http://www.conitec.net/beta/ac_move.htm
If ACTIVATE_TRIGGER is set, a nearby entities' event function is triggered when it's ENABLE_TRIGGER flag is set and either a) tThe sum of the moved entities' trigger_range and the nearby entities' trigger_range is bigger than the distance between the move target position and the nearby entities' origin, or b) the nearby entities' trigger_range is zero, its passable flag is set and the move target position is inside it's bounding box.
http://www.conitec.net/beta/avec_accelerate.htm
Returns:
amount of distance
I think it returns distance vector instead,not amount.

That's right - thanks for the info.

Thank you jcl. And here is another small error on vec_to_angle
http://www.conitec.net/beta/avec_to_angle.htm
I think it may return angle instead of Length of the vector.

No, this time it's correct, the length is really returned.