Chemical Markup Language - CML

XML is a mainstream approach providing semantics for science, such as MathML, SBML/BIOPAX (biology), GML and KML (geo) SVG (graphics) and NLM-DTD, ODT and OOXML (documents). CML provides support for most chemistry, especially molecules, compounds, reactions, spectra, crystals and computational chemistry (compchem).

CML has been developed by Peter Murray-Rust and Henry Rzepa since 1995 and is the de facto XML for chemistry is accepted by publishers and has more than 1 million lines of Open Source code supporting it. CML can be validated and built into authoring tools (for example the Chemistry Add-in for Microsoft Word).

The infrastructure includes legacy converters, dictionaries, Semantic Web and Linked Open Data.

There are several versions of the CML schema. The last stable release was Schema 2.4 and has remained unchanged since 2005.

The most recent schema is 3 beta. As indicated by the beta this schema is still in development but essentially it consists of the original Schema 2.4 but with a much reduced content model. This allows users to put together the elements and attributes in a more flexible manner to fit the data that they want to represent more easily.