For example it is needed to calculate SUM of two totalizers.
To resolve that I tried to use the PI Analyses and the PI PE. Еvents for opening/closing totalizing periods can be posted later than corresponding timestamps for archive. So the result tag archive doesn't have reguired events for start and end of the accounting period (at 00:00:00 and at 00:00:01 - for day totals).
I would try to play with the PI Recalculator Subsystem but I found out that "An inserted event is set at the source event time stamp +1 sec.". So if I use it I will never get my accounting period as result (at 00:00:00 and at 00:00:01) because of that timestamp distortion.