Second, MathML equations are normalized and transformed to TeX. An XProc library entitled mml‐normalize has a number of built‐in heuristics to normalize badly authored equations e.g., resolving superscripts with an empty base symbol. After this step, the XProc library mml2tex transforms MathML and inserts the TeX equations as processing instructions into the XML document. When you take the example from the Pandoc section as input, this would be the output of mml2tex:

<?xml version="1.0" encoding="UTF‑8"?>
<article xmlns="http://docbook.org/ns/docbook" version="5.0">
  <title>Area enclosed by a circle</title>
  <equation>
    <?mml2tex A=\frac{a^{4}}{4}\cdot \sqrt{3}?>
  </equation>
</article>

The third step is the central aspect of an xml2tex conversion. The xml2tex configuration is converted to an XSLT stylesheet which is applied on the XML input document later. But let me walk you through the main aspects of our xml2tex configuration.