You can certainly save stuff in differing modes and open them too but you would need to know the programme he used to save the data in before you could open it. When I get these, and various people send me stuff for the magazine that they have saved on their PCs or Macs, I used to use the "Let M/Soft identify the programme" option that came up on the screen but it never, ever, found a way to open anything so in the end I just decided to send such discs straight back with a note saying "Please save this in Word Format and resend it to me as I cannot open it". It saves me grief and is quicker, in the end, than struggling with the things.
There are too many non M/soft programmes available and people cannot reasonably expect you to have them all.