This is off the USOS website:
"As riders dropped in, they had the choice of either hitting a down rail or flat-down box, with stairs in between to keep the gnar factor high. It was then balls-to-the-wall as they charged a quad kicker line. Stomping was essential as anything less would zap your speed, forcing you to either bite the knuckle or skip a jump entirely. This risk didn’t seem to stop anyone from digging deep into their bag of tricks. After the kicker line, riders chose to hit either an up-flat-down box or flat-bar rail."