At United every empoloyee has a company address. The address is the airport which that person works at, and then a two letter department code. The department codes carry over to each airport. All flight attendants have there base city+SW. The SW is the flight attendant office/base.
Exapmples would be:
SFOMM-Line maintence at SFO
SFOSW-Flight Attendants at SFO
SFOFO- I believe that this the Pilot office
I'll try to find out more of the codes for you.
BTW. London is a crew base too, as well as santiago, and Hong Kong or Tokyo (i'm not sure, but i know that they have an asia base)
Here are all of the Flight Attendant Bases:
STOSW Is STO Santiago's code?