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<h1 class="settitle" align="center"><small>GDB</small>’s Obsolete Annotations</h1>
<p>This file documents <small>GDB</small>’s obsolete annotations.
</p>
<p>Copyright © 1994-2018 Free Software Foundation, Inc.
</p>
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts. A copy of the license is included in the section entitled “GNU
Free Documentation License”.
</p>
<a name="Top"></a>
<div class="header">
<p>
Next: <a href="#Annotations-Overview" accesskey="n" rel="next">Annotations Overview</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="GDB-Annotations"></a>
<h1 class="top">GDB Annotations</h1>
<p>This document describes the obsolete level two annotation interface
implemented in older <small>GDB</small> versions.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="#Annotations-Overview" accesskey="1">Annotations Overview</a>:</td><td> </td><td align="left" valign="top">What annotations are; the general syntax.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Limitations" accesskey="2">Limitations</a>:</td><td> </td><td align="left" valign="top">Limitations of the annotation interface.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Migrating-to-GDB_002fMI" accesskey="3">Migrating to GDB/MI</a>:</td><td> </td><td align="left" valign="top">Migrating to GDB/MI
</td></tr>
<tr><td align="left" valign="top">• <a href="#Server-Prefix" accesskey="4">Server Prefix</a>:</td><td> </td><td align="left" valign="top">Issuing a command without affecting user state.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Value-Annotations" accesskey="5">Value Annotations</a>:</td><td> </td><td align="left" valign="top">Values are marked as such.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Frame-Annotations" accesskey="6">Frame Annotations</a>:</td><td> </td><td align="left" valign="top">Stack frames are annotated.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Displays" accesskey="7">Displays</a>:</td><td> </td><td align="left" valign="top"><small>GDB</small> can be told to display something periodically.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Prompting" accesskey="8">Prompting</a>:</td><td> </td><td align="left" valign="top">Annotations marking <small>GDB</small>’s need for input.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Errors" accesskey="9">Errors</a>:</td><td> </td><td align="left" valign="top">Annotations for error messages.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Breakpoint-Info">Breakpoint Info</a>:</td><td> </td><td align="left" valign="top">Information on breakpoints.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Invalidation">Invalidation</a>:</td><td> </td><td align="left" valign="top">Some annotations describe things now invalid.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Annotations-for-Running">Annotations for Running</a>:</td><td> </td><td align="left" valign="top">
Whether the program is running, how it stopped, etc.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Source-Annotations">Source Annotations</a>:</td><td> </td><td align="left" valign="top">Annotations describing source code.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Multi_002dthreaded-Apps">Multi-threaded Apps</a>:</td><td> </td><td align="left" valign="top">An annotation that reports multi-threadedness.
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
</pre></th></tr><tr><td align="left" valign="top">• <a href="#GNU-Free-Documentation-License">GNU Free Documentation License</a>:</td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>
<div class="contents">
<ul class="no-bullet">
<li><a name="toc-What-is-an-Annotation_003f" href="#Annotations-Overview">1 What is an Annotation?</a></li>
<li><a name="toc-Limitations-of-the-Annotation-Interface" href="#Limitations">2 Limitations of the Annotation Interface</a>
<ul class="no-bullet">
<li><a name="toc-Dependant-on-CLI-output" href="#Dependant-on-CLI-output">2.1 Dependant on <small>CLI</small> output</a></li>
<li><a name="toc-Scalability" href="#Scalability">2.2 Scalability</a></li>
<li><a name="toc-Correctness" href="#Correctness">2.3 Correctness</a></li>
<li><a name="toc-Reliability" href="#Reliability">2.4 Reliability</a></li>
<li><a name="toc-Maintainability" href="#Maintainability">2.5 Maintainability</a></li>
</ul></li>
<li><a name="toc-Migrating-to-GDB_002fMI-1" href="#Migrating-to-GDB_002fMI">3 Migrating to <small>GDB/MI</small></a></li>
<li><a name="toc-The-Server-Prefix" href="#Server-Prefix">4 The Server Prefix</a></li>
<li><a name="toc-Values" href="#Value-Annotations">5 Values</a></li>
<li><a name="toc-Frames" href="#Frame-Annotations">6 Frames</a></li>
<li><a name="toc-Displays-1" href="#Displays">7 Displays</a></li>
<li><a name="toc-Annotation-for-GDB-Input" href="#Prompting">8 Annotation for <small>GDB</small> Input</a></li>
<li><a name="toc-Errors-1" href="#Errors">9 Errors</a></li>
<li><a name="toc-Information-on-Breakpoints" href="#Breakpoint-Info">10 Information on Breakpoints</a></li>
<li><a name="toc-Invalidation-Notices" href="#Invalidation">11 Invalidation Notices</a></li>
<li><a name="toc-Running-the-Program" href="#Annotations-for-Running">12 Running the Program</a></li>
<li><a name="toc-Displaying-Source" href="#Source-Annotations">13 Displaying Source</a></li>
<li><a name="toc-Multi_002dthreaded-Applications" href="#Multi_002dthreaded-Apps">14 Multi-threaded Applications</a></li>
<li><a name="toc-GNU-Free-Documentation-License-1" href="#GNU-Free-Documentation-License">Appendix A GNU Free Documentation License</a></li>
</ul>
</div>
<hr>
<a name="Annotations-Overview"></a>
<div class="header">
<p>
Next: <a href="#Limitations" accesskey="n" rel="next">Limitations</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="What-is-an-Annotation_003f"></a>
<h2 class="chapter">1 What is an Annotation?</h2>
<a name="index-annotations"></a>
<p>To produce obsolete level two annotations, start <small>GDB</small> with the
<code>--annotate=2</code> option.
</p>
<p>Annotations start with a newline character, two ‘<samp>control-z</samp>’
characters, and the name of the annotation. If there is no additional
information associated with this annotation, the name of the annotation
is followed immediately by a newline. If there is additional
information, the name of the annotation is followed by a space, the
additional information, and a newline. The additional information
cannot contain newline characters.
</p>
<p>Any output not beginning with a newline and two ‘<samp>control-z</samp>’
characters denotes literal output from <small>GDB</small>. Currently there is
no need for <small>GDB</small> to output a newline followed by two
‘<samp>control-z</samp>’ characters, but if there was such a need, the
annotations could be extended with an ‘<samp>escape</samp>’ annotation which
means those three characters as output.
</p>
<p>A simple example of starting up <small>GDB</small> with annotations is:
</p>
<div class="smallexample">
<pre class="smallexample">$ gdb --annotate=2
GNU GDB 5.0
Copyright 2000 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it
under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty"
for details.
This GDB was configured as "sparc-sun-sunos4.1.3"
^Z^Zpre-prompt
(gdb)
^Z^Zprompt
quit
^Z^Zpost-prompt
$
</pre></div>
<p>Here ‘<samp>quit</samp>’ is input to <small>GDB</small>; the rest is output from
<small>GDB</small>. The three lines beginning ‘<samp>^Z^Z</samp>’ (where ‘<samp>^Z</samp>’
denotes a ‘<samp>control-z</samp>’ character) are annotations; the rest is
output from <small>GDB</small>.
</p>
<hr>
<a name="Limitations"></a>
<div class="header">
<p>
Next: <a href="#Migrating-to-GDB_002fMI" accesskey="n" rel="next">Migrating to GDB/MI</a>, Previous: <a href="#Annotations-Overview" accesskey="p" rel="prev">Annotations Overview</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Limitations-of-the-Annotation-Interface"></a>
<h2 class="chapter">2 Limitations of the Annotation Interface</h2>
<p>The level two annotations mechanism is known to have a number of
technical and architectural limitations. As a consequence, in 2001,
with the release of <small>GDB</small> 5.1 and the addition of <small>GDB/MI</small>,
the annotation interface was marked as deprecated.
</p>
<p>This chapter discusses the known problems.
</p>
<a name="Dependant-on-CLI-output"></a>
<h3 class="section">2.1 Dependant on <small>CLI</small> output</h3>
<p>The annotation interface works by interspersing markups with
<small>GDB</small> normal command-line interpreter output. Unfortunately, this
makes the annotation client dependant on not just the annotations, but
also the <small>CLI</small> output. This is because the client is forced to
assume that specific <small>GDB</small> commands provide specific information.
Any change to <small>GDB</small>’s <small>CLI</small> output modifies or removes that
information and, consequently, likely breaks the client.
</p>
<p>Since the <small>GDB/MI</small> output is independent of the <small>CLI</small>, it does not
have this problem.
</p>
<a name="Scalability"></a>
<h3 class="section">2.2 Scalability</h3>
<p>The annotation interface relies on value annotations (see <a href="#Value-Annotations">Value Annotations</a>) and the display mechanism as a way of obtaining up-to-date
value information. These mechanisms are not scalable.
</p>
<p>In a graphical environment, where many values can be displayed
simultaneously, a serious performance problem occurs when the client
tries to first extract from <small>GDB</small>, and then re-display, all those
values. The client should instead only request and update the values
that changed.
</p>
<p>The <small>GDB/MI</small> Variable Objects provide just that mechanism.
</p>
<a name="Correctness"></a>
<h3 class="section">2.3 Correctness</h3>
<p>The annotation interface assumes that a variable’s value can only be
changed when the target is running. This assumption is not correct. A
single assignment to a single variable can result in the entire target,
and all displayed values, needing an update.
</p>
<p>The <small>GDB/MI</small> Variable Objects include a mechanism for efficiently
reporting such changes.
</p>
<a name="Reliability"></a>
<h3 class="section">2.4 Reliability</h3>
<p>The <small>GDB/MI</small> interface includes a dedicated test directory
(<samp>gdb/gdb.mi</samp>), and any addition or fix to <small>GDB/MI</small> must include
testsuite changes.
</p>
<a name="Maintainability"></a>
<h3 class="section">2.5 Maintainability</h3>
<p>The annotation mechanism was implemented by interspersing <small>CLI</small> print
statements with various annotations. As a consequence, any <small>CLI</small>
output change can alter the annotation output.
</p>
<p>Since the <small>GDB/MI</small> output is independent of the <small>CLI</small>, and the
<small>GDB/MI</small> is increasingly implemented independent of the <small>CLI</small>
code, its long term maintenance is much easier.
</p>
<hr>
<a name="Migrating-to-GDB_002fMI"></a>
<div class="header">
<p>
Next: <a href="#Server-Prefix" accesskey="n" rel="next">Server Prefix</a>, Previous: <a href="#Limitations" accesskey="p" rel="prev">Limitations</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Migrating-to-GDB_002fMI-1"></a>
<h2 class="chapter">3 Migrating to <small>GDB/MI</small></h2>
<p>By using the ‘<samp>interp mi</samp>’ command, it is possible for annotation
clients to invoke <small>GDB/MI</small> commands, and hence access the
<small>GDB/MI</small>. By doing this, existing annotation clients have a
migration path from this obsolete interface to <small>GDB/MI</small>.
</p>
<hr>
<a name="Server-Prefix"></a>
<div class="header">
<p>
Next: <a href="#Value-Annotations" accesskey="n" rel="next">Value Annotations</a>, Previous: <a href="#Migrating-to-GDB_002fMI" accesskey="p" rel="prev">Migrating to GDB/MI</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="The-Server-Prefix"></a>
<h2 class="chapter">4 The Server Prefix</h2>
<a name="index-server-prefix-for-annotations"></a>
<p>To issue a command to <small>GDB</small> without affecting certain aspects of
the state which is seen by users, prefix it with ‘<samp>server </samp>’. This
means that this command will not affect the command history, nor will it
affect <small>GDB</small>’s notion of which command to repeat if <tt class="key">RET</tt> is
pressed on a line by itself.
</p>
<p>The server prefix does not affect the recording of values into the value
history; to print a value without recording it into the value history,
use the <code>output</code> command instead of the <code>print</code> command.
</p>
<hr>
<a name="Value-Annotations"></a>
<div class="header">
<p>
Next: <a href="#Frame-Annotations" accesskey="n" rel="next">Frame Annotations</a>, Previous: <a href="#Server-Prefix" accesskey="p" rel="prev">Server Prefix</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Values"></a>
<h2 class="chapter">5 Values</h2>
<p><em>Value Annotations have been removed. <small>GDB/MI</small> instead provides
Variable Objects.</em>
</p>
<a name="index-annotations-for-values"></a>
<p>When a value is printed in various contexts, <small>GDB</small> uses
annotations to delimit the value from the surrounding text.
</p>
<a name="index-value_002dhistory_002dbegin"></a>
<a name="index-value_002dhistory_002dvalue"></a>
<a name="index-value_002dhistory_002dend"></a>
<p>If a value is printed using <code>print</code> and added to the value history,
the annotation looks like
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zvalue-history-begin <var>history-number</var> <var>value-flags</var>
<var>history-string</var>
^Z^Zvalue-history-value
<var>the-value</var>
^Z^Zvalue-history-end
</pre></div>
<p>where <var>history-number</var> is the number it is getting in the value
history, <var>history-string</var> is a string, such as ‘<samp>$5 = </samp>’, which
introduces the value to the user, <var>the-value</var> is the output
corresponding to the value itself, and <var>value-flags</var> is ‘<samp>*</samp>’ for
a value which can be dereferenced and ‘<samp>-</samp>’ for a value which cannot.
</p>
<a name="index-value_002dbegin"></a>
<a name="index-value_002dend"></a>
<p>If the value is not added to the value history (it is an invalid float
or it is printed with the <code>output</code> command), the annotation is similar:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zvalue-begin <var>value-flags</var>
<var>the-value</var>
^Z^Zvalue-end
</pre></div>
<a name="index-arg_002dbegin"></a>
<a name="index-arg_002dname_002dend"></a>
<a name="index-arg_002dvalue"></a>
<a name="index-arg_002dend"></a>
<p>When <small>GDB</small> prints an argument to a function (for example, in the output
from the <code>backtrace</code> command), it annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarg-begin
<var>argument-name</var>
^Z^Zarg-name-end
<var>separator-string</var>
^Z^Zarg-value <var>value-flags</var>
<var>the-value</var>
^Z^Zarg-end
</pre></div>
<p>where <var>argument-name</var> is the name of the argument,
<var>separator-string</var> is text which separates the name from the value
for the user’s benefit (such as ‘<samp>=</samp>’), and <var>value-flags</var> and
<var>the-value</var> have the same meanings as in a
<code>value-history-begin</code> annotation.
</p>
<a name="index-field_002dbegin"></a>
<a name="index-field_002dname_002dend"></a>
<a name="index-field_002dvalue"></a>
<a name="index-field_002dend"></a>
<p>When printing a structure, <small>GDB</small> annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zfield-begin <var>value-flags</var>
<var>field-name</var>
^Z^Zfield-name-end
<var>separator-string</var>
^Z^Zfield-value
<var>the-value</var>
^Z^Zfield-end
</pre></div>
<p>where <var>field-name</var> is the name of the field, <var>separator-string</var>
is text which separates the name from the value for the user’s benefit
(such as ‘<samp>=</samp>’), and <var>value-flags</var> and <var>the-value</var> have the
same meanings as in a <code>value-history-begin</code> annotation.
</p>
<p>When printing an array, <small>GDB</small> annotates it as follows:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarray-section-begin <var>array-index</var> <var>value-flags</var>
</pre></div>
<p>where <var>array-index</var> is the index of the first element being
annotated and <var>value-flags</var> has the same meaning as in a
<code>value-history-begin</code> annotation. This is followed by any number
of elements, where is element can be either a single element:
</p>
<a name="index-elt"></a>
<div class="smallexample">
<pre class="smallexample">‘<samp>,</samp>’ <var>whitespace</var> ; <span class="roman">omitted for the first element</span>
<var>the-value</var>
^Z^Zelt
</pre></div>
<p>or a repeated element
</p>
<a name="index-elt_002drep"></a>
<a name="index-elt_002drep_002dend"></a>
<div class="smallexample">
<pre class="smallexample">‘<samp>,</samp>’ <var>whitespace</var> ; <span class="roman">omitted for the first element</span>
<var>the-value</var>
^Z^Zelt-rep <var>number-of-repetitions</var>
<var>repetition-string</var>
^Z^Zelt-rep-end
</pre></div>
<p>In both cases, <var>the-value</var> is the output for the value of the
element and <var>whitespace</var> can contain spaces, tabs, and newlines. In
the repeated case, <var>number-of-repetitions</var> is the number of
consecutive array elements which contain that value, and
<var>repetition-string</var> is a string which is designed to convey to the
user that repetition is being depicted.
</p>
<a name="index-array_002dsection_002dend"></a>
<p>Once all the array elements have been output, the array annotation is
ended with
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zarray-section-end
</pre></div>
<hr>
<a name="Frame-Annotations"></a>
<div class="header">
<p>
Next: <a href="#Displays" accesskey="n" rel="next">Displays</a>, Previous: <a href="#Value-Annotations" accesskey="p" rel="prev">Value Annotations</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Frames"></a>
<h2 class="chapter">6 Frames</h2>
<p><em>Value Annotations have been removed. <small>GDB/MI</small> instead provides
a number of frame commands.</em>
</p>
<p><em>Frame annotations are no longer available. The <small>GDB/MI</small>
provides ‘<samp>-stack-list-arguments</samp>’, ‘<samp>-stack-list-locals</samp>’, and
‘<samp>-stack-list-frames</samp>’ commands.</em>
</p>
<a name="index-annotations-for-frames"></a>
<p>Whenever <small>GDB</small> prints a frame, it annotates it. For example, this applies
to frames printed when <small>GDB</small> stops, output from commands such as
<code>backtrace</code> or <code>up</code>, etc.
</p>
<a name="index-frame_002dbegin"></a>
<p>The frame annotation begins with
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-begin <var>level</var> <var>address</var>
<var>level-string</var>
</pre></div>
<p>where <var>level</var> is the number of the frame (0 is the innermost frame,
and other frames have positive numbers), <var>address</var> is the address of
the code executing in that frame, and <var>level-string</var> is a string
designed to convey the level to the user. <var>address</var> is in the form
‘<samp>0x</samp>’ followed by one or more lowercase hex digits (note that this
does not depend on the language). The frame ends with
</p>
<a name="index-frame_002dend"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-end
</pre></div>
<p>Between these annotations is the main body of the frame, which can
consist of
</p>
<ul>
<li> <a name="index-function_002dcall"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zfunction-call
<var>function-call-string</var>
</pre></div>
where <var>function-call-string</var> is text designed to convey to the user
that this frame is associated with a function call made by <small>GDB</small> to a
function in the program being debugged.
</li><li> <a name="index-signal_002dhandler_002dcaller"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zsignal-handler-caller
<var>signal-handler-caller-string</var>
</pre></div>
where <var>signal-handler-caller-string</var> is text designed to convey to
the user that this frame is associated with whatever mechanism is used
by this operating system to call a signal handler (it is the frame which
calls the signal handler, not the frame for the signal handler itself).
</li><li> A normal frame.
<a name="index-frame_002daddress"></a>
<a name="index-frame_002daddress_002dend"></a>
<p>This can optionally (depending on whether this is thought of as
interesting information for the user to see) begin with
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-address
<var>address</var>
^Z^Zframe-address-end
<var>separator-string</var>
</pre></div>
<p>where <var>address</var> is the address executing in the frame (the same
address as in the <code>frame-begin</code> annotation, but printed in a form
which is intended for user consumption—in particular, the syntax varies
depending on the language), and <var>separator-string</var> is a string
intended to separate this address from what follows for the user’s
benefit.
</p>
<a name="index-frame_002dfunction_002dname"></a>
<a name="index-frame_002dargs"></a>
<p>Then comes
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-function-name
<var>function-name</var>
^Z^Zframe-args
<var>arguments</var>
</pre></div>
<p>where <var>function-name</var> is the name of the function executing in the
frame, or ‘<samp>??</samp>’ if not known, and <var>arguments</var> are the arguments
to the frame, with parentheses around them (each argument is annotated
individually as well, see <a href="#Value-Annotations">Value Annotations</a>).
</p>
<a name="index-frame_002dsource_002dbegin"></a>
<a name="index-frame_002dsource_002dfile"></a>
<a name="index-frame_002dsource_002dfile_002dend"></a>
<a name="index-frame_002dsource_002dline"></a>
<a name="index-frame_002dsource_002dend"></a>
<p>If source information is available, a reference to it is then printed:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-source-begin
<var>source-intro-string</var>
^Z^Zframe-source-file
<var>filename</var>
^Z^Zframe-source-file-end
:
^Z^Zframe-source-line
<var>line-number</var>
^Z^Zframe-source-end
</pre></div>
<p>where <var>source-intro-string</var> separates for the user’s benefit the
reference from the text which precedes it, <var>filename</var> is the name of
the source file, and <var>line-number</var> is the line number within that
file (the first line is line 1).
</p>
<a name="index-frame_002dwhere"></a>
<p>If <small>GDB</small> prints some information about where the frame is from (which
library, which load segment, etc.; currently only done on the RS/6000),
it is annotated with
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zframe-where
<var>information</var>
</pre></div>
<p>Then, if source is to actually be displayed for this frame (for example,
this is not true for output from the <code>backtrace</code> command), then a
<code>source</code> annotation (see <a href="#Source-Annotations">Source Annotations</a>) is displayed. Unlike
most annotations, this is output instead of the normal text which would be
output, not in addition.
</p></li></ul>
<hr>
<a name="Displays"></a>
<div class="header">
<p>
Next: <a href="#Prompting" accesskey="n" rel="next">Prompting</a>, Previous: <a href="#Frame-Annotations" accesskey="p" rel="prev">Frame Annotations</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Displays-1"></a>
<h2 class="chapter">7 Displays</h2>
<p><em>Display Annotations have been removed. <small>GDB/MI</small> instead
provides Variable Objects.</em>
</p>
<a name="index-display_002dbegin"></a>
<a name="index-display_002dnumber_002dend"></a>
<a name="index-display_002dformat"></a>
<a name="index-display_002dexpression"></a>
<a name="index-display_002dexpression_002dend"></a>
<a name="index-display_002dvalue"></a>
<a name="index-display_002dend"></a>
<a name="index-annotations-for-display"></a>
<p>When <small>GDB</small> is told to display something using the <code>display</code> command,
the results of the display are annotated:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zdisplay-begin
<var>number</var>
^Z^Zdisplay-number-end
<var>number-separator</var>
^Z^Zdisplay-format
<var>format</var>
^Z^Zdisplay-expression
<var>expression</var>
^Z^Zdisplay-expression-end
<var>expression-separator</var>
^Z^Zdisplay-value
<var>value</var>
^Z^Zdisplay-end
</pre></div>
<p>where <var>number</var> is the number of the display, <var>number-separator</var>
is intended to separate the number from what follows for the user,
<var>format</var> includes information such as the size, format, or other
information about how the value is being displayed, <var>expression</var> is
the expression being displayed, <var>expression-separator</var> is intended
to separate the expression from the text that follows for the user,
and <var>value</var> is the actual value being displayed.
</p>
<hr>
<a name="Prompting"></a>
<div class="header">
<p>
Next: <a href="#Errors" accesskey="n" rel="next">Errors</a>, Previous: <a href="#Displays" accesskey="p" rel="prev">Displays</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Annotation-for-GDB-Input"></a>
<h2 class="chapter">8 Annotation for <small>GDB</small> Input</h2>
<a name="index-annotations-for-prompts"></a>
<p>When <small>GDB</small> prompts for input, it annotates this fact so it is possible
to know when to send output, when the output from a given command is
over, etc.
</p>
<p>Different kinds of input each have a different <em>input type</em>. Each
input type has three annotations: a <code>pre-</code> annotation, which
denotes the beginning of any prompt which is being output, a plain
annotation, which denotes the end of the prompt, and then a <code>post-</code>
annotation which denotes the end of any echo which may (or may not) be
associated with the input. For example, the <code>prompt</code> input type
features the following annotations:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zpre-prompt
^Z^Zprompt
^Z^Zpost-prompt
</pre></div>
<p>The input types are
</p>
<dl compact="compact">
<dd><a name="index-pre_002dprompt"></a>
<a name="index-prompt"></a>
<a name="index-post_002dprompt"></a>
</dd>
<dt><code>prompt</code></dt>
<dd><p>When <small>GDB</small> is prompting for a command (the main <small>GDB</small> prompt).
</p>
<a name="index-pre_002dcommands"></a>
<a name="index-commands"></a>
<a name="index-post_002dcommands"></a>
</dd>
<dt><code>commands</code></dt>
<dd><p>When <small>GDB</small> prompts for a set of commands, like in the <code>commands</code>
command. The annotations are repeated for each command which is input.
</p>
<a name="index-pre_002doverload_002dchoice"></a>
<a name="index-overload_002dchoice"></a>
<a name="index-post_002doverload_002dchoice"></a>
</dd>
<dt><code>overload-choice</code></dt>
<dd><p>When <small>GDB</small> wants the user to select between various overloaded functions.
</p>
<a name="index-pre_002dquery"></a>
<a name="index-query"></a>
<a name="index-post_002dquery"></a>
</dd>
<dt><code>query</code></dt>
<dd><p>When <small>GDB</small> wants the user to confirm a potentially dangerous operation.
</p>
<a name="index-pre_002dprompt_002dfor_002dcontinue"></a>
<a name="index-prompt_002dfor_002dcontinue"></a>
<a name="index-post_002dprompt_002dfor_002dcontinue"></a>
</dd>
<dt><code>prompt-for-continue</code></dt>
<dd><p>When <small>GDB</small> is asking the user to press return to continue. Note: Don’t
expect this to work well; instead use <code>set height 0</code> to disable
prompting. This is because the counting of lines is buggy in the
presence of annotations.
</p></dd>
</dl>
<hr>
<a name="Errors"></a>
<div class="header">
<p>
Next: <a href="#Breakpoint-Info" accesskey="n" rel="next">Breakpoint Info</a>, Previous: <a href="#Prompting" accesskey="p" rel="prev">Prompting</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Errors-1"></a>
<h2 class="chapter">9 Errors</h2>
<a name="index-annotations-for-errors_002c-warnings-and-interrupts"></a>
<a name="index-quit"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zquit
</pre></div>
<p>This annotation occurs right before <small>GDB</small> responds to an interrupt.
</p>
<a name="index-error"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zerror
</pre></div>
<p>This annotation occurs right before <small>GDB</small> responds to an error.
</p>
<p>Quit and error annotations indicate that any annotations which <small>GDB</small> was
in the middle of may end abruptly. For example, if a
<code>value-history-begin</code> annotation is followed by a <code>error</code>, one
cannot expect to receive the matching <code>value-history-end</code>. One
cannot expect not to receive it either, however; an error annotation
does not necessarily mean that <small>GDB</small> is immediately returning all the way
to the top level.
</p>
<a name="index-error_002dbegin"></a>
<p>A quit or error annotation may be preceded by
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zerror-begin
</pre></div>
<p>Any output between that and the quit or error annotation is the error
message.
</p>
<p>Warning messages are not yet annotated.
</p>
<hr>
<a name="Breakpoint-Info"></a>
<div class="header">
<p>
Next: <a href="#Invalidation" accesskey="n" rel="next">Invalidation</a>, Previous: <a href="#Errors" accesskey="p" rel="prev">Errors</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Information-on-Breakpoints"></a>
<h2 class="chapter">10 Information on Breakpoints</h2>
<p><em>Breakpoint Annotations have been removed. <small>GDB/MI</small> instead
provides breakpoint commands.</em>
</p>
<a name="index-annotations-for-breakpoints"></a>
<p>The output from the <code>info breakpoints</code> command is annotated as follows:
</p>
<a name="index-breakpoints_002dheaders"></a>
<a name="index-breakpoints_002dtable"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zbreakpoints-headers
<var>header-entry</var>
^Z^Zbreakpoints-table
</pre></div>
<p>where <var>header-entry</var> has the same syntax as an entry (see below) but
instead of containing data, it contains strings which are intended to
convey the meaning of each field to the user. This is followed by any
number of entries. If a field does not apply for this entry, it is
omitted. Fields may contain trailing whitespace. Each entry consists
of:
</p>
<a name="index-record"></a>
<a name="index-field"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zrecord
^Z^Zfield 0
<var>number</var>
^Z^Zfield 1
<var>type</var>
^Z^Zfield 2
<var>disposition</var>
^Z^Zfield 3
<var>enable</var>
^Z^Zfield 4
<var>address</var>
^Z^Zfield 5
<var>what</var>
^Z^Zfield 6
<var>frame</var>
^Z^Zfield 7
<var>condition</var>
^Z^Zfield 8
<var>ignore-count</var>
^Z^Zfield 9
<var>commands</var>
</pre></div>
<p>Note that <var>address</var> is intended for user consumption—the syntax
varies depending on the language.
</p>
<p>The output ends with
</p>
<a name="index-breakpoints_002dtable_002dend"></a>
<div class="smallexample">
<pre class="smallexample">^Z^Zbreakpoints-table-end
</pre></div>
<hr>
<a name="Invalidation"></a>
<div class="header">
<p>
Next: <a href="#Annotations-for-Running" accesskey="n" rel="next">Annotations for Running</a>, Previous: <a href="#Breakpoint-Info" accesskey="p" rel="prev">Breakpoint Info</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Invalidation-Notices"></a>
<h2 class="chapter">11 Invalidation Notices</h2>
<a name="index-annotations-for-invalidation-messages"></a>
<p>The following annotations say that certain pieces of state may have
changed.
</p>
<dl compact="compact">
<dd><a name="index-frames_002dinvalid"></a>
</dd>
<dt><code>^Z^Zframes-invalid</code></dt>
<dd>
<p>The frames (for example, output from the <code>backtrace</code> command) may
have changed.
</p>
<a name="index-breakpoints_002dinvalid"></a>
</dd>
<dt><code>^Z^Zbreakpoints-invalid</code></dt>
<dd>
<p>The breakpoints may have changed. For example, the user just added or
deleted a breakpoint.
</p></dd>
</dl>
<hr>
<a name="Annotations-for-Running"></a>
<div class="header">
<p>
Next: <a href="#Source-Annotations" accesskey="n" rel="next">Source Annotations</a>, Previous: <a href="#Invalidation" accesskey="p" rel="prev">Invalidation</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Running-the-Program"></a>
<h2 class="chapter">12 Running the Program</h2>
<a name="index-annotations-for-running-programs"></a>
<a name="index-starting"></a>
<a name="index-stopping"></a>
<p>When the program starts executing due to a <small>GDB</small> command such as
<code>step</code> or <code>continue</code>,
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zstarting
</pre></div>
<p>is output. When the program stops,
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zstopped
</pre></div>
<p>is output. Before the <code>stopped</code> annotation, a variety of
annotations describe how the program stopped.
</p>
<dl compact="compact">
<dd><a name="index-exited"></a>
</dd>
<dt><code>^Z^Zexited <var>exit-status</var></code></dt>
<dd><p>The program exited, and <var>exit-status</var> is the exit status (zero for
successful exit, otherwise nonzero).
</p>
<a name="index-signalled"></a>
<a name="index-signal_002dname"></a>
<a name="index-signal_002dname_002dend"></a>
<a name="index-signal_002dstring"></a>
<a name="index-signal_002dstring_002dend"></a>
</dd>
<dt><code>^Z^Zsignalled</code></dt>
<dd><p>The program exited with a signal. After the <code>^Z^Zsignalled</code>, the
annotation continues:
</p>
<div class="smallexample">
<pre class="smallexample"><var>intro-text</var>
^Z^Zsignal-name
<var>name</var>
^Z^Zsignal-name-end
<var>middle-text</var>
^Z^Zsignal-string
<var>string</var>
^Z^Zsignal-string-end
<var>end-text</var>
</pre></div>
<p>where <var>name</var> is the name of the signal, such as <code>SIGILL</code> or
<code>SIGSEGV</code>, and <var>string</var> is the explanation of the signal, such
as <code>Illegal Instruction</code> or <code>Segmentation fault</code>.
<var>intro-text</var>, <var>middle-text</var>, and <var>end-text</var> are for the
user’s benefit and have no particular format.
</p>
<a name="index-signal"></a>
</dd>
<dt><code>^Z^Zsignal</code></dt>
<dd><p>The syntax of this annotation is just like <code>signalled</code>, but <small>GDB</small> is
just saying that the program received the signal, not that it was
terminated with it.
</p>
<a name="index-breakpoint"></a>
</dd>
<dt><code>^Z^Zbreakpoint <var>number</var></code></dt>
<dd><p>The program hit breakpoint number <var>number</var>.
</p>
<a name="index-watchpoint"></a>
</dd>
<dt><code>^Z^Zwatchpoint <var>number</var></code></dt>
<dd><p>The program hit watchpoint number <var>number</var>.
</p></dd>
</dl>
<hr>
<a name="Source-Annotations"></a>
<div class="header">
<p>
Next: <a href="#Multi_002dthreaded-Apps" accesskey="n" rel="next">Multi-threaded Apps</a>, Previous: <a href="#Annotations-for-Running" accesskey="p" rel="prev">Annotations for Running</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Displaying-Source"></a>
<h2 class="chapter">13 Displaying Source</h2>
<a name="index-annotations-for-source-display"></a>
<a name="index-source"></a>
<p>The following annotation is used instead of displaying source code:
</p>
<div class="smallexample">
<pre class="smallexample">^Z^Zsource <var>filename</var>:<var>line</var>:<var>character</var>:<var>middle</var>:<var>addr</var>
</pre></div>
<p>where <var>filename</var> is an absolute file name indicating which source
file, <var>line</var> is the line number within that file (where 1 is the
first line in the file), <var>character</var> is the character position
within the file (where 0 is the first character in the file) (for most
debug formats this will necessarily point to the beginning of a line),
<var>middle</var> is ‘<samp>middle</samp>’ if <var>addr</var> is in the middle of the
line, or ‘<samp>beg</samp>’ if <var>addr</var> is at the beginning of the line, and
<var>addr</var> is the address in the target program associated with the
source which is being displayed. <var>addr</var> is in the form ‘<samp>0x</samp>’
followed by one or more lowercase hex digits (note that this does not
depend on the language).
</p>
<hr>
<a name="Multi_002dthreaded-Apps"></a>
<div class="header">
<p>
Next: <a href="#GNU-Free-Documentation-License" accesskey="n" rel="next">GNU Free Documentation License</a>, Previous: <a href="#Source-Annotations" accesskey="p" rel="prev">Source Annotations</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="Multi_002dthreaded-Applications"></a>
<h2 class="chapter">14 Multi-threaded Applications</h2>
<a name="index-annotations-for-multi_002dthreaded-apps"></a>
<p>The following annotations report thread related changes of state.
</p>
<dl compact="compact">
<dd><a name="index-new_002dthread_002c-annotation"></a>
</dd>
<dt><code>^Z^Znew-thread</code></dt>
<dd>
<p>This annotation is issued once for each thread that is created apart from
the main thread, which is not reported.
</p>
<a name="index-thread_002dchanged_002c-annotation"></a>
</dd>
<dt><code>^Z^Zthread-changed</code></dt>
<dd>
<p>The selected thread has changed. This may occur at the request of the
user with the <code>thread</code> command, or as a result of execution,
e.g., another thread hits a breakpoint.
</p>
</dd>
</dl>
<hr>
<a name="GNU-Free-Documentation-License"></a>
<div class="header">
<p>
Previous: <a href="#Multi_002dthreaded-Apps" accesskey="p" rel="prev">Multi-threaded Apps</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
</div>
<a name="GNU-Free-Documentation-License-1"></a>
<h2 class="appendix">Appendix A GNU Free Documentation License</h2>
<div align="center">Version 1.3, 3 November 2008
</div>
<div class="display">
<pre class="display">Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<a href="http://fsf.org/">http://fsf.org/</a>
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
</pre></div>
<ol start="0">
<li> PREAMBLE
<p>The purpose of this License is to make a manual, textbook, or other
functional and useful document <em>free</em> in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or noncommercially.
Secondarily, this License preserves for the author and publisher a way
to get credit for their work, while not being considered responsible
for modifications made by others.
</p>
<p>This License is a kind of “copyleft”, which means that derivative
works of the document must themselves be free in the same sense. It
complements the GNU General Public License, which is a copyleft
license designed for free software.
</p>
<p>We have designed this License in order to use it for manuals for free
software, because free software needs free documentation: a free
program should come with manuals providing the same freedoms that the
software does. But this License is not limited to software manuals;
it can be used for any textual work, regardless of subject matter or
whether it is published as a printed book. We recommend this License
principally for works whose purpose is instruction or reference.
</p>
</li><li> APPLICABILITY AND DEFINITIONS
<p>This License applies to any manual or other work, in any medium, that
contains a notice placed by the copyright holder saying it can be
distributed under the terms of this License. Such a notice grants a
world-wide, royalty-free license, unlimited in duration, to use that
work under the conditions stated herein. The “Document”, below,
refers to any such manual or work. Any member of the public is a
licensee, and is addressed as “you”. You accept the license if you
copy, modify or distribute the work in a way requiring permission
under copyright law.
</p>
<p>A “Modified Version” of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
</p>
<p>A “Secondary Section” is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document’s overall
subject (or to related matters) and contains nothing that could fall
directly within that overall subject. (Thus, if the Document is in
part a textbook of mathematics, a Secondary Section may not explain
any mathematics.) The relationship could be a matter of historical
connection with the subject or with related matters, or of legal,
commercial, philosophical, ethical or political position regarding
them.
</p>
<p>The “Invariant Sections” are certain Secondary Sections whose titles
are designated, as being those of Invariant Sections, in the notice
that says that the Document is released under this License. If a
section does not fit the above definition of Secondary then it is not
allowed to be designated as Invariant. The Document may contain zero
Invariant Sections. If the Document does not identify any Invariant
Sections then there are none.
</p>
<p>The “Cover Texts” are certain short passages of text that are listed,
as Front-Cover Texts or Back-Cover Texts, in the notice that says that
the Document is released under this License. A Front-Cover Text may
be at most 5 words, and a Back-Cover Text may be at most 25 words.
</p>
<p>A “Transparent” copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed of
pixels) generic paint programs or (for drawings) some widely available
drawing editor, and that is suitable for input to text formatters or
for automatic translation to a variety of formats suitable for input
to text formatters. A copy made in an otherwise Transparent file
format whose markup, or absence of markup, has been arranged to thwart
or discourage subsequent modification by readers is not Transparent.
An image format is not Transparent if used for any substantial amount
of text. A copy that is not “Transparent” is called “Opaque”.
</p>
<p>Examples of suitable formats for Transparent copies include plain
<small>ASCII</small> without markup, Texinfo input format, LaTeX input
format, <acronym>SGML</acronym> or <acronym>XML</acronym> using a publicly available
<acronym>DTD</acronym>, and standard-conforming simple <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> designed for human modification. Examples
of transparent image formats include <acronym>PNG</acronym>, <acronym>XCF</acronym> and
<acronym>JPG</acronym>. Opaque formats include proprietary formats that can be
read and edited only by proprietary word processors, <acronym>SGML</acronym> or
<acronym>XML</acronym> for which the <acronym>DTD</acronym> and/or processing tools are
not generally available, and the machine-generated <acronym>HTML</acronym>,
PostScript or <acronym>PDF</acronym> produced by some word processors for
output purposes only.
</p>
<p>The “Title Page” means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the material
this License requires to appear in the title page. For works in
formats which do not have any title page as such, “Title Page” means
the text near the most prominent appearance of the work’s title,
preceding the beginning of the body of the text.
</p>
<p>The “publisher” means any person or entity that distributes copies
of the Document to the public.
</p>
<p>A section “Entitled XYZ” means a named subunit of the Document whose
title either is precisely XYZ or contains XYZ in parentheses following
text that translates XYZ in another language. (Here XYZ stands for a
specific section name mentioned below, such as “Acknowledgements”,
“Dedications”, “Endorsements”, or “History”.) To “Preserve the Title”
of such a section when you modify the Document means that it remains a
section “Entitled XYZ” according to this definition.
</p>
<p>The Document may include Warranty Disclaimers next to the notice which
states that this License applies to the Document. These Warranty
Disclaimers are considered to be included by reference in this
License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and has
no effect on the meaning of this License.
</p>
</li><li> VERBATIM COPYING
<p>You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License applies
to the Document are reproduced in all copies, and that you add no other
conditions whatsoever to those of this License. You may not use
technical measures to obstruct or control the reading or further
copying of the copies you make or distribute. However, you may accept
compensation in exchange for copies. If you distribute a large enough
number of copies you must also follow the conditions in section 3.
</p>
<p>You may also lend copies, under the same conditions stated above, and
you may publicly display copies.
</p>
</li><li> COPYING IN QUANTITY
<p>If you publish printed copies (or copies in media that commonly have
printed covers) of the Document, numbering more than 100, and the
Document’s license notice requires Cover Texts, you must enclose the
copies in covers that carry, clearly and legibly, all these Cover
Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
the back cover. Both covers must also clearly and legibly identify
you as the publisher of these copies. The front cover must present
the full title with all words of the title equally prominent and
visible. You may add other material on the covers in addition.
Copying with changes limited to the covers, as long as they preserve
the title of the Document and satisfy these conditions, can be treated
as verbatim copying in other respects.
</p>
<p>If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto adjacent
pages.
</p>
<p>If you publish or distribute Opaque copies of the Document numbering
more than 100, you must either include a machine-readable Transparent
copy along with each Opaque copy, or state in or with each Opaque copy
a computer-network location from which the general network-using
public has access to download using public-standard network protocols
a complete Transparent copy of the Document, free of added material.
If you use the latter option, you must take reasonably prudent steps,
when you begin distribution of Opaque copies in quantity, to ensure
that this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you distribute an
Opaque copy (directly or through your agents or retailers) of that
edition to the public.
</p>
<p>It is requested, but not required, that you contact the authors of the
Document well before redistributing any large number of copies, to give
them a chance to provide you with an updated version of the Document.
</p>
</li><li> MODIFICATIONS
<p>You may copy and distribute a Modified Version of the Document under
the conditions of sections 2 and 3 above, provided that you release
the Modified Version under precisely this License, with the Modified
Version filling the role of the Document, thus licensing distribution
and modification of the Modified Version to whoever possesses a copy
of it. In addition, you must do these things in the Modified Version:
</p>
<ol type="A" start="1">
<li> Use in the Title Page (and on the covers, if any) a title distinct
from that of the Document, and from those of previous versions
(which should, if there were any, be listed in the History section
of the Document). You may use the same title as a previous version
if the original publisher of that version gives permission.
</li><li> List on the Title Page, as authors, one or more persons or entities
responsible for authorship of the modifications in the Modified
Version, together with at least five of the principal authors of the
Document (all of its principal authors, if it has fewer than five),
unless they release you from this requirement.
</li><li> State on the Title page the name of the publisher of the
Modified Version, as the publisher.
</li><li> Preserve all the copyright notices of the Document.
</li><li> Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
</li><li> Include, immediately after the copyright notices, a license notice
giving the public permission to use the Modified Version under the
terms of this License, in the form shown in the Addendum below.
</li><li> Preserve in that license notice the full lists of Invariant Sections
and required Cover Texts given in the Document’s license notice.
</li><li> Include an unaltered copy of this License.
</li><li> Preserve the section Entitled “History”, Preserve its Title, and add
to it an item stating at least the title, year, new authors, and
publisher of the Modified Version as given on the Title Page. If
there is no section Entitled “History” in the Document, create one
stating the title, year, authors, and publisher of the Document as
given on its Title Page, then add an item describing the Modified
Version as stated in the previous sentence.
</li><li> Preserve the network location, if any, given in the Document for
public access to a Transparent copy of the Document, and likewise
the network locations given in the Document for previous versions
it was based on. These may be placed in the “History” section.
You may omit a network location for a work that was published at
least four years before the Document itself, or if the original
publisher of the version it refers to gives permission.
</li><li> For any section Entitled “Acknowledgements” or “Dedications”, Preserve
the Title of the section, and preserve in the section all the
substance and tone of each of the contributor acknowledgements and/or
dedications given therein.
</li><li> Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section titles.
</li><li> Delete any section Entitled “Endorsements”. Such a section
may not be included in the Modified Version.
</li><li> Do not retitle any existing section to be Entitled “Endorsements” or
to conflict in title with any Invariant Section.
</li><li> Preserve any Warranty Disclaimers.
</li></ol>
<p>If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no material
copied from the Document, you may at your option designate some or all
of these sections as invariant. To do this, add their titles to the
list of Invariant Sections in the Modified Version’s license notice.
These titles must be distinct from any other section titles.
</p>
<p>You may add a section Entitled “Endorsements”, provided it contains
nothing but endorsements of your Modified Version by various
parties—for example, statements of peer review or that the text has
been approved by an organization as the authoritative definition of a
standard.
</p>
<p>You may add a passage of up to five words as a Front-Cover Text, and a
passage of up to 25 words as a Back-Cover Text, to the end of the list
of Cover Texts in the Modified Version. Only one passage of
Front-Cover Text and one of Back-Cover Text may be added by (or
through arrangements made by) any one entity. If the Document already
includes a cover text for the same cover, previously added by you or
by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
</p>
<p>The author(s) and publisher(s) of the Document do not by this License
give permission to use their names for publicity for or to assert or
imply endorsement of any Modified Version.
</p>
</li><li> COMBINING DOCUMENTS
<p>You may combine the Document with other documents released under this
License, under the terms defined in section 4 above for modified
versions, provided that you include in the combination all of the
Invariant Sections of all of the original documents, unmodified, and
list them all as Invariant Sections of your combined work in its
license notice, and that you preserve all their Warranty Disclaimers.
</p>
<p>The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name but
different contents, make the title of each such section unique by
adding at the end of it, in parentheses, the name of the original
author or publisher of that section if known, or else a unique number.
Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
</p>
<p>In the combination, you must combine any sections Entitled “History”
in the various original documents, forming one section Entitled
“History”; likewise combine any sections Entitled “Acknowledgements”,
and any sections Entitled “Dedications”. You must delete all
sections Entitled “Endorsements.”
</p>
</li><li> COLLECTIONS OF DOCUMENTS
<p>You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this
License in the various documents with a single copy that is included in
the collection, provided that you follow the rules of this License for
verbatim copying of each of the documents in all other respects.
</p>
<p>You may extract a single document from such a collection, and distribute
it individually under this License, provided you insert a copy of this
License into the extracted document, and follow this License in all
other respects regarding verbatim copying of that document.
</p>
</li><li> AGGREGATION WITH INDEPENDENT WORKS
<p>A compilation of the Document or its derivatives with other separate
and independent documents or works, in or on a volume of a storage or
distribution medium, is called an “aggregate” if the copyright
resulting from the compilation is not used to limit the legal rights
of the compilation’s users beyond what the individual works permit.
When the Document is included in an aggregate, this License does not
apply to the other works in the aggregate which are not themselves
derivative works of the Document.
</p>
<p>If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half of
the entire aggregate, the Document’s Cover Texts may be placed on
covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic form.
Otherwise they must appear on printed covers that bracket the whole
aggregate.
</p>
</li><li> TRANSLATION
<p>Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section 4.
Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also include
the original English version of this License and the original versions
of those notices and disclaimers. In case of a disagreement between
the translation and the original version of this License or a notice
or disclaimer, the original version will prevail.
</p>
<p>If a section in the Document is Entitled “Acknowledgements”,
“Dedications”, or “History”, the requirement (section 4) to Preserve
its Title (section 1) will typically require changing the actual
title.
</p>
</li><li> TERMINATION
<p>You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void, and
will automatically terminate your rights under this License.
</p>
<p>However, if you cease all violation of this License, then your license
from a particular copyright holder is reinstated (a) provisionally,
unless and until the copyright holder explicitly and finally
terminates your license, and (b) permanently, if the copyright holder
fails to notify you of the violation by some reasonable means prior to
60 days after the cessation.
</p>
<p>Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.
</p>
<p>Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License. If your rights have been terminated and not permanently
reinstated, receipt of a copy of some or all of the same material does
not give you any rights to use it.
</p>
</li><li> FUTURE REVISIONS OF THIS LICENSE
<p>The Free Software Foundation may publish new, revised versions
of the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
<a href="http://www.gnu.org/copyleft/">http://www.gnu.org/copyleft/</a>.
</p>
<p>Each version of the License is given a distinguishing version number.
If the Document specifies that a particular numbered version of this
License “or any later version” applies to it, you have the option of
following the terms and conditions either of that specified version or
of any later version that has been published (not as a draft) by the
Free Software Foundation. If the Document does not specify a version
number of this License, you may choose any version ever published (not
as a draft) by the Free Software Foundation. If the Document
specifies that a proxy can decide which future versions of this
License can be used, that proxy’s public statement of acceptance of a
version permanently authorizes you to choose that version for the
Document.
</p>
</li><li> RELICENSING
<p>“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server. A
“Massive Multiauthor Collaboration” (or “MMC”) contained in the
site means any set of copyrightable works thus published on the MMC
site.
</p>
<p>“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
</p>
<p>“Incorporate” means to publish or republish a Document, in whole or
in part, as part of another Document.
</p>
<p>An MMC is “eligible for relicensing” if it is licensed under this
License, and if all works that were first published under this License
somewhere other than this MMC, and subsequently incorporated in whole
or in part into the MMC, (1) had no cover texts or invariant sections,
and (2) were thus incorporated prior to November 1, 2008.
</p>
<p>The operator of an MMC Site may republish an MMC contained in the site
under CC-BY-SA on the same site at any time before August 1, 2009,
provided the MMC is eligible for relicensing.
</p>
</li></ol>
<a name="ADDENDUM_003a-How-to-use-this-License-for-your-documents"></a>
<h3 class="heading">ADDENDUM: How to use this License for your documents</h3>
<p>To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and
license notices just after the title page:
</p>
<div class="smallexample">
<pre class="smallexample"> Copyright (C) <var>year</var> <var>your name</var>.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
</pre></div>
<p>If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
replace the “with…Texts.” line with this:
</p>
<div class="smallexample">
<pre class="smallexample"> with the Invariant Sections being <var>list their titles</var>, with
the Front-Cover Texts being <var>list</var>, and with the Back-Cover Texts
being <var>list</var>.
</pre></div>
<p>If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.
</p>
<p>If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
free software license, such as the GNU General Public License,
to permit their use in free software.
</p>
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