Mathematical Markup Language (MathML) is an application of XML for describing mathematical notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web documents.
Oxygen offers support for editing and validating MathML 2.0 documents.
A file is considered to be a MathML document when the root element name is a math or it's namespace is http://www.w3.org/1998/Math/MathML.
The schema used for these documents is located in ${frameworks}/mathml2/dtd/mathml2.dtd, where ${frameworks} is a subdirectory of the Oxygen install directory.