{ctanrefs}
-\item[AUC-TeX]\CTANref{auctex}
-\item[clsguide.pdf]\CTANref{clsguide}
-\item[docmfp.sty]\CTANref{docmfp}
-\item[docstrip.tex]Part of the \LaTeX{} distribution
-\item[DTX tutorial]\CTANref{dtxtut}
-\item[dtxgen]\CTANref{dtxgen}
-\item[makedtx]\CTANref{makedtx}
-\item[sty2dtx]\CTANref{sty2dtx}
-\end{ctanrefs}
-\LastEdit{2014-06-03}
-
-\Question[Q-whatenc]{What are encodings?}
-
-Let's start by defining two concepts, the \emph{character} and the
-\emph{glyph}.
-The character is the abstract idea of the `atom' of a
-language or other dialogue: so it might be a letter in an alphabetic
-language, a syllable in a syllabic language, or an ideogram in an
-ideographic language.  The glyph is the mark created on screen or
-paper which represents a character.  Of
-course, if reading is to be possible, there must be some agreed
-relationship between the glyph and the character, so while the precise
-shape of the glyph can be affected by many other factors, such as the
-capabilities of the writing medium and the designer's style, the
-essence of the underlying character must be retained.
-
-Whenever a computer has to represent characters, someone has to define
-the relationship between a set of numbers and the characters they
-represent.  This is the essence of an encoding: it is a mapping
-between a set of numbers and a set of things to be represented.
-
-\TeX{} of course deals in encoded characters all the time: the
-characters presented to it in its input are encoded, and it emits
-encoded characters in its \acro{DVI} or \acro{PDF} output.  These
-encodings have rather different properties.
-
-The \TeX{} input stream was pretty unruly back in the days when Knuth
-first implemented the language.  Knuth himself prepared documents on
-terminals that produced all sorts of odd characters, and as a result
-\TeX{} contains some provision for translating its input (however
-encoded) to something regular.  Nowadays, 
-the operating system translates keystrokes into a code appropriate for
-the user's language: the encoding used is usually a national or
-international standard, though some operating systems use ``code
-pages'' (as defined by Microsoft).  These standards and code pages often
-contain characters that may not appear in the \TeX{} system's input
-stream.  Somehow, these characters have to be dealt with~--- so
-an input character like ``\'e'' needs to be interpreted by \TeX{} in
-a way that that at least mimics the way it interprets ``\csx{'}\texttt{e}''.  
-
-The \TeX{} output stream is in a somewhat different situation:
-characters in it are to be used to select glyphs from the fonts to be
-used.  Thus the encoding of the output stream is notionally a font
-encoding (though the font in question may be a
-% beware line break (twice)
-\nothtml{virtual one~--- see }%
-\Qref[question]{virtual font}{Q-virtualfonts}).  In principle, a
-fair bit of what appears in the output stream could be direct
-transcription of what arrived in the input, but the output stream
-also contains the product of commands in the input, and translations
-of the input such as ligatures like %
-\texttt{fi}\nothtml{\ensuremath\Rightarrow``fi''}.
-
-Font encodings became a hot topic when the
-\Qref*{Cork encoding}{Q-ECfonts}
-appeared, because of the possibility of suppressing
-\csx{accent} commands in the output stream (and hence improving the
-quality of the hyphenation of text in inflected languages, which is
-interrupted by the \csx{accent} commands~--- see
-% beware line break
-\Qref[question]{``how does hyphenation work''}{Q-hyphen}).
-To take advantage of the diacriticised characters represented in the
-fonts, it is necessary to arrange that whenever the
-command sequence ``\csx{'}\texttt{e}'' has been input
-(explicitly, or implicitly via the sort of mapping of input mentioned
-above), the character that codes the position of the ``\'e'' glyph is
-used.
-
-Thus we could have the odd arrangement that the diacriticised character in
-the \TeX{} input stream is translated into \TeX{} commands that would
-generate something looking like the input character; this sequence of
-\TeX{} commands is then translated back again into a single
-diacriticised glyph as the output is created.  This is in fact
-precisely what the \LaTeX{} packages \Package{inputenc} and
-\Package{fontenc} do, if operated in tandem on (most) characters in
-the \acro{ISO}~Latin-1 input encoding and the \acro{T}1 font encoding.
-At first sight, it seems eccentric to have the first package do a thing, and
-the second precisely undo it, but it doesn't always happen that way:
-most font encodings can't match the corresponding input encoding
-nearly so well, and the two packages provide the sort of symmetry the
-\LaTeX{} system needs.
-
-\Question[Q-ECfonts]{What are the \acro{EC} fonts?}
-
-A font provides a number of \emph{glyphs}. In order that the glyphs
-may be printed, they are \Qref*{\emph{encoded}}{Q-whatenc}, and the
-encoding is used as an index into tables within the font.  For various
-reasons, Knuth chose deeply eccentric encodings for his Computer
-Modern family of fonts; in particular, he chose different encodings
-for different fonts, so that the application using the fonts has to
-remember which font of the family it's using before selecting a
-particular glyph.
-
-When \TeX{} version 3 arrived, most of the drivers for the
-eccentricity of Knuth's encodings went away, and at \acro{TUG}'s Cork
-meeting, an encoding for a set of 256 glyphs, for use in \TeX{} text,
-was defined.  The intention was that these glyphs should cover `most'
-European languages that use Latin alphabets, in the sense of including
-all accented letters needed.  (Knuth's \acro{CMR} fonts missed things
-necessary for Icelandic and Polish, for example, which the Cork fonts
-do have, though even Cork encoding's coverage isn't complete.)
-\latex{} refers to the Cork encoding as \acro{T}1, and provides the
-means to use fonts thus encoded to avoid problems with the interaction
-of accents and hyphenation % ! line break
-(see \Qref[question]{hyphenation of accented words}{Q-hyphenaccents}).
-
-The first \MF{}-fonts to conform to the Cork encoding were the \acro{EC}
-fonts. They look \acro{CM}-like, though their metrics differ from \acro{CM}-font
-metrics in several areas.  They have long been regarded as `stable' (in
-the same sense that the \acro{CM} fonts are stable: their metrics are
-unlikely ever to change).  Each \acro{EC} font is, of course, roughly twice the
-size of the corresponding \acro{CM} font, and there are far more of them than
-there are CM fonts.  The simple number of fonts proved problematic in
-the production of Type~1 versions of the fonts, but \acro{EC} or
-\acro{EC}-equivalent fonts in Type~1 or TrueType form (the latter only from
-\begin{wideversion}
-  \Qref{commercial suppliers}{Q-commercial}).
-\end{wideversion}
-\begin{narrowversion}
-  % ( <- paren matching
-  commercial suppliers~--- \Qref{question}{Q-commercial}).
-\end{narrowversion}
-Free \Qref*{auto-traced versions}{Q-textrace}~--- the \acro{CM}-super and
-the \acro{LGC} fonts, and the Latin Modern series (rather directly generated
-from Metafont sources), are available.
-
-Note that the Cork encoding doesn't cover mathematics (so that no
-``T1-encoded'' font families can not support it).  If you're using
-Computer-Modern-alike fonts, this doesn't actually matter: your system
-will have the original Computer Modern mathematical fonts (or the
-those distributed with the Latin Modern set), which cover `basic' \TeX{}
-mathematics; more advanced mathematics are likely to need separate
-fonts anyway.  Suitable mathematics fonts for use with other font
-families are discussed in % ! line break 
-``\Qref*{choice of scalable fonts}{Q-psfchoice}''.
-
-The \acro{EC} fonts are distributed with a set of `Text Companion' (\acro{TC}) fonts
-that provide glyphs for symbols commonly used in text. The \acro{TC} fonts
-are encoded according to the \latex{} \acro{TS}1 encoding, and are not
-necessarily as `stable' are the \acro{EC} fonts are.  Note that modern
-distributions tend not to distribute the \acro{EC} fonts in outline format, but
-rather to provide Latin Modern for \acro{T}1-encoded Computer Modern-style
-fonts.  This can sometimes cause confusion when users are recompiling
-old documents.
-
-The Cork encoding is also implemented by virtual fonts provided in the
-\acro{PSNFSS} system, for Adobe Type 1 fonts, and also by most other such
-fonts that have been developed (or otherwise made available) for use
-with \alltex{}. 
-
-Note that \acro{T}1 (and other eight-bit font encodings) are superseded in
-the developing \TeX{}-family members \Qref*{\xetex{}}{Q-xetex} and
-\Qref*{\luatex{}}{Q-luatex}, which use Unicode as their base encoding,
-and use Unicode-encoded fonts (typically in \FontFormat{ttf} or
-\FontFormat{otf} formats).  The \Package{cm-unicode} fonts carry the
-flag in this arena, along with the Latin Modern set.
-\begin{ctanrefs}
-\item[CM-super fonts]\CTANref{cm-super}
-\item[CM-LGC fonts]\CTANref{cm-lgc}
-\item[CM unicode fonts]\CTANref{cm-unicode}
-\item[EC and TC fonts]\CTANref{ec}
-\item[Latin Modern fonts]\CTANref{lm}
-\end{ctanrefs}
-
-\Question[Q-unicode]{Unicode and \tex{}}
-
-Unicode is a character code scheme that has the capacity to express
-the text of the languages of the world, as well as important symbols
-(including mathematics).  Any coding scheme that is directly
-applicable to \tex{} may be expressed in single bytes (expressing up
-to 256 characters); Unicode characters may require several bytes, and
-the scheme may express a very large number of characters.
-
-For ``old-style'' applications (\tex{} or \pdftex{}) to deal with
-Unicode input, the sequence of bytes to make up Unicode character are
-processed by a set of macros that deliver a glyph number in an
-appropriate font.  The macros that read these bytes is complicated,
-and manifests as \pkgoption{utf8} option for the \latex{} distribution
-\Package{inputenc} package; the coverage of that option is limited to
-Unicode characters that can be represented using ``\latex{} standard
-encodings''.  The separate package \Package{ucs} provides wider, but
-less robust, coverage via an \Package{inputenc} option
-\pkgoption{utf8x}.  As a general rule, you should never use
-\pkgoption{utf8x} until you have convinced yourself that
-\pkgoption{utf8} can not do the job for you.
-
-`Modern' \tex{}-alike applications, \Qref*{\xetex{}}{Q-xetex} and
-\Qref*{\luatex{}}{Q-luatex} read their input using \acro{UTF}-8
-representations of Unicode as standard.  They also use TrueType or
-OpenType fonts for output; each such font has tables that tell the
-application which part(s) of the Unicode space it covers; the tables
-enable the engines to decide which font to use for which character
-(assuming there is any choice at all).
-\begin{ctanrefs}
-\item[inputenc.sty]Part of the \CTANref{latex} distribution
-\item[ucs.sty]\CTANref{ucs}
-\end{ctanrefs}
-\LastEdit{2012-04-20}
-
-\Question[Q-tds]{What is the \acro{TDS}?}
-
-\acro{TDS} is an acronym for ``\TeX{} Directory Structure''; it
-specifies a standard way of organising all the \TeX{}-related files on
-a computer system.
-
-Most modern distributions arrange their \tex{} files in conformance
-with the \acro{TDS}, using both a `distribution' directory tree and a
-(set of) `local' directory trees, each containing \TeX{}-related
-files.  The \acro{TDS} recommends the name \texttt{texmf} for the name
-of the root directory (folder) of an hierarchy; in practice there are
-typically several such trees, each of which has a name that compounds
-that (e.g., \texttt{texmf-dist}, \texttt{texmf-var}).
-
-Files supplied as part of the distribution are put into the
-distribution's tree, but the location of the distribution's hierarchy is
-system dependent.  (On a Unix system it might be at
-\path{/usr/share/texmf} or \path{/opt/texmf}, or a similar location.)
-
-There may be more than one `local' hierarchy in which additional files
-can be stored.  An installation will also typically offer a local
-hierarchy, while each user may have an individual local hierarchy.
-
-The \acro{TDS} itself is published as the output of a \acro{TUG} % ! line break
-\Qref*{Technical Working Group}{Q-TUG*}.  You may browse an
-\href{http://tug.org/tds/}{on-line version} of the standard, and
-copies in several other formats (including source) are available on
-\acro{CTAN}.
-\begin{ctanrefs}
-\item[\nothtml{\rmfamily}\acro{TDS} specification]\CTANref{tds}
-\end{ctanrefs}
-
-\Question[Q-eps]{What is ``Encapsulated \PS{}'' (``\acro{EPS}'')?}
-
-\PS{} has been for many years a \emph{lingua franca} of powerful
-printers (though modern high-quality printers now tend to require some
-constrained form of Adobe Acrobat, instead); since \PS{} is also a
-powerful graphical programming language, it is commonly used as an
-output medium for drawing (and other) packages.
-
-However, since \PS{} \emph{is} such a powerful language, some
-rules need to be imposed, so that the output drawing may be included
-in a document as a figure without ``leaking'' (and thereby destroying
-the surrounding document, or failing to draw at all).
-
-Appendix \acro{H} of the \PS{} Language Reference Manual (second
-and subsequent editions), specifies a set of rules for \PS{} to
-be used as figures in this way.  The important features are:
-\begin{itemize}
-\item certain ``structured comments'' are required; important ones are
-  the identification of the file type, and information about the
-  ``bounding box'' of the figure (i.e., the minimum rectangle
-  enclosing it);
-\item some commands are forbidden~--- for example, a \texttt{showpage}
-  command will cause the image to disappear, in most \TeX{}-output
-  environments; and
-\item ``preview information'' is permitted, for the benefit of things
-  such as word processors that don't have the ability to draw
-  \PS{} in their own right~--- this preview information may be in
-  any one of a number of system-specific formats, and any viewing
-  program may choose to ignore it.
-\end{itemize}
-A \PS{} figure that conforms to these rules is said to be in
-``Encapsulated \PS{}'' (\acro{EPS}) format.  Most \AllTeX{} packages for
-including \PS{} are structured to use Encapsulated \PS{};
-which of course leads to much hilarity as exasperated \AllTeX{} users
-struggle to cope with the output of drawing software whose authors
-don't know the rules.
-
-\Question[Q-adobetypen]{Adobe font formats}
-\keywords{type1 type3}
-
-Adobe has specified a number of formats for files to represent fonts
-in \PS{} files; this question doesn't attempt to be encyclopaedic, so
-we only discuss the two formats most commonly encountered in the
-\AllTeX{} context, types~1 and 3.  In particular, we don't discuss the
-OpenType format, whose many advantages now becoming accessible to most
-\AllTeX{} users (by means of
-\begin{hyperversion}
-  the widely-used \Qref{\xetex{}}{Q-xetex} and the more experimental
-  \Qref{\LuaTeX{}}{Q-luatex}).
-\end{hyperversion}
-\begin{flatversion}
-  the widely-used \xetex{}~--- see \Qref[question]{}{Q-xetex}~--- and
-  the more experimental \LuaTeX{}~--- see \Qref[question]{}{Q-luatex}).
-\end{flatversion}
-
-Adobe Type~1 format specifies a means to represent outlines of the glyphs
-in a font.  The `language' used is closely restricted, to ensure that
-the font is rendered as quickly as possible.  (Or rather, as quickly
-as possible with Adobe's technology at the time the specification was
-written: the structure could well be different if it were specified
-now.)  The format has long been the basis of the digital type-foundry
-business, though nowadays most new fonts are released in OpenType format.
-
-%% Type~1 fonts are directly supported by some operating system software,
-%% and at least one \TeX{} system, the commercial % line break!
-%% \Qref*{\YandY{} system}{Q-commercial}, bases its entire
-%% operation on the use of Type~1 fonts.
-
-In the \AllTeX{} context, Type~1 fonts are extremely important.  Apart
-from their simple 
-availability (there are thousands of commercial Type~1 text fonts around), the
-commonest reader for \acro{PDF} files has long (in effect) \emph{insisted} on
-their use (see below).
-
-Type~3 fonts have a more forgiving specification.  A wide range of
-\PS{} operators is permissible, including bitmap specifiers.  Type~3
-is therefore the natural format to be used for programs such as
-\ProgName{dvips} when they auto-generate something to represent
-\MF{}-generated fonts in a \PS{} file.  It's Adobe Acrobat Viewer's
-treatment of bitmap Type~3 fonts that has made direct \MF{} output
-increasingly unattractive, in recent years.  If you have a \acro{PDF}
-document in which the text looks fuzzy and uneven in Acrobat Reader,
-ask Reader for the \texttt{File}\arrowhyph{}%
-\texttt{Document Properties}\arrowhyph{}%
-\texttt{Fonts ...}, and it will likely show some font or other as
-``Type~3'' (usually with encoding ``Custom'').  The problem has
-disappeared with version 6 of Acrobat Reader.  See % line break
-\Qref[question]{\acro{PDF} quality}{Q-dvips-pdf} for a discussion of
-the issue, and for ways of addressing it.
-
-Type~3 fonts should not entirely be dismissed, however.  Acrobat
-Reader's failure with them is entirely derived from its failure to use
-the anti-aliasing techniques common in \TeX{}-ware.  Choose a
-different set of \PS{} graphical operators, and you can make pleasing
-Type~3 fonts that don't ``annoy'' Reader.  For example, you may not
-change colour within a Type~1 font glyph, but there's no such
-restriction on a Type~3 font, which opens opportunities for some
-startling effects.
-
-\Question[Q-resolns]{What are ``resolutions''?}
-
-``Resolution'' is a word that is used with little concern for its
-multiple meanings, in computer equipment marketing.  The word suggests
-a measure of what an observer (perhaps the human eye) can resolve; yet
-we regularly see advertisements for printers whose resolution is
-1200dpi~--- far finer than the unaided human eye can distinguish.  The
-advertisements are talking about the precision with which the printer
-can place spots on the printed image, which affects the fineness of
-the representation of fonts, and the accuracy of the placement of
-glyphs and other marks on the page.
-
-In fact, there are two sorts of ``resolution'' on the printed page
-that we need to consider for \AllTeX{}'s purposes:
-\begin{itemize}
-\item the positioning accuracy, and
-\item the quality of the fonts.
-\end{itemize}
-In the case where \AllTeX{} output is being sent direct to a printer,
-in the printer's ``native'' language, it's plain that the \acro{DVI}
-processor must know all such details, and must take detailed account
-of both types of resolution.
-
-In the case where output is being sent to an intermediate distribution
-format, that has potential for printing (or displaying) we know not
-where, the final translator, that connects to directly to the printer
-or display, has the knowledge of the device's properties: the
-\acro{DVI} processor need not know, and should not presume to guess.
-
-Both \PS{} and \acro{PDF} output are in this category.  While \PS{} is
-used less frequently for document distribution nowadays, it is
-regularly used as the source for distillation into \acro{PDF}; and
-\acro{PDF} is the workhorse of an enormous explosion of document
-distribution.
-
-Therefore, we need \acro{DVI} processors that will produce
-``resolution independent'' \PS{} or \acro{PDF} output; of course, the
-independence needs to extend to both forms of independence outlined
-above.
-
-Resolution-independence of fonts was for a  long time forced upon the
-world by the feebleness of Adobe's \ProgName{Acrobat}
-\ProgName{Reader} at dealing with bitmap files: a sequence of answers
-starting with one aiming at the % ! line break
-\Qref*{quality of \acro{PDF} from \PS{}}{Q-dvips-pdf} addresses
-the problems that arise.
-
-Resolution-independence of positioning is more troublesome:
-\ProgName{dvips} is somewhat notorious for insisting on positioning to
-the accuracy of the declared resolution of the printer.
-One commonly-used approach is to declare a resolution of 8000 (``better
-than any device''), and this is reasonably successful though it does
-have its \Qref*{problems}{Q-8000}.
-
-\Question[Q-fontname]{What is the ``Berry naming scheme''?}
-
-In the olden days, \AllTeX{} distributions were limited by the
-feebleness of file systems' ability to represent long names.  (The
-\MSDOS{} file system was a particular bugbear: fortunately any current
-Microsoft system allows rather more freedom to specify file names.
-Sadly, the ISO~9660 standard for the structure of \CDROM{}s has a
-similar failing, but that too has been modified by various extension
-mechanisms.)
-
-One area in which these short file names posed a particular problem
-was that of file names for Type~1 fonts.
-These fonts are distributed by their vendors with
-pretty meaningless short names, and there's a natural ambition to
-change the name to something that identifies the font somewhat
-precisely.  Unfortunately, names such as ``BaskervilleMT'' are
-already far beyond the abilities of the typical feeble file system,
-and add the specifier of a font shape or variant, and the difficulties
-spiral out of control.  Font companies deal with the issue by
-inventing silly names, and providing a map file to show what the
-``real'' names.  Thus the Monotype Corporation provides the
-translations:
-\begin{quote}
-  \texttt{bas\_\_\_\_\_ BaskervilleMT}\\
-  \texttt{basb\_\_\_\_ BaskervilleMT-Bold}\\
-  \texttt{basbi\_\_\_ BaskervilleMT-BoldItalic}
-\end{quote}
-and so on.  These names could be used within \AllTeX{} programs,
-except that they are not unique: there's nothing to stop Adobe using
-`\texttt{bas\_\_\_\_\_}' for \emph{their} Baskerville font.
-
-Thus arose the Berry naming scheme.
-
-The basis of the scheme is to encode the meanings of the various parts
-of the file's specification in an extremely terse way, so that enough
-font names can be expressed even in impoverished file name-spaces.  The
-encoding allocates one character to the font ``foundry'' (Adobe, Monotype,
-and so on), two to the typeface name (Baskerville, Times Roman, and so
-on), one to the weight, shape, and encoding and so on.  
-
-The whole scheme is outlined in the \Package{fontname} distribution,
-which includes extensive documentation and a set of tables of fonts
-whose names have been systematised.
-\begin{ctanrefs}
-\item[fontname distribution]\CTANref{fontname}
-\end{ctanrefs}
-
-- 
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