Linux kernel complete licence check, Q.22

["Giacomo A. Catenazzi" <cate@debian.org>]

Hello.

In parport.h header file:

/*
 * Any part of this program may be used in documents licensed under
 * the GNU Free Documentation License, Version 1.1 or any later version
 * published by the Free Software Foundation.
 */

No other notices.
1) Do this file be licensed under GPL2 (as main COPYING)
2) GFDL only for documentation?
3) GPL still valid for documentation? Or documentaion are licensed only with
   GFDL, so extra restriction, thus no more GPLable?

ciao
	giacomo