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(From these references no 0018 text was directly copied.) 0019 0020 Copyright 2007, 2008, 2009, 2010, 2011, 2012, 2013, 0021 2014, 2015, 2016, 2017, 2018 Karl Berry. 0022 0023 Copyright 1988, 1994, 2007 Stephen Gilmore. 0024 0025 Copyright 1994, 1995, 1996 Torsten Martinsen. 0026 0027 Permission is granted to make and distribute verbatim copies of 0028 this manual provided the copyright notice and this permission notice 0029 are preserved on all copies. 0030 0031 0032 Permission is granted to copy and distribute modified versions of this 0033 manual under the conditions for verbatim copying, provided that the entire 0034 resulting derived work is distributed under the terms of a permission 0035 notice identical to this one. 0036 0037 Permission is granted to copy and distribute translations of this manual 0038 into another language, under the above conditions for modified versions. --> 0039 <!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> 0040 <head> 0041 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 0042 <title>\protect (LaTeX2e unofficial reference manual (November 2018))</title> 0043 0044 <meta name="description" content="\protect (LaTeX2e unofficial reference manual (November 2018))"> 0045 <meta name="keywords" content="\protect (LaTeX2e unofficial reference manual (November 2018))"> 0046 <meta name="resource-type" content="document"> 0047 <meta name="distribution" content="global"> 0048 <meta name="Generator" content="makeinfo"> 0049 <link href="index.html#Top" rel="start" title="Top"> 0050 <link href="IndexDocument.html#Index" rel="index" title="Index"> 0051 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 0052 <link href="Definitions.html#Definitions" rel="up" title="Definitions"> 0053 <link href="_005cignorespaces-_0026-_005cignorespacesafterend.html#g_t_005cignorespaces-_0026-_005cignorespacesafterend" rel="next" title="\ignorespaces & \ignorespacesafterend"> 0054 <link href="_005cnewfont.html#g_t_005cnewfont" rel="prev" title="\newfont"> 0055 <style type="text/css"> 0056 <!-- 0057 /* $Id: latex2e.css 690 2018-09-15 15:20:19Z jimhefferon $ 0058 Minor css for latexrefman. Public domain. 0059 Originally written by Jim Hefferon and Karl Berry, 2018. */ 0060 0061 /* So you can style for yourself */ 0062 @import url("/css/latexreflocal.css"); 0063 0064 0065 0066 a.summary-letter {text-decoration: none} 0067 blockquote.indentedblock {margin-right: 0em} 0068 blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 0069 blockquote.smallquotation {font-size: smaller} 0070 div.display {margin-left: 3.2em} 0071 div.example {margin-left: 3.2em} 0072 div.lisp {margin-left: 3.2em} 0073 div.smalldisplay {margin-left: 3.2em} 0074 div.smallexample {margin-left: 3.2em} 0075 div.smalllisp {margin-left: 3.2em} 0076 kbd {font-style: oblique} 0077 pre.display {font-family: inherit} 0078 pre.format {font-family: inherit} 0079 pre.menu-comment {font-family: serif} 0080 pre.menu-preformatted {font-family: serif} 0081 pre.smalldisplay {font-family: inherit; font-size: smaller} 0082 pre.smallexample {font-size: smaller} 0083 pre.smallformat {font-family: inherit; font-size: smaller} 0084 pre.smalllisp {font-size: smaller} 0085 span.nolinebreak {white-space: nowrap} 0086 span.roman {font-family: initial; font-weight: normal} 0087 span.sansserif {font-family: sans-serif; font-weight: normal} 0088 ul.no-bullet {list-style: none} 0089 BODY { 0090 margin-top: 1em; 0091 margin-left: 1em; /* auto results in two-digit <ol> lost off left */ 0092 margin-right: 1em; 0093 margin-bottom: 1em; 0094 /* the idea is to use the whole window, unless it is ridiculously 0095 wide, probably with too-small fonts, too. */ 0096 max-width: 64em; 0097 } 0098 0099 /* Because we want @math{... @code ...} to be upright, not slanted, 0100 and Texinfo won't fix it. */ 0101 code {font-style:normal; font-family:monospace; } 0102 0103 /* We put a link to our own home page at the bottom. */ 0104 div.referenceinfo {font-size:small;} 0105 0106 --> 0107 </style> 0108 0109 0110 </head> 0111 0112 <body lang="en"> 0113 <a name="g_t_005cprotect"></a> 0114 <div class="header"> 0115 <p> 0116 Next: <a href="_005cignorespaces-_0026-_005cignorespacesafterend.html#g_t_005cignorespaces-_0026-_005cignorespacesafterend" accesskey="n" rel="next">\ignorespaces & \ignorespacesafterend</a>, Previous: <a href="_005cnewfont.html#g_t_005cnewfont" accesskey="p" rel="prev">\newfont</a>, Up: <a href="Definitions.html#Definitions" accesskey="u" rel="up">Definitions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="IndexDocument.html#Index" title="Index" rel="index">Index</a>]</p> 0117 </div> 0118 <hr> 0119 <a name="g_t_005cprotect-1"></a> 0120 <h3 class="section">12.11 <code>\protect</code></h3> 0121 0122 <a name="index-_005cprotect"></a> 0123 <a name="index-fragile-commands"></a> 0124 <a name="index-robust-commands"></a> 0125 0126 <p>All LaTeX commands are either <em>fragile</em> or <em>robust</em>. A 0127 fragile command can break when it is used in the argument to certain 0128 other commands. Commands that contain data that LaTeX writes to an 0129 auxiliary file and re-reads later are fragile. This includes material 0130 that goes into a table of contents, list of figures, list of tables, 0131 etc. Fragile commands also include line breaks, any command that has an 0132 optional argument, and many more. To prevent such commands from 0133 breaking, one solution is to preceded them with the command 0134 <code>\protect</code>. 0135 </p> 0136 <p>For example, when LaTeX runs the <code>\section{<var>section 0137 name</var>}</code> command it writes the <var>section name</var> text to the 0138 <samp>.aux</samp> auxiliary file, moving it there for use elsewhere in the 0139 document such as in the table of contents. Any argument that is 0140 internally expanded by LaTeX without typesetting it directly is 0141 referred to as a 0142 <a name="index-moving-arguments"></a> 0143 <em>moving argument</em>. A command is fragile if it can 0144 expand during this process into invalid TeX code. Some examples of 0145 moving arguments are those that appear in the <code>\caption{...}</code> 0146 command (see <a href="figure.html#figure">figure</a>), in the <code>\thanks{...}</code> command 0147 (see <a href="_005cmaketitle.html#g_t_005cmaketitle">\maketitle</a>), and in @-expressions in the <code>tabular</code> and 0148 <code>array</code> environments (see <a href="tabular.html#tabular">tabular</a>). 0149 </p> 0150 <p>If you get strange errors from commands used in moving arguments, try 0151 preceding it with <code>\protect</code>. Every fragile commands must be 0152 protected with their own <code>\protect</code>. 0153 </p> 0154 <p>Although usually a <code>\protect</code> command doesn’t hurt, length 0155 commands are robust and should not be preceded by a <code>\protect</code> 0156 command. Nor can a <code>\protect</code> command be used in the argument to 0157 <code>\addtocounter</code> or <code>\setcounter</code> command. 0158 </p> 0159 <p>In this example the <code>\caption</code> command gives a mysterious error 0160 about an extra curly brace. Fix the problem by preceding each 0161 <code>\raisebox</code> command with <code>\protect</code>. 0162 </p> 0163 <div class="example"> 0164 <pre class="example">\begin{figure} 0165 ... 0166 \caption{Company headquarters of A\raisebox{1pt}{B}\raisebox{-1pt}{C}} 0167 \end{figure} 0168 </pre></div> 0169 0170 <p>In the next example the <code>\tableofcontents</code> command gives an error 0171 because the <code>\(..\)</code> in the section title expands to illegal TeX 0172 in the <samp>.toc</samp> file. You can solve this by changing <code>\(..\)</code> 0173 to <code>\protect\(..\protect\)</code>. 0174 </p> 0175 <div class="example"> 0176 <pre class="example">\begin{document} 0177 \tableofcontents 0178 ... 0179 \section{Einstein's \( e=mc^2 \)} 0180 ... 0181 </pre></div> 0182 0183 0184 0185 0186 <hr/><div class='referenceinfo'> <a href='https://latexref.xyz/'> <i>Unofficial LaTeX2e reference manual</i></a></div> 0187 </body> 0188 </html>