Andrew,you would have to look at the actual logged flights,as they may have been say,one for aircraft handling(ie stalling/asymmetric/circuits),and another for role(ie.bombing/SAR/Tactics/crew co-ord).In the `trucking world` everybody had a seperate `Cat Card` which defined what you had as `qualifications`,in addition to the Logbook,as normally you carried the CC with you,but not the logbook.Many ,many yrs ago I renewed my TC `B` Cat at the end of April`67 and `B`cat`SAR by the 2 `local` examiners,then the following week the UK Transport Command Examiners arrived,and I was `done`again,and got an `A` Cat TC,but retained a `B` Cat SAR as they could not `examine` above `B`` CAT..and the `A`cat. was valid for 2yrs...!