Nope its the European RDS system it allows auto tuning to a selected station on different frequencies spaced across an area as one signal becomes weak it auto tunes the same broadcaster on a different stronger frequency
You search via station type using the PTY button such as ROCK/POP/CLASSICAL/NEWS/TRAFFIC type of thing
The U is what we call FM and the M is medium wave or what we would call AM older radios used to have L for Long Wave but thats not really used since FM
http://en.wikipedia.org/wiki/Radio_Data_System