If you specify the NEST option, the block level and the DO-level are printed to the right of the statement or line number under the headings LEV and NT respectively, as in the following example:
Line.File LV NT
1.0 A: PROC OPTIONS(MAIN);
2.0 1 B: PROC;
3.0 2 DCL K(10,10) FIXED BIN (15);
4.0 2 DCL Y FIXED BIN (15) INIT (6);
5.0 2 DO I=1 TO 10;
6.0 2 1 DO J=1 TO 10;
7.0 2 2 K(I,J) = N;
8.0 2 2 END;
9.0 2 1 BEGIN;
10.0 3 1 K(1,1)=Y;
11.0 3 1 END;
12.0 2 1 END B;
13.0 1 END A;