Re: GPL preamble removal

[Nathanael Nerode <neroden@twcny.rr.com>]

Brian Sniffen:
>Thanks for the response -- I hadn't noticed that phrasing before.
>But if I give *you* a copy of Sniffmacs under the Sniffen GPL,
>wouldn't you then be bound only to give others the SGPL, not the GGPL
>with its Preamble?

Now we get into a subtle point of copyright law.  This is how I believe it 
works:
If work B is a derivative work of work A,
then to make a derivative work of work B (unless you carefully avoid all the 
parts derived from work A), you need licenses granted by the copyright 
holders of work B and work A.

If Sniffmacs is work B and GNU emacs is work A, then in order to make a 
derivative of Sniffmacs, I need a license to work B (Sniffen GPL), which does 
not require preamble inclusion.  But I also need a license to work A, and the 
license to work A specifies the inclusion of a copy of the GNU GPL.

The GPL grants "you", the recipient, a separate license for each particular 
work.  Term 6 is the term which propagates each individual license to the 
recipients of all modified works.

Normally this sort of thing isn't an issue in free software.  I only know 
about it because I looked at one point into the issues of making a sequel to 
a book which had characters used under license from two other books.  (You 
have to get separate licenses from all three authors.)  IANAL, of course....