Min, max and unit size

[MMrug]

I really love the system when I see it explained, but the rulebook is really confusing at times and strange when explaining things.
My question is about army lists - min, max and unit size... Let's take the example from the book: "You con see that we have up to 12 mounted companions and they can be in TuGs with 4 or 6 bases." what does 12 mean?

-12 bases in the whole army?
-12 figures in the whole TUG?
-12 TUGs in the whole army?
The forth option is "12 bases in a TUG" but that contradicts the 4,6 unit size.

Also - what does a minmium 0 mean- If it means that the troop type is optional does that mean that that troops with positive minimums are mandatory?

[SimonStokes]

It's 12 bases in the whole army.
i.e. two TUGs of 6 bases or three TUGs of 4 bases.

A minimum of zero just means that the army is not forced to have any UGs of that troop type.