UID prefix letters in use as at August 2019:

Letter

Note

A

2

B

2

C

1

D

 

E

 

F

2

G

1

H

 

I

3

J

2

K

2

L

1

M

2

N

2

O

 

P

1

Q

2

R


S

2

T

 

U

2

V

2

W

1

X

2

Y

1

Z

4


1) UID prefix letters used for permanent trains, buses and ships; also for temporary services where sufficient unused UIDs are available. The letters originally represented a British Rail regional train planning office: Crewe, Glasgow, Liverpool Street, Paddington, Waterloo and York. Each letter is now allocated to services operated by groups of TOCs, which may or may not coincide with the old regional boundaries.


2) UID prefix letters used for temporary services. Some of the letters with no note above may also have been used for this purpose in the past and may be again sometime in the future.


3) UIDs with an “I” prefix were reserved for manual editing of trains in the CRS reservation system. Though CRS ceased to exist several years ago the availability of “I” series has not been taken up in ITPS.


4) Prefix letter reserved for Manual Services edits within PMS.