Never heard it called that ... but I've seen tanks like that.
You've basically just got a sump built into the back of the tank... a place separated from the display area that you can do whatever you want with...
Put a HOB
skimmer back there ... the intake and discharge for it wont be in the display area.
Put some sand in the bottom and some small pieces of rock, and you've got a place for 'pods
to multiply without getting eaten.
The macro algae back there is also a good idea... keeps it away from any herbivorous fish you may have.