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@@ -34,46 +34,42 @@ the &sources-list; file contains references to more than one distribution
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(for example, <literal>stable</literal> and <literal>testing</literal>).
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APT assigns a priority to each version that is available.
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Subject to dependency constraints, <command>apt-get</command> selects the
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-version with the highest priority for installation. If multiple
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-versions are available with equal priorities, the higher version will
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-be selected.
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+version with the highest priority for installation.
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The APT preferences file overrides the priorities that APT assigns to
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package versions by default, thus giving the user control over which
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one is selected for installation.
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</para>
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-
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<para>
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-If the selected version of a package is available from more than one
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-source, for example if more than one mirror of the same packages is
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-listed in <filename>sources.list</>, apt will select the source listed
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+Several instances of the same version of a package may be available when
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+the &sources-list; file contains references to more than one source.
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+In this case <command>apt-get</command> downloads the instance listed
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earliest in the &sources-list; file.
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-
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-The APT preferences file does not affect which download source is
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-used, only which versions of packages are selected for installation.
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+The APT preferences file does not affect the choice of instance, only
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+the choice of version.
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</para>
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<RefSect2><Title>APT's Default Priority Assignments</>
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<para>
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-If there is no preferences file, or if there is no entry in the file
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-that applies to a particular version, then certain defaults are
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-supplied.
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+If there is no preferences file or if there is no entry in the file
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+that applies to a particular version then the priority assigned to that
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+version is the priority of the distribution to which that version
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+belongs. It is possible to single out a distribution, "the target release",
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+which receives a higher priority than other distributions do by default.
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+The target release can be set on the <command>apt-get</command> command
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+line or in the APT configuration file <filename>/etc/apt/apt.conf</filename>.
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+For example,
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+<programlisting>
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+<command>apt-get install -t testing <replaceable>some-package</replaceable></command>
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+</programlisting>
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+<programlisting>
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+APT::Default-Release "stable";
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+</programlisting>
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</para>
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-<variablelist>
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-<varlistentry>
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-<term>Installed packages</term>
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-<listitem><simpara>The currently installed version of a package, if any, is
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-assigned priority 100.</simpara></listitem>
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-</varlistentry>
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-
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-<varlistentry>
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-<term></term>
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-<listitem><simpara>The currently installed version of a package, if any, is
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-assigned priority 100.</simpara></listitem>
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-</varlistentry>
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-
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<para>
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+If the target release has been specified then APT uses the following
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+algorithm to set the priorities of the versions of a package. Assign:
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<variablelist>
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<varlistentry>
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<term>priority 100</term>
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@@ -90,16 +86,6 @@ assigned priority 100.</simpara></listitem>
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</variablelist>
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</para>
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-For example,
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-<programlisting>
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-<command>apt-get install -t testing <replaceable>some-package</replaceable></command>
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-</programlisting>
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-<programlisting>
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-APT::Default-Release "stable";
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-</programlisting>
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-</para>
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-
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-
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<para>
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If the target release has not been specified then APT simply assigns
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priority 100 to all installed package versions and priority 500 to all
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Arch Librarian