Arexx Compiler
Well I looked at the docs for ExecRexx and didn't find any author
information either Tom. But it looks like it may have been written by "The
Dissidents" who have written various Arexx utilities. You might use the
Amiga Filefinder here on CIS for the keyword "Dissidents" to see what you
come up with. Chances are one of their other utilities has their address.