Final answer:
The officer who temporarily succeeds the CO/OIC signs official command correspondence in their absence. In the case of the lieutenant governor, the president pro tempore of the Senate assumes their duties.
Step-by-step explanation:
In the absence of the CO/OIC (Commanding Officer/Officer in Charge), the officer who temporarily succeeds them would sign official command correspondence. In the case of the lieutenant governor, if the office becomes vacant or if the lieutenant governor is absent or temporarily unable to act, the duties would be performed by the president pro tempore of the Senate. This means that the president pro tempore, who is elected by the members of the Senate, would assume the responsibilities of the lieutenant governor until a successor is elected or the lieutenant governor is able to resume their duties.