Original: The Southern Railway (SR) gave the designations 6-PUL, 6-CITY and 6-PAN to electric multiple units built to work the routes between London and Brighton, West Worthing and Eastbourne.
Simplified: The Southern Railway (SR) gave the designations 6Pul, 6Cit and 6Pan to electric multiple units built to work the routes between London and Brighton, West Worthing and Eastbourne.