Visible crew/equipment: When Colonel Potter and Charles exit the mess tent carrying the trays, so they can serve breakfast in bed to the winners, they split up and as Charles walks to the Swamp saying, "What a shame to have wasted all these years as a doctor," we have a great view of the boom and boom mic at the left side of the screen as it moves backwards away from Charles, outside the Swamp.
Visible crew/equipment: After Margaret and BJ win the bridge game, just as Charles stands up we can see the top of the Officers Club set, and we see it again when Klinger tells Father Mulcahy, "Everyone bet on either Potter or Winchester."
Visible crew/equipment: After Hawkeye shows the photo of his father to the North Korean, when it cuts to the shot in the Officers Club just as Klinger says, "And these players you can't tell anything," the shadow of the boom mic can be seen moving at the top, right corner of the screen.
Visible crew/equipment: At the start, when BJ calls Hawkeye "twinkle toes" before Hawkeye leaves, the edge of the Swamp set can be seen at the top, left corner of the screen.
Answer: It is actually Cencompac for Central Command of the Pacific. It is like the headquarters for all military activity in the Pacific Region (Japan, Korea, Okinawa, etc. The newer version of that is United States Pacific Command (USPACOM).
EMTurbo
And the abbreviations were used mainly by the Navy. Especially CENCOMPAC.
Https://en.wikipedia.org/wiki/United_States_Indo-Pacific_Command.