Hello, I'm a grad. student in statistics and am looking for some information on how R draws its contours. I suspect you are using a Bezier spline. I have the C code but am curious about how it works. Riley A. Metzger University of Waterloo Waterloo, Ontario, N2L 3G1 (519) 888-4567 Ext. 3715 rileymetzger at alumni.uwaterloo.ca