It appears to use a similar approach to lite-C's EVENT_FRAME, if I'm not mistaken. Of course, lite-C's frame event could more easily get quite convoluted since the same event/function will be used with any other events that the entity detects (EVENT_IMPACT and so on).

Unity appears to separate these, and it looks quite nice.

Jibb

EDIT: Okay, thanks for the explanation, Slin. (I had the reply window open for too long).