2009/1/12 Anthony wikimail@inbox.org:
It most certainly is a requirement of the GFDL (not sure what your weasel-word of "direct" is supposed to mean).
The GFDL requires crediting principal authors, and it requires change tracking. Given the obvious intent of the principal authors clause to limit inflating bylines, and given the way these clauses have always been interpreted, specified and implemented, you really have no case that simplifying the change tracking requirements through CC-BY-SA constitutes an unreasonable change.