I now have definitive written proof of a numeric indexing system (delineated in a popular textbook for secretaries, and published by a company which did significant business in Germany) from the mid-1920s with increasingly more detail into the 1940s and a fifth edition published in 1950. It’s exactly like, but notably predates, Niklas Luhmann’s alphanumeric system which he started in 1952. I’ll write up some of the details shortly with specific references, but thought I’d tease it here a bit first.

Angle down on a small, light brown wooden card index. The box has several manilla 1/5 cut 3x5" card dividers inside along with some white index cards. Outside of the box on the table in front of it are a typewritten index card and a black metal Rotring 800 0.5mm mechanical pencil. Off to one side is a white ceramic bowl full of lemons.

While digging about in indexing and filing systems, I ran across this chart created by the Oxford Filing Supply Company for a special Filing Supplies section of the May 1934 issue of Office Appliances magazine (Volume 59, Issue 5). It delineates the broad characteristics of most of the major commercially available filing systems of the era.

Twenty Four Correspondence Filing Systems

Of course, by itself, it may not make much sense, so for those interested in older indexing and filing systems, take a peek at Remington Rand’s textbook Progressive Indexing and Filing (1950) which provides lots of images, examples, and full descriptions by many of the bigger manufacturers.

Perhaps these, which are all fairly similar, may help someone in designing their indexing system for a zettelkasten or commonplace book practices.

The rest of the articles in the magazine also have some fascinating history.