Wrathchild answered the question that I'd bet was being asked. Just for the sake of completeness, I'll answer the other side of the question.
And that is: separate websites may be listed even if they are on the same domain, in the same subdomain, or in subdirectories.
In this context "separate" means on behalf of different persons, also on behalf of different entities, and also on different subjects, and also not "e-tailing" sites -- and any other limitations we need to add in order to whack the doorway spammers.
Thus, Geocities subdirectories, or tripod subdomains, or the Reformed-delusion Iffusionist Church site maintained by deacon Fred Jones as a subsite of "jones-contracting.com" which is mostly about his crew of electricians, would all be listable without qualms.