Request licence review

[Andrew Sidwell <andy@entai.co.uk>]

Hi,

I've recently taken over development of a game (Angband) and have
contacting all previous contributors to place it under the GPL.  The
code relicencing is almost done, but we have a problem with
documentation.  I'd really like to adopt a new manual, but it's by
someone we can't contact, and it's under a custom licence:

Redistribution of unaltered copies of this document is permitted without
restriction.  Distribution of altered copies is permitted without
restriction as long as the alteration does not significantly alter the
content (For example, translation and conversion to another format is
permitted.).  Distribution of all other altered copies is permitted as
long as credit for previous authors is maintained, the contact
information is replaced with that of the alterer, and redistribution is
not further restricted.


I'd just like to check if this is DFSG-free or not; I think it is, but
since one of the reasons for making the code Free is so it can be
included in Linux distributions and use services like SourceForge, I
don't want to inadvertently introduce non-free stuff into the game.

Thanks,
Andrew Sidwell