+
+<refsect2>
+<title>Tracking the evolution of a codename release</title>
+
+<para>The following APT preferences file will cause APT to assign a
+priority higher than the default (500) to all package versions belonging
+to a specified codename of a distribution and a prohibitively low priority to
+package versions belonging to other <literal>Debian</literal> distributions,
+codenames and archives.
+Note that with this APT preference APT will follow the migration of a release
+from the archive <literal>testing</literal> to <literal>stable</literal> and
+later <literal>oldstable</literal>. If you want to follow for example the progress
+in <literal>testing</literal> notwithstanding the codename changes you should use
+the example configurations above.
+
+<programlisting>
+Explanation: Uninstall or do not install any Debian-originated package versions
+Explanation: other than those in the distribution codenamed with squeeze or sid
+Package: *
+Pin: release n=squeeze
+Pin-Priority: 900
+
+Explanation: Debian unstable is always codenamed with sid
+Package: *
+Pin: release a=sid
+Pin-Priority: 800
+
+Package: *
+Pin: release o=Debian
+Pin-Priority: -10
+</programlisting>
+</para>
+
+<para>With a suitable &sources-list; file and the above preferences file,
+any of the following commands will cause APT to upgrade to the
+latest version(s) in the release codenamed with <literal>squeeze</literal>.
+
+<programlisting>
+apt-get install <replaceable>package-name</replaceable>
+apt-get upgrade
+apt-get dist-upgrade
+</programlisting>
+</para>
+
+<para>The following command will cause APT to upgrade the specified
+package to the latest version from the <literal>sid</literal> distribution.
+Thereafter, <command>apt-get upgrade</command> will upgrade
+the package to the most recent <literal>squeeze</literal> version if that is
+more recent than the installed version, otherwise, to the most recent
+<literal>sid</literal> version if that is more recent than the installed
+version.
+
+<programlisting>
+apt-get install <replaceable>package</replaceable>/sid
+</programlisting>
+</para>