CML - Specifications
There are several versions of the CML schema, the current version being Schema 3. Examples from both Schema 3 and the earlier Schema 2.4 are available from this website, and both schemas can be downloaded.
Different domains of chemistry think about chemistry differently; often this means a very tight specification
of rules in your area of expertise and very little if any applied to the rest. The loosening of the
CML content model in Schema 3 allows users to combine the elements and attributes as they need to represent
data. However, users still need to be able to specify a set of rules (constraints) which model their particular
domain. This can be likened to thinking of the elements and attributes of CML as representing the allowed
vocabulary and the set of rules as a grammar specifying how these words are allowed to be put together.
The entire set of constraints which the CML should conform to is called a
Dictionaries allow CML to be understood by machines. Much of physical science is managed through the dictionary mechanism. We find terms and units relating to a aspect of science (such as heat of formation, melting point, point group) and create entries for these items in a dictionary.
CML dictionaries conform to a well-defined specification.
Since it is critical to be able to check the validity of any CML code that claims to be well-formed, this website provides an online validation service for users and consumers of CML.
The validation report is couched in a specific report language for maximum clarity.