These rules for manually creating soundex codes for numbers and how to index names and titles were taken from the images 6 through 19 on FamilySearch‘s “Michigan, Eastern District, Naturalization Index, 1907-1995” (created from the NARA microfilm publication M1917). Images made from digital image of microfilm roll 1 from the M1917 NARA publication.
Interesting reading for those who use images of soundex card indexes to records (post images 1-4) or print indexes (post images 5-14). Card indexes based upon soundex codes for names were created before computerized records made them virtually obselete. 
5 Responses
Is this still aplacable today?
The craziest index I came across was indexed (if I remember correctly) by first names. It was a county deed book. I was trying to find the surname of my ancestor to see who else was there in the county. Perhaps it was by the initial of the last name, then you had to look for the first name. Surname started with “B.”, then had to look thru. all the B’s for the surname I was looking for. All persons with that surname were not grouped together.
I’ve encountered a few of those and it can be difficult to remind yourself while searching it that it’s not made the way they normally are. The most frustrating census I ever used was from Switzerland where the residents of the village were listed from oldest to youngest. Destroyed the family structures as well in that case.
I thought I understood the basics of soundex, but that’s lots of rules I was unaware of. Some of the records in my state archives are still indexed by soundex; it’s difficult for today’s patrons to understand.
To those unfamiliar with how it’s set up, it can be confusing.