Inside <period> the duration in seconds (as a real number) of an alarm to be given by the dive computer at a certain event is set. The alarm signal — determined via <alarmtype> — needs not to be acknowledged.
Note: In an alarm which shall be acknowledged, the <acknowledge/> switch must be given.
If neither <acknowledge/> nor <period> is given, the dive computer generates the alarm signal for a certain time span; an acknowledgement is not necessary in this case.
(see also <dcalarm>)
<!-- alarm of 10 seconds --> <period>10.0</period>