The Chemical Entities of Biological Interest (ChEBI) ontology is downloaded weekly from EMBL-EBI at http://www.ebi.ac.uk/chebi/. The data is made available under the Creative Commons License (CC BY 3.0, http://creativecommons.org/licenses/by/3.0/). For more information see: Degtyarenko et al. (2008) ChEBI: a database and ontology for chemical entities of biological interest. Nucleic Acids Res. 36, D344–D350.
A partially-defined glycan in which the number and type of monosaccharides (hexose, pentose, etc.) is known, but the identities of the individual monosaccharides and the connectivity and configuration of the anomeric linkages are not known. See http://purl.obolibrary.org/obo/GNO_00000013.