XSLT stylesheet omml2mml.xsl used to convert OpenXML math to MathML 
is part of the XSL stylesheets for TEI XML (Stylesheets/docx/from/omml2mml.xsl).

More information about the XSL stylesheets for TEI XML:
http://www.tei-c.org/Tools/Stylesheets/

However the original omml2mml.xsl has been reformatted and ported back 
to XSLT 1.0 by XMLmind.
