Having now watched a fair number of autocross videos of various sorts, and scrolling through performance times of several events, I think I understand the method (generally speaking) and the means by which times are generated, but I'm not sure. For almost every event of which I've watched video, the driver begins his run upon the hand (and verbal?) signal of a race official. The driver dashes through the course and crosses a finish area which has an electronic timing device aimed along/over the finish line so as to register finish time. Is there also a "start time" electronic eye sort of apparatus that registers start time? I presume so, but often can't see it in the vids. What standards are expected of the mechanical framework and the officials that place and keep stable the timing elements? Times are generally registered in thousandths of seconds; at that level, even a slight nudge of the apparatus can affect time registered, I'd guess. What is the expected level of reproducibility of results? Are there other standards expected of timing of these events? Any special considerations one must undertake to do it properly?