GPL software with GPL+compatibility specific patent license

[Jeff Breidenbach]

I think I understand the GPL pretty well, but I would like to get a
considered, expert opinion on the following scenario. For example,
consider a particular audio compression technology with the following
components:

A = software based compressor and decompressor
B = the file format of the compressed music
C = patents covering the generic technology
Q = entity who developed/owns all of the above

If entity Q does the following:

*  A is licensed under the GPL

*  B is published w/all rights reserved by Q

*  C are licensed royalty-free for GPL software
   complying with B.

*  A and/or C are additionally available for commercial
   licensing, under a fee-bearing proprietary license.

The goal of the compatibility-with-B requirement in the patent
licensing is to prevent interoperability problems.

Two questions:

1) Is this all ok in theory with respect to the 
   GPL?

2) Is this all ok in practice, or will entities
   like the FSF or others object to something?

Thank you,
Jeff



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