Rational Developer for System z
PL/I for Windows, Version 7.6, Programming Guide

Sequential access

To open a SEQUENTIAL file that is used to process a REGIONAL(1) data set, use either the INPUT or UPDATE attribute. You must not include the KEY option in data transmission statements, but the file can have the KEYED attribute, since you can use the KEYTO option. If the target character string referenced in the KEYTO option has more than 10 characters, the value returned (the 10-character region number) is padded on the left with blanks. If the target string has fewer than 10 characters, the value returned is truncated on the left.

Sequential access is in the order of ascending region numbers. All records are retrieved, whether dummy or actual, and you must ensure that your PL/I program recognizes dummy records.

Using sequential input with a REGIONAL(1) data set, you can read all the records in ascending region-number sequence, and in sequential update you can read and rewrite each record in turn.

The rules governing the relationship between READ and REWRITE statements for a SEQUENTIAL UPDATE file that accesses a REGIONAL(1) data set are identical to those for a consecutive data set. A discussion of using READ and REWRITE statements can be found in Accessing and updating a data set with record I/O.


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