GFDL is a DFSG-compliant license
I've just heard today that there are people on this list who believe that the
GFDL is not DFSG-compliant. The GFDL text very clearly specifies that the
invariant sections must be "Secondary" in nature, and then goes on to define
secondary sections as follows:
A "Secondary Section" is a named appendix or a front-matter
section of the Document that deals exclusively with the
relationship of the publishers or authors of the Document to the
Document's overall subject (or to related matters) and contains
nothing that could fall directly within that overall subject. (For
example, if the Document is in part a textbook of mathematics,
a Secondary Section may not explain any mathematics.) The
relationship could be a matter of historical connection with
the subject or with related matters, or of legal, commercial,
philosophical, ethical or political position regarding them.
If this makes the GFDL non-DFSG-compatible, then no license that requires
that license text, attribution or copyright notices be invariant is
DFSG-compliant: which is just about every one of them - even the MIT or BSD
license requires that. This is taking the definition to the point of absurdity.
The GFDL is a DFSG-compliant license.