Job Output
The ID statement in the PROC PRINT step tells SAS which variable(s) to use instead of the (stupid) OBS column that normally is shown in the output.
The Proc Print output.

Example 3, with different data

ID    SCORE     GRADE    NOFORMAT

 1    F           F          0.0
 2        -1                -1.0
 3    A           A        101.0
 4    B           B         82.1
 5      89.1      B         89.1
 6         .                  .

Note that you can tell now that SCORE is a numeric variable and GRADE is character variable.