Name of front-end

[Marc Espie]

In article <Pine.BSF.4.58.0312061840220.28341@acrux.dbai.tuwien.ac.at> you write:
>On Sat, 6 Dec 2003, Henrik Sorensen wrote:
>> But does it matter for the name of the front-end, whether or not the
>> copyright has been assigned ?
>
>No necessarily, as far as I know.  However, you must not call any software
>"GNU Something" unless the FSF explicitly approved that, so you should do
>that first.

'Must not', or 'should not' ? Is GNU registered as a trademark or something
that prevents its use like this ? And then what should the status of
gnuplot be ?