Well, don't let that bother you. All it is means is Internal Release, being for team members and beta testers only.I'm still kind of new about this IR thing other then team members playing it.
And because I can't just say a little bit and shut up;

While coding (or modeling or mapping or whatever) the mod, these guys make many changes in one day. And of course there is no point in giving everything to the beta team, each and every day. So at some point, Jb or someone will decide that we are at a good 'stopping point', and they will put everything they have together, code, models, whatever, and put a number on it.
This then is a way for us to track bugs and stuff too. We try to know whats wrong in IR9, and then compare that to IR10,,etc etc blah blah.
Eventually we'll get to one called RC1, which stands for Release Candidate. Which means of course, we think it's ready for the public, and it's time for us bug hunters to earn our daily meat scraps.

Why then do we even mention it, if you can't go get it? Well, the reason we do that is just a way of keeping you updated on our progress. Simply to keep you informed. So that you know we are not just blowing steam here, we really are doing stuff.