Thanks for all the responses.

Frank, AFAIK the application was compiled to 10.10, which is what it
currently runs on. Apologies for the vague response, but I don't have
access to the developer, and there is very little documentation. One
bit of information I do have is that someone (yes, that vague
'someone'...) tried to run the application several years ago on 10.20,
and was not able to do so. Again, this is secondhand, and I don't have
any documentation of what the errors were... :Grrrrrrrrr

It's basically an inventory and process control app for a small
munfacturing concern, it does have libraries - I am just getting my
hands around the structure, so I don't have a whole lot of details. I
am going to very hands-on with application for the next few weeks, so I
should know a great deal more then.

As to what I'd like it to run on, I'd like to run on at least 11.0. I
will have my hands on the D210 quite shortly, which is supposed to come
with 11.0. It's worth a try to see if it will run, as perhaps I have
fallen into the trap of assuming without verifying.

Again, thanks all for the advice.