Licence of VO-DML files?

[Markus Demleitner]

Dear DM,

I'm currently trying to get DaCHS into Debian main.  This requires
that I'm figuring out the licences for all the various files I'm
distributing.

Although right now, there's no operational necessity to do so,
because of the various annotation experiments that ran in DaCHS over
the time, there are a few VO-DML files in the package.  These, right
now, have no explicit licence.  I'll *probably* get away with that,
but, really, it would be better if I didn't have to worry about
getting caught.

So... can we formulate a policy there?

My take: VO-DML files are close enough to software that we shouldn't
use CC-X-Y (see
https://creativecommons.org/faq/#can-i-apply-a-creative-commons-license-to-software
for the reasoning).  This would leave a software licence, and then
we're knee-deep in the various incompatibilties.  Still, I think some
version of the BSD or MIT licences might work; perhaps even the LGPL.
The full GPL we certainly cannot afford.

Or we could go for CC-0, which is compatible to all software licences
known to humankind (or so I think) and nicely works for
software-linke things
(https://wiki.creativecommons.org/wiki/CC0_FAQ#May_I_apply_CC0_to_computer_software.3F_If_so.2C_is_there_a_recommended_implementation.3F).
It's also what our vocabularies (http://www.ivoa.net/rdf) use at the
moment (and hopefully even after VocInVO2 is REC).

So... Do people have thoughts on this?  Action plans perhaps, even?

         -- Markus