Ok, well using HxD (a hex editor for Windows) I get the following out of the very beginning of the file:
V5.00 Copyright (C) by Compulife Software Inc., 1993
Googling Compulife Software took me here. Their products are here.
A bit more digging around gives:
Compulife offers an historical CD which contains past editions of our software.
The CD also contains instructions about how to install the past editions,
which are in a zipped format.
The history covers almost every month from the current month back to:
April 1990
The hex dump said 1993, so there may be some hope here. I'd say your best bet is to contact Compulife themselves. Failing that I can say that the file appears to have a fixed length record format, with some data as text and some in other 8 or 16bit encodings.
I'd start charging about now.