The "correct" spelling of surnames, especially surnames of immigrants, often eluded nineteenth century Americans. The Soundex code was created to group names which sound alike into a single code. The code consists of four characters, the first letter of the surname plus three numbers, coded as follows:
B, P, F, V
C, S, K, G, J, Q, X, Z
Disregard the letters A, E, I, O, U, W, Y, and H. Double letters should be treated as a single sound. If a surname does not have three sounding letters, a 0 is used to complete the three-digit code.