What is definition of chip to chip time in CNC machine?

It is the idle time when no cutting is taking place. The bigger picture is , to take the total idle time and express it as a percentage of the cycle time. The idea is to get this percentage as small as possible. It is use full on multi slide or multi turret machines where the cutting of two tools can overlap and so reduce chip to chip time. The programmer determines the chip to chip time . The smaller the chip to chip time the smarter the programmer. Efficiency and productivity improves