In the launch of the space shuttle discovery what does "auto sequence start" mean?

The countdown clock before a rocket launches is one of the most remarkable timepieces in the world. As indicated by the "T-minus" mark, the hours and minutes tick down to launch. “Auto sequence start” is a breakdown of some of the big milestones leading up to that final moment. If there are no technical issues, at T-minus 31 seconds, the ‘go’ command will be given “Auto sequence start” which means the Ground launch sequencer will hand off primary control. It will be handed off to the shuttle’s onboard computers.

answer; the correct answer is (operating system);