The following process outlines the Soundex coding guide:
- Retain the first letter of the name.
Drop all occurrences of the following letters:
A, E, I, O, U, Y, H, W
in other positions.
Assign the following number to the remaining letters after the first letter:
1 = B, F, P, V
2 = C, G, J, K, Q, S X, Z
3 = D, T
4 = L
5 = M, N
6 = R
- If two or more letters with the same code are adjacent in the original name or adjacent except for any intervening H or W, omit all but the first.
- Convert the form “letter, digit, digit, digit,” by adding trailing zeros if less than three digits.
- Drop the rightmost digits if more than three digits.
Names with adjacent letters having the same equivalent number are coded as one letter with a single number
Surname prefixes are generally not used.