Position 39 is used to reset a numeric field to zeros or a character field to blanks. If the field is conditioned by indicators in positions 23 through 31, the blank after is also conditioned. This position must be blank for look-ahead, user date special words, *PLACE, named constants, and constants.
Resetting fields to zeros is useful when totals are accumulated and written for each control group in a program. After the total is accumulated and written for one control group, the total field can be reset to zeros before accumulation begins on the total for the next control group.
If blank after (position 39) is specified for a field to be written more than once, the B should be entered on the last line specifying output for that field, or else the field named may be set to blanks or zeros after the field is written to the output record.
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