document the difference between associate/affect
document the difference between associate/affect

This is a subtle thing that annoys people when
first writing element assembly routines
using APF.
Hopefully these comments will help future users.

YetAnotherMinion/core,yangf4/core,YetAnotherMinion/core,YetAnotherMinion/core,yangf4/core,YetAnotherMinion/core,YetAnotherMinion/core,yangf4/core,yangf4/core,yangf4/core