In early versions of the MacPlot driver, selecting an architectural D-size paper caused an incorrect drawing size to be displayed. If the drawing size is reset under Drawing... by clicking in the gray box, the paper size becomes Zero x Zero.
This information was provided by Claris Corporation on 16 March 1998, and incorporated into Apple Computer's Tech Info Library.
Versions of the MacPlot driver created after October 1989 do not exhibit this issue.