Answering my own question:
http://pages.cs.wisc.edu/~ghost/doc/AFPL/6.50/Language.htm#Transparency
For some reason this was a bit difficult to find.
I just needed to adjust the code:
{ gsave
[ /ca .5 /SetTransparency pdfmark
.5 .setopacityalpha true .settextknockout
...
ed to recognize it.
Any suggestions? This is rather difficult to find information about!
Thank you,
Walt
-~
Answering my own question, inserting this line solved the problem:
> { gsave
> [ /ca .5 /SetTransparencypdfmark
.5 .setopacityalpha true .settextknockout
Walt
-~
