Sample DocBook document with profiling information

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<!DOCTYPE chapter PUBLIC '-//OASIS//DTD DocBook XML V4.1.2//EN'
<title>How to setup SGML catalogs</title>

<para>Many existing SGML tools are able to map public identifiers to
files on your local file system. Mapping is specified in so called
catalog file. List of catalog files to use is stored in environment
variable <envar>SGML_CATALOG_FILES</envar>.</para>

<para os="unix">On Unix systems you can set this variable by invoking
command <command>export SGML_CATALOG_FILES=/usr/lib/catalog</command>
on command line. If you want maintain value of the variable between
sessions, place this command into startup file,
e.g. <filename>.profile</filename>.</para>

<para os="win">In Windows NT/2000 you can set environment variable by
issuing command <menuchoice><guimenu>Start</guimenu>
<guisubmenu>Settings</guisubmenu> <guisubmenu>Control
<guimenuitem>System</guimenuitem></menuchoice>. Then select
<guilabel>Advanced</guilabel> card in the dialog box and click on the
<guibutton>Environment Variables...</guibutton> button. Using the
<guibutton>New</guibutton> button you can add new environment variable
into your system.</para>