If the NODUPKEY procedure
option is specified when the SORT procedure is invoked, the SORTSUMF
system option can be used to specify whether the host sort utility
supports the SUM FIELDS=NONE statement.
Note that duplicate
keys are not the same as duplicate records. Duplicate keys can be
eliminated with the NODUPKEY option, whereas duplicate records can
be eliminated with the NODUP option in the PROC SORT statement.
For information about
specifying the appropriate setting for the SORTSUMF option, see the
documentation for your sort utility.