Rob, You've encountered the non-support of contours in Ferret v4.91. Curvilinear coordinates were originally (in v4.91) only supported in the "SHADE" and "FILL" commands. Version v5.0 of Ferret (now in a quite stable 'beta' release) adds curvilinear support for "CONTOUR" and a first attempt at providing curvilinear support for "VECTOR". -- Jonathan Callahan