Factual error: In one episode in the hospital tent, Hawkeye hands a Hershey Chocolate Bar to a wounded soldier lying in bed. The back of the candy bar had a Universal Product Code (UPC) on it. UPCs were not used until the 1970s.
Factual error: Throughout the series, actors are seen wearing cuffless permapress fatigues. Neither cuffless nor permapress utilities were available until the 1970s.
Factual error: Throughout the series, there are repeated instances of "I Corps" being pronounced, "Eye Corps." Since Army corps are designated by Roman numerals, it should be pronounced, "First Corps." (I wonder how they would have pronounced "III Corps" or "XVII Corps?").
Factual error: The Spot-A-Card pinball machine in the Officers' Club didn't come out until the 60's.
Factual error: Trapper John and Hawkeye have a still in the Swamp. Distilling gin requires water, juniper berries, flavourings, magnesium and potassium carbonate. Ordering any of these as "medical supplies" would have had both men court-martialled, as would distilling illicit alcohol in a military unit during the Koren war - with or without stolen medical supplies. The only alcohol available to them would have been via the bar in the officers' mess, and no MASH unit had one. Not one.
Factual error: Nearly every show depicts the use of disposable plastic syringes, which weren't introduced till 1955, two years after the war ended.
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.