James, that may work, but the old school JPS files do seem to be different than the new school JPS files. I have a few quite old Javad receivers, and some topcon units, and you are correct, you could change the extension and they are the same file.
However, I can't say the JPS files coming out of my T1Ms are the same, as it no longer worked for me trying to go back to older software with the newer files.