[Rules] Transported units and stacking

[qwirz]

Hi all!
New to the game, reading the 3rd ed rules I'm now on section 4.0.
Perhaps this is a question will be answered later in the rules but I need to know this in order not to forget it after.
Do transported combat unit count regard the Three Combat units stacking limit?
Or there can be Three fully loaded transporters plus three combats in a hex?

Thanks
And sorry if the question was already been answered but I have still to know well this amazing site!

Ruben