From f41a5d46017f730e9586332f28744912872326f5 Mon Sep 17 00:00:00 2001 From: Norbert Preining Date: Sat, 28 Sep 2019 03:00:42 +0000 Subject: CTAN sync 201909280300 --- help/uk-tex-faq/faq-bits+pieces.tex | 1174 ----------------------------------- 1 file changed, 1174 deletions(-) delete mode 100644 help/uk-tex-faq/faq-bits+pieces.tex (limited to 'help/uk-tex-faq/faq-bits+pieces.tex') diff --git a/help/uk-tex-faq/faq-bits+pieces.tex b/help/uk-tex-faq/faq-bits+pieces.tex deleted file mode 100644 index 113d1139e4..0000000000 --- a/help/uk-tex-faq/faq-bits+pieces.tex +++ /dev/null @@ -1,1174 +0,0 @@ -% $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 -\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} - -- cgit v1.2.3