> For the complete documentation index, see [llms.txt](https://mandober.gitbook.io/math-debrief/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mandober.gitbook.io/math-debrief/900-index/980-hierarchy/classification/math-classifications.md). # Mathematics Subject Classification Structure * MSC is a 3 level deep hierarchical scheme * classification code can have 2, 3 or 5 digits, depending on specificity Levels 1. The first level code (FLC) is a 2-digit number. 2. The second level code (SLC) is a letter or a dash. 3. The third level code (TLC) is 2-digit number. For example * `53-xx`: Differential geometry (or just `53`) * `53Axx`: Classical differential geometry (or just `53A`) * `53A45`: Vector and tensor analysis **First level** * *64 mathematical disciplines* are labeled with a unique 2-digit code. * there are top-level categories for typical areas and for the overlaps * mathematical physics is well represented taking categories 70-86 * valid MSC classification codes must have at least FLC. **Second level** * SLC are a *letter* or a *dash*. * 2nd-level is for specific fields of the 1st-level disciplines. * SLC vary across the disciplines. e.g.: * `53` : Differential Geometry's FLC * `53A`: Classical Differential Geometry * `53B`: Local Differential Geometry * `53C`: Global Differential Geometry * `53D`: Symplectic Geometry And Contact Geometry Second level's special subsection * dash marks the special subsection, always with the same contents: * `FLC-00`: General reference works * `FLC-01`: Instructional exposition * `FLC-02`: Research exposition * `FLC-03`: Historical * `FLC-04`: Explicit machine computation and programs * `FLC-06`: Proceedings, conferences, collections, etc. * it is not valid to use trailing dash, e.g. "53-", just use `53` **Third level** * 3rd-level codes are the most specific subjects * TLC ending in 99 is "none-of-the-above", "other" placement for every category ## Using the scheme The AMS recommends that papers submitted to its journals for publication have one primary classification and one or more optional secondary classifications. A typical MSC subject class line on a research paper looks like:\ `MSC Primary 03C90; Secondary 03-02;` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://mandober.gitbook.io/math-debrief/900-index/980-hierarchy/classification/math-classifications.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.