I've only ever seen pre and post 2001 on any website including DSA etc so if he has provisional A entitlement and wants to ride a 125cc scooter he'll need a CBT to validate that entitlement.
This will allow him to ride on L plates, not carry a pillion or use motorways etc etc. Valid for 2 years and then he'll need to repeat it to stay on the road.
Everyone (who doesn't have a full motorcycle licence! grrrr @ Geoff!
) needs a CBT for over 50cc and under 125cc.