[ikka]

There he held a Top Secret, Q, SI, security clearance.

I am not a security guru. But I know that Q clearance is the lowest clearance you can have. There is Q, Secret, Top Secret, SCI, then a bunch of others that basically clear you into particular kinds of information or places. For instance, Yankee White clearance is held by the guys who fly Marine One.

[Poohbah]

Actually, Confidential is the lowest. "Q" is a Department of Energy clearance for nuclear information.

[FReepaholic]

I once held "Secret". Never heard of "Q".