From Open Babel
@ARTICLE{mr03,
author = {P. Murray--Rust and H. S. Rzepa},
title = {Chemical {M}arkup, {XML} and the {W}orld--{W}ide {W}eb. 4. {CML}
{S}chema},
journal = {J. {C}hem. {I}nf. {C}omput. {S}ci.},
year = {2003},
volume = {43},
pages = {757--772},
abstract = {A revision to {C}hemical {M}arkup {L}anguage ({CML}) is presented
as a {XML} {S}chema compliant form, modularized into nonchemical
and chemical components. {STMML} contains generic concepts for numeric
data and scientific units, while {CMLC}ore retains most of the chemical
functionality of the original {CML} 1.0 and extends it by adding
handlers for chemical substances, extended bonding models and names.
{W}e propose extension via new namespaced components for chemical
queries, reactions, spectra, and computational chemistry. {T}he
conformance with {XML} schemas allows much greater control over
datatyping, document validation, and structure.},
doi = {10.1021/ci0256541},
}