From the W3C Weekly News - 16 November 2003 e-mailing:

MathML Working Group Notes Published

  The Math Working Group has released "Units in MathML," "Structured
  Types in MathML 2.0" and "Bound Variables in MathML" as Working Group
  Notes. MathML is an XML application that allows mathematical notation
  and content to be served, received and processed on the Web. Visit the
  Math home page.

http://www.w3.org/TR/2003/NOTE-mathml-units-20031110/

http://www.w3.org/TR/2003/NOTE-mathml-types-20031110/  
http://www.w3.org/TR/2003/NOTE-mathml-bvar-20031110/

http://www.w3.org/Math/