These functions are represented as LaTeX, because that's the gold standard for rendering math. But, they also want them available as XML so they're in a more sensible format for archiving.<p>So, funnily, as part of this, NIST maintain a LaTeX to XML converter.[0] It's a pretty complete LaTeX runtime. (Yes, runtime -- TeX is a programming language, not a markup language!)<p>This is the thing that powers arXiv Vanity[1] and other academic publishing projects.<p>I just find it quite amusing that the US Government maintains a LaTeX runtime written in Perl.<p>[0] <a href="https://dlmf.nist.gov/LaTeXML/" rel="nofollow">https://dlmf.nist.gov/LaTeXML/</a><p>[1] <a href="https://www.arxiv-vanity.com/" rel="nofollow">https://www.arxiv-vanity.com/</a>