Working with IMS database descriptions (DBD)
You can visualize the structure of IMS™ databases, including logical relationships and indexes, by using IMS Explorer. You can use the IMS DBD editor to view the segment hierarchy for an IMS database and to edit the field attributes for a segment.
A database description (DBD) is the collection of macro parameter statements that define the characteristics of a database, such as the database's organization and access method, the segments and fields in a database record, and the relationship between types of segments.