To build VSAM into a data view, you must code a series of DDI statements to define your records. You can also supply your IMS with additional information on COBOL records by coding DDI statements.
The purpose of VSAM DDI source is to supply your VSAM files, record indexes, and COBOL record descriptions to a data view. See DDI statements - VSAM for complete information on coding VSAM DDI source.
The purpose of a DDI source for an IMS data view is to establish a correlation between the IMS you load and build into a data view and the COBOL records in the corresponding copybook. See DDI statements - IMS DB for complete information on coding IMS DDI source.