Sandman
'Only Adobe can call a plug-in a "Photoshop Plug-in"'

Eric Stevens
And quite right too. Once Adobe has called it that, so too can other people. If you haven't got Adobe's approval, the proper way to describe it is as a 'plug-in for Photoshop'.

nospam
once again, there is no approval necessary to write and sell a photoshop plug-in and call it that, which is what a lot of companies do.

Eric Stevens
Ever heard of protecting a trademark?

nospam
calling something a photoshop plug-in is not infringing. it is, after all, a photoshop plug-in. it does not in any way mean it was authored by adobe.

Eric Stevens
Hmm. The same plugins will often run with Paint Shop Pro, Gimp, Irfan VIew etc. Does that make them Paint Shop Pro, Gimp, Irfan View plugins?

You should see http://www.thepluginsite.com/knowhow/tutorials/introduction/introduction.htm which will give you some idea of why, when and how Adobe may restrict the use of Photoshop as part of the name of plugins.