The purpose of a DDI source for IMS DB is to establish a correlation between the IMS Program Specification Blocks (PSBs) and Data Base Definitions (DBDs) contained in the data view, and their corresponding COBOL records in copybooks. To add this information to a data view, you must create a file in your project's DDISRC directory that contains a series of manually coded DDI statements that identify PSBs, DBDs, and corresponding COBOL record descriptions. Follow these guidelines when creating and coding a DDISRC file: