If, in a state of national emergency, the Secretary of Energy was acting as commander-in-chief but was not about to assume the role as president (let's say they knew the president was alive and ok but he could not get to a place where he could command military forces) what would her (secretary's) title be and how would military leaders address her in person?
If, to complicate matters, she was onboard an aircraft carrier and was in command (by default as highest-ranked civil government official) would she be actually addressed as "sir" as, in example Dr. Crusher was on Next Generation when in temporary command of the Enterprise-D?
Odd questions . . .actually for a friend's fan-fic but we're arguing over some picky details so . . .