THE naming of R.A.F. aircraft follows no hard and fast rule, but, in general, fighter names have an aggressive connotation and, until the coming of the V-class (Valiant, Vulcan, Victor), bombers were named after towns. Trainer names often have association with training activities and most transport types are also named after towns. With the official name of the aircraft is associated a mark number designation. These designations tend to be complicated, but serve the important purpose of distinguishing versions of the same aircraft which have either different operating characteristics or different servicing requirements.