Unsure what restriction codes are on a licence? 

Aswell as category codes, you may have restriction codes showing  on your driving licence. These restriction codes can show on your licence categories and they could vary depending on if you have to wear glasses whilst you're behind the wheel, the weight of the vehicle itself and you also might be limited to how many seats the vehicle can have. 

The codes below have been provided for your information by LICENCECHECK from the DVLA.

Check them out - Are all your drivers allowed to drive the vehicle that you have issued? These are the descriptions of information codes which appear on UK driving licences.

1 Eyesight correction
2 Hearing / communication aid
10 Modified transmission
15 Modified clutch
20 Modified braking systems
25 Modified accelerator systems
30 Combined braking and accelerator systems
35 Modified control layouts
40 Modified steering
42 Modified rear - view mirror(s)
43 Modified driving seats
44 Modifications to motorcycles. (1) single opertaed brake. (2) (adjusted) hand operated brake (front wheel). (3) (adjusted) foot operated brake (back wheel). (4) (adjusted) accelerator handle. (5) (adjusted) manual transmission and manual clutch. (6) (adjusted) rear-view mirror(s). (7) (adjusted) commands (direction indicators, brake light, etc.). (8) seat height allowing the driver, in sitting position to have two feet on the road at the same time.
45 Motorcycle only with sidecar
70 Exchange of licence from a different issuing country
71 Duplicate of licence
78 Restricted to vehicles with automatic transmission
79 Restricted to vehicles in conformity with the specifications stated in brackets
101 Not for hire or reward
102 Drawbar trailers only
103 Subject to certificate of competence
105 Not more than 5.5m long
106 Restricted to vehicles with automatic transmission
107 Not more than 8250kg
108 Subject to minimum age requirements
110 Limited to invalid carriages
111 Limited to 16 passenger seats
113 Limited to 16 passenger seats except for automatics
114 With any special controls required for safe driving
115 Organ donor
118 Start date is for earliest entitlement
119 Weight limit does not apply
120 Complies with health standard for category D1
121 Restricted to conditions specified in the Secretary of State's notice.

Valid on successful completion: Basic Moped Training Course