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.
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.