All UK military registered aircraft irrespective of whether they are a UOR or not are supposed to have a name, a mark number and a role prefix letter/letters.
http://www.maa.mod.uk/linkedfiles/re...ies/ra5307.pdf
It's supposed to be mandatory! It bugs me: as mentioned there's Globemaster, Airseeker, Watchkeeper and Reaper. Atlas has one but only published in the RTS so far.