Catalog Search Interface (CSI) is a read-only general-use programming interface that is used to obtain information about entries contained in catalogs. The catalog entries are selected using a generic filter key provided as input. The generic filter key can be a fully-qualified entry name, in which case one entry is returned, or the generic filter key can contain "wild cards" so that multiple entries can be selected on a single invocation. The type or types of entries desired can also be specified. For instance, all non-VSAM entries that begin with "ABC" could be selected.

Field information for each entry is requested by specifying field names. This eliminates the need for the caller to know whether the information is in the Basic Catalog Structure (BCS) or in the VSAM Volume Data Set (VVDS).

A work area, whose address and size is provided on input, is used to return the selected entries and the field information for those entries. If all of the entries cannot be contained in the work area provided, then as many as possible are returned in one invocation, and an indicator is set to reflect that more entries exist. Subsequent invocations can specify that the request is being resumed and the additional entries can be obtained. Resumes can be repeated until all entries have been returned. The resume process allows the delivery of large amounts of information to the user program without impacting catalog resources.