Originally posted by Hans Vermeylen:
1) There are few things more canon in the Traveller universe than the very names of the various services ranks and ratings.
		
		
	 
I have to disagree with you there. Using the character generation rules to infer facts about the 3rd Imperium specifically is, IMO, very dicey. The CGR are extremely generic. They apply to every army and navy in Charted Space (Except for the few that later got their own writeup, such as the Sword Worlds). Unless one is prepared to believe that every stellar navy from the Solomani Rim to the far Zhodani fringe has ten officer ranks, every one the same name as their counterparts in every other navy, that is...
As for the Imperial Navy, we actually have canonical evidence of two more ranks that isn't mentioned in the CGR: Rear and Vice Admiral. They both show up in various TNS newsbriefs and elsewhere.
Please note that I don't claim that Rear and Vice Admiral *has* to be extra ranks (I used to claim that, but Chris Thrash convinced me otherwise). But it certainly is the most reasonable explanation, considering that there are mentions of retired vice admirals and of someone being promoted to vice admiral.
We also have a mention of an Army Vice-marshal, BTW, but unfortunately (IMO) Doug Berry chose[*] to interpret that as a post rather than a rank in 
Ground Forces. Personally I think the Imperium is so big that it could do with 12 army ranks and 14 navy ranks, but alas...[**]
[*] Or maybe his editor required him to do so.
[**] Oh well, IMTU that's just how things are.
Hans