If the first four manuals on a five manual organ are named Choir, Great, Swell, and Solo, what is the fifth manual most likely called? Echo? Or something else???
Thanks. (Google results are more confusing than helpful, and I can’t figure out how to get in touch with anyone appropriate at the AGO.)
–LB
Okay, cant call myself an organist, but I have visited a few (in the UK) cathedral organs and the one I got to actually play was at Chichester Cathedral. A friend of mine was taking formal lessons there when we were 12-13 years old… It was a thunderous experience… Heavy metal rushes from wind and very long pipes… 
Shook the building. He got in trouble for that! 
Here is the spec sheet, the “Nave” might be what you are looking for. Its only 4 manuals however…
http://www.chichestercathedral.org.uk/dyn/_assets/_pdfs/1Organspecification.pdf
https://i.ytimg.com/vi/30BN8wvWm4A/maxresdefault.jpg
Hope an expert steps in here for you. 
nice reminiscence for me for sure! 
Yes. Well, those young experiences can be kickers!
A Nave Organ in my experience is a separate set of pipes which is located (guess where!) in the Nave. They are playable from the regular manuals but are considered a ‘separate organ.’ Not a manual name that I’ve ever heard. But thanks for your post, it was entertaining.
–LB