Progress 8.2c is even older than DEC Tru64. It was retired prior to y2k.
Having said that... extracting the data is relatively simple for an experienced person. If you want to do it yourself you could just go into the data dictionary (which you have already found) and take the "dump" options under "admin".
Of course if this is a large database (large in terms of the vintage HW it is running on) that might take a while. Possibly even a very, very long while. (The dictionary dump is single threaded.)
And it isn't likely to be in a form that you want it in for importing to Oracle. (The dictionary dump is space delimited quote ascii.)
But is that your real problem? Or do you just need to get this system ported to a supportable platform? The technical part of porting it is (or should be) relatively easy and you can probably run it on a much smaller server with vastly better results -- Moore's Law has been hard at work for more than 10 years since that system was put in place. Licensing is likely the stumbling block. The software on the Tru64 server isn't binary compatible with anything and if you haven't been paying Progress maintenance it could be very expensive to get up to date. OTOH you said "our vendor" so maybe you are up to date -- if so then this becomes really, really easy. (Well, in theory anyway. Sometimes vendors aren't so easy to work with...)
