(radio call sign) appears to be the call sign used in 1968 for the AM radio station referred to as X E R A in the liner notes to (British) KRAZY KAT LP #KK 7426. It was an AM radio station technically located at Ciudad Acuña, Coahuila, Mexico, although in fact operating largely across the Rio Grande at Del Rio, Texas. Wolfman Jack was featured by the station. Radio station X E R F was operating in 1968, at Ciudad Acuna, Coahuila, Mexico.