International
Tables for
Crystallography
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G. ch. 2.6, p. 69

Section 2.6.6.2.4. CATEGORY_GROUP_LIST

J. D. Westbrook,a* H. M. Bermana and S. R. Hallb

a Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers, The State University of New Jersey, Department of Chemistry and Chemical Biology, 610 Taylor Road, Piscataway, NJ 08854-8087, USA, and bSchool of Biomedical and Chemical Sciences, University of Western Australia, Crawley, Perth, WA 6009, Australia
Correspondence e-mail:  jwest@rcsb.rutgers.edu

2.6.6.2.4. CATEGORY_GROUP_LIST

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The DDL category CATEGORY_GROUP_LIST holds data items that define category groups. Category groups are collections of related categories. Parent–child relationships may be defined for these groups. The specification of category groups and the relationships between these groups allow a complicated collection of categories to be organized into a hierarchy of more relevant groups. This higher level of structure is essential for large application dictionaries that may contain hundreds of category definitions.

The category CATEGORY_GROUP_LIST holds the description of each category group, _category_group_list.description, and an optional identifier of the parent group, _category_group_list.parent_id. Category groups can be formed from collections of base categories, those categories that hold data. Category groups can also be formed from collections of base categories and category groups.

Example 2.6.6.2[link] illustrates the category groups that are defined in this DDL. These include the group of categories that define categories, the group of categories defining data items and the group of categories that define properties of the dictionary. An additional compliance group is also defined for categories that are included specifically for compliance with previous versions of DDL. Each of these category groups is defined as a child of the group named ddl_group to which all of the base DDL categories belong.

Example 2.6.6.2. Category groups defined in the DDL2 dictionary.

[Scheme scheme8]








































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