@fresco,
Call it what you like, occurrences, happenings, motion, 'stuff'...stuff moves.
If you like, you can assign meaning to the motion of stuff and define that as 'happenings'.
The way I was looking at it, motion is an occurrence, whether or not I know about it, and whether or not it has any meaning to me.
What btw, do you mean by co-extensive?