Marc Lavallée wrote:
Modifying a software does create a derivative work. Static linking also create a derivative work. But using a software never create derivative works. A PD patch could be interpreted by some other software, like a tiff image created with the Gimp could be opened and modified using Photoshop.
which interpreter is used to run a Pd-patch does not affect the license of the pd-patch. see http://www.fsf.org/licensing/licenses/gpl-faq.html#InterpreterIncompat
what matju was referring to is this article: http://www.fsf.org/licensing/licenses/gpl-faq.html#NFUseGPLPlugins which says: "If the program uses fork and exec to invoke plug-ins, then the plug-ins are separate programs, so the license of the plug-in makes no requirements about the main program."
if a Pd-patch is seen as a program, then it makes use of plug-ins (externals) via Pd's built-in loading mechanism, which is NOT based on "fork and exec" (or similar). continuing the quote: "If the program dynamically links plug-ins, and they make function calls to each other and share data structures, we believe they form a single program, which must be treated as an extension of both the main program and the plug-ins. In order to use the GPL-covered plug-ins, the main program must be released under the GPL or a GPL-compatible free software license..."
according to http://en.wikipedia.org/wiki/Plug-in i think that Pd-externals are "plug-ins". objects within pd make function calls to each other via Pd's inlet/outlet concept and share data structures (e.g. lists of atoms)
mfg.asdr. IOhannes