Calculate Check Letter for Rollingstock and Locomotives
Enter the vehicle class and number into the fields above.
If you're calculating a check letter for a loco which has no class letters (i.e. 830, 930, 44 class etc) then leave the Vehicle Class empty
For vehicles that just have a name enter the first 4 letters of the vehicle name in the vehicle class field and put 0 as a vehicle number
How it works
Excerpt from "Code and Practice For the Defined Interstate Rail Network"
2.4.2 The check letter should be determined in accordance with the following procedure:
- Alpha characters are allocatd a numerical value according to their position in the alphabet, viz A = 1, B = 2, C = 3, ..., Y = 25, Z = 26
- Leading zeroes are instered if necessary between the alpha group and the number to form a 9 character vehicle classification.
- Assign numberical values to each character to form a sequence a1, a2, a3, a4, N1, N2, N3, N4, N5, where a1 to a4 correspond to the vehicle class and N1 to N5 refer to the vehicle number.
- Calculate the value of the following series: (1 * a1) + (2 * a2) + (3 * a3) + (4 * a4) + (5 * N1) + (6 * N2) + (7 * N3) + (8 * N4) + (9 * N5)
- Divide the sum by 23 and add one (1) to the remainder to give the position of the check letter in the alphabet. A check letter character of I is to be recorded as X, and O is recorded as Y.