nice counter-point, but again, by that same reasoning, XOOPS would also be useless without the php code to rest upon, which by your statement, it's useless without the php core, just as a XOOPS module would be useless without xoops.
now, it could be rewritten to be used in another code base, just like pretty much everything else, so i think that explanation maybe fails in that regard.
i'm not trying to be argumentative, i enjoy this discussion
i do agree with what you stated, that modules which actually depend upon XOOPS functions to exist are definitely gnu/gpl, whereas modules that are often 'ported' don't need to be gnu/gpl
but where do you draw the line? (just tossing this out for discussion)
at some point, XOOPS likely uses unique functions that are part of the php core, without which it would obviously break. modules use unique php functions, without which they would obviously break. so actually, it's quite possible to say that all php code should be gnu/gpl, since it depends on a gnu/gpl system to function.
heh, since that is not the case though (and since i appear to just be rambling now), it seems as though as long as you don't include exact or modified version of gpl code, then you can license it however you want
anyways, i'm probably wrong
but i'm trying to make a valid point