#6 is titled "No Discrimination Against Fields of Endeavour" and explicitly refers to commercial use as a field of endeavour. The annotated version[1] says:
> Rationale: The major intention of this clause is to prohibit license traps that prevent open source from being used commercially. We want commercial users to join our community, not feel excluded from it.
Restricting commercial distribution of modified versions would discriminate against commercial users. I argue that the word "use" in this context is referring not only to running the program but to the exercise of any of the freedoms outlined in the Open Source Definition.
That depends on whether or not "use" and "distribute" are seen as two completely different "things", or whether distribution is a subtype of usage. It makes more sense, to me, for it to be the latter - but the actual text of the OSD is a little bit ambiguous on that point. At least to my reading.
Still, regardless of how one justifies it, I feel like it's pretty well accepted that a "you can't sell this commercially" clause in a license makes it non-OSD compliant. As it should be.
#1 OTOH deals with "selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources." This would seem to be the clause that would be violated by a "you can't sell this commercially" clause. Although, looking at it, I just realized that somebody could argue that due to the use of the phrase "component of an aggregate software distribution", that this actually isn't violated by a restriction on selling the software alone! I'm pretty sure that's not the way that was ever intended to be interpreted though, and that an aggregate can include as few as 1 components. Otherwise it would be silly, because you could always then in turn create an "aggregate" by adding some arbitrary files of your own.