timers defined in the other directives.</para>
<para>These are monotonic timers, independent of wall-clock time and timezones. If the computer is
- temporarily suspended, the monotonic clock pauses, too.</para>
+ temporarily suspended, the monotonic clock generally pauses, too. Note that if
+ <varname>WakeSystem=</varname> is used, a different monotonic clock is selected that continues to
+ advance while the system is suspended and thus can be used as the trigger to resume the
+ system.</para>
<para>If the empty string is assigned to any of these options, the list of timers is reset (both
monotonic timers and <varname>OnCalendar=</varname> timers, see below), and all prior assignments
<varname>false</varname>.</para>
<para>Note that this functionality requires privileges and is thus generally only available in the
- system service manager.</para></listitem>
+ system service manager.</para>
+
+ <para>Note that behaviour of monotonic clock timers (as configured with
+ <varname>OnActiveSec=</varname>, <varname>OnBootSec=</varname>, <varname>OnStartupSec=</varname>,
+ <varname>OnUnitActiveSec=</varname>, <varname>OnUnitInactiveSec=</varname>, see above) is altered
+ depending on this option. If false, a monotonic clock is used that is paused during system suspend
+ (<constant>CLOCK_MONOTONIC</constant>), if true a different monotonic clock is used that continues
+ advancing during system suspend (<constant>CLOCK_BOOTTIME</constant>), see
+ <citerefentry><refentrytitle>clock_getres</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
+ details.</para></listitem>
</varlistentry>
<varlistentry>