Recently PDF has been accepted as a standard for production of electronic documents, as ISO 32000-1:2008, with an acronym of PDF/UA (for “Universal Accessibility”). The second draft ISO 32000-2:2009 is to include specifications for including MathML tagging of mathematical environments and expressions. This talk presents a report on work-in-progress, aimed at: developing the primitive commands for pdfTeX needed to support the production of fully tagged PDF documents; writing appropriate TeX and LaTeX macros to make effective use of the new primitives; authoring changes to internal LaTeX structures to use these macros automatically at appropriate places within the existing code-base for LaTeX. This is work that is being undertaken together with Hàn Thế Thành, author of pdfTeX [Thành, Hàn Thế; Thesis – pdfTeX, published as: TUGboat, 21:4, (2000). http://www.tug.org/TUGboat/Contents/contents21-4.html], who has added some new primitive commands to an experimental version of this software tool.