If you select option X, you must specify either a DASD-resident sequential or partitioned data set. The index listing is recorded in the ISPF list data set. For a partitioned data set, the index listing includes general information about the data set followed by a member list. For a sequential data set, the index listing includes general information only. See the topic about Listing Formats in z/OS ISPF User's Guide Vol I for examples of the index listing format for source libraries and load libraries.