For those interested in the obscurities of library classification systems:
Academic libraries use a different classification system called “Library of Congress” classification. It is a combination of letters and numbers that allows finer/more specific classification with shorter nomenclature than Dewy supports.
But that isn’t universal among universities. The largest Dewey collection I know is (?was?) the collection of the university of Illinois systems. Aye yi yi. The limitations of Dewey for a huge collection caused them to create some fancy idiosyncratic additional nomenclature, if I remember correctly.
Then, there are all kinds of classification systems created for specific subjects. The National Library of Medicine has a classification system for health books. There is a specialized system for Theological collections used by church libraries.
The federal government has its own classification system called Superintendent of Documents …SUDOCS for short…to organize the bezillion publications it produces. My library was a “depository” library that housed hundreds of thousands of documents issued by the Feds. Same idea for state publications, all of the states I worked in had depository programs where they sent publications to participating libraries and those documents were classed according to whatever the state system used.
And then, there are the amateur systems designed by…amateurs who think they are doing it good. My large urban library had a couple of these applied to special collections, invented by long dead librarians. Over several years we re-classed those collections into standard Dewey.