i confirm what Doud and Richard have said 1) the pamp is rigid 2) subclasses can help you the pupose of this not is to point a typo in doug's mail Class Other_Clone Is_a_subclass_of Clone Filter "NOT cDNA, NOT YAC" is not corret you want to change the coma into and AND Class Other_Clone Is_a_subclass_of Clone Filter "NOT cDNA AND NOT YAC" ---