+ <term><option>-b <optional><replaceable>ID</replaceable></optional></option></term>
+ <term><option>--boot=<optional><replaceable>ID</replaceable></optional></option></term>
+
+ <listitem><para>Show messages from the specified
+ boot <replaceable>ID</replaceable> or from
+ current boot if no <replaceable>ID</replaceable>
+ is given. This will add a match for
+ <literal>_BOOT_ID=</literal>.</para>
+
+ <para>The argument is a 128 bit ID given in
+ short or UUID form and optionally followed by
+ <literal>:n</literal> which identifies the nth
+ boot relative to the boot ID given to the left
+ of <literal>:</literal>. Supplying a negative
+ value for n will look for a past boot and a
+ positive value for a future boot. The boot IDs
+ are searched for in chronological order. If no
+ number is provided after <literal>:</literal>,
+ <literal>-1</literal> is assumed. A value of 0
+ is valid and equivalent to omitting
+ <literal>:0</literal>.</para>
+
+ <para>Alternatively, the argument may constist
+ only of <literal>:n</literal>. In this case, a
+ positive value will look up the nth boot
+ starting from the beginning of the jouranl, a
+ negative value will look up a previous boot
+ relative to the current boot. <literal>:0</literal>
+ will look for the current boot ID. Thus,
+ <literal>:1</literal> is the first boot found in
+ the journal, <literal>:2</literal> the second
+ and so on; while <literal>:-1</literal> is the
+ previous boot, <literal>:-2</literal> the boot
+ before that and so on. Omitting a value after
+ <literal>:</literal> will look for the previous
+ boot.</para></listitem>
+ </varlistentry>