What are the specific military ranks of the Necron?

I know the general guide of course: Warrior, Important, Royal Warden, Nemesor etc. but is there anything specific ranks within those titles? My understanding is Royal Warden is a general term like officer. Is there specific ranks for Lieutenant or Captain? If a Royal Warden has their tiles on the left arm and therefore making them distinguishable as officers, what is the warden-like model in the kill team box? Is that supposed to be some kind of NCO? Also, if a Royal Warden holds the rank of a Lieutenant or Captain and a Nemesor is a General, what is the in between called? Does anyone know?