Valid CIF data names and the permitted data value type(s) for each name are expressed in a computer-readable dictionary, where the dictionary syntax is defined in a separate Dictionary Definition Language (DDL).
enCIFer is able to load dictionaries which conform to the DLL1.4.1 format (referred to as DDL1) including the small molecule core dictionary and the powder diffraction dictionary. The current DDL1 dictionaries available from the IUCr are included in the enCIFer distribution with the permission of the IUCr, who hold the copyright. EnCIFer supports neither DDL2 nor the proposed DDLm, CIF files or dictionaries, e.g. the macromolecular CIF dictionary mmCIF.
The latest small-molecule core and other DDL1 dictionaries and details of the DDL can be found on the IUCr website: http://www.iucr.org.