- <term><option>link-layer-time</option> </term>
- <term><option>link-layer</option> </term>
- <term><option>uuid</option> </term>
- <listitem><para>Those values are parsed and can be used to set the DUID type
- field, but DUID contents must be provided using <varname>DUIDRawData=</varname>.
+ <term><option>uuid</option></term>
+ <listitem><para>If <literal>DUIDType=uuid</literal>, and <varname>DUIDRawData=</varname> is not set,
+ then the product UUID is used as a DUID value. If a system does not have valid product UUID, then
+ an application-specific
+ <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ is used as a DUID value. About the application-specific machine ID, see
+ <citerefentry><refentrytitle>sd_id128_get_machine_app_specific</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>link-layer-time[:<replaceable>TIME</replaceable>]</option></term>
+ <term><option>link-layer</option></term>
+ <listitem><para>If <literal>link-layer-time</literal> or <literal>link-layer</literal> is specified,
+ then the MAC address of the interface is used as a DUID value. The value <literal>link-layer-time</literal>
+ can take additional time value after a colon, e.g. <literal>link-layer-time:2018-01-23 12:34:56 UTC</literal>.
+ The default time value is <literal>2000-01-01 00:00:00 UTC</literal>.