Continuity mistake: When Hawkeye and Lt. Johnson are sharing Hawkeye's bottle of "wine" there's a closeup of Johnson's hand holding the glass, and in the closeup that hand has short nails, whereas in all other shots Johnson has long nails.
Visible crew/equipment: When Klinger walks into Henry's office while Margaret and Frank are there, we can see the chalk T-mark on the floor behind Margaret where Radar was standing moments ago.
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.