GKS is a 2D graphics package developed in the late 1970s. It is a vector based package, and based on display lists. It was later replaced by PHIGS, which is a 3D grapics package. PHIGS and Core have similar functionality, but are quite different in their internal details. -- Dr. Mark Green mark(a)cs.ualberta.ca Professor (780) 492-4584 Director, Research Institute for Multimedia Systems (RIMS) Department of Computing Science (780) 492-1071 (FAX) University of Alberta, Edmonton, Alberta, T6G 2H1, Canada