I'm not sure I understood her use of "sub tier"
To me "sub" means "below". But I think taking the message as a whole she meant "equal"
A sub tier would be a subsection of something else - a part of it, rather than a separate thing. Ergo a sub tier is a part of a single tier.
Tionese - 1.1
Columi - 1.2
Rakata - 1.3
Campaign/Black Hole - 2.1
[NiM EC and HM TFB] - 2.2
[NiM TFB] - 2.3
Yeah, looks like we're going to get 3.1 in late Dec 2012 or early Jan 2013.