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diff --git a/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex b/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex new file mode 100644 index 00000000000..c0c0d0a450f --- /dev/null +++ b/Master/texmf-dist/doc/generic/FAQ-en/faq-wdidt.tex @@ -0,0 +1,1783 @@ +% $Id: faq-wdidt.tex,v 1.2 2009/09/01 06:53:22 rf10 Exp rf10 $ + +\section{Why does it \emph{do} that?} + +\subsection{Common errors} + +\Question[Q-crossref]{\LaTeX{} gets cross-references wrong} + +Sometimes, however many times you run \LaTeX{}, the cross-references +are just wrong. Remember that +the \csx{label} command must come \emph{after} the \csx{caption} command, or +be part of it. For example, +\htmlignore +\par\noindent +\begin{tabular}{@{}lll} +| \begin{figure}| & & |\begin{figure}|\\ +| \caption{A Figure}| & or & |\caption{A Figure%| \\ +| \label{fig}| & & | \label{fig}}| \\ +| \end{figure}| & & |\end{figure}| \\ +\end{tabular} +\endhtmlignore +\begin{htmlversion} +\begin{verbatim} + \begin{figure} \begin{figure} + \caption{A Figure} or \caption{A Figure% + \label{fig} \label{fig}} + \end{figure} \end{figure} +\end{verbatim} +\end{htmlversion} + +You can, just as effectively, shield the \csx{caption} command from its +associated \csx{label} command, by enclosing the caption in an +environment of its own. For example, people commonly seek help after: +\begin{quote} +\begin{verbatim} +\begin{center} + \caption{A Figure} +\end{center} +\label{fig} +\end{verbatim} +\end{quote} +has failed to label correctly. If you really need this centring (and +those in the know commonly reject it), code it as: +\begin{quote} +\begin{verbatim} +\begin{center} + \caption{A Figure} + \label{fig} +\end{center} +\end{verbatim} +\end{quote} + +\Question[Q-newlineargs]{Start of line goes awry} +\keywords{asterisk square bracket start line} + +This answer concerns two sorts of problems: errors of the form +\begin{quote} +\begin{verbatim} +! Missing number, treated as zero. +<to be read again> + g +<*> [grump] +\end{verbatim} +\end{quote} +and those where a single asterisk at the start of a line mysteriously +fails to appear in the output. + +Both problems arise because |\|{}|\| takes optional arguments. The +command |\|{}|\*| means ``break the line here, and inhibit page break +following the line break''; the command |\|{}|\[|\meta{dimen}|]| +means ``break the line here and add \meta{dimen} extra vertical space +afterwards''. + +So why does |\|{}|\| get confused by these things at the start of a +line? It's looking for the first non-blank thing, and in the test it +uses ignores the end of the line in your input text. + +The solution is to enclose the stuff at the start of the new line in +braces: +\begin{quote} +\begin{verbatim} +{\ttfamily + /* C-language comment\\ + {[grump]} I don't like this format\\ + {*}/ +} +\end{verbatim} +\end{quote} +(The above text derives from an actual post to +\Newsgroup{comp.text.tex}; this particular bit of typesetting could +plainly also be done using the \environment{verbatim} environment.) + +The problem also appears in maths mode, in arrays and so on. In this +case, large-scale bracketing of things is \emph{not} a good idea; the +\TeX{} primitive \csx{relax} (which does nothing except to block +searches of this nature) may be used. From another +\Newsgroup{comp.text.tex} example: +\begin{quote} +\begin{verbatim} +\begin{eqnarray} + [a] &=& b \\ + \relax[a] &=& b +\end{eqnarray} +\end{verbatim} +\end{quote} +which is a usage this \acro{FAQ} would not recommend, anyway: refer +to the \Qref*{reason not to use \environment{eqnarray}}{Q-eqnarray}. + +Note that the \Package{amsmath} package modifies the behaviour of +\texttt{\bsbs } in maths. With \Package{amsmath}, the \environment{eqnarray} +example doesn't need any special measures. + +\Question[Q-verbwithin]{Why doesn't verbatim work within\,\dots{}?} + +The \LaTeX{} verbatim commands work by changing category codes. Knuth +says of this sort of thing ``Some care is needed to get the timing +right\dots{}'', since once the category code has been assigned to a +character, it doesn't change. So \csx{verb} and +\cmdinvoke{begin}{verbatim} have to assume that they are getting the +first look at the parameter text; if they aren't, \TeX{} has already +assigned category codes so that the verbatim command doesn't have a +chance. For example: +\begin{quote} +\begin{verbatim} +\verb+\error+ +\end{verbatim} +\end{quote} +will work (typesetting `\csx{error}'), but +\begin{quote} +\begin{verbatim} +\newcommand{\unbrace}[1]{#1} +\unbrace{\verb+\error+} +\end{verbatim} +\end{quote} +will not (it will attempt to execute \csx{error}). Other errors one +may encounter are `\csx{verb} ended by end of line', or even the +rather more helpful `\csx{verb} illegal in command argument'. The +same sorts of thing happen with \cmdinvoke{begin}{verbatim} \dots{} +\cmdinvoke{end}{verbatim}: +\begin{quote} +\begin{quoteverbatim} +\ifthenelse{\boolean{foo}}{% +\begin{verbatim} +foobar +\end{verbatim} +}{% +\begin{verbatim} +barfoo +\end{verbatim} +} +\end{quoteverbatim} +\end{quote} +provokes errors like `File ended while scanning use of +\csx{@xverbatim}', as \cmdinvoke{begin}{verbatim} fails to see its +matching \cmdinvoke{end}{verbatim}. + +This is why the \LaTeX{} book insists that verbatim +commands must not appear in the argument of any other command; they +aren't just fragile, they're quite unusable in any command parameter, +regardless of \Qref*{\csx{protect}ion}{Q-protect}. (The \csx{verb} +command tries hard to detect if you're misusing it; unfortunately, it +can't always do so, and the error message is therefore not a reliable +indication of problems.) + +The first question to ask yourself is: ``is \csx{verb} actually +necessary?''. +\begin{itemize} +\item If \cmdinvoke{texttt}{\emph{your text}} produces the same result + as \csx{verb}\texttt{+\emph{your text}+}, then there's no need of + \csx{verb} in the first place. +\item If you're using \csx{verb} to typeset a \acro{URL} or email + address or the like, then the \csx{url} command from the + \Package{url} will help: it doesn't suffer from all the problems of + \csx{verb}, though it's still not robust; % ! line break + ``\Qref*{typesetting \acro{URL}s}{Q-setURL}'' offers advice here. +\item If you're putting \csx{verb} into the argument of a boxing + command (such as \csx{fbox}), consider using the \environment{lrbox} + environment: +\begin{quote} +\begin{verbatim} +\newsavebox{\mybox} +... +\begin{lrbox}{\mybox} + \verb!VerbatimStuff! +\end{lrbox} +\fbox{\usebox{\mybox}} +\end{verbatim} +\end{quote} +\end{itemize} + +Otherwise, there are three partial solutions to the problem. +\begin{itemize} +\item Some packages have macros which are designed to be responsive + to verbatim text in their arguments. For example, + the \Package{fancyvrb} package defines a command + \csx{VerbatimFootnotes}, which redefines the \csx{footnotetext} + command, and hence also the behaviour of the \csx{footnote}) + command, in such a way that you can include \csx{verb} commands in + its argument. This approach could in principle be extended to the + arguments of other commands, but it can clash with other packages: + for example, \csx{VerbatimFootnotes} interacts poorly with the + \pkgoption{para} option of the \Package{footmisc} package. + + The \Class{memoir} class defines its \csx{footnote} command so that + it will accept verbatim in its arguments, without any supporting package. +\item The \Package{fancyvrb} package defines a command \csx{SaveVerb}, + with a corresponding \csx{UseVerb} command, that allow you to save + and then to reuse the content of its argument; for details of this + extremely powerful facility, see the package documentation. + + Rather simpler is the \Package{verbdef} package, whose \csx{verbdef} + command defines a (robust) command which expands to the verbatim + argument given. +\item If you have a single character that is giving trouble (in + its absence you could simply use \csx{texttt}), consider using + \csx{string}. \cmdinvoke{texttt}{my\csx{string}\_name} + typesets the same as + |\verb+my_name+|, and will work in the argument of a command. It + won't, however, work in a moving argument, and no amount of + \Qref*{\csx{protect}ion}{Q-protect} will make it work in + such a case. + + A robust alternative is: + \begin{quote} +\begin{verbatim} +\chardef\us=`\_ +... +\section{... \texttt{my\us name}} +\end{verbatim} + \end{quote} + Such a definition is `naturally' robust; the construction + ``\meta{back-tick}\csx{\meta{char}}'' may be used for any + troublesome character (though it's plainly not necessary for things + like percent signs for which \AllTeX{} already provides + robust macros). +\end{itemize} +Documentation of both \Package{url} and \Package{verbdef} is in the +package files. +\begin{ctanrefs} +\item[fancyvrb.sty]\CTANref{fancyvrb} +\item[memoir.cls]\CTANref{memoir} +\item[url.sty]\CTANref{url} +\item[verbdef.sty]\CTANref{verbdef} +\end{ctanrefs} + +\Question[Q-noline]{No line here to end} + +The error +\begin{quote} +\begin{wideversion} +\begin{verbatim} +! LaTeX Error: There's no line here to end. + +See the LaTeX manual or LaTeX Companion for explanation. +\end{verbatim} +\end{wideversion} +\begin{narrowversion} +\begin{verbatim} +! LaTeX Error: There's no line here to end. + +See the LaTeX manual or LaTeX Companion +... for explanation. +\end{verbatim} +\end{narrowversion} +\end{quote} +comes in reaction to you giving \LaTeX{} a |\|{}|\| command at a time +when it's not expecting it. The commonest case is where you've +decided you want the label of a list item to be on a line of its own, +so you've written (for example): +\begin{quote} +\begin{verbatim} +\begin{description} +\item[Very long label] \\ + Text... +\end{description} +\end{verbatim} +\end{quote} +|\|{}|\| is actually a rather bad command to use in this case (even if +it worked), since it would force the `paragraph' that's made up of the +text of the item to terminate a line which has nothing on it but the +label. This would lead to an ``|Underfull \hbox|'' warning message +(usually with `infinite' badness of 10000); while this message doesn't +do any actual harm other than slowing down your \LaTeX{} run, any +message that doesn't convey any information distracts for no useful +purpose. + +The proper solution to the problem is to write a new sort of +\environment{description} environment, that does just what you're after. (The +\nothtml{\emph{\LaTeX{} Companion}~--- see }% ! line wrap +\Qref[question]{\emph{\LaTeX{} Companion}}{Q-books}\nothtml{~---} offers a +rather wide selection of variants of these things.) + +The quick-and-easy solution, which avoids the warning, is to write: +\begin{quote} +\begin{verbatim} +\begin{description} +\item[Very long label] \hspace*{\fill} \\ + Text... +\end{description} +\end{verbatim} +\end{quote} +which fills out the under-full line before forcing its closure. The +\Package{expdlist} package provides the same functionality with its +\csx{breaklabel} command, and \Package{mdwlist} provides it via its +\csx{desclabelstyle} command. + +The other common occasion for the message is when you're using the +\texttt{center} (or \environment{flushleft} or \environment{flushright}) +environment, and have decided you need extra separation between lines +in the environment: +\begin{quote} +\begin{verbatim} +\begin{center} + First (heading) line\\ + \\ + body of the centred text... +\end{center} +\end{verbatim} +\end{quote} +The solution here is plain: use the \texttt{\bsbs } command in the way it's +supposed to be used, to provide more than just a single line break +space. \texttt{\bsbs } takes an optional argument, which specifies +how much extra space to add; the required effect in the text above can +be had by saying: +\begin{quote} +\begin{verbatim} +\begin{center} + First (heading) line\\[\baselineskip] + body of the centred text... +\end{center} +\end{verbatim} +\end{quote} +\begin{ctanrefs} +\item[expdlist.sty]\CTANref{expdlist} +\item[mdwlist.sty]Distributed as part of \CTANref{mdwtools} +\end{ctanrefs} + +% other instances: \[no]linebreak in vertical mode + +\Question[Q-2colfltorder]{Two-column float numbers out of order} + +When \LaTeX{} can't place a float immediately, it places it on one of +several ``defer'' lists. If another float of the same type comes +along, and the ``defer'' list for that type still has something in it, +the later float has to wait for everything earlier in the list. + +Now, standard \LaTeX{} has different lists for single-column floats, +and double-column floats; this means that single-column figures can +overtake double-column figures (or vice-versa), and you observe later +figures appear in the document before early ones. The same is true, +of course, for tables, or for any user-defined float. + +The \LaTeX{} team recognise the problem, and provides a package +(\Package{fixltx2e}) to deal with it. \Package{Fixltx2e} amalgamates +the two defer lists, so that floats don't get out of order. + +For those who are still running an older \LaTeX{} distribution, the +package \Package{fix2col} should serve. This package (also by a +member of the \LaTeX{} team) was the basis of the relevant part of +\Package{fixltx2e}. The functionality has also been included in +\Package{dblfloatfix}, which also has code to place full-width floats +at \Qref*{\texttt{[b]} placement}{Q-2colfloat}. + +Once you have loaded the package, no more remains to be done: the +whole requirement is to patch the output routine; no extra commands +are needed. +\begin{ctanrefs} +\item[dblfloatfix.sty]\CTANref{dblfloatfix} +\item[fix2col.sty]Distributed as part of \CTANref{carlisle} +\item[fixltx2e.sty]Part of the \LaTeX{} distribution +\end{ctanrefs} + +\Question[Q-tabacc]{Accents misbehave in \environment{tabbing}} + +So you are constructing a \environment{tabbing} environment, and you +have the need of some diacriticised text~--- perhaps something as simple +as \cmdinvoke{'}{e}~--- and the accent disappears because it has been +interpreted as a \environment{tabbing} command, and everything goes +wrong. + +This is really a rather ghastly feature of the \environment{tabbing} +environment; in order to type accented characters you need to use the +\csx{a} kludge: so \cmdinvoke{a'}{e} inside \environment{tabbing} for +\cmdinvoke{'}{e} outside, and similarly \csx{a`} for \csx{`} and \csx{a=} +for \csx{=}. This whole procedure is of course hideous and +error-prone. + +The simplest alternative is to type in an encoding that has the +diacriticised characters in it, and to use an appropriate encoding +definition file in the \Package{inputenc} package. So for example, +type: +\begin{quote} + \cmdinvoke{usepackage}[latin1]{inputenc}\\ + \texttt{...}\\ + \cmdinvoke{begin}{tabbing}\\ + \texttt{...}\\ + \texttt{...} \csx{>} \texttt{voil\`a} \csx{>} \texttt{...} +\end{quote} +for: +\begin{quote} + \dots{}\quad voil\`a\quad \dots{} +\end{quote} +and the internal mechanisms of the \Package{inputenc} package will put +the right version of the accent command in there. + +A witty reversal of the r\^oles is introduced by the package +\Package{Tabbing} (note the capital ``T''): it provides a +\environment{Tabbing} environment which duplicates +\environment{tabbing}, but all the single-character commands become +complicated objects. So \environment{tabbing}'s \csx{>} becomes +\csx{TAB>}, \csx{=} becomes \csx{TAB=}, and so on. The above trivial +example would therefore become: +\begin{quote} +\begin{verbatim} +\usepackage{Tabbing} +... +\begin{Tabbing} + ... ... \TAB> voil\`a \TAB> ... +\end{verbatim} +\end{quote} +\begin{ctanrefs} +\item[Tabbing.sty]\CTANref{Tabbing} +\end{ctanrefs} + +\Question[Q-alreadydef]{Package reports ``command already defined''} + +You load a pair of packages, and the second reports that one of the +commands it defines is already present. For example, both the +\Package{txfonts} and \Package{amsmath} define a command \csx{iint} +(and \csx{iiint} and so on); so +\begin{quote} +\begin{verbatim} +... +\usepackage{txfonts} +\usepackage{amsmath} +\end{verbatim} +\end{quote} +produces a string of error messages of the form: +\begin{quote} +\begin{wideversion} +\begin{verbatim} +! LaTeX Error: Command \iint already defined. + Or name \end... illegal, see p.192 of the manual. +\end{verbatim} +\end{wideversion} +\begin{narrowversion} +\begin{verbatim} +! LaTeX Error: Command \iint already + defined. Or name \end... illegal, + see p.192 of the manual. +\end{verbatim} +\end{narrowversion} +\end{quote} +As a general rule, things that \Package{amsmath} defines, it defines +well; however, there is a good case for using the \Package{txfonts} +version of \csx{iint}~--- the associated \FontName{tx} fonts have a +double integral symbol that doesn't need to be ``faked'' in the way +\Package{amsmath} does. In the case that you are loading several +symbol packages, every one of which defines the same symbol, you are +likely to experience the problem in a big way (\csx{euro} is a common +victim). + +There are similar cases where one package redefines another's command, +but no error occurs because the redefining package doesn't use +\csx{newcommand}. Often, in such a case, you only notice the change +because you assume the definition given by the first package. The +\Package{amsmath}--\Package{txfonts} packages are just such a pair; +\Package{txfonts} doesn't provoke errors. + +You may deal with the problem by saving and restoring the command. +Macro programmers may care to do this for themselves; for the rest of +us, there's the package \Package{savesym}. The sequence: +\begin{quote} +\begin{verbatim} +\usepackage{savesym} +\usepackage{amsmath} +\savesymbol{iint} +\usepackage{txfonts} +\restoresymbol{TXF}{iint} +\end{verbatim} +\end{quote} +does the job; restoring the \Package{amsmath} version of the command, +and making the \Package{txfonts} version of the command available as +\csx{TXFiint}. + +Documentation of \Package{savesym} doesn't amount to much: the only +commands are \csx{savesymbol} and \csx{restoresymbol}, as noted above. +\begin{ctanrefs} +\item[amsmath.sty]Part of \CTANref{amslatex} +\item[savesym.sty]\CTANref{savesym} +\item[txfonts.sty]Part of \CTANref{txfonts} +\end{ctanrefs} + +\Question[Q-zerochap]{Why are my sections numbered 0.1\,\dots{}?} + +This happens when your document is using the standard \Class{book} or +\Class{report} class (or one similar), and you've got a \csx{section} +before your first \csx{chapter}. + +What happens is, that the class numbers sections as % ! line break +``\meta{chapter no}.\meta{section no}'', and until the first +chapter has appeared, the chapter number is 0. + +If you're doing this, it's quite likely that the \Class{article} class +is for you; try it and see. Otherwise, give your sections a +`superior' chapter, or do away with section numbering by using +\csx{section*} instead. An alternative way of avoiding numbering is +discussed in % ! line break +``\Qref*{unnumbered sections in the table of contents}{Q-secnumdep}''. + +\Question[Q-breaklinks]{Link text doesn't break at end line} +\keywords{hyperref overfull link} + +When using the \Package{hyperref} package, you make a block of text +``active'' when you define a hyper-link (when the user clicks on +that text, the reader program will divert to the \emph{target} of the +link). + +The \Package{hyperref} package uses a \emph{driver} (in the same way +as the \Package{graphics} package does), to determine how to implement +all that hyper-stuff. + +If you use the driver for \ProgName{dvips} output (presumably you want +to distill the resulting \PS{}), limitations in the way \ProgName{dvips} +deals with the \csx{special} commands mean that \Package{hyperref} +must prevent link anchors from breaking at the end of lines. Other +drivers (notably those for \PDFTeX{} and for \ProgName{dvipdfm}) don't +suffer from this problem. + +The problem may occur in a number of different circumstances. For a +couple of them, there are work-arounds: + +First, if you have an \acro{URL} which is active (so that clicking on +it will activate your web browser to ``go to'' the \acro{URL}). In +this case \Package{hyperref} employs the \Package{url} package to +split up the \acro{URL} (as described in % ! line break +\Qref[question]{typesetting \acro{URL}s}{Q-setURL}), but the +\ProgName{dvips} driver then suppresses the breaks. The way out is +the \Package{breakurl} package, which modifies the \csx{url} command +to produce several smaller pieces, between each of which a line break +is permitted. Each group of pieces, that ends up together in one +line, is converted to a single clickable link. + +Second, if you have a table of contents, list of figure or tables, or +the like, \Package{hyperref} will ordinarily make the titles in the +table of contents, or captions in the lists, active. If the title or +caption is long, it will need to break within the table, but the +\ProgName{dvips} driver will prevent that. In this case, load +\Package{hyperref} with the option \pkgoption{linktocpage}, and only +the page number will be made active. + +Otherwise, if you have a lengthy piece of text that you want active, +you have at present no simple solution: you have to rewrite your text, +or to use a different \acro{PDF} generation mechanism. +\begin{ctanrefs} +\item[breakurl.sty]\CTANref{breakurl} +\end{ctanrefs} + +\Question[Q-wrongpn]{Page number is wrong at start of page} + +This is a long story, whose sources are deep inside the workings of +\TeX{} itself; it all derives from the \TeX{}'s striving to generate +the best possible output. + +The page number is conventionally stored in \csx{count0}; \LaTeX{} +users see this as the counter \texttt{page}, and may typeset its value +using \csx{thepage}. + +The number (that is to say, \csx{count0}) is only updated when \TeX{} +actually outputs a page. \TeX{} only even tries to do this when it +detects a hint that it may be a good thing to do. From \TeX{}'s point +of view, the end of a paragraph is a good time to consider outputting +a page; it will output a page if it has \emph{more} than a page's +worth of material to output. (Ensuring it always has something in +hand makes some optimisations possible.) As a result, \csx{count0} +(\csx{thepage}) is almost always wrong in the first paragraph of a +page (the exception is where the page number has been ``forcibly'' +changed, either by changing its value directly, or by breaking the +page where \TeX{} wouldn't necessarily have chosen to break). + +\LaTeX{} provides a safe way of referring to the page number, by using +label references. So, rather than writing: +\begin{quote} +\begin{verbatim} +Here is page \thepage{}. +\end{verbatim} +\end{quote} +you should write: +\begin{quote} +\begin{verbatim} +Here is page \pageref{here}\label{here}. +\end{verbatim} +\end{quote} +(note: no space between the \csx{pageref} and the \csx{label}, since +that could potentially end up as a page-break space itself, which +rather defeats the purpose of the exercise!). + +\Question[Q-matchbrak]{My brackets don't match} + +\AllTeX{} has a low-level mechanism for matching braces in document +text. This means you can type something like: +\begin{quote} +\begin{verbatim} +\section{All \emph{OK} now.} +\end{verbatim} +\end{quote} +and know that the first brace (for the argument of \csx{section}) will +be matched with the last brace, and the internal pair of braces (for +the argument of \csx{emph}) will be matched with each other. It's all +very simple. + +However, \LaTeX{} has a convention of enclosing optional arguments in +brackets, as in: +\begin{quote} +\begin{verbatim} +\section[OK]{All \emph{OK} now.} +\end{verbatim} +\end{quote} +These brackets are not matched by \TeX{} mechanisms, despite the +superficial similarity of their use. As a result, +straightforward-looking usages like: +\begin{quote} +\begin{verbatim} +\section[All [OK] now]{All \emph{OK} now.} +\end{verbatim} +\end{quote} +aren't \acro{OK} at all~--- the optional argument comes to consist of +``All [OK'', and \csx{section} takes the single character ``n'' (of +the first ``now'') as its argument. + +Fortunately, \TeX{}'s scanning mechanisms helps us by accepting the +syntax ``\texttt{\{]\}}'' to `hide' the closing bracket from the +scanning mechanism that \LaTeX{} uses. In practice, the commonest way +to use this facility is: +\begin{quote} +\begin{verbatim} +\section[All {[OK]} now]{All \emph{OK} now.} +\end{verbatim} +\end{quote} +since bracing the bracket on its own ``looks odd''. + +\LaTeX{} has another argument syntax, even less regular, where the +argument is enclosed in parentheses, as in: +\begin{quote} +\begin{verbatim} +\put(1,2){foo} +\end{verbatim} +\end{quote} +(a picture environment command). + +This mechanism is also prone to problems with matching closing +parentheses, but the issue seldom arises since such arguments rarely +contain text. If it were to arise, the same solution (enclosing the +confused characters in braces) would solve the problem. + +\Question[Q-pdf-fig-chars]{Characters disappear from figures in \PDFTeX{}} + +You have a \acro{PDF} figure, which you want to use in your +\PDFLaTeX{} document. When you compile the document, \PDFTeX{} +complains about ``missing glyphs'', and some (or all) of the labelling +text or symbols in the original figure is no longer visible. + +What has happened is: +\begin{enumerate} +\item Your figure file (say \File{fig.pdf}) has a font \File{font.pfb} + embedded in it. +\item \PDFTeX{} notes that it has \File{font.pfb} on disc, and loads + that in place of the copy in \File{fig.pdf}. +\item It turns out that the copy in \File{fig.pdf} has glyphs that + aren't in \File{font.pfb} on disc, so that you get errors while + compiling and you see that characters are missing when you view the + output. (\PDFTeX{} can't know that the fonts are different, since + they have the same name.) +\end{enumerate} +Which is all very undesirable. + +\PDFTeX{} does this to keep file sizes down: suppose you have a +document that loads figures \File{fig1.pdf} and \File{fig2.pdf}; both +of those use font \File{font.pfb}. If \PDFTeX{} takes no action, +there will be \emph{two} copies of \File{font.pfb} in the output. +(If your document also uses the font, there could be three copies.) + +A real case is the \acro{URW} font \File{NimbusRomNo9L-Regu} (a clone +of Times Roman), which is available in a version with Cyrillic +letters, while the version in \TeX{} distributions doesn't have those +letters. Both versions, as distributed, have the same name. + +The simple (``quick and dirty'') solution is to add the command +\begin{quote} + \csx{pdfinclusioncopyfonts}\texttt{=1} +\end{quote} +to the preamble of your document. + +The ``real'' solution is that one or other font should be renamed. In +either case, this would require that you reconfigure some program's +(\TeX{}'s or your drawing package's) font tables~--- inevitably a +tiresome job. + +\subsection{Common misunderstandings} + +\Question[Q-include]{What's going on in my \csx{include} commands?} + +The original \LaTeX{} provided the \csx{include} command to address the +problem of long documents: with the relatively slow computers of the +time, the companion \csx{includeonly} facility was a boon. With the +vast increase in computer speed, \csx{includeonly} is less valuable +(though it still has its place in some very large projects). +Nevertheless, the facility is retained in current \LaTeX{}, and causes +some confusion to those who misunderstand it. + +In order for \csx{includeonly} to work, \csx{include} makes a separate +\extension{aux} file for each included file, and makes a `checkpoint' of +important parameters (such as page, figure, table and footnote +numbers); as a direct result, it \emph{must} clear the current page +both before and after the \csx{include} command. What's more, this +mechanism doesn't work if a \csx{include} command appears in a file +that was \csx{include}d itself: \LaTeX{} diagnoses this as an error. + +So, we can now answer the two commonest questions about \csx{include}: +\begin{itemize} +\item Why does \LaTeX{} throw a page before and after \csx{include} + commands? + + Answer: because it has to. If you don't like it, replace the + \csx{include} command with \csx{input}~--- you won't be able to use + \csx{includeonly} any more, but you probably don't need it anyway, so + don't worry. +\begin{htmlversion} + +\end{htmlversion} +\item Why can't I nest \csx{include}d files?~--- I always used to be + able to under \LaTeXo{}. + + Answer: in fact, you couldn't, even under \LaTeXo{}, but the failure + wasn't diagnosed. However, since you were happy with the behaviour + under \LaTeXo{}, replace the \csx{include} commands with \csx{input} + commands (with \csx{clearpage} as appropriate). +\end{itemize} + + +\Question[Q-paraparam]{Why does it ignore paragraph parameters?} + +When \TeX{} is laying out text, it doesn't work from word to word, or +from line to line; the smallest complete unit it formats is the +paragraph. The paragraph is laid down in a buffer, as it appears, and +isn't touched further until the end-paragraph marker is processed. +It's at this point that the paragraph parameters have effect; and it's +because of this sequence that one often makes mistakes that lead to +the paragraph parameters not doing what one would have hoped (or +expected). + +Consider the following sequence of \LaTeX{}: +\begin{quote} +\begin{verbatim} +{\raggedright % declaration for ragged text +Here's text to be ranged left in our output, +but it's the only such paragraph, so we now +end the group.} + +Here's more that needn't be ragged... +\end{verbatim} +\end{quote} +\TeX{} will open a group, and impose the ragged-setting parameters within +that group; it will then save a couple of sentences of text and +close the group (thus restoring the previous value of the +parameters that \csx{raggedright} set). Then \TeX{} encounters a blank +line, which it knows to treat as a \csx{par} token, so it typesets the +two sentences; but because the enclosing group has now been closed, +the parameter settings have been lost, and the paragraph will be +typeset normally. + +The solution is simple: close the paragraph inside the group, so that +the setting parameters remain in place. An appropriate way of doing +that is to replace the last three lines above with: +\begin{quote} +\begin{verbatim} +end the group.\par} +Here's more that needn't be ragged... +\end{verbatim} +\end{quote} +In this way, the paragraph is completed while \csx{raggedright}'s +parameters are still in force within the enclosing group. + +Another alternative is to define an environment that does the +appropriate job for you. For the above example, \LaTeX{} already +defines an appropriate one: +\begin{quote} +\begin{verbatim} +\begin{flushleft} +Here's text to be ranged left... +\end{flushleft} +\end{verbatim} +\end{quote} + +In fact, there are a number of parameters for which \TeX{} only +maintains one value per paragraph. A tiresome one is the set of upper +case/lower case translations, which (oddly enough) constrains +hyphenation of mutilingual texts. Another that regularly creates +confusion is \Qref*{\csx{baselineskip}}{Q-baselinepar}. + +\Question[Q-casechange]{Case-changing oddities} + +\TeX{} provides two primitive commands \csx{uppercase} and +\csx{lowercase} to change the case of text; they're not much used, but +are capable creating confusion. + +The two commands do not expand the text that is their parameter~--- +the result of \cmdinvoke{uppercase}{abc} is `\texttt{ABC}', but +\cmdinvoke{uppercase}{\csx{abc}} is always `\csx{abc}', whatever the +meaning of \csx{abc}. The commands are simply interpreting a table of +equivalences between upper- and lowercase characters. +They have (for example) no mathematical sense, and +\begin{quote} +\begin{verbatim} +\uppercase{About $y=f(x)$} +\end{verbatim} +\end{quote} +will produce +\begin{quote} +\begin{verbatim} +ABOUT $Y=F(X)$ +\end{verbatim} +\end{quote} +which is probably not what is wanted. + +In addition, \csx{uppercase} and \csx{lowercase} do not deal very well +with non-American characters, for example +\cmdinvoke{uppercase}{\csx{ae}} is the same as \csx{ae}. + +\LaTeX{} provides commands \csx{MakeUppercase} and \csx{MakeLowercase} +which fixes the latter problem. These commands are used in the +standard classes to produce upper case running heads for chapters +and sections. + +Unfortunately \csx{MakeUppercase} and \csx{MakeLowercase} do not solve +the other problems with \csx{uppercase}, so for example a section +title containing \cmdinvoke{begin}{tabular} \dots{} +\cmdinvoke{end}{tabular} will produce a running head containing +\cmdinvoke{begin}{TABULAR}. The simplest solution to this problem is +using a user-defined command, for example: +\begin{quote} +\begin{verbatim} +\newcommand{\mytable}{\begin{tabular}... + \end{tabular}} +\section{A section title \protect\mytable{} + with a table} +\end{verbatim} +\end{quote} +Note that \csx{mytable} has to be protected, otherwise it will be +expanded and made upper case; you can achieve the same result by +declaring it with \csx{DeclareRobustCommand}, in which case the +\csx{protect} won't be necessary. + +David Carlisle's \Package{textcase} package +addresses many of these problems in a transparent way. It defines +commands \csx{MakeTextUppercase} and \csx{MakeTextLowercase} which do +upper- or lowercase, with the fancier features of the \LaTeX{} +standard \csx{Make*}-commands but without the problems +mentioned above. Load the package with +\cmdinvoke{usepackage}[overload]{textcase}, and it will redefine the \LaTeX{} +commands (\emph{not} the \TeX{} primitive commands \csx{uppercase} and +\csx{lowercase}), so that section headings and the like don't produce +broken page headings. +\begin{ctanrefs} +\item[textcase.sty]\CTANref{textcase} +\end{ctanrefs} + +\Question[Q-splitfoot]{Why does \LaTeX{} split footnotes across pages?} + +\LaTeX{} splits footnotes when it can think of nothing better to do. +Typically, when this happens, the footnote mark is at the bottom of +the page, and the complete footnote would overfill the page. \LaTeX{} +could try to salvage this problem by making the page short of both the +footnote and the line with the footnote mark, but its priorities told +it that splitting the footnote would be preferable. + +As always, the best solution is to change your text so that the +problem doesn't occur in the first place. Consider whether the text +that bears the footnote could move earlier in the current page, or on +to the next page. + +If this isn't possible, you might want to change \LaTeX{}'s perception +of its priorities: they're controlled by +\csx{interfootnotelinepenalty}~--- the larger it is, the less willing +\LaTeX{} is to split footnotes. + +Setting +\begin{quote} +\begin{verbatim} +\interfootnotelinepenalty=10000 +\end{verbatim} +\end{quote} +inhibits split footnotes altogether, which will cause `\texttt{Underfull} +\csx{vbox}' messages unless you also specify \csx{raggedbottom}. The +default value of the penalty is \texttt{100}, which is rather mild. + +An alternative technique is to juggle with the actual size of the +pages. \csx{enlargethispage} changes the size of the current page by +its argument (for example, you might say +\cmdinvoke{enlargethispage}{\csx{baselineskip}} to add a single line +to the page, but you can use any ordinary \TeX{} length such as +\texttt{15mm} or \texttt{-20pt} as argument). Reducing the size of +the current page could force the offending text to the next page; +increasing the size of the page may allow the footnote to be included +in its entirety. It may be necessary to change the size of more than +one page. + +The \Package{fnbreak} package detects (and generates warnings about) +split footnotes. +\begin{ctanrefs} +\item[fnbreak.sty]\CTANref{fnbreak} +\end{ctanrefs} + +\Question[Q-marginparside]{Getting \csx{marginpar} on the right side} + +In an ideal world, marginal notes would be in ``analogous'' places on +every page: notes on an even-side page would be in the left margin, +while those on an odd-side page would be in the right margin. A +moment's thought shows that a marginal note on the left needs to be +typeset differently from a marginal note on the right. The \LaTeX{} +\csx{marginpar} command therefore takes two arguments in a +\texttt{twoside} documents: % beware line break +\cmdinvoke*{marginpar}[left text]{right text}. \LaTeX{} uses the +``obvious'' test to +get the \csx{marginpar}s in the correct margin, but a booby-trap arises +because \TeX{} runs its page maker asynchronously. If a +\csx{marginpar} is processed while page \ensuremath{n} is being built, but +doesn't get used until page \ensuremath{n}+1, then the \csx{marginpar} will turn +up on the wrong side of the page. This is an instance of a general +problem: see +% beware line break +``\Qref*{finding if you're on an odd or an even page}{Q-oddpage}''. + +The solution to the problem is for \LaTeX{} to `remember' which side +of the page each \csx{marginpar} \emph{should} be on. The +\Package{mparhack} package does this, using label-like marks stored in +the \extension{aux} file; the \Class{memoir} class does likewise. +\begin{ctanrefs} +\item[memoir.cls]\CTANref{memoir} +\item[mparhack.sty]\CTANref{mparhack} +\end{ctanrefs} + +\Question[Q-misschar]{Where have my characters gone?} + +You've typed some apparently reasonable text and processed it, but the +result contains no sign of some of the characters you typed. A likely +reason is that the font you selected just doesn't have a +representation for the character in question. + +For example, if I type ``that will be \pounds{}44.00'' into an ordinary +\AllTeX{} document, or if I select the font |rsfs10| (which contains +uppercase letters only) and type pretty much anything, the \pounds{} +sign, or any lowercase letters or digits will not appear in the +output. There's no actual error message, either: you have to read the +log file, where you'll find cryptic little messages like +\begin{quote} +\begin{wideversion} +\begin{verbatim} +Missing character: There is no ^^a3 in font cmr10! +Missing character: There is no 3 in font rsfs10! +\end{verbatim} +\end{wideversion} +\begin{narrowversion} +\begin{verbatim} +Missing character: + There is no ^^a3 in font cmr10! +Missing character: + There is no 3 in font rsfs10! +\end{verbatim} +\end{narrowversion} +\end{quote} +(the former demonstrating my \TeX{}'s unwillingness to deal in characters +which have the eighth bit set, while the \texttt{rsfs10} example shows that +\TeX{} will log the actual character in error, if it thinks it's +possible). + +Somewhat more understandable are the diagnostics you may get from +\Package{dvips} when using the \acro{OT}1 and \acro{T}1 versions of +fonts that were supplied in Adobe standard encoding: +\begin{quote} +\begin{verbatim} +dvips: Warning: missing glyph `Delta' +\end{verbatim} +\end{quote} +The process that generates the metrics for using the fonts generates +an instruction to \Package{dvips} to produce these diagnostics, so +that their non-appearance in the printed output is less surprising +than it might be. Quite a few glyphs provided in Knuth's text +encodings and in the Cork encoding are not available in the Adobe +fonts. In these cases, there \emph{is} a typeset sign of the +character: \ProgName{dvips} produces a black rectangle of whatever +size the concocted font file has specified. + +\Question[Q-rerun]{``Rerun'' messages won't go away} + +The \LaTeX{} message ``Rerun to get crossreferences right'' is +supposed to warn the user that the job needs to be processed again, +since labels seem to have changed since the previous run. (\LaTeX{} +compares the labels it has created this time round with what it found +from the previous run when it started; it does this comparison at +\cmdinvoke{end}{document}.) + +Sometimes, the message won't go away: however often you reprocess your +document, \LaTeX{} still tells you that ``Label(s) may have +changed''. This can sometimes be caused by a broken package: both +\Package{footmisc} (with the |perpage| option) and \Package{hyperref} +have been known to give trouble, in the past: if you are using either, +check you have the latest version, and upgrade if possible. + +However, there \emph{is} a rare occasion when this error can happen +as a result of pathological structure of the document itself. Suppose +you have pages numbered in roman, and you add a reference to a label +on page ``ix'' (9). The presence of the reference pushes the thing +referred to onto page ``x'' (10), but since that's a shorter reference +the label moves back to page ``ix'' at the next run. Such a sequence +can obviously not terminate. + +The only solution to this problem is to make a small change to your +document (something as small as adding or deleting a comma will often +be enough). +\begin{ctanrefs} +\item[footmisc.sty]\CTANref{footmisc} +\item[hyperref.sty]\CTANref{hyperref} +\end{ctanrefs} + +\Question[Q-xspace]{Commands gobble following space} + +People are forever surprised that simple commands gobble the space +after them: this is just the way it is. The effect arises from the +way \TeX{} works, and Lamport describes a solution (place a pair of braces +after a command's invocation) in the description of \LaTeX{} syntax. +Thus the requirement is in effect part of the definition of \LaTeX{}. + +This \acro{FAQ}, +for example, is written with definitions that \emph{require} one to +type \cmdinvoke{fred}{\relax} % the \relax prevents {} being gobbled + % in html production (sigh) +for almost all macro invocations, regardless +of whether the following space is required: however, this \acro{FAQ} +is written by highly dedicated (and, some would say, eccentric) +people. Many users find all those braces become very tedious very +quickly, and would really rather not type them all. + +An alternative structure, that doesn't violate the design of \LaTeX{}, +is to say \csx{fred}\csx{ }~--- the \csx{ } command is ``self +terminating'' (like |\|{}|\|) and you don't need braces after +\emph{it}. Thus one can reduce to one the extra characters one needs +to type. + +If even that one character is too many, the package \Package{xspace} +defines a command \csx{xspace} that guesses whether there should have +been a space after it, and if so introduces that space. So +% beware line wrap +``\texttt{fred\csx{xspace} jim}'' produces ``fred jim'', while +``\texttt{fred\csx{xspace}.\@ jim}'' produces ``fred. jim''. Which +usage would of course be completely pointless; but you can incorporate +\csx{xspace} in your own macros: +\begin{quote} +\begin{wideversion} +\begin{verbatim} +\usepackage{xspace} +... +\newcommand{\restenergy}{\ensuremath{mc^2}\xspace} +... +and we find \restenergy available to us... +\end{verbatim} +\end{wideversion} +\begin{narrowversion} +\begin{verbatim} +\usepackage{xspace} +... +\newcommand{\restenergy}% + {\ensuremath{mc^2}\xspace} +... +and we find \restenergy available to us... +\end{verbatim} +\end{narrowversion} +\end{quote} +The \csx{xspace} command must be the last thing in your macro +definition (as in the example); it's not completely foolproof, but it +copes with most obvious situations in running text. + +The \Package{xspace} package doesn't save you anything if you only use +a modified macro once or twice within your document. In any case, be +careful with usage of \csx{xspace}~--- it changes your input syntax, +which can be confusing, notably to a collaborating author +(particularly if you create some commands which use it and some which +don't). Of course, no command built into \LaTeX{} or into any +``standard'' class or package will use \csx{xspace}. +\begin{ctanrefs} +\item[xspace.sty]Distributed as part of \CTANref{2etools} +\end{ctanrefs} + +\Question[Q-overfull]{\AllTeX{} makes overfull lines} + +When \TeX{} is building a paragraph, it can make several attempts to +get the line-breaking right; on each attempt it runs the same +algorithm, but gives it different parameters. You can affect the way +\TeX{}'s line breaking works by adjusting the parameters: this answer +deals with the ``tolerance'' and stretchability parameters. The other +vital `parameter' is the set of hyphenations to be applied: see +``\Qref*[question]{my words aren't being hyphenated}{Q-nohyph}'' +(and the questions it references) for advice. + +If you're getting an undesired ``overfull box'', what has happened is +that \TeX{} has given up: the parameters you gave it don't allow it to +produce a result that \emph{doesn't} overfill. In this circumstance, +Knuth decided the best thing to do was to produce a warning, and to +allow the user to solve the problem. (The alternative, silently to go +beyond the envelope of ``good taste'' defined for this run of \TeX{}, +would be distasteful to any discerning typographer.) The user can +almost always address the problem by rewriting the text that's +provoking the problem~--- but that's not always possible, and in some +cases it's impossible to solve the problem without adjusting the +parameters. This answer discusses the approaches one might take to +resolution of the problem, on the assumption that you've got the +hyphenation correct. + +The simplest case is where a `small' word fails to break at the end of +a line; pushing the entire word to a new line isn't going to make much +difference, but it might make things just bad enough that \TeX{} won't +do it by default. In such a case on can \emph{try} the \LaTeX{} +\csx{linebreak} command: it may solve the problem, and if it does, it +will save an awful lot of fiddling. Otherwise, one needs to adjust +parameters: to do that we need to recap the details of \TeX{}'s line +breaking mechanisms. + +\TeX{}'s first attempt at breaking lines is performed without even +trying hyphenation: \TeX{} sets its ``tolerance'' of line breaking +oddities to the internal value \csx{pretolerance}, and sees what +happens. If it can't get an acceptable break, \TeX{} adds the +hyphenation points allowed by the current patterns, and tries again +using the internal \csx{tolerance} value. If this pass also fails, and +the internal \csx{emergencystretch} value is positive, \TeX{} will try +a pass that allows \csx{emergencystretch} worth of extra stretchability +to the spaces in each line. + +In principle, therefore, there are three parameters (other than +hyphenation) that you can change: \csx{pretolerance}, \csx{tolerance} +and \csx{emergencystretch}. Both the \texttt{tolerance} values are +simple numbers, and should be set by \TeX{} primitive count +assignment~--- for example +\begin{quote} +\begin{verbatim} +\pretolerance=150 +\end{verbatim} +\end{quote} +For both, an ``infinite'' tolerance is represented by the value +|10|\nothtml{\,}|000|, but infinite tolerance is rarely +appropriate, since it can lead to very bad line breaks indeed. + +\csx{emergencystretch} is a \TeX{}-internal `dimen' register, and can +be set as normal for dimens in \plaintex{}; in \LaTeX{}, use +\csx{setlength}~--- for example: +\begin{quote} +\begin{verbatim} +\setlength{\emergencystretch}{3em} +\end{verbatim} +\end{quote} + +The choice of method has time implications~--- each of the +passes takes time, so adding a pass (by changing +\csx{emergencystretch}) is less desirable than suppressing one (by +changing \csx{pretolerance}). However, it's unusual nowadays to find a +computer that's slow enough that the extra passes are really +troublesome. + +In practice, \csx{pretolerance} is rarely used other than to manipulate +the use of hyphenation; \plaintex{} and \LaTeX{} both set its value +to |100|. To suppress the first scan of paragraphs, set +\csx{pretolerance} to |-1|. + +\csx{tolerance} is often a good method for adjusting spacing; +\plaintex{} and \LaTeX{} both set its value to |200|. \LaTeX{}'s +\csx{sloppy} command sets it to |9999|, as does the +\environment{sloppypar} environment. This value is the largest +available, this side of infinity, and can allow pretty poor-looking +breaks (this author rarely uses \csx{sloppy} ``bare'', though he does +occasionally use \environment{sloppypar}~--- that way, the change of +\csx{tolerance} is confined to the environment). More satisfactory is +to make small changes to \csx{tolerance}, incrementally, and then to look to +see how the change affects the result; very small increases can often +do what's necessary. Remember that \csx{tolerance} is a paragraph +parameter, so you need to ensure it's actually applied~--- see +``\Qref*[question]{ignoring paragraph parameters}{Q-paraparam}''. +\LaTeX{} users could use an environment like: +\begin{quote} +\begin{verbatim} +\newenvironment{tolerant}[1]{% + \par\tolerance=#1\relax +}{% + \par +} +\end{verbatim} +\end{quote} +enclosing entire paragraphs (or set of paragraphs) in it. + +The value of \csx{emergencystretch} is added to the assumed +stretchability of each line of a paragraph, in a further run of the +paragraph formatter in case that the paragraph can't be made to look +right any other way. (The extra scan happens if +\csx{emergencystretch\textgreater0pt}~--- if it's zero or negative, no gain +could be had from rerunning the paragraph setter.) The example above +set it to \texttt{3em}; the Computer Modern fonts ordinarily fit three +space skips to the \texttt{em}, so the change would allow anything up +to the equivalent of nine extra spaces in each line. In a line with +lots of spaces, this could be reasonable, but with (say) only three +spaces on the line, each could stretch to four times its natural +width. It is therefore clear that \csx{emergencystretch} needs to be +treated with a degree of caution. + +More subtle (but more tricky to manage) are the microtypographic +extensions provided by \PDFTeX{}. Since \PDFTeX{} is the default +`engine' for \LaTeX{} and \CONTeXT{} work in all distributions, +nowadays, the extensions are available to all. There are two +extensions, margin kerning and font expansion; margin kerning only +affects the visual effect of the typeset page, and has little effect +on the ability of the paragraph setter to ``get things right''. +Font expansion works like a subtler version of the trick that +\csx{emergencystretch} plays: \PDFTeX{} `knows' that your current font +may be stretched (or shrunk) to a certain extent, and will do that +``on the fly'' to optimise the setting of a paragraph. This is a +powerful tool in the armoury of the typesetter. + +As mentioned above, the microtypographic extensions are tricky beasts +to control; however, the \Package{microtype} package relieves the user +of the tedious work of specifying how to perform margin adjustments +and how much to scale each font~\dots{}\@ for the fonts the package +knows about; it's a good tool, and users who can take on the +specification of adjustments for yet more fonts are always welcome. +\begin{ctanrefs} +\item[microtype.sty]\CTANref{microtype} +\end{ctanrefs} + +\Question[Q-exscale]{Maths symbols don't scale up} + +By default, the ``large'' maths symbols stay at the same size +regardless of the font size of the text of the document. There's good +reason for this: the \FontName{cmex} fonts aren't really designed to +scale, so that \TeX{}'s maths placement algorithms don't perform as +well as they might when the fonts are scaled. + +However, this behaviour confounds user expectations, and can lead to +slightly odd-looking documents. If you want the fonts to scale, +despite the warning above, use the \Package{exscale} package~--- just +loading it is enough. +%% +%% (Note: if you are using bitmap versions of the \FontName{cmex} fonts, +%% you will find extra bitmaps are generated. The extended sizes are not +%% ordinarily generated for any other purpose.) +\begin{ctanrefs} +\item[exscale.sty]Part of the \LaTeX{} distribution. +\end{ctanrefs} + +\Question[Q-linespread]{Why doesn't \csx{linespread} work?} + +The command \cmdinvoke*{linespread}{factor} is supposed to multiply +the current \csx{baselineskip} by \meta{factor}; but, to all +appearances, it doesn't. + +In fact, the command is equivalent to +\cmdinvoke{renewcommand}{\csx{baselinestretch}}{factor}: written that +way, it somehow feels less surprising that the effect isn't immediate. +The \csx{baselinestretch} factor is only used when a font is selected; +a mere change of \csx{baselinestretch} doesn't change the font, any +more than does the command +\cmdinvoke*{fontsize}{size}{baselineskip}~--- you have to follow +either command with \csx{selectfont}. So: +\begin{quote} +\begin{verbatim} +\fontsize{10}{12}% +\selectfont +\end{verbatim} +\end{quote} +or: +\begin{quote} +\begin{verbatim} +\linespread{1.2}% +\selectfont +\end{verbatim} +\end{quote} +Of course, a package such as \Package{setspace}, whose job is to +manage the baseline, will deal with all this stuff~--- see +``\Qref*[question]{managing double-spaced documents}{Q-linespace}''. If +you want to avoid \Package{setspace}, beware the behaviour of +linespread changes within a paragraph: read % ! line break +``\Qref*[question]{\csx{baselineskip} is a paragraph parameter}{Q-baselinepar}''. +\begin{ctanrefs} +\item[setspace.sty]\CTANref{setspace} +\end{ctanrefs} + +\Question[Q-baselinepar]{Only one \csx{baselineskip} per paragraph} + +The \csx{baselineskip} is not (as one might hope) a property of a +line, but of a paragraph. As a result, in a \texttt{10pt} (nominal) +document (with a default \csx{baselineskip} of \texttt{12pt}), a +single character with a larger size, as: +\begin{quote} +\begin{verbatim} +{\Huge A} +\end{verbatim} +\end{quote} +will be squashed into the paragraph: \TeX{} will make sure it doesn't +scrape up against the line above, but won't give it ``room to +breathe'', as it does the text at standard size; that is, its size +(\texttt{24.88pt}) is taken account of, but its \csx{baselineskip} +(\texttt{30pt}) isn't. Similarly +\begin{quote} +\begin{verbatim} +Paragraph text ... +{\footnotesize Extended interjection ... + ... into the paragraph.} + ... paragraph continues ... +\end{verbatim} +\end{quote} +will look silly, since the \texttt{8pt} interjection will end up set +on the \texttt{12pt} \csx{baselineskip} of the paragraph, rather than +its preferred \texttt{8.5pt}. Finally, something like +\begin{quote} +\begin{verbatim} +Paragraph text ... + ... paragraph body ends. +{\footnotesize Short comment on paragraph.} + +Next paragraph starts... +\end{verbatim} +\end{quote} +will set the body of the first paragraph on the constricted +\csx{baselineskip} of the \csx{footnotesize} comment. + +So, how to deal with these problems? The oversized (short) section is +typically corrected by a \emph{strut}: this word comes from movable +metal typography, and refers to a spacer that held the boxes (that +contained the metal character shapes) apart. Every time you change +font size, \LaTeX{} redefines the command \csx{strut} to provide the +equivalent of a metal-type strut for the size chosen. So for the +example above, we would type +\begin{quote} +\begin{verbatim} +Paragraph text ... + {\Huge A\strut} + ... paragraph continues ... +\end{verbatim} +\end{quote} +However, more extended insertions (whether of larger or smaller text) +are always going to cause problems; while you can strut larger text, +ensuring that you strut every line will be tiresome, and there's no +such thing as a ``negative strut'' that pulls the lines together for +smaller text. + +The only satisfactory way to deal with an extended insertion at a +different size is to set it off as a separate paragraph. A +satisfactory route to achieving this is the \environment{quote} +environment, which sets its text modestly inset from the enclosing +paragraph: +\begin{quote} +\begin{verbatim} +Paragraph text ... +\begin{quote} + \footnotesize This is an inset account + of something relevant to the enclosing + paragraph... +\end{quote} +... paragraph continues ... +\end{verbatim} +\end{quote} +Such quote-bracketing also deals with the problem of a trailing +comment on the paragraph. + +\Question[Q-tocloftwrong]{Numbers too large in table of contents, etc.} + +\LaTeX{} constructs the table of contents, list of figures, tables, +and similar tables, on the basis of a layout specified in the class. +As a result, they do \emph{not} react to the sizes of things in them, +as they would if a \environment{tabular} environment (or something +similar) was used. + +This arrangement can provoke problems, most commonly with deep section +nesting or very large page numbers: the numbers in question just don't +fit in the space allowed for them in the class. + +A separate answer discusses % ! line break +\nothtml{re-designing the tables ---} % ! line break +\Qref{re-designing the tables}{Q-tocloft}\nothtml{ ---} +and those techniques can be employed to make the numbers fit. + +\Question[Q-gutter]{Why is the inside margin so narrow?} + +If you give the standard classes the \pkgoption{twoside} option, the +class sets the margins narrow on the left of odd-numbered pages, and +on the right of even-numbered pages. This is often thought to look +odd, but it is quite right. + +The idea is that the typographic urge for symmetry should also apply +to margins: if you lay an even numbered page to the left of an +odd-numbered one, you will see that you've three equal chunks of +un-printed paper: the left margin of the even page, the right margin +of the odd page, and the two abutting margins together. + +This is all very fine in the abstract, but in practical book(let) +production it only works ``sometimes''. + +If your booklet is produced on double-width paper and stapled, the +effect will be good; if your book(let) is produced using a so-called +``perfect'' binding, the effect will again be good. + +However, almost any ``quality'' book-binder will need some of your +paper to grab hold of, and a book bound in such a way won't exhibit +the treasured symmetry unless you've done something about the margin +settings. + +The packages recommended in % ! line break +``\Qref*{setting up margins}{Q-marginpkgs}'' mostly have provision for +a ``binding offset'' or a ``binding correction''~--- search for +``binding'' in the manuals (\Package{vmargin} doesn't help, here). + +If you're doing the job by hand (see % ! line break +\Qref[question]{manual margin setup}{Q-marginmanual}), the trick is to +calculate your page and margin dimensions as normal, and then: +\begin{itemize} +\item subtract the binding offset from \csx{evensidemargin}, and +\item add the binding offset to \csx{oddsidemargin}. +\end{itemize} +which can be achieved by: +\begin{quote} +\begin{verbatim} +\addtolength{\evensidemargin}{-offset} +\addtolength{\oddsidemargin}{offset} +\end{verbatim} +\end{quote} +(substituting something sensible like ``\texttt{5mm}'' for +``\texttt{offset}'', above). + +The above may not be the best you can do: you may well choose to +change the \csx{textwidth} in the presence of the binding offset; but +the changes do work for constant \csx{textwidth}. + +\subsection{Why shouldn't I?} + +\Question[Q-t1enc]{Why use \Package{fontenc} rather than \Package{t1enc}?} + +In the very earliest days of \LaTeXe{}, the only way to use the +\acro{T}1 encoding was \Package{t1enc}; with the summer 1994 +``production'' release, the \Package{fontenc} package appeared, and +provided comprehensive support for use of the encoding. + +Nevertheless, the \Package{t1enc} package remains (as part of the +\LaTeXo{} compatibility code), but it does very little: it merely +selects font encoding \acro{T}1, and leaves to the user the business +of generating the character codes required. + +Generating such character codes could be a simple matter, \emph{if} +the \acro{T}1 encoding matched any widely-supported encoding standard, +since in that case, one might expect one's keyboard to generate the +character codes. However, the \acro{T}1 encoding is a mix of several +standard encodings, and includes code points in areas of the table +which standard encodings specifically exclude, so no \acro{T}1 +keyboards have been (or ever will be) manufactured. + +By contrast, the \Package{fontenc} package generates the \acro{T}1 +code points from ordinary \LaTeX{} commands (e.g., it generates the +\texttt{\'e} character codepoint from the command |\'|{}|e|). So, unless you +have program-generated \acro{T}1 input, use +\cmdinvoke{usepackage}[T1]{fontenc} rather than +\cmdinvoke{usepackage}{t1enc}. + +\Question[Q-why-inp-font]{Why bother with \Package{inputenc} and \Package{fontenc}?} + +The standard input encoding for Western Europe (pending the arrival of +Unicode) is \acro{ISO}~8859--1 (commonly known by the standard's +subtitle `Latin-1'). Latin-1 is remarkably close, in the codepoints +it covers, to the \AllTeX{} \acro{T}1 encoding. + +In this circumstance, why should one bother with \Package{inputenc} +and \Package{fontenc}? Since they're pretty exactly mirroring each +other, one could do away with both, and use just \Package{t1enc}, +despite its \Qref*{shortcomings}{Q-t1enc}. + +One doesn't do this for a variety of small reasons: +\begin{description} +\item[Confusion] You've been happily working in this mode, and for + some reason find you're to switch to writing in German: the effect + of using ``\texttt{\ss}'' is somewhat startling, since \acro{T}1 + and Latin-1 treat the codepoint differently. +\item[Compatibility] You find yourself needing to work with a + colleague in Eastern Europe: their keyboard is likely to be set to + produce Latin-2, so that the simple mapping doesn't work. +\item[Traditional \LaTeX{}] You lapse and write something like + |\'|{}|e| rather than typing \texttt{\'e}; only \Package{fontenc} + has the means to convert this \LaTeX{} sequence into the \acro{T}1 + character, so an \csx{accent} primitive slips through into the + output, and hyphenation is in danger. +\end{description} +The \Package{inputenc}--\Package{fontenc} combination seems slow and +cumbersome, but it's safe. + +\Question[Q-eqnarray]{Why not use \environment{eqnarray}?} + +The environment \environment{eqnarray} is attractive for the +occasional user of mathematics in \LaTeX{} documents: it seems to +allow aligned systems of equations. Indeed it \emph{does} supply such +things, but it makes a serious mess of spacing. In the system: +\begin{quote} +\begin{verbatim} +\begin{eqnarray} + a & = & b + c \\ + x & = & y - z +\end{eqnarray} +\end{verbatim} +\end{quote} +the spacing around the ``='' signs is \emph{not} that defined in the +metrics for the font from which the glyph comes~--- it's +\csx{arraycolsep}, which may be set to some very odd value for reasons +associated with real arrays elsewhere in the document. + +The user is far better served by the \AMSLaTeX{} bundle, which +provides an \environment{align} environment, which is designed with +the needs of mathematicians in mind (as opposed to the convenience of +\LaTeX{} programmers). For this simple case (align is capable of far +greater things), code as: +\begin{quote} +\begin{verbatim} +\begin{align} + a & = b + c \\ + x & = y - z +\end{align} +\end{verbatim} +\end{quote} +The matter is discussed in more detail in a % ! line break +\href{http://tug.org/pracjourn/2006-4/madsen/madsen.pdf}{Prac\TeX{} journal paper} +by Lars Madsen. +\begin{ctanrefs} +\item[AMSLaTeX]\CTANref{amslatex} +\end{ctanrefs} + +\Question[Q-dolldoll]{Why use \csx{[}\,\dots{}\csx{]} in place of \texttt{\$\$}\,\dots{}\texttt{\$\$}?} + +\LaTeX{} defines inline- and display-maths commands, apparently +s those that derive from the \TeX{} primitive maths +sequences bracketing maths commands with single (or pairs of) dollar signs. + +As it turns out, \LaTeX{}'s inline maths grouping, % !line break +\csx{(}\texttt{ ... }\csx{)}, has precisely the same effect as the +\TeX{} primitive version \texttt{\$ ... \$}. (Except that +the \LaTeX{} version checks to ensure you don't put \csx{(} and +\csx{)} the wrong way round.) + +In this circumstance, one often finds \LaTeX{} users, who have some +experience of using \plaintex{}, merely assuming that \LaTeX{}'s +display maths grouping \csx{[}\texttt{ ... }\csx{]} may be replaced by +the \TeX{} primitive display maths \texttt{\$\$ ... \$\$}. + +Unfortunately, they are wrong: if \LaTeX{} code is going to patch display +maths, it can only do so by patching \csx{[} and \csx{]}. The most +obvious way this turns up, is that the class option \pkgoption{fleqn} +simply does not work for equations coded using % ! line break +\texttt{\$\$ ... \$\$}, whether you're using the standard classes +alone, or using package \Package{amsmath}. Also, the \csx{[} and +\csx{]} construct has code for rationalising vertical spacing in some extreme +cases; that code is not available in \texttt{\$\$ ... \$\$}, so if you +use the non-standard version, you may occasionally observe +inconsistent vertical spacing . + +There are more subtle effects (especially with package +\Package{amsmath}), and the simple rule is ``use % ! line break +\csx{[}\texttt{ ... }\csx{]} whenever displayed maths is needed in +\LaTeX{}''. + +\Question[Q-2letterfontcmd]{What's wrong with \csx{bf}, \csx{it}, etc.?} + +The font-selection commands of \LaTeXo{} were \csx{rm}, \csx{sf}, +\csx{tt}, \csx{it}, \csx{sl}, \csx{em} and \csx{bf}; they were modal +commands, so you used them as: +\begin{quote} +\begin{verbatim} +{\bf Fred} was {\it here\/}}. +\end{verbatim} +\end{quote} +with the font change enclosed in a group, so as to limit its effect; +note the italic correction command \csx{/} that was necessary at the +end of a section in italics. + +At the release of \LaTeXe{} in summer 1994, these simple commands were +deprecated, but recognising that their use is deeply embedded in the +brains of \LaTeX{} users, the commands themselves remain in \LaTeX{}, +\emph{with their \LaTeXo{} semantics}. Those semantics were part of +the reason they were deprecated: each |\|\emph{\texttt{xx}} overrides +any other font settings, keeping only the size. So, for example, +\begin{quote} +\begin{verbatim} +{\bf\it Here we are again\/} +\end{verbatim} +\end{quote} +ignores \csx{bf} and produces text in italic, medium weight (and the +italic correction has a real effect), whereas +\begin{quote} +\begin{verbatim} +{\it\bf happy as can be\/} +\end{verbatim} +\end{quote} +ignore \csx{it} and produces upright text at bold weight (and the +italic correction has nothing to do). The same holds if you mix +\LaTeXe{} font selections with the old style commands: +\begin{quote} +\begin{verbatim} +\textbf{\tt all good friends} +\end{verbatim} +\end{quote} +ignores the \csx{textbf} that encloses the text, and produces +typewriter text at medium weight. + +So why are these commands deprecated?~--- it is because of confusions +such as that in the last example. The alternative (\LaTeXe{}) +commands are discussed in the rest of this answer. + +\LaTeXe{}'s font commands come in two forms: modal commands and +text-block commands. The default set of modal commands offers weights +\csx{mdseries} and \csx{bfseries}, shapes \csx{upshape}, +\csx{itshape}, \csx{scshape} and \csx{slshape}, and families +\csx{rmfamily}, \csx{sffamily} and \csx{ttfamily}. A font selection +requires a family, a shape and a series (as well as a size, of +course). A few examples +\begin{quote} +\begin{narrowversion} +\begin{verbatim} +{\bfseries\ttfamily + and jolly good company!} +\end{verbatim} +\end{narrowversion} +\begin{wideversion} +\begin{verbatim} +{\bfseries\ttfamily and jolly good company!} +\end{verbatim} +\end{wideversion} +\end{quote} +produces bold typewriter text (but note the lack of a % ! line break, big time +\begin{narrowversion} % non hyper version + bold typewriter font~--- \Qref{}{Q-bold-extras}~--- +\end{narrowversion} +\begin{wideversion} + \Qref{bold typewriter font}{Q-bold-extras} +\end{wideversion} +in the default Computer Modern fonts), or +\begin{quote} +\begin{narrowversion} +\begin{verbatim} +{\slshape\sffamily + Never mind the weather\/} +\end{verbatim} +\end{narrowversion} +\begin{wideversion} +\begin{verbatim} +{\slshape\sffamily Never mind the weather\/} +\end{verbatim} +\end{wideversion} +\end{quote} +(note the italic correction needed on slanted fonts, too). + +\LaTeXe{}'s text block commands take the first two letters of the +modal commands, and form a \csx{text}\emph{\texttt{xx}} command from +them. Thus \csx{bfseries} becomes \cmdinvoke*{textbf}{text}, +\csx{itshape} becomes \cmdinvoke*{textit}{text}, and \csx{ttfamily} +becomes \cmdinvoke*{texttt}{text}. Block commands may be nested, as: +\begin{quote} +\begin{verbatim} +\textit{\textbf{Never mind the rain}} +\end{verbatim} +\end{quote} +to produce bold italic text (note that the block commands supply +italic corrections where necessary), and they be nested with the +\LaTeXe{} modal commands, too: +\begin{quote} +\begin{narrowversion} +\begin{verbatim} +\texttt{\bfseries + So long as we're together} +\end{verbatim} +\end{narrowversion} +\begin{wideversion} +\begin{verbatim} +\texttt{\bfseries So long as we're together} +\end{verbatim} +\end{wideversion} +\end{quote} +for bold typewriter, or +\begin{quote} +\begin{narrowversion} +\begin{verbatim} +{\slshape\textbf{% + Whoops! she goes again}\/} +\end{verbatim} +\end{narrowversion} +\begin{wideversion} +\begin{verbatim} +{\slshape \textbf{Whoops! she goes again}\/} +\end{verbatim} +\end{wideversion} +\end{quote} +for a bold slanted instance of the current family (note the italic +correction applied at the end of the modal command group, again). + +The new commands (as noted above) override commands of the same type. +In almost all cases, this merely excludes ludicrous ideas such as +``upright slanted'' fonts, or ``teletype roman'' fonts. There are a +couple of immediate oddities, though. The first is the conflict +between \csx{itshape} (or \csx{slshape}) and \csx{scshape}: while many +claim that an italic small-caps font is typographically unsound, such +fonts do exist. Daniel Taupin's \Package{smallcap} package enables +use of the instances in the \Qref*{\acro{EC} fonts}{Q-ECfonts}, and +similar techniques could be brought to bear on many other font sets. +The second is the conflict between \csx{upshape} and \csx{itshape}: +Knuth actually offers an upright-italic font which \LaTeX{} uses for +the ``\pounds{}'' symbol in the default font set. The combination is +sufficiently weird that, while there's a defined font shape, no +default \LaTeX{} commands exist; to use the shape, the (eccentric) user +needs \LaTeX{}'s simplest font selection commands: +\begin{quote} +\begin{narrowversion} +\begin{verbatim} +{\fontshape{ui}\selectfont + Tra la la, di dee} +\end{verbatim} +\end{narrowversion} +\begin{wideversion} +\begin{verbatim} +{\fontshape{ui}\selectfont Tra la la, di dee} +\end{verbatim} +\end{wideversion} +\end{quote} +\begin{ctanrefs} +\item[smallcap.sty]\CTANref{smallcap} +\end{ctanrefs} + +\Question[Q-newfont*]{What's wrong with \csx{newfont}?} + +If all else fails, you \emph{can} specify a font using the \LaTeX{} +\csx{newfont} command. The font so specified doesn't fit into the +\LaTeX{} font selection mechanism, but the technique can be tempting +under several circumstances. The command is merely the thinnest of +wrappers around the \csx{font} primitive, and doesn't really fit with +\LaTeX{} at all. A simple, but really rather funny, example of the +problems it poses, may be seen in: +\begin{quote} +\begin{verbatim} +\documentclass[10pt]{article} +\begin{document} +\newfont{\myfont}{cmr17 scaled 2000} +\myfont +\LaTeX +\end{document} +\end{verbatim} +\end{quote} +(the reader is encouraged to try this). The ``A'' of \csx{LaTeX} pretty +much disappears: \LaTeX{} chooses the size on the ``A'' according to +\emph{its} idea of the font size (10pt), but positions it according to +the dimensions of ``\csx{myfont}'', which is more than three times +that size. + +Another ``\csx{myfont}'' example arises from an entirely different +source. The mini-document: +\begin{quote} +\begin{verbatim} +\documentclass{article} +\begin{document} +\newfont{\myfont}{ecrm1000} +{\myfont voil\`a} +\end{document} +\end{verbatim} +\end{quote} +gives you ``German low double quotes'' (under the ``a'') in place of +the grave accent. This happens because \FontName{ecrm1000} is in a +different \Qref*{font encoding}{Q-whatenc} than \LaTeX{} is +expecting~--- if you use the \LaTeX{} \Package{fontenc} package to +select the \acro{EC} fonts, all these tiresome encoding issues are +solved for you, behind the scenes. + +There does however remain a circumstance when you will be tempted to +use \csx{newfont}~--- viz., to get a font size that doesn't fall into +the Knuth standard set of sizes: \LaTeX{} (by default) won't allow you +to use such a size. Don't despair: see the answer % ! line break +``\Qref*{arbitrary font sizes}{Q-fontsize}''. + + |