Logged In: YES user_id=38388 Sorry for not getting back to you earlier: I didn't see you last message. 1-4) Python defines a macro during the Python build process that is not defined when compiling extensions: Py_BUILD_CORE You can use that macro to compile things differently for core things vs. extensions. 5) Fair enough; I don't see a point in creating a new numbering for each and every module. Please just use 1, 2, 3, 4, ... 6) Hope this makes sense :-)