GPL + advertising clause

[Chris F Clark]

Sorry to interrupt the semi-continual mild-flamefest that seems to
have developed on the group, but . . .

A few days back someone mentioned doing a GPL with an advertising
clause.  I would like to focus some discussion on that possibility.  I
represent a commercial software house that is thinking of releasing
some of its previously proprietary software under an open source
license (similar to the way Ghostscript is released).  The license of
choice would normally be the GPL (as it provides some restrictions
that allow us hope of still having a commerical market left for our
software after releasing an open source version of it).

However, we would like the open version to be distributed under the
same (registered) trademark as our commercial version (so that the
open source version could serve as advertising for the commercial
version).  Under the current GPL we cannot add an advertising clause
to the license without becoming incompatible with the GPL and thus
negating the primary desired effect of releasing our software as open
source (to have our software used in other open source projects).

Thus, it would be desirable if a version of the GPL was developed that
allowed combination with licenses with advertising clauses (or that
included its (parameterizable) own advertising clause).  If done right,
this would have the advantage of making the GPL compatible with the
BSD licenses as well as making it suitable for our needs.

Thank you for your consideration,
-Chris Clark