Details:

Security clearances run concurrent to the needed rank. If you no longer have the rank, you no longer have the security clearance. Exception: if you are granted that clearance by the holder of the rank. For that, it’s usually a limited clearance, donated by an added letter after the clearance level (i.e.: Secret A-3b would be level b limited Alpha-3 clearance. Get it?).

Top Secret Clearances (designated by a TS before the clearance level) can only be granted by a Galaxy Commander or up. All Star Colonels automatically have a TS Alpha-3 clearance, but cannot grant TS clearance. Basically, TS clearance deals with matters concerning the whole Clan, i.e.: invasion plans, etc., plans usually directed by the Khans or Galaxy Commanders, but meant for people without Alpha-4 or higher clearance (yes, the Star Captains who do the bulk of war planning do occasionally need to see the whole plan).

Only a Khan may grant an Eyes Only clearance to someone not of rank for that level of clearance. For example, a Star Colonel automatically has Alpha-3, TS Alpha-3, and Eyes Only Alpha-3 clearance. But only a Khan may grant a Star Captain Eyes Only Alpha-3 clearance, while a Galaxy Commander may grant that Star Captain Alpha-3 and TS Alpha-3, and a Star Colonel can grant Alpha-3(limited).

The Loremaster may designate a Beta, TS Beta, or Eyes Only Beta level to something. The same rules apply: only a Khan may grant Eyes Only Beta clearance to someone. Otherwise, the Loremaster may grant Beta and TS Beta clearance.