/KEY

   Describes key fields, including the position, size, sorting
   order, and data type. Both the position and size of the key field
   must be specified, except for floating point data types where the
   size is known. By default, Sort reorders a file by sorting entire
   records with character data in ascending order. Any other type of
   key field must be specified. When you specify multiple keys, use
   a separate /KEY qualifier for each key.

   Format

     /KEY=(field [,...])
 

Additional information available:

Fields          Full_Description                Example