I am brand new to ATT, brand new to Tau, and brand new to 40k in general. Yikes.
I'm trying to be careful about where I post this, building or rules, but while it is about building, I don't think the Earth Caste handles this kind of question.
So, once I decided I was going to play, started building and playing, and then painting, I started researching too.
I built my first ADN before I was finished building my Tau "Start Playing" set. Then I saw some of the cool things on Pinterest and thought "I can do that". Both the ADN and the fortification shown below were either complete or in progress before I realized "Hey wait, there are actually rules for these things!"
So here is my question. I put together the fortification shown below. It is bare bones because once I realized this possible issue I didn't want to continue work. It is about 12 inches high. From what I am seeing, that is non-standard. It also has battlements, but if I understand movement correctly that is quite a bit to reasonably move in a turn; basically you'd have a unit out of action for a full turn. OR - do the rules allow you to enter through an approved access point and then just exit through another one even if it is farther away than normal? I know there is a building ability that puts an exit like 12 inches away... (Note that the building does not show access points yet. I plan to put one on the battlement later.)
Finally, what about a special rule - "Battle Elevator" - a unit may enter and is lifted quickly to a battle position, allowing egress ... I don't know, in the following movement phase?
Anyway, like I said - work in progress. I just don't want to do anything more with it right now if it turns out it is just way too tall to be feasible or legal. It is tall enough that it definitely gives a line of sight advantage.