Actually, the answer varies. (don't you just love it?)

Depends on which line of the form you are on.
You could be counting all bodies.
You could be counting members only.
You could be only counting *part* of the members present (Primary, for example)
You could, or could not, be counting people away on other church assignments, you could be counting specific members ----
**Some** of the data is last month of the quarter
**Some** of the data is an average
Attendance, for example, can be an average, is sometimes an absolute sorta ( if someone attended 1 time ever, then they count---) :p
I always pull down the "help" for the page in MLS and print it out as I do the report -- just to make sure I have it right.