...the benefits and pitfalls of
defining my own extensions in terms of the mechanics of the program. What
troubles might this land me in with regard to other NB transactions such as
file conversion for example.
I am quite cavalier about file extensions. I have a few .NB files, but most
of my work files have no extns at all, to save (mis-)typing the period when
calling them from the cmd line. Some of my programs have the .RUN extn, but
some (sent by XyWrite people such as Carl) have .PM and others have .XPL.
Others have none at all.