Exit E14 may be used to change the contents of data fields, or to delete or sum records during Phase 1. Unlike an E15 exit routine, it cannot be used to add records. An E14 exit program requires:
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at least one SORTWKxx data set, assigned to disk;
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fixed-length input records.
This exit is given control whenever MFX is about to add a record to an output sequence. Since it does not take control before the first record of that sequence, the routine always has access to a pair of sequenced records (e.g., for summation purposes). MFX passes the exit program a two-word parameter list by loading its address into Register 1. The exit must not destroy the contents of this parameter list. The first word, which is on a fullword boundary, contains the address of the record about to be placed in an output sequence; the second word contains the address of the record that has just been put into the output buffer.
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There are two constraints on the type of processing the exit may accord this record pair:
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Sort control fields should not be changed since this may cause an out-of-sequence condition.
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If a record is to be changed, it should first be moved to a work area.
After record processing is completed, the exit routine must place the appropriate return code in Register 15. The exit must save and restore all registers except those used in linking to the sort/merge.