I'm not sure if you are serious but just so that newbies have better information, if I can use software to spend and receive bitcoins then the software, at a high level, is Bitcoin. Classic, unlimited, and XT are Bitcoin forks and become "Bitcoin" if enough people believe them to be. They fork not only the codebase but would also fork the Bitcoin blockchain. Even if one of the forks dies, including the old fork we are all currently using, the bitcoins you held before the fork would continue to function as bitcoins albiet with some changes due to the different code of the new fork. So far in Bitcoin history this has already happened twice and it continues to be the case that the current newest fork is the one we all call "Bitcoin". The only difference is that those two prior forks were non-contentious and the old forks died out quickly.

On the other hand, if someone forks the Bitcoin codebase and starts it over with a new blockchain then I cannot spend and receive bitcoins using it. It is thus an altcoin.

So let us please maintain some credibility among ourselves and just admit that the reason that Classic, XT, and others aren't allowed is because the administrator of this forum, theymos, believes that Bitcoin should not be forked at the current time at least in such a way as the authors of Classic and XT have proposed and he has chosen to have the forum reflect that belief.