Also a set of vertex's can be assigned to several groups.  So a part that is weighted to a value of 1.0 or 100% will not be effected by other weighted constraints.  However, if they overlap is set to lower values then they will have an effect on the other groups.  Such as one part might want to be pulled down but another smaller part is weighted to go up the overlap may not go down as far as if they didn't have that slight upward pull.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13, 14