{\TeX\ + \MathML\ for Tagged \PDF, the next frontier in mathematical typesetting} {Ross Moore} {This talk will be a follow-on to the introduction to ``Tagged \PDF'' given at last year's \TUG\ meeting. Here I'll present several examples of tagged \PDF\ documents containing real-world mathematical layouts, which demonstrate the advantages that tagging provides, in terms of long-term Archivability (\acro{PDF/A}) and Accessibility (\acro{PDF/UA}) and sharing of content and markup via export to \XML. A script, written in Perl, is under continuing development. This script combines the \MathML\ presentational description of a piece of mathematics with corresponding \LaTeX\ source for its visual appearance, creating a detailed \TeX\ coding using new primitives that are processed by an enhanced version of pdf\TeX\ to produce fully tagged \PDF\ documents. If time permits we can discuss some of the complications that arise due to differences in the way mathematical structures are handled by \TeX\ and for \MathML. This is joint work with \Thanh\ (River Valley Technologies), author of pdf\TeX.}