obsolete V4L2-API:
	http://linuxtv.org/downloads/legacy/video4linux/API/V4L2_API/spec-single/v4l2.html
	(an even more obsolete version 0.24 of this document used to be included
	here, but is no longer)

current V4L2-API:
	http://linuxtv.org/downloads/v4l-dvb-apis/
	(unfortunately this is multi-page)