We can use the OUTFIL statement to select or sample records based on their Relative Record Number (RRN), which refers to the position of a record in the input dataset. The implicit relative record numbers start from 1 for the first record and n for the last record (n is the total number of records).

Syntax -

//SYSIN DD *
   SORT FILEDS=...
	OUTFIL FNAMES=DDname-n,STARTREC=starting_RRN,
	   ENDREC=ending_RRN
/*

STARTREC=starting_RRN	Specifies the first record to be included in the output, based on its relative position.
ENDREC=ending_RRN	Specifies the last record to be included in the output, based on its relative position.

Examples -

Scenario1 - Selecting Records by Relative Record Number (RRN).

//SYSIN   DD  *
  SORT FIELDS=COPY
  OUTFIL FNAMES=SORTOUT,STARTREC=5,ENDREC=10
/*

Starts output from the 5th record and stops after the 10th record. Only records from 5 to 10 (inclusive) are written to the output file SORTOUT.

Scenario2 - Sampling Every nth Record.

//SYSIN   DD  *
  SORT FIELDS=COPY
  OUTFIL FNAMES=SORTOUT,SAMPLE=3
/*

Selects every 3rd record from the input file. Only records with RRNs of 3, 6, 9, etc., are written to the output file.

Scenario3 - Combining Sampling and Record Range.

//SYSIN   DD  *
  SORT FIELDS=COPY
  OUTFIL FNAMES=SORTOUT,STARTREC=10,ENDREC=50,SAMPLE=5
/*

Selects records between the 10th and 50th records. From those selected records, every 5th record is written to the output, starting from the 10th record.

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