A non-zero value indicates that the Event-Timestamp
attribute must be used in the dynamic authorization
communication exchange between the NAS and the RADIUS
server. Such a value determines the time window (in
seconds) within which RADIUS packets carrying the
Event-Timestamp attribute will be considered as current
and accepted for processing by the NAS and the RADIUS
Server. Zero value disables checking for the
Event-Timestamp attribute. The default time window
is 300 seconds.