A pair of punches that can be calculated is considered an interval, one IN punch and one OUT punch. If you have four punches there will be 2 intervals. For Example, if an employee punches at 8:00AM, 12:00PM, 1:00PM and 5:00PM there will be 2 intervals; 8:00AM to 12:00PM and 1:00PM to 5:00pm.