dfsg-free global digital elevation model (GDEM)?

[karme@berlios.de]

Hello,

I am looking for a DFSG-free [0] global digital elevation model (GDEM)
which I ultimately want to package for debian.

is the SRTM [1] data DFSG-free?
is the ASTER [2] data DFSG-free?
is there a void-filled/combined DFSG-free dataset?
Looks like the cgiar [3] dataset is unfortunately non-free [4].
Maybe TanDEM-X [5] will provide a DFSG-free dataset in the near future?

Thanks for any comments,
Greetings,
karme

[0] http://en.wikipedia.org/wiki/DFSG
[1] http://en.wikipedia.org/wiki/SRTM
[2] http://en.wikipedia.org/wiki/ASTER_GDEM
[3] http://srtm.csi.cgiar.org/
[4] http://srtm.csi.cgiar.org/SRTM_FAQ.asp
[5] http://en.wikipedia.org/wiki/TanDEM-X