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</div>
<div>
<p class="pubdate">$Date: 2002/08/23 14:31:13 $</p>
</div>
<hr class="component-separator" />
</div>
<div class="section">
<div class="titlepage">
<div>
<h2 class="title" style="clear: both"><a
id="sec.texforbeginners"
name="sec.texforbeginners"></a>What Is TeX?</h2>
</div>
</div>
<p>TeX<a id="id2856076" class="indexterm"
name="id2856076"></a><a id="id2855998" class="indexterm"
name="id2855998"></a> is a <span
class="emphasis"><em>typesetting system</em></span>. It is
a collection of programs, files, and procedures for
producing professional quality documents with minimum
effort.</p>
<p>TeX's job is to translate the text you type into a
beautiful<a id="id2856025" class="indexterm"
name="id2856025"></a> typeset page. The key word here is
“beautiful,” and it is a very lofty
goal.<sup>[<a id="id2856038" name="id2856038"
href="#ftn.id2856038">1</a>]</sup> What I mean by beautiful
is that TeX, when presented with several paragraphs of
plain text and left to its own devices, produces a
remarkably aesthetic page. Despite the fact that TeX may
have to contend with multiple fonts<a id="id2856069"
class="indexterm" name="id2856069"></a> and mathematics<a
id="id2857340" class="indexterm" name="id2857340"></a>, it
still manages to typeset pages in which each of the
following aesthetic principles hold <span
class="emphasis"><em>simultaneously:</em></span></p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>The right margin is justified<a id="id2857364"
class="indexterm" name="id2857364"></a>.</p>
</li>
<li>
<p>Proper justification is achieved without
letterspacing<a id="id2857382" class="indexterm"
name="id2857382"></a>.</p>
</li>
<li>
<p>Interword spacing is neither too tight nor too
loose.<a id="id2857400" class="indexterm"
name="id2857400"></a></p>
</li>
<li>
<p>The page is evenly gray.</p>
</li>
<li>
<p>The baselines<a id="id2857426" class="indexterm"
name="id2857426"></a><a id="id2857433"
class="indexterm" name="id2857433"></a> of multiple
fonts are properly aligned.</p>
</li>
<li>
<p>Hyphenation<a id="id2857454" class="indexterm"
name="id2857454"></a> is automatic, if required, and
usually correct.</p>
</li>
<li>
<p>Ladders<a id="id2857471" class="indexterm"
name="id2857471"></a> are avoided.</p>
</li>
</ul>
</div>
<p>TeX processes documents a paragraph at a time, rather
than a line at a time like most other programs. Internally,
TeX computes a value called <span
class="emphasis"><em>badness<a id="id2857492"
class="indexterm" name="id2857492"></a></em></span> for
each line of the paragraph<a id="id2857501"
class="indexterm" name="id2857501"></a>. Anything that
detracts from the appearance of a line (tight or loose
spacing, a hyphen, etc.) increases the badness associated
with that line. Every paragraph that TeX produces is
optimal in terms of the total amount of badness present.
Because TeX searches for an optimal solution, changing the
last word of a paragraph can affect the spacing of the
first line of the paragraph. After you've gained a little
bit of experience with TeX, you'll be able to override any
one, or all, of the rules it uses to compute badness, but
in most situations you won't want to. I will describe more
of TeX's approach to text formatting and how it differs
from that of word processors, desktop publishers, and other
markup languages in the following sections.</p>
<p>TeX is not a simple program, but a set of programs,
tools, fonts, and other types of files. Two programs form
the core of the TeX typesetting system. One of them is TeX
itself, the program that reads your input files and
transforms them into typeset form. The other program is
MetaFont, a tool for creating fonts. Producing TeX
documents involves a series of steps, including editing the
document, running TeX itself, and processing TeX's output
in various ways.</p>
<p>Over the years, TeX has been made available on almost
every computer platform<a id="id2857542" class="indexterm"
name="id2857542"></a>, so it is probably available for the
computer system that you use. Compiling TeX on different
systems has been possible, in large part, because TeX is a
text formatter and not a word processor. Unlike a word
processor, TeX never deals directly with displaying text on
the screen or interacting with input from the keyboard
(except in a very basic way). These features of an
application are typically the most difficult to port from
one system to another.</p>
<p>Beyond the technical details that make translation from
one system to another possible, Donald Knuth<a
id="id2857571" class="indexterm" name="id2857571"></a>
added an important stipulation to the free distribution of
TeX: in order for any program to be called
“TeX,” it must pass a rigorous test suite<a
id="id2857586" class="indexterm" name="id2857586"></a>.
This means that the TeX you use behaves exactly like the
TeX I use.<sup>[<a id="id2857595" name="id2857595"
href="#ftn.id2857595">2</a>]</sup> This feature has
contributed greatly to TeX's success. It means that a large
community of TeX users can transparently share<a
id="id2857615" class="indexterm" name="id2857615"></a>
documents.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h2 class="title" style="clear: both"><a id="id2857628"
name="id2857628"></a>TeX for Beginners</h2>
</div>
</div>
<p>If you are already familiar with TeX, you may find some
of the material in this section repetitive. If so, just
skim it quickly. This section will help you understand how
TeX interprets the things you type into your input file.
When you understand the concepts discussed here, you'll be
ready to write really, really simple documents in TeX.</p>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="sec.tex.controlsequences"
name="sec.tex.controlsequences"></a>Boxes and
Glue</h3>
</div>
</div>
<a id="boxes.start" class="indexterm"
name="boxes.start"></a>
<p>Despite the apparent complexity of TeX's job, it uses
a very simple metaphor: all typographic elements are
boxes<a id="id2857670" class="indexterm"
name="id2857670"></a>. The simplest boxes, individual
characters<a id="id2857681" class="indexterm"
name="id2857681"></a><a id="id2857691" class="indexterm"
name="id2857691"></a> have a set shape defined by the
font they come from. There are three parameters that
define a box: width<a id="id2857704" class="indexterm"
name="id2857704"></a><a id="id2857714" class="indexterm"
name="id2857714"></a>, height<a id="id2857725"
class="indexterm" name="id2857725"></a><a id="id2857735"
class="indexterm" name="id2857735"></a>, and depth<a
id="id2857744" class="indexterm" name="id2857744"></a><a
id="id2857754" class="indexterm" name="id2857754"></a>.
The distinction between height and depth is a bit subtle.
When a row of characters is typeset, every character
rests on an imaginary line called the <span
class="emphasis"><em>baseline</em></span>. Some
characters, like the lowercase “g,” descend
below the baseline<a id="id2857774" class="indexterm"
name="id2857774"></a>. The distance from the baseline to
the top of a box is its height; the distance from the
baseline to the bottom is its depth.</p>
<p>Figure <a href="ch01.html#fig.charbox"
title="Figure 1.1. The Letters g and h inside their boxes.">
Figure 1.1</a> shows the character boxes formed by
the Computer Modern<a id="id2857800" class="indexterm"
name="id2857800"></a> Roman letters “g” and
“h.” The <span
class="emphasis"><em>x-y</em></span> distance of each box
is its height and the <span
class="emphasis"><em>y-z</em></span> distance is its
depth. The <span class="emphasis"><em>reference
point</em></span><a id="id2857830" class="indexterm"
name="id2857830"></a> of the box, marked with an <span
class="emphasis"><em>r</em></span>, is on the leftmost
edge of the box where the height and depth meet.
Characters that have no <span
class="emphasis"><em>descenders<a id="id2857848"
class="indexterm" name="id2857848"></a></em></span> (no
elements that go below the baseline), have a depth of
zero. TeX uses the character box metrics, but font
designers are free to allow glyphs to extend outside the
box (for example, at the top of the “g”).</p>
<div class="figure">
<a id="fig.charbox" name="fig.charbox"></a>
<p class="title"><b>Figure 1.1. The Letters
“g” and “h” inside their
boxes.</b></p>
<div class="mediaobject">
<img src="figures/g-h.png"
alt="The Letters 'g' and 'h' inside their boxes" />
</div>
</div>
<p>The following paragraph demonstrates how TeX uses the
metrics from the physical dimensions of each character to
build word, line, and paragraph boxes.</p>
<p class="box">TeX “glues”<a id="id2857937"
class="indexterm" name="id2857937"></a> character boxes
together to form words. When boxes are joined, they are
always joined so their reference points are horizontally
aligned as shown in <a href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a>.<sup>[<a id="id2857956"
name="id2857956" href="#ftn.id2857956">3</a>]</sup>
Character-boxes (like <span class="box">t</span><span
class="box">h</span><span class="box">i</span><span
class="box">s</span>) are joined to form words,
word-boxes<a id="id2857992" class="indexterm"
name="id2857992"></a> (like <span
class="box">this</span>) are joined to form lines, and
line-boxes<a id="id2858011" class="indexterm"
name="id2858011"></a> form paragraphs. TeX accomplishes
the task of forming a justified paragraph by allowing the
glue between words to stretch<a id="id2858026"
class="indexterm" name="id2858026"></a> and shrink<a
id="id2858037" class="indexterm" name="id2858037"></a> a
little bit and by occasionally breaking the glue between
characters to insert a hyphen. Although the rules are
slightly different, TeX builds a page out of vertical
boxes (paragraphs, figures, etc.) in an analogous
manner.</p>
<p>This is a very generalized overview. In reality, a lot
of subtlety is required to capture all of the nuances of
typographical appearance.</p>
<a id="id2858059" class="indexterm" name="id2858059"></a>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2858068"
name="id2858068"></a>Control Sequences</h3>
</div>
</div>
<p>A <span class="emphasis"><em>control sequence<a
id="id2858081" class="indexterm"
name="id2858081"></a></em></span> is a special
“word” that you put in your document. These
extra words are instructions for TeX, and they do not
usually appear in your typeset document. Example <a
href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a> shows a contrived example of a TeX
document that uses several control sequences.</p>
<div class="example">
<a id="ex.csexample" name="ex.csexample"></a>
<p class="title"><b>Example 1.1. An Example
of a TeX Document</b></p>
<pre class="screen">
\def\ora{O'Reilly \& Associates}
\font\orafont=grlg10
\parskip=\baselineskip
\parindent=0pt
\pageno=5
This book is published by \ora in
the \textit{Nutshell} series.
\bye
</pre>
</div>
<p>In most macro packages, a control sequence is a
backslash followed by a sequence of letters.<sup>[<a
id="id2858135" name="id2858135"
href="#ftn.id2858135">4</a>]</sup> TeX is case-sensitive,
so the control sequence \large is different from \Large
(these control sequences switch to large and very large
fonts in the LaTeX macro package). Control sequences end
with the first non-letter, even if it isn't a space. For
example, \parskip0pt is the control sequence \parskip
followed by <tt>0pt</tt>. This control sequence tells TeX
to insert zero points of extra space between
paragraphs.</p>
<p>Unless instructed otherwise (with control sequences),
TeX builds rectangular paragraphs out of lines of words.
Changing fonts, building tables, and typesetting
mathematical equations<a id="id2858193" class="indexterm"
name="id2858193"></a> are examples of situations in your
document where TeX needs extra information.</p>
<p>The number of control sequences used in a TeX document
may seem overwhelming at first. Luckily, every control
sequence falls into one of several categories:</p>
<div class="variablelist">
<dl>
<dt><span class="term">Macro control
sequences</span></dt>
<dd>
<p>Macro control sequences<a id="id2858228"
class="indexterm" name="id2858228"></a> associate a
name with an arbitrary string of text (including
other control sequences). They are interpreted by
replacing the control sequence with the text of its
definition.<sup>[<a id="id2858243" name="id2858243"
href="#ftn.id2858243">5</a>]</sup></p>
<p>Macro control sequences are the root of TeX's
tremendous flexibility. By defining control
sequences with meaningful names, like \chapter and
\footnote, TeX can present a reasonably simple
interface to the user. By redefining those control
sequences, the typeset output can be modified
without requiring you to retype large quantities of
text.</p>
<p>In <a href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a>, the macro control sequence
\ora is defined as a shortcut for typing
“O'Reilly & Associates.” This is a
simple example of how a macro control sequence can
be used.</p>
</dd>
<dt><span class="term">Font control sequences<a
id="id2858301" class="indexterm"
name="id2858301"></a></span></dt>
<dd>
<p>In <a href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a>, the line \font\orafont=grlg10
creates a font control sequence called \orafont.
When \orafont is used, TeX will begin typesetting
in the font <tt>grlg10</tt>. The name of the font,
<tt>grlg10</tt> in this case, refers to an external
file that contains font metric information. Fonts
are discussed in Chapter <a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a>,
<span class="emphasis"><em><a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a></em></span>.</p>
</dd>
<dt><span class="term">Registers</span></dt>
<dd>
<p>Registers<a id="id2858391" class="indexterm"
name="id2858391"></a> are like variables in a
programming language. They hold a single value of a
particular type. Many types of values can be
stored: numbers (also called “count”
values because they are simple counting numbers
like 1, 2, 17, or -5), dimensions (also called
“lengths”; they are distances like
3.5pt or 2in), boxes, glue, and token lists (an
internal representation of your document used by
TeX).<sup>[<a id="id2858415" name="id2858415"
href="#ftn.id2858415">6</a>]</sup></p>
<p>If you are unfamiliar with computer programming,
think of these registers as place holders. When TeX
needs to save a piece of information, like how much
space should be inserted between paragraphs, it
stores the information in a register. When the
information is needed again, in this case when TeX
has finished typesetting one paragraph and is about
to start another, it can retrieve that information
from the register. Registers are usually given
names that at least hint at how they are used. This
helps people read and modify the rules that TeX
uses to typeset documents.</p>
<p>In Example <a href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a>, \parskip, \baselineskip, and
\parindent are dimension registers. The \pageno
control sequence is a count register.</p>
<p>There are only 256 registers of each type. The
type of information (number, dimension, or token
list) that a register can contain is defined when
the control sequence is created. Once a variable
like \parindent is created to hold a dimension, it
can never hold a number or a token list.<sup>[<a
id="id2858485" name="id2858485"
href="#ftn.id2858485">7</a>]</sup></p>
<p>Registers may seem unnecessary now that you know
about macro control sequences, which can store
arbitrary information. However, registers differ
from macro control sequences not only in the types
of values they can hold, but also in the types of
operations that can be performed on them. There is
a TeX command called \advance, for example, that
can increment the value stored in a register by an
arbitrary amount. You can't \advance a macro
control sequence.</p>
</dd>
<dt><span class="term">Built-in commands</span></dt>
<dd>
<p>A number of control<a id="id2858535"
class="indexterm" name="id2858535"></a> sequences
are built into TeX. These “primitive”
operations form the basis for all higher-level
functionality. There are a wide variety of control
sequences of this type. Everything that can be done
in TeX can be reduced to a sequence of primitive
operations.</p>
<p>There is no way to know, simply by inspection,
if a control sequence is one of the built-in
sequences or not. Luckily, it doesn't matter very
often; it really only matters when you are writing
complex macros.</p>
<p>The \font control sequence in <a
href="ch01.html#ex.csexample"
title="Example 1.1. An Example of a TeX Document">
Example 1.1</a> is a built-in control
sequence. So is \advance, mentioned above.</p>
</dd>
</dl>
</div>
<p>The number and kind of control sequences available
depends upon the macro package that you are using. (Macro
packages are discussed fully in Chapter <a
href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a>,
<span class="emphasis"><em><a href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a></em></span>.)
For the rest of this chapter, the default settings of
Plain TeX<a id="id2858616" class="indexterm"
name="id2858616"></a> are assumed.<sup>[<a id="id2858627"
name="id2858627" href="#ftn.id2858627">8</a>]</sup> There
are other macro packages, like LaTeX, Lollipop, and
TeXinfo, which have different default values.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="sec.textformVSwordproc"
name="sec.textformVSwordproc"></a>Special
Characters</h3>
</div>
</div>
<a id="id2858665" class="indexterm" name="id2858665"></a>
<p>In addition to control sequences, TeX reserves several
characters <a id="id2858675" class="indexterm"
name="id2858675"></a> for special purposes. Most of them
do not occur very frequently in ordinary text, but you
must be aware of them because there will be very
surprising consequences if you use them incorrectly.</p>
<p>Table <a href="ch01.html#tab.activechars"
title="Table 1.1. Special Characters in Plain TeX ">
Table 1.1</a> shows all of the special characters in
Plain TeX.<sup>[<a id="id2858704" name="id2858704"
href="#ftn.id2858704">9</a>]</sup> Most of these
characters are special in other macro packages as well.
Font-specific characters are not reserved by TeX, but
they don't produce the results you would expect when
typeset in Computer Modern because of the way TeX expects
fonts to be laid out. Fonts are discussed in detail in
Chapter <a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a>,
<span class="emphasis"><em><a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a></em></span>.</p>
<div class="table">
<a id="tab.activechars" name="tab.activechars"></a>
<p class="title"><b>Table 1.1. Special
Characters in Plain TeX <a id="id2858750"
class="indexterm" name="id2858750"></a></b></p>
<table
summary="Special Characters in Plain TeX charactersspecialtypesetting"
border="1">
<colgroup>
<col align="center" />
<col />
</colgroup>
<thead>
<tr>
<th align="center">Character</th>
<th>Meaning</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">#</td>
<td>Used for parameter definition in macros and
tables</td>
</tr>
<tr>
<td align="center">$</td>
<td>Toggles in and out of math mode</td>
</tr>
<tr>
<td align="center">%</td>
<td>A comment (TeX ignores everything to the end
of the line)</td>
</tr>
<tr>
<td align="center">&</td>
<td>The column separator in tables</td>
</tr>
<tr>
<td align="center">~</td>
<td>The active space (an unbreakable space)</td>
</tr>
<tr>
<td align="center">_</td>
<td>Marks a subscript (valid only in math
mode)</td>
</tr>
<tr>
<td align="center">^</td>
<td>Marks a superscript (valid only in math
mode)</td>
</tr>
<tr>
<td align="center">\</td>
<td>Begins a control sequence</td>
</tr>
<tr>
<td align="center">{</td>
<td>Begins a group</td>
</tr>
<tr>
<td align="center">}</td>
<td>Ends a group</td>
</tr>
<tr>
<td align="center">|</td>
<td>Produces an em-dash (—)
(font-specific)</td>
</tr>
<tr>
<td align="center"><</td>
<td>Produces an upside down exclamation mark (¡)
(font-specific)</td>
</tr>
<tr>
<td align="center">></td>
<td>Produces an upside down question mark (¿)
(font-specific)</td>
</tr>
<tr>
<td align="center">"</td>
<td>Incorrect for quoted text; use “ and
” instead (font-specific)</td>
</tr>
</tbody>
</table>
</div>
<p>It is best to avoid these characters until you are
familiar with TeX. If you need to typeset<a
id="id2859024" class="indexterm" name="id2859024"></a>
one of these characters, <a href="ch01.html#tab.acttype"
title="Table 1.2. How to Typeset Special Characters">
Table 1.2</a> shows what to put in your document.
You should also avoid characters outside the standard
printable ASCII character set<a id="id2859048"
class="indexterm" name="id2859048"></a> (characters with
ASCII values below 32 and above 126). TeX can be
configured to accept characters outside the printable
ASCII range, to support non-English languages, for
example, but it is not configured to do so “out of
the box.” Chapter <a href="ch07.html"
title="Chapter 7. International Considerations">
Chapter 7</a>, <span class="emphasis"><em><a
href="ch07.html"
title="Chapter 7. International Considerations">
Chapter 7</a></em></span>, discusses the issues of
typesetting in different languages.</p>
<div class="table">
<a id="tab.acttype" name="tab.acttype"></a>
<p class="title"><b>Table 1.2. How to Typeset
Special Characters<a id="id2859097" class="indexterm"
name="id2859097"></a></b></p>
<table
summary="How to Typeset Special Charactersspecial characterstypesetting"
border="1">
<colgroup>
<col align="center" />
<col />
</colgroup>
<thead>
<tr>
<th align="center">To Get</th>
<th>Put This in Your Document</th>
</tr>
</thead>
<tbody>
<tr>
<td align="center">#</td>
<td>\#</td>
</tr>
<tr>
<td align="center">$</td>
<td>\$</td>
</tr>
<tr>
<td align="center">%</td>
<td>\%</td>
</tr>
<tr>
<td align="center">&</td>
<td>\&</td>
</tr>
<tr>
<td align="center">“</td>
<td>``</td>
</tr>
<tr>
<td align="center">”</td>
<td>''</td>
</tr>
<tr>
<td align="center">~</td>
<td>\~</td>
</tr>
<tr>
<td align="center">{</td>
<td>$\{$</td>
</tr>
<tr>
<td align="center">}</td>
<td>$\}$</td>
</tr>
<tr>
<td align="center"><</td>
<td>$<$</td>
</tr>
<tr>
<td align="center">></td>
<td>$>$</td>
</tr>
<tr>
<td align="center">|</td>
<td>$|$</td>
</tr>
<tr>
<td align="center">_</td>
<td>$\underbar{\hbox{\ }}$</td>
</tr>
<tr>
<td align="center">^</td>
<td>$\hat{\hbox{ }}$</td>
</tr>
<tr>
<td align="center">\</td>
<td>$\backslash$</td>
</tr>
</tbody>
</table>
</div>
<div class="sidebar">
<p>Some of the suggestions in <a
href="ch01.html#tab.acttype"
title="Table 1.2. How to Typeset Special Characters">
Table 1.2</a> will not always produce exactly what
you want. The entry for “~” really produces
a tilde accent, not a tilde character and the entries
for “{” through “\” all get the
actual characters from TeX's math fonts. The Computer
Modern text fonts don't include these characters so it
is necessary to get them from the math fonts. However,
if you are using PostScript or other kinds of fonts,
you may very well have curly braces, angle brackets,
underscores, etc. in the font. You can access these
characters directly with the \char primitive. I
strongly recommend that you always define macros for
this purpose, so that you can easily switch to some
other method if you change fonts. Introducing \char
primitives makes your document less portable. To use
the \char primitive, simply put the decimal ASCII value
of the character that you want to print. For example,
this book is typeset with PostScript fonts that include
a backslash character at position 92, so I defined \bs
to print a backslash like this:</p>
<pre class="screen">
\def\bs{\char92\relax}
</pre>
<p>Using \relax after the decimal value assures that
TeX won't get confused if I put a backslash in front of
other digits like this \bs300dpi.</p>
</div>
<p>The braces<a id="id2859474" class="indexterm"
name="id2859474"></a> “{” and “}”
are a very special case. TeX uses curly braces to delimit
arguments and make changes (like switching fonts) that
are local to a small section of the document. These are
called <span class="emphasis"><em>grouping characters<a
id="id2859497" class="indexterm"
name="id2859497"></a></em></span><a id="id2859504"
class="indexterm" name="id2859504"></a> in TeX jargon.
For example, to typeset a single word in boldface, you
put {\bf word} into your input file. The \bf control
sequence switches to boldface type, and the curly braces
localize the effect to the single word <span
class="bold">word</span>. As a result, it is very
important that you avoid braces (except when you use them
as delimiters) and that you carefully match all opening
and closing braces. One of the most common errors in TeX
is to forget a closing brace.</p>
<p>One last special character is the blank space<a
id="id2859543" class="indexterm" name="id2859543"></a>.
For the most part, TeX doesn't care how you space your
lines of text. Any space that occurs is simply a word
break to TeX, and inserting multiple spaces doesn't
influence how TeX typesets the line. TeX also considers
the end of a line an implicit space. If you are trying to
control the layout of your input text and want to break a
line without introducing a space, place a comment
character (% in most macro packages)<a id="id2859552"
class="indexterm" name="id2859552"></a> at the very end
of the line. If the last character of a line is the
comment character, TeX ignores the line break and all the
leading spaces on the following line. This allows you to
use indentation<a id="id2859574" class="indexterm"
name="id2859574"></a> to make your input file more
readable. \goodbreak</p>
<p>For example, the following lines in your input
file:</p>
<pre class="screen">
“This is some ex
ample text.”
</pre>
<p>and this line:</p>
<pre class="screen">
“This is some example text.”
</pre>
<p>both produce:</p>
<div class="literallayout">
<p>
“This is some example text.”</p>
</div>
<p>in your typeset document.</p>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h2 class="title" style="clear: both"><a id="id2859644"
name="id2859644"></a>Text Formatting Versus Word
Processing</h2>
</div>
</div>
<p>For many people, writing documents with a computer
implies using a word processor like WordPerfect<a
id="id2859660" class="indexterm" name="id2859660"></a> or
Microsoft Word<a id="id2859674" class="indexterm"
name="id2859674"></a>.<a id="id2859683" class="indexterm"
name="id2859683"></a><a id="id2859696" class="indexterm"
name="id2859696"></a> The word processing program controls
every aspect of what you do: it's where you type your text,
where you see what it will look like, where you print, and
where you do everything else. Some of these environments,
the so-called WYSIWYG<a id="id2859715" class="indexterm"
name="id2859715"></a> (what-you-see-is-what-you-get)
programs, attempt to show you what the printed document
will actually look like <span
class="emphasis"><em>while</em></span> you edit it.<sup>[<a
id="id2859730" name="id2859730"
href="#ftn.id2859730">10</a>]</sup></p>
<p>If WYSIWYG environments are what you're used to, or what
you expect, TeX's approach may seem very strange at first
because TeX is a <span class="emphasis"><em>text
formatter</em></span>,<a id="id2859754" class="indexterm"
name="id2859754"></a><a id="id2859767" class="indexterm"
name="id2859767"></a> not a word processor. Instead of
trying to show you what your document will look like while
you type, TeX expects you to do all the typing somewhere
else, and then pass it a source file containing all of your
text plus control sequences that tell TeX how you'd like it
printed.</p>
<p>In <span class="emphasis"><em>The Psychology of Everyday
Things</em></span> [<a
href="bi01.html#dn:psyeveryday">dn:psyeveryday</a>], Donald
Norman<a id="id2859798" class="indexterm"
name="id2859798"></a> describes these two modes of
interaction as first person and third person. First person
interaction provides the user with the ability to directly
manipulate the elements of a task, whether it's flying an
airplane or resizing text. Third person interaction, on the
other hand, occurs where the user is expected to type
commands to the computer in an appropriate command
language; the shell prompt is a good example of third
person interaction.</p>
<p>Is first person interaction really better? Well, it
depends. Norman writes, “Although they [WYSIWYG
environments] are often easy to use, fun, and entertaining,
it is often difficult to do a really good job with
them.” The problem which arises is that the user is
required to do the task, and he or she may not be very good
at it. Third person systems are better when the computer
program can be trusted to do a better job of the task than
the user.</p>
<p>Is TeX really better than a word processor? Well, it
depends on the task and the person doing it. TeX probably
isn't better for designing one page flyers with lots of
fonts and graphics (although I've done it). But for longer
documents, TeX offers all of these advantages:</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>TeX has a precise understanding of the rules of
typesetting,<a id="id2859861" class="indexterm"
name="id2859861"></a> so you don't have to.</p>
</li>
<li>
<p>Predefined styles allow experts to extend (or
bend) the rules of typesetting without burdening the
user.</p>
</li>
<li>
<p>Journals and magazines can achieve consistency of
appearance much more reliably because the consistency
is in the style files.</p>
</li>
<li>
<p>TeX runs on cheap systems (old PCs with monochrome
monitors and no graphics capability, for
example).</p>
</li>
<li>
<p>Although complex and difficult to learn, TeX
offers incredibly flexible table construction
tools.</p>
</li>
<li>
<p>Few, if any, word processors can provide running
headers and footers as flexibly as TeX. Imagine the
task of writing a dictionary: the left and right hand
side headers change on each page, each time a new
entry is added.</p>
</li>
<li>
<p>TeX offers flexible bibliography layouts.</p>
</li>
<li>
<p>TeX is extensible.<a id="id2859945"
class="indexterm" name="id2859945"></a> Its behavior
can be modified by defining new commands and
environments without changing the actual program.</p>
</li>
</ul>
</div>
<p>There are some other good reasons to separate document
creation from text formatting:</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>Documents are portable.<a id="id2859978"
class="indexterm" name="id2859978"></a> Because the
source files are just plain text without any
nonprintable characters, they can easily be copied
from one system to another.</p>
</li>
<li>
<p>TeX is portable. TeX runs everywhere. You can
process your documents with TeX on unix workstations;
personal computers running MS-DOS, OS/2, and Windows;
IBM mainframes running VM/CMS; workstations running
VAX/VMS; Macintoshes; Amigas; Ataris; and just about
every other computer with a reasonable amount of
memory. And the typeset output will be the same! This
adds another dimension of portability to your
documents.</p>
</li>
<li>
<p>TeX is free. You can afford to have it on every
system you use. Several sources of TeX software are
listed in the preface of this book.</p>
</li>
<li>
<p>TeX allows you to separate markup and output.
Logical divisions in the text (chapters, sections,
itemized lists, etc.) are identified by control
sequences. An entirely different page layout can
result from simply changing the definition of a few
control sequences.</p>
<p>This means that the look of your documents can be
changed (to fit the style guidelines of a particular
journal or publisher, for example) without changing
the text of your documents at all.</p>
</li>
<li>
<p>Plain text files are easier to manipulate with
other tools than specially encoded word processor
files are. This means that you can use standard
utilities on your documents: revision control, grep,
shell scripts, etc. This is a less common practice in
non-unix environments, but it is still
convenient.</p>
</li>
<li>
<p>You can continue to use your favorite editing
tools. The extent to which you find this advantageous
is dependent, naturally, on the extent to which you
have a favorite editing program. Nevertheless, this
can be a considerable advantage. For example, users
familiar with <b>emacs</b><a id="id2860077"
class="indexterm" name="id2860077"></a> can continue
to rely on all of the features they are used to,
including interactive spellchecking, access to online
services like Webster's dictionary, customized editor
macros, and convenient services like reading
mail.</p>
</li>
<li>
<p>You get better looking output. TeX gives you far
more precise control over the placement of elements
on the page than most word processing programs. And
TeX is very intelligent about typesetting (paragraph
breaking, kerning<a id="id2860098" class="indexterm"
name="id2860098"></a>, ligatures<a id="id2860112"
class="indexterm" name="id2860112"></a>, etc.).</p>
</li>
</ul>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="sec.howtexworks"
name="sec.howtexworks"></a>What About Desktop
Publishing?</h3>
</div>
</div>
<p>Desktop publishing systems<a id="id2860137"
class="indexterm" name="id2860137"></a><a id="id2860150"
class="indexterm" name="id2860150"></a> like Ventura
Publisher<a id="id2860171" class="indexterm"
name="id2860171"></a> and Aldus PageMaker<a
id="id2860185" class="indexterm" name="id2860185"></a>
are noted for their ability to incorporate multiple fonts
and graphics into a document. As word processors become
more sophisticated, the line between word processing and
desktop publishing is becoming blurry.</p>
<p>This book shows you many ways that TeX can provide
access to the same sophisticated features. TeX can
incorporate pictures and figures in a number of ways
(just take a look at the way I've wrapped text around
this kiwi),<sup>[<a id="id2860201" name="id2860201"
href="#ftn.id2860201">11</a>]</sup> and TeX can use
almost any font that another program can use---it can
certainly use <span class="emphasis"><em>all</em></span>
of the popular types of fonts. Like typical word
processors, desktop publishing programs force you to use
a single application to create your entire document, and
they lack the flexibility required to combine just the
pieces that you want. All of the advantages of text
formatting over word processing also apply to desktop
publishing programs. I'll grant, however, that WYSIWYG
environments are easier for first-time users. But that
doesn't make them better, it just makes them more
popular.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2860232"
name="id2860232"></a>What About troff?</h3>
</div>
</div>
<p><b>troff</b><a id="id2860245" class="indexterm"
name="id2860245"></a> <a id="id2860259" class="indexterm"
name="id2860259"></a> is the “other” text
formatting system. If you've ever tried to read a unix
reference page without formatting it first, you've seen
<b>troff</b>. For a long time it was distributed as part
of all unix systems. Now it is more likely an extra-cost
option. The Free Software Foundation's <a id="id2860290"
class="indexterm" name="id2860290"></a><b>groff</b><a
id="id2860303" class="indexterm" name="id2860303"></a>
processor is a free, <b>troff</b>-compatible system.</p>
<p>On the surface, it is easier to compare TeX and troff
than to compare TeX to the other document preparation
systems described in this chapter. In reality, the
differences are subtle: TeX and troff have the same
general paradigm; they are equally powerful to a large
extent, and both have advantages and disadvantages.</p>
<p><b>troff</b> is similar to TeX in many ways. Like TeX,
troff processes a plain text file and produces a typeset
document. TeX and troff differ in the way that formatting
information is inserted into the text. TeX uses control
sequences<a id="id2860356" class="indexterm"
name="id2860356"></a>, where troff uses a mixture of
control sequences<sup>[<a id="id2860372" name="id2860372"
href="#ftn.id2860372">12</a>]</sup> and “dot”
commands (lines of text that begin with a period and
contain typesetting commands).</p>
<p>Although I am inclined to say that troff documents are
far more cryptic than TeX documents, I am certain that
there are plenty of troff users who would disagree
(strongly).</p>
<p>Objectively, TeX handles mathematical typesetting<a
id="id2860407" class="indexterm" name="id2860407"></a>
far better than troff and probably has better support for
multilingual documents<a id="id2860424" class="indexterm"
name="id2860424"></a><a id="id2860434" class="indexterm"
name="id2860434"></a>. The <b>nroff</b><a id="id2860451"
class="indexterm" name="id2860451"></a> processor, which
produces plain text output from a troff document, at one
time provided a strong argument in favor of troff for
typesetting documents required in both typeset and plain
text formats. However, the TeXinfo<a id="id2860469"
class="indexterm" name="id2860469"></a> macro package for
TeX has largely defeated that argument. In troff's
defense, TeXinfo is very, very different from other TeX
macro packages, so it really is necessary to plan ahead
and learn a very different set of macros to typeset both
plain text and typeset documents with TeXinfo.
Chapter <a href="ch10.html"
title="Chapter 10. Online Documentation">Chapter 10</a>,
<span class="emphasis"><em><a href="ch10.html"
title="Chapter 10. Online Documentation">Chapter 10</a></em></span>,
discusses this issue further.</p>
<p>In my experience, there is more free support for TeX
than troff. TeX is supported by a large community of
users actively producing new, useful document-preparation
formats, styles, and tools. In addition, TeX is more
widely available than troff: a TeX port exists for almost
every practical computer system, whereas troff is still
mostly confined to unix systems (although the Free
Software Foundation's <b>groff</b> package has been
ported to similar systems like MS-DOS, Windows NT, and
OS/2).</p>
<p>The following fragments show a side-by-side comparison
of TeX commands, on the left, and troff commands, on the
right:</p>
<pre class="screen">
\begin{figure} .(z
\begin{center} .hl
\hrule Text to be floated.
\vspace{8pt} .sp
Text to be floated. .ce
\hrule .hl
\caption{Example figure...} Figure \*[fig]: Example figure...
\vspace{8pt} .)z
\end{center}
\end{figure}
</pre>
<p>Both examples produce a floating figure that looks
like this:</p>
<div class="figure">
<a id="id2860574" name="id2860574"></a>
<p class="title"><b>Figure 1.2. Example
figure produced by both TeX and troff</b></p>
<div class="informaltable">
<table width="100%" border="1">
<colgroup>
<col />
</colgroup>
<tbody>
<tr>
<td>Text to be floated.</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2860619"
name="id2860619"></a>What About SGML?</h3>
</div>
</div>
<p>The Standard Generalized Markup Language (SGML)<a
id="id2860629" class="indexterm" name="id2860629"></a> is
a document description language. SGML aims to separate
the content of a document from its presentation. In other
words, SGML identifies the features of a document
(chapter headings, paragraphs, etc.) without specifying
how they are to be presented.</p>
<p>This means that all SGML documents must interact with
a document formatter of some sort. Many people are
finding that TeX is a natural choice when selecting a
document formatter for their SGML environment. In fact,
LaTeX<a id="id2860647" class="indexterm"
name="id2860647"></a> already provides many SGML-like
commands because it was designed to separate markup from
presentation. One of the specific goals of an effort
(currently underway) to develop a new version of LaTeX is
to make SGML and LaTeX work together easily, cleanly, and
efficiently. For more information about the goals of this
project and information about what you can do to help,
please read <span class="emphasis"><em>The LaTeX3
Project</em></span> [<a
href="bi01.html#l3:project">l3:project</a>].</p>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h2 class="title" style="clear: both"><a id="id2860690"
name="id2860690"></a>How TeX Works</h2>
</div>
</div>
<p>A functioning TeX system<a id="id2860698"
class="indexterm" name="id2860698"></a> in which you are
producing documents of medium size and complexity is really
a collection of tools and files that are related to each
other in well defined (if somewhat subtle) ways.</p>
<p>One of the fundamental goals of this book is to shed
light on these relationships and allow you to put together
a TeX system that quickly and easily does the jobs you need
to accomplish.</p>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="subsubsec.runningtex"
name="subsubsec.runningtex"></a>TeXing a Simple
Document</h3>
</div>
</div>
<p>This section briefly describes what you need to know
about how TeX processes a simple document (that is, one
that does not contain complex document elements like a
table of contents, indexes, bibliographies, etc.).
Figure <a href="ch01.html#fig.wholesimple"
title="Figure 1.3. A high-level view of TeX">Figure 1.3</a>
shows how the standard TeX tools fit together at the most
basic level.</p>
<div class="figure">
<a id="fig.wholesimple" name="fig.wholesimple"></a>
<p class="title"><b>Figure 1.3. A high-level
view of TeX</b></p>
<div class="mediaobject">
<img src="figures/tex.01.03.png" />
</div>
</div>
<p>Figure <a href="ch01.html#fig.wholething"
title="Figure 1.4. High-level view of TeX including more detail">
Figure 1.4</a> expands on Figure <a
href="ch01.html#fig.wholesimple"
title="Figure 1.3. A high-level view of TeX">Figure 1.3</a>,
showing additional tools and files that you'll often need
to use.</p>
<div class="figure">
<a id="fig.wholething" name="fig.wholething"></a>
<p class="title"><b>Figure 1.4. High-level
view of TeX including more detail</b></p>
<div class="mediaobject">
<img src="figures/tex.01.04.png" />
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h4 class="title"><a id="id2860862"
name="id2860862"></a>Editing your document</h4>
</div>
</div>
<p>The most tangible and important part of your TeX
system is your document<a id="id2860872"
class="indexterm" name="id2860872"></a>. This is the
file (or files) in which you write down what you want
to typeset with TeX. In addition to the actual text,
you include control sequences to describe how you want
the final text to appear (size, font, justification,
etc.). The section “<a
href="ch01.html#sec.texforbeginners"
title="What Is TeX?">the section called “What Is
TeX?”</a>” earlier in this chapter tells
you briefly what goes into your document file.</p>
<p>The most common way to create a document is with an
editor<a id="id2860909" class="indexterm"
name="id2860909"></a><a id="id2860916"
class="indexterm" name="id2860916"></a><a
id="id2860926" class="indexterm" name="id2860926"></a>,
which can provide you with a number of features to make
typing TeX documents easier. For example, an editor can
help you insert common control sequences<a
id="id2860940" class="indexterm" name="id2860940"></a>
automatically, run TeX automatically (from within the
editor), and keep you from making common mistakes (like
typing a left brace, but not the matching right one).
These features and how they work in editors including
GNU Emacs, aucTeX, and Multi-Edit are described in
Chapter <a href="ch02.html"
title="Chapter 2. Editing">Chapter 2</a>,
<span class="emphasis"><em><a href="ch02.html"
title="Chapter 2. Editing">Chapter 2</a></em></span>.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h4 class="title"><a id="id2860982"
name="id2860982"></a>Running TeX</h4>
</div>
</div>
<p>Once you have prepared your document file, it is
time to run<a id="id2860991" class="indexterm"
name="id2860991"></a><a id="id2861001"
class="indexterm" name="id2861001"></a> the TeX program
itself. This may not be as easy as it sounds. You need
to determine the name of the TeX program at your site,
to make sure all of the files TeX needs are available
to it; you also need to specify the correct
command-line options. Chapter <a href="ch03.html"
title="Chapter 3. Running TeX">Chapter 3</a>,
<span class="emphasis"><em><a href="ch03.html"
title="Chapter 3. Running TeX">Chapter 3</a></em></span>,
describes everything you need to know.</p>
<p>TeX may find errors in your document (places where
TeX doesn't understand the instructions you used; not
spelling or grammatical errors, unfortunately ;-).
Chapter <a href="ch03.html"
title="Chapter 3. Running TeX">Chapter 3</a>
also describes the most common errors you're likely to
make and gives advice for interpreting error
messages.</p>
<p>If TeX is successful in formatting your document
(i.e., your document doesn't contain any errors), it
produces a <tt>DVI</tt> (DeVice Independent)<a
id="id2861075" class="indexterm" name="id2861075"></a>
file. The <tt>DVI</tt> file is a device-independent
representation of the typeset output of your document.
<tt>DVI</tt> files are transitory. Although there are a
few programs that can manipulate them (to rearrange the
order of the pages in the output, for example), most of
the time you will immediately transform them into
something else---either printed output or previewed
output on the screen. (See the following section
“<a href="ch01.html#subsubsec.printpreview"
title="Using macros">the section called “Using
macros”</a>.”)</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h4 class="title"><a id="subsubsec.printpreview"
name="subsubsec.printpreview"></a>Using macros</h4>
</div>
</div>
<p>The control sequences<a id="id2861139"
class="indexterm" name="id2861139"></a> that you insert
in your document are defined by a macro package<a
id="id2861152" class="indexterm"
name="id2861152"></a>.<sup>[<a id="id2861160"
name="id2861160" href="#ftn.id2861160">13</a>]</sup>
Macro packages are collections of TeX commands (macros)
that extend TeX. Macro packages are frequently stored
in format files, specially compiled versions of the
macro package. The iniTeX<a id="id2861169"
class="indexterm" name="id2861169"></a> program
interprets all of the control sequences in a macro
package to create a format file that TeX reads when it
runs.</p>
<p>Many macro packages are particularly effective in
implementing particular document styles or supporting
particular types of writing. Two of the most common are
Plain TeX<a id="id2861194" class="indexterm"
name="id2861194"></a> and LaTeX<a id="id2861205"
class="indexterm" name="id2861205"></a>.
Chapter <a href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a>,
<span class="emphasis"><em><a href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a></em></span>,
describes Plain TeX, LaTeX, and a number of other macro
packages that extend the power and ease of TeX.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h4 class="title"><a id="id2861241"
name="id2861241"></a>Using fonts</h4>
</div>
</div>
<p>One of TeX's strengths is its support for a myriad
of predefined fonts<a id="id2861249" class="indexterm"
name="id2861249"></a> and its ability to let you create
fonts of your own. In addition to your document and the
format file, when TeX runs it needs font information as
well. This is provided in the form of a set of
<tt>TFM</tt> (TeX Font Metric)<a id="id2861277"
class="indexterm" name="id2861277"></a> files that tell
TeX the size and shape (roughly speaking, at least) of
each character, as well as some other information about
how characters are related to each other.</p>
<p>Historically, the MetaFont<a id="id2861292"
class="indexterm" name="id2861292"></a> program was the
way a TeX user created fonts. Like TeX itself, MetaFont
is about ten years old. Ten years ago, it was a unique
program that was indispensible for creating the type of
output TeX produces. Today there are many competing
font technologies, all of them more common than
MetaFont, and MetaFont's role is diminishing. Many
people use TeX today without ever using MetaFont at
all. Nevertheless, MetaFont still has some importance,
and we describe how to run and use it in
Chapter <a href="ch11.html"
title="Chapter 11. Introducing MetaFont">Chapter 11</a>,
<span class="emphasis"><em><a href="ch11.html"
title="Chapter 11. Introducing MetaFont">Chapter 11</a></em></span>.
Because the standard fonts that come with TeX are still
the fonts produced by MetaFont, it will also be
mentioned elsewhere in this book.</p>
<p>If you are writing complex documents, you may need
to learn a lot about fonts and how to define and use
them. Chapter <a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a>,
<span class="emphasis"><em><a href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a></em></span>,
tells you everything you need to know, including
information about the New Font Selection Scheme, a new
way of describing and selecting fonts in TeX.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h4 class="title"><a id="id2861369"
name="id2861369"></a>Previewing or printing TeX
documents</h4>
</div>
</div>
<p>After you have produced a <tt>DVI</tt> file, as
described in the section “<a
href="ch01.html#subsubsec.runningtex"
title="TeXing a Simple Document">the section called
“TeXing a Simple Document”</a>,”
later in this chapter, you run another program
(generically called a DVI driver)<a id="id2861405"
class="indexterm" name="id2861405"></a> to translate
the <tt>DVI</tt> file so you can either preview or
print your document. Driver programs need your
<tt>DVI</tt> file and some collection of fonts (usually
<tt>PK</tt> (packed)<a id="id2861442" class="indexterm"
name="id2861442"></a><a id="id2861461"
class="indexterm" name="id2861461"></a><a
id="id2861469" class="indexterm" name="id2861469"></a>
font files).<sup>[<a id="id2861489" name="id2861489"
href="#ftn.id2861489">14</a>]</sup> Many different
kinds of fonts are described in Chapter <a
href="ch05.html"
title="Chapter 5. Fonts">Chapter 5</a>.</p>
<p>Chapter <a href="ch08.html"
title="Chapter 8. Printing">Chapter 8</a>,
<span class="emphasis"><em><a href="ch08.html"
title="Chapter 8. Printing">Chapter 8</a></em></span>,
tells you how to print<a id="id2861540"
class="indexterm" name="id2861540"></a><a
id="id2861546" class="indexterm" name="id2861546"></a>
your documents and deal with the problems you may
encounter using bitmapped or scalable fonts, printing
pictures and figures, and other printing issues.</p>
<p>Often you will want to look at your document before
you actually print it. Because TeX is not a WYSIWYG
system,<sup>[<a id="id2861567" name="id2861567"
href="#ftn.id2861567">15</a>]</sup> you cannot do this
until you have processed the <tt>DVI</tt> file. There
are a number of good previewing products<a
id="id2861597" class="indexterm"
name="id2861597"></a><a id="id2861603"
class="indexterm" name="id2861603"></a>, including
xdvi<a id="id2861617" class="indexterm"
name="id2861617"></a>, <b>dvimswin</b><a id="id2861634"
class="indexterm" name="id2861634"></a>, and
<b>dviscr</b><a id="id2861648" class="indexterm"
name="id2861648"></a>, that let you look at your
processed document on the screen before you decide
whether to print it. See Chapter <a
href="ch09.html"
title="Chapter 9. Previewing">Chapter 9</a>,
<span class="emphasis"><em><a href="ch09.html"
title="Chapter 9. Previewing">Chapter 9</a></em></span>,
for complete information.</p>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2861683"
name="id2861683"></a>TeXing More Complex
Documents</h3>
</div>
</div>
<p>This section briefly describes how TeX processes a
more complex document (that is, one that includes
elements like a table of contents, indexes,
bibliographies, etc.).</p>
<p>Many TeX formats implement sophisticated
cross-referencing schemes. Cross references<a
id="id2861700" class="indexterm" name="id2861700"></a>
may sound rather esoteric, but they occur frequently.
Tables of contents, figure and table numbers, indexes,
and bibliographic references are all flavors of cross
referencing.</p>
<p>Cross references make your document more complex
because they require more information than is immediately
available when TeX initially processes your document. For
example, if you refer to a figure which occurs later in
the document, TeX has no way of knowing what figure
number to insert into the text at the point of the
reference. These are called <span
class="emphasis"><em>forward references</em></span><a
id="id2861726" class="indexterm"
name="id2861726"></a>.</p>
<p>TeX macro packages that support cross referencing
overcome the difficulty of forward references by
requiring you to process your document more than once.
Each time your document is processed, the necessary
reference information is stored into a separate file. If
that file exists when you process your document, the
information saved <span class="emphasis"><em>last
time</em></span> is loaded so that it is available <span
class="emphasis"><em>this time</em></span>. The practical
implication of this functionality is that documents with
cross references frequently have to be processed twice.
Occasionally, you may have to process a document three
times. This occurs when the inserted reference causes TeX
to format a paragraph differently, which in turn causes
TeX to change a page break.<sup>[<a id="id2861760"
name="id2861760" href="#ftn.id2861760">16</a>]</sup>
Because most changes are incremental while revising a
document, this is normally only an issue the first time
you process a document.</p>
<p>The following sections describe the LaTeX methods for
constructing a table of contents, figure references, an
index, and a bibliography. LaTeX is used in this example
because it is a very common macro package and is typical
of the way macro packages provide these features. Similar
mechanisms exist in most formats, except Plain TeX.</p>
<p>Figure <a href="ch01.html#fig.texcmplx"
title="Figure 1.5. TeXing a More Complex Document">
Figure 1.5</a> shows the relationships between many
of the components described in the following sections.
LaTeX creates several sorts of auxiliary files depending
on the kind of cross references required by your document
and the style files you use. These auxiliary files may be
modified (and others may be created) by other sorts of
post-processing programs (like <b>MakeIndex</b><a
id="id2861811" class="indexterm" name="id2861811"></a>
for constructing indexes or BibTeX<a id="id2861819"
class="indexterm" name="id2861819"></a> for constructing
bibliographies). LaTeX uses these auxiliary files, if
they exist, to update your document when it is processed
again.</p>
<div class="figure">
<a id="fig.texcmplx" name="fig.texcmplx"></a>
<p class="title"><b>Figure 1.5. TeXing a More
Complex Document</b></p>
<div class="mediaobject">
<img src="figures/tex.01.05.png" />
</div>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2861875"
name="id2861875"></a>Building a Table of
Contents</h3>
</div>
</div>
<p>A table of contents<a id="id2861885" class="indexterm"
name="id2861885"></a> is the simplest form of cross
reference. In LaTeX, you request a table of contents by
inserting the \tableofcontents command wherever you want
it to appear in your document. If you request the table
of contents at the end of your document rather than the
beginning, your document can be printed with only one
pass through TeX.</p>
<p>LaTeX uses a file with the same name as your document
and the extension <tt>.toc</tt> to hold the table of
contents entries. You can control the level of detail in
your table of contents by setting the \secnumdepth
counter. A value of zero includes only chapters; one
includes chapters and sections; two includes chapters,
sections, and subsections, and so on.</p>
<p>The LaTeX commands \listoftables and \listoffigures
perform the same functions as \tableofcontents for lists
of tables and figures. They use external files with the
extensions <tt>.lot</tt><a id="id2861950"
class="indexterm" name="id2861950"></a> and
<tt>.lof</tt><a id="id2861966" class="indexterm"
name="id2861966"></a>, respectively. As with the table of
contents, your document can be correctly formatted in one
pass if the \listoftables and \listoffigures commands are
placed at the end of the document.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2861991"
name="id2861991"></a>Figure References</h3>
</div>
</div>
<p>Figure references<a id="id2862000" class="indexterm"
name="id2862000"></a> are a special case of LaTeX's cross
referencing mechanism. The LaTeX command
\label{<i><tt>string</tt></i>} creates a referent. You
refer to the label with the command
\ref{<i><tt>string</tt></i>}. In normal body text, the
label refers to the current section or subsection. In a
figure or table environment, the label refers to that
figure or table.</p>
<p>If your document contains no forward references<a
id="id2862038" class="indexterm" name="id2862038"></a>
(if all \label commands occur before the \ref's that
refer to them) then it can be formatted in one pass.
Otherwise, TeX will have to be run two or three times to
make all of the references correct.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2862061"
name="id2862061"></a>Indexes and Glossaries</h3>
</div>
</div>
<p>Indexes<a id="id2862070" class="indexterm"
name="id2862070"></a> and glossaries<a id="id2862079"
class="indexterm" name="id2862079"></a> differ from the
preceding forms of reference in that they must be
processed by a separate program. In general, this is true
regardless of the macro package or format you use. An
external program is required because indexes and
glossaries must be alphabetized, and in indexes,
consecutive page numbers have to be converted into
ranges, and so on.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2862096"
name="id2862096"></a>Bibliographies</h3>
</div>
</div>
<p>LaTeX works in conjunction with another program,
called BibTeX<a id="id2862105" class="indexterm"
name="id2862105"></a>, to provide a flexible, convenient
way to construct bibliographies<a id="id2862119"
class="indexterm" name="id2862119"></a>. The \cite
commands allows you to refer to other documents in much
the same way that the \ref command allows you to refer to
other portions of the same document.</p>
<p>You make a citation by placing the command
\cite{<i><tt>string</tt></i>} where you wish the citation
to occur. The <span
class="emphasis"><em>string</em></span> is a key that
refers to the document in your bibliography database that
you wish to cite. Example <a
href="ch01.html#ex.knuthbbl"
title="Example 1.2. A typical bibliography database entry">
Example 1.2</a> is a typical entry in a bibliography
database. It describes Knuth's<a id="id2862157"
class="indexterm" name="id2862157"></a> classic book
<span class="emphasis"><em>The
TeXbook</em></span> [<a
href="bi01.html#kn:texbook">kn:texbook</a>]. The key for
this entry is “kn:texbook.”</p>
<div class="example">
<a id="ex.knuthbbl" name="ex.knuthbbl"></a>
<p class="title"><b>Example 1.2. A typical
bibliography database entry</b></p>
<pre class="screen">
@Book{kn:texbook,
author = "Donald E. Knuth",
title = "The {TeX}book",
publisher = "Addison-Wesley",
year = 1989,
edition = "Fifteenth",
isbn = "0-201-13447-0"
note = "Paperback ISBN: 0-201-13448-9"
}
</pre>
</div>
<p>Each entry in the database consists of a type (book,
article, magazine, etc.), a key, and a number of fields.
The number and names of the fields depend on the type of
entry. The database is simply a plain ASCII file
containing any number of entries. You can have multiple
databases.</p>
<p>These are the commands you use, in addition to \cite,
to include a bibliography in your document:</p>
<pre class="screen">
\bibliographystyle{plain}
\bibliography{textools,refbooks}
</pre>
<p>The \bibliographystyle command tells BibTeX how to
format the bibliography, and the \bibliography command
identifies which bibliographic databases contain the
citations that you have made. The “plain”
style of bibliography is selected, and the
<tt>textools</tt> and <tt>refbooks</tt> files contain the
bibliographic information for the documents cited.
Document styles can be used to alter the format of
citations in your text. The default extension for
bibliographic styles is <tt>.bst</tt><a id="id2862291"
class="indexterm" name="id2862291"></a>. The default
extension for database files is <tt>.bib</tt><a
id="id2862308" class="indexterm"
name="id2862308"></a>.</p>
<p>LaTeX places citations and bibliography information
into the <tt>.aux</tt> file<a id="id2862331"
class="indexterm" name="id2862331"></a>. BibTeX reads the
<tt>.aux</tt><a id="id2862348" class="indexterm"
name="id2862348"></a> file and constructs a bibliography,
which it places into a file with the extension
<tt>.bbl</tt><a id="id2862366" class="indexterm"
name="id2862366"></a>, using the entries you cited and
the bibliography style you selected.</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<h3 class="title"><a id="id2862381"
name="id2862381"></a>Special Things</h3>
</div>
</div>
<p>Sometimes, producing a complex document requires the
ability to interface with objects outside of TeX
(pictures or figures created by high-end graphics
packages, special features of a particular printer,
etc.). To support this kind of communication, TeX
provides a control sequence called \special. The
arguments passed to the \special command are written
directly to the <tt>DVI</tt> file for the DVI driver. It
is the responsibility of the DVI driver to handle them.
DVI drivers typically ignore \special commands that they
do not recognize.</p>
<p>You will find \special commands of various kinds
described throughout this book, particularly when
discussing color typesetting in Chapter <a
href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a>,
<span class="emphasis"><em><a href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a></em></span>,
and graphics in Chapter <a href="ch06.html"
title="Chapter 6. Pictures and Figures">Chapter 6</a>,
<span class="emphasis"><em><a href="ch06.html"
title="Chapter 6. Pictures and Figures">Chapter 6</a></em></span>.</p>
</div>
</div>
<div class="footnotes">
<br />
<hr width="100" align="left" />
<div class="footnote">
<p><sup>[<a id="ftn.id2856038" name="ftn.id2856038"
href="#id2856038">1</a>]</sup> Before I proceed, the
notion of beautiful in this context needs some
explanation. Several people have pointed out that the
logo type used by many TeX-related programs (including
TeX itself) is intrinsically ugly. These same folks argue
that a sentence like “TeX is designed to typeset
beautiful pages” is self-contradictory because it
begins with such an ugly construction. Obviously, TeX
can't <span class="emphasis"><em>prevent</em></span> you
from typesetting ugly things. But TeX can typeset
beautiful things too. We at O'Reilly & Associates
think that this book, typeset completely in TeX, is an
excellent example.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2857595" name="ftn.id2857595"
href="#id2857595">2</a>]</sup> This is not a whole-truth.
Implementors of TeX may make some system-dependent
alterations as long as the resulting program still passes
the test suite; so our TeXs may not behave <span
class="emphasis"><em>exactly</em></span> the same way.
They will, however, produce identical documents given
identical input (unless the input relies on
system-dependent features not available in both TeXs,
naturally. ;-)</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2857956" name="ftn.id2857956"
href="#id2857956">3</a>]</sup> This is subtly different
from saying that they are joined at the baseline. There
are TeX commands which can change the position of the
reference point in a box, whereas the baseline is an
imaginary line that depends solely on the shape of the
character.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858135" name="ftn.id2858135"
href="#id2858135">4</a>]</sup> Technically, it's any
character defined to be in the “escape”
category followed by any sequence of characters defined
to be in the “letter” category or a single
character in the “other” category.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858243" name="ftn.id2858243"
href="#id2858243">5</a>]</sup> Actually, macro expansion
differs from pure textual replacement in a number of
technical ways, but they aren't important here.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858415" name="ftn.id2858415"
href="#id2858415">6</a>]</sup> Technically, several other
kinds of values are stored this way as well, but they are
less common and won't be discussed in this book at
all.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858485" name="ftn.id2858485"
href="#id2858485">7</a>]</sup> Most control sequences can
be redefined to hold different kinds of values, but they
can never hold different kinds of values at the same
time. A dimension register can be redefined to hold
tokens, for example, but then it can't hold dimensions
anymore (unless it is redefined again).</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858627" name="ftn.id2858627"
href="#id2858627">8</a>]</sup> Plain TeX is the name of a
particular macro package. I selected it for the purpose
of example in this chapter because it is always installed
with TeX. Most of what follows in this chapter is true in
other macro packages as well, but some of the details are
different. See Chapter <a href="ch04.html"
title="Chapter 4. Macro Packages">Chapter 4</a>
for more information.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2858704" name="ftn.id2858704"
href="#id2858704">9</a>]</sup> All of these special
characters are configurable, but most macro packages use
the Plain TeX defaults.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2859730" name="ftn.id2859730"
href="#id2859730">10</a>]</sup> TeX pundits, and other
folks who have been frustrated by the limitations of
these environments, frequently refer to this as
WYSIAYG—what you see is <span
class="emphasis"><em>all</em></span> you get.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2860201" name="ftn.id2860201"
href="#id2860201">11</a>]</sup> TeX doesn't do this sort
of thing automatically, but it isn't hard to do. Why the
kiwi? It was on my business card at the time.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2860372" name="ftn.id2860372"
href="#id2860372">12</a>]</sup> Although it has a very
different notion of what constitutes a control
sequence.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2861160" name="ftn.id2861160"
href="#id2861160">13</a>]</sup> Well, actually, they're
TeX primitives, are defined by a macro package, defined
in a file loaded by a macro package, or defined in your
document.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2861489" name="ftn.id2861489"
href="#id2861489">14</a>]</sup> Some drivers may also
benefit from loading the <tt>TFM</tt> files used to
create your document.</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2861567" name="ftn.id2861567"
href="#id2861567">15</a>]</sup> Textures for the Mac and
<b>Scientific Word</b> offer WYSIWYG-like environments,
but that's not the point ;-)</p>
</div>
<div class="footnote">
<p><sup>[<a id="ftn.id2861760" name="ftn.id2861760"
href="#id2861760">16</a>]</sup> With extreme cleverness
or extreme bad luck you can create a document which will
<span class="emphasis"><em>never</em></span> format
correctly.</p>
</div>
</div>
</div>
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