The Data Dictionary (DD) is the store of database definitions. A data dictionary contains metadata (data about data). All the definitions of all the various entities (whether or not the entities appear in the database) are taken from the data dictionary. There is an interesting reciprocal relationship between the data dictionary and the database. On the one hand, the database uses the data dictionary and derives definitions from it. On the other hand, the data dictionary is equally dependent on the database for its own internal organization. The data dictionary is the DA's primary work tool. The repository is a special kind of data dictionary.

• See also Component 3.11 of the SCT

• See also Data Administrator

• The Data Dictionary is part of the organizational infrastructure software facility. See the Infrastructure Systems sub-volume under Specifics.