The Data Dictionary is used to store a number of predefined field configurations (so called data dictionary entries, or data dictionary fields).
These entries exhibit most of the properties of normal fields; however, they are not used to represent actual data fields, but are templates for the configuration of actual fields in the data tables of your schema.
For example, a schema might define several tables that contain a "phone number" string field; common configuration for this field type (edit masks, display formats, field captions) might be defined in a common data dictionary entry, which is then referenced from the individual "phone number" fields using their DataDictionary property. The fields will then inherit their configuration from the commonly shared dictionary entry, rather than having to duplicate the settings. Changes to the dictionary entry will automatically reflect in all the actual fields.
- TDADataDictionary (Delphi)