The psum function is an aggregation function and can be used on participation fields. It will sum the participations together and return a total sum mask for all channels.
|participation||participation||The participation is a binary value and shows which channels are active.|
The following query draws the total amount of sessions on the baseline of channel 1:
draw number using pres(1, result) as value from ( using psum(baseline) as result from @sessions ) as p