wanted: viewgraph maker for troff with ellipses and arrows

[utzoo!decvax!ucbvax!unix-wizards]

>From walton at LL-XN Wed Sep 23 22:39:50 1981
Does anyone know of an extension to troff, perhaps like tbl or eqn,
for doing graphics such as making viewgraphs with diagrams and
data graphs.  Ideally should be able to draw square and elliptical
boxes and lines and arrows between, plus various graphical data
displays: a kind of troff + tektronics.