INTERNATIONAL TABLES

for CRYSTALLOGRAPHY

Volume G

Definition and Exchange of Crystallographic Data

2.5. Specification of the core CIF dictionary definition language (DDL1)

S. R. Hall and A. P. F. Cook

Abstract

Data dictionaries serve to identify and describe STAR File data items which are exchanged and archived. When STAR Files are written or read, dictionaries can play an important supplementary role of validating individual items and checking the overall conformance of the data structure.

A STAR File dictionary contains definitions for each data item. These definitions are composed of a sequence of data attributes which, individually and collectively, specify the properties of an item. These attributes are considered to be the vocabulary of a STAR File dictionary definition language (DDL).

This chapter describes the concepts and specification of the STAR File DDL dictionaries used to define the data items for core crystallographic, powder diffraction, modulated-structures and electron-density applications. For these applications, it discusses the purpose of data dictionaries, the structure of a DDL dictionary file, the function of DDL attributes and the specification of DDL attributes.

References

Allen, F. H., Barnard, J. M., Cook, A. P. F. & Hall, S. R. (1995). The Molecular Information File (MIF): core specifications of a new standard format for chemical data. J. Chem. Inf. Comput. Sci. 35, 412-427.

Bourne, P. E., Berman, H. M., McMahon, B., Watenpaugh, K. D., Westbrook, J. D. & Fitzgerald, P. M. D. (1997). Macromolecular Crystallographic Information File. Methods Enzymol. 277, 571-590.

Gray, P. M. D., Kulkarni, K. G. & Paton, N. W. (1992). Object oriented databases. New York: Prentice Hall.

Hall, S. R. (1991). The STAR file: a new format for electronic data transfer and archiving. J. Chem. Inf. Comput. Sci. 31, 326-333.

Hall, S. R., Allen, F. H. & Brown, I. D. (1991). The Crystallographic Information File (CIF): a new standard archive file for crystallography. Acta Cryst. A47, 655-685. See also [web] [cdrom] HTML version (http://www.iucr.org/iucr-top/cif/standard/cifstd1.html).

Hall, S. R. & Cook, A. P. F. (1995). STAR dictionary definition language: initial specification. J. Chem. Inf. Comput. Sci. 35, 819-825.

Hall, S. R. & Spadaccini, N. (1994). The STAR File: detailed specifications. J. Chem. Inf. Comput. Sci. 34, 505-508.

IEEE (1991). IEEE Standard for Information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and utilities, Vol. 1, IEEE Standard 1003.2-1992. New York: The Institute of Electrical and Electronic Engineers, Inc. See also http://www.opengroup.org/onlinepubs/009695399/.

Kim, W. (1990). Introduction to object oriented databases. Boston: MIT Press.

Westbrook, J. D. & Hall, S. R. (1995). A dictionary description language for macromolecular structure. http://ndbserver.rutgers.edu/mmcif/ddl.