Birtwistle, G.Zhang, H.2008-02-272008-02-271992-02-01http://hdl.handle.net/1880/45729We report on the specification of a subset of graphics package called Polygon Groper. We used \o'\fIZ\(ap'\fR and its associated specification schema methodology to specify the datastructures of Polygon Groper, the set of primitive functions over these data structures, and the set of commands that compose functions over these datastructures. Working strictly from these specifications, we have located and corrected several serious errors in Polygon Groper. The techniques are straightforward and may be applied to any system.EngComputer Scienceunknown1992-465-310.11575/PRISM/30392