Emma's Potern and Potern III Are smaller gates leading through the wall out along the bastion. The entrances are not carved into the walls as the other gates so they don't show up on a top down map.
I've thought about how to visualize that, but other than drawing lines on the walls for all the underground passages, I can't figure it out.
Here's one of the detail sketches i made when i considered adding a lot of those. As you can see, there's a lot happening inside the walls. There are somewhere around 3kms of passages just in the southern walls. In front of the bastions there's 2 passages leading south for 500m all the way to the block houses on the first line.
Found a photo that shows the gate fron the inside.. somewhat. In the middle of the brick are is the gate (the other doors are into supply vaults and the ones on top are doors to the ammunition storage)