Z Code has a special jam detection circuit that allows the HALO to determine when an internal jam occurs (out-of-round paint for example). It then initiates a jam clearing sequence which attempts to clear the jam (three times) before changing to a fail safe mode which protects the motor and circuitry for being damaged. This advanced technology has allowed an increase the rotational force/speed of the HALO without risk of damage. Z Code still includes all of the features of past software updates. When in fail-safe mode, the HALO will rapidly flash the LED red and green to let the user know of the jam. The user can then clear the jam and turn the HALO off and back on normally. When battery levels are too low, the same flashing will occur to alert the user. Mfg. Release Date: August 15, 2003. If your HALO was manufactured before August 15, 2003 it does NOT have the most up to date Z code.How to check if your HALO has Z code: While your HALO is running without paint in it, reach down with your fingers and stop the drive cone from spinning (you need to press down on it fairly hard to FULLY stall it so that it does not move at all). If you hold it down and the motor pulses three times and then the LED starts blinking red and green, you have Z code. If the HALO just keeps “humming“ and does not stall out within 5 seconds, you do not have Z code.