<acknowledge/> is a switch to indicate that an alarm to be given by a dive computer at a specific incident has to be acknowledged by the diver. The alarm signal — set via <alarmtype> — will be repeated until the diver presses a certain button to stop it.
If neither <acknowledge/> nor <period> are given, the dive computer has to create the alarm for a certain time span; then an acknowledgement is not necessary.
<dcalarm>
<dcalarm>
see <dcalarm>