When an employee is called back to work, you must reduce his/her On-Call hours by the number of hours calculated for Callback. In this example the On Call Hours were 15.5 and the Call Back Hours are 2.8 (adjusted from 2.83 using rounding rules).
Adjust the On-Call hours for Friday, 05/04/12. Enter the desired information into the Fri field. Enter "12.6".