A %DateInterval% is added to now. It is the *maximum lifetime* of the ticket. If a ticket already exists that expires a sixth earlier than demanded, it suffices and will be resused. So for a year, that is approximately two months.
No tolerance is applied to a %DateTime%. It must be valid to exactly that date.
When the service call should be executed. Might be in the past, but the earliest time the call is actually processed is after the current request has finished.
When the service should be executed. When float/int is given, it is in seconds from the time of the call, with a significant sub second part behind the comma.