This DATA step does not create a data set. Instead, it creates a data component and, eventually, an output object.

The SET statement reads the data set GRAIN_PRODUCTION. The WHERE statement subsets the data set so that the output object contains information only for rice and corn production in 1996. (This is done simply to make the entire table visible in the screen dumps that are used in the hardcopy book.)

data _null_;
   set grain_production;
   where type  in ('Rice', 'Corn') and year=1996;