Dictionary definition language

Definition

A machine-readable formalism for defining and describing data items in computer data exchange files. In crystallography, a committee of the International Union of Crystallography is responsible for maintaining dictionaries of standard data names that identify specific items of crystallographic data in files used for the publication and database deposition of crystal structure reports.

These dictionaries are machine-readable compilations of tags identifying different data items and the attributes of the associated data. They exist for different applications within crystallography, e.g. small-molecule and inorganic ('core') structures; macromolecular structures; powder diffraction; modulated and composite structures; electron density; image data; symmetry data. Two distinct versions of crystallographic dictionary definition languages are currently in widespread use, differing in the attributes they record and the expression of relationships between different data items. A third such language (DDLm) provides machine-readable and executable algorithms allowing the derivation of certain data from other related items in the same file.

See also

• Hall, S. R. and Cook, A. P. F. (1995). J. Chem. Inf. Comput. Sci. 35, 819-825. STAR dictionary definition language: initial specification
• Chapters 2.5 and 2.6 of International Tables for Crystallography, Volume G