  Including LaTeX source of mathematical expressions, within the PDF document
of a text-book or research paper, has definite benefits regarding
`Accessibility' considerations. Here we describe three ways in which this can
be done, fully compatibly with international standards ISO 32000, ISO 19005-3,
and the forthcoming ISO 32000-2 (PDF 2.0). Two methods use embedded files, also
known as `attachments', holding information in either LaTeX or MathML formats,
but use different PDF structures to relate these attachments to regions of the
document window. One uses structure, so is applicable to a fully `Tagged PDF'
context, while the other uses /AF tagging of the relevant content. The third
method requires no tagging at all, instead including the source coding as the
/ActualText replacement of a so-called `fake space'. Information provided this
way is extracted via simple Select/Copy/Paste actions, and is available to
existing screen-reading software and assistive technologies.
