Binary package “w3-dtd-mathml” in ubuntu trusty
Mathematical Markup Language V2.0 DTD
The Mathematical Markup Language (MathML) V2.0 is an XML
application for describing mathematical notation
and capturing both its structure and content.
The docbook-mathml package allows you to generate output
documents from source files that use MathML markup.
.
Includes a prototype extension of the XHTML 1.1 DTD
that incorporates MathML 2.0.