Other mistake: In the opening, when the flags were raised, the United Nations flag is hung upside down.
Other mistake: It's 1952 when Potter arrives at the 4077. He tells Radar that he joined the army during WWI when he was 15 (he lied about his age). That would mean that Potter was 50 when he arrives. But he said that he'd be retiring in 18 months. Also, in the episode "Point of View" Potter states that this was the first time in 37 years that he missed calling Mildred for their anniversary. That would mean that Potter was 13 when he got married.
The Late Captain Pierce - S4-E4
Other mistake: When Digger shows Hawkeye the copy of the death certificate, Hawkeye steps out of the shower stall and its door swings back and forth. As Hawkeye wipes his face with the towel, we can see the top of the flesh colored covering Hawkeye is wearing. (00:08:05)
Other mistake: When the Colonel Griswald of the 1st Cavalry goes to leave camp, the Jeep he gets in is marked "4077 MASH" on the bumper instead of 1st Cav.
Other mistake: As Burns, driving the tank, runs over the Swamp, there's no sign of the still anywhere.
The Price of Tomato Juice - S4-E15
Other mistake: Actor Jeff Maxwell plays Private Igor Straminsky, however when Maj. Burns is in line and asks for his name, he replies "Maxwell" and Burns in turn repeats the name "Maxwell", instead of "Straminsky."
Other mistake: Frank Burns states when he is talking to a patient who just got a purple heart, that he would like to get a purple heart, but in the earlier episode ‘The Kids', Frank Burns received a purple heart due to a injury, and in the S1 episode ‘Sometimes You Hear the Bullet', Frank Burns gets another Purple Heart. Despite them both being stolen, they still count on his army record.
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.