Chemical Markup Language (ChemML or CML) is an approach to managing molecular information using tools such as XML and Java. It was the first domain specific implementation based strictly on XML, first based on a DTD and later on an XML Schema, the most robust and widely used system for precise information management in many areas. It has been developed over more than a decade by Murray-Rust, Rzepa and others and has been tested in many areas and on a variety of machines.