Thanks for your comments Icaro and MB; I didn't understand the patent issue
before you explained it. This is how I understand it now:
Some proprietary formats work on both proprietary sofware and free software.
Some proprietary formats work on proprietary software only. Using free
software to play a proprietary format risks infringing a proprietary format
patent. Is that right?
The confidentiality issue may be a reason to use free formats instead of
proprietary formats. Do I have this wrong?:
Some proprietary formats allow people to use free software. But fear of
infringing a patent may encourage people to use patent-holder-authorized
proprietary software instead. Proprietary software can be a back-door to a
computer. [Is that right?]. This may not be ideal, for a lawyer who keeps
clients' confidential information on his computer.
