No subject

other separate and independent documents or works, in or on a volume
of a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which are
not themselves derivative works of the Document. "

So the pertinent question, at least in terms of GFDL compliance, is
what constitutes "separate and independent documents or works".

Anthony