| 1 - 99 | Main aspect signals on the Main Lines. Evens on the down, odds on the up. | 
| 1xx | Main aspect signals on the Badminton and Kemble Lines. Evens on the down, odds on the up. (Except SN125 & SN125R at Box) | 
| 20x | Position light signals at Thingley Jn. | 
| 21x | Position light signals at Highworth. | 
| 22x | Position light signals at Highworth and Swindon West. | 
| 23x | Position light signals at Swindon Down Goods and Swindon West. | 
| 24x | Position light signals at Swindon East. | 
| 25x | Position light signals at Swindon East. | 
| 26x | Position light signals at Swindon Down Goods and Swindon West. | 
| 27x | Position light signals at Wootton Bassett Stone Terminal. | 
| 28x | Position light signals at Thingley Jn and Wootton Bassett. | 
| 29x | Position light signals at Kemble. | 
| 30x | Reversible crossovers at Uffington and Bourton. | 
| 31x | Points at South Marston Euroterminal. | 
| 32x | Points at Highworth Junction and Loop. | 
| 33x - 34x | Points at Swindon East. | 
| 35x - 36x | Points at Swindon West / Swindon Jn. (368 at Loco Yard) | 
| 37x | (Former points at Rodbourne GFs, etc?) | 
| 38x | Points at Rushey Platt. | 
| 40x | Points at Wootton Bassett East | 
| 41x | Reversible crossovers at Wootton Bassett (Main Line). (Except 419 at Chippenham) | 
| 42x | Reversible crossover at Chippenham and Thingley Junction poitns. | 
| 44x | Points at Kemble. | 
| 45x | Reversible crossovers at Wootton Bassett West. | 
| 46x | Points at Hullavington. | 
| 6xx | Reversible Main aspect signals on the Main Lines. Evens on the down, odds on the up. Reversible signals are gernerally number 600 higher than the main line equivalent. | 
| 7xx | Reversible Main aspect signals on the Badminton Lines. Evens on the down, odds on the up. Reversible signals are gernerally number 600 higher than the main line equivalent. | 
| 89x | Main aspect signals at South Marston Euroterminal. | 
| DBxx | Main aspect signals on the Down Badminton. | 
| DMxx | Main aspect signals on the Down Main. | 
| MXx | Minety Crossing Signals. | 
| UBxx | Main aspect signals on the Up Badminton. | 
| UMxx | Main aspect signals on the Up Main. |