I couldn’t find 343 directly addressing Specializations. I sort of figured it to be the Tactical Package part of the loadout and the Support Upgrade of the loadout(at the end: http://www.youtube.com/watch?v=2YtO7JHK1iw). 4
But I may be wrong, what are specializations? And don’t quote the bulletin from 20(ish) days ago because in that bulletin they specifically said they would give more information at E3 (which is now over). Who knows what specializations are?