The SEQUENTIAL and DIRECT access attributes apply only to RECORD files, and specify how the records in the file are accessed.
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Abbreviation: SEQL for SEQUENTIAL
Default: SEQUENTIAL
The DIRECT attribute specifies that records in a data set are directly accessed. The location of the record in the data set is determined by a character-string key. Therefore, the DIRECT attribute implies the KEYED attribute. The associated data set must be on a direct-access storage device.
The SEQUENTIAL attribute specifies that records in a consecutive or relative data set are accessed in physical sequence, and that records in an indexed data set are accessed in key sequence order. For certain data set organizations, a file with the SEQUENTIAL attribute can also be used for direct access or for a mixture of random and sequential access. In this case, the file must have the additive attribute KEYED. Existing records of a data set in a SEQUENTIAL UPDATE file can be modified, ignored, or, if the data set is indexed, deleted.