F12 F11 F481 F55 F989 E1 E2 E3

8204 20160930 1064.848 test Y 10

8204A 20160930 1064.505 test Y 6 4

Thanks for all the help.Now things are getting lil more from previous.We have three more columns added E1,E2 ,E3.E3 doesnt have anything as off now .Just a placeholder. Now a new logic must be bulit for as below: F481 = IF (E2 NOT NULL) then (E1 - E2) / 2 ELSE (F481) So after computations the output must be as:

F12 F11 F481 F55 F989

8204 20160930 1064.848 test Y

8204A 20160930 1 test Y

The final output record format will be as per previous format .The first record meets the else part and hence remain unchanged . The second record gets computed as above.The new columns are never part of actual output