The value of tVrrpHstUnrchEvtType specifies whether
this event is a 'delta' or an 'explicit' event. When the event
is 'set', the value of tVrrpHstUnrchEvtPriority will
be subtracted from the in-use priority in case of a 'delta' event
or the in-use priority will be explicitly overridden by the value
of tVrrpHstUnrchEvtPriority in case of an 'explicit'
event.