Actually IVO of 1.5 BTDC would change to 0.5 ATDC and EVO of 49.5 BBDC becomes 47.5 BBDC..add 2 to every one of those events.
1.5 + 2 =3.5, etc.
Hmmmm... Here is a screen shot from Desktop Dyno 2000, it clearly shows a (-) number. I know people don't like DD2KActually IVO of 1.5 BTDC would change to 0.5 ATDC and EVO of 49.5 BBDC becomes 47.5 BBDC..
To the OP: probably a typo but (-) is not used in timing events.