Rolling Forward on to the Board
Standing up for kiteboarding means getting your body on top of your feet. It doesn't mean "straightening your legs," we call that "straightening you legs." If your whole body is on top of your feet, then you have "stood up." If you need to adjust your riding stance, you may need to bend or straighten your legs, but that is different than rolling forward on to the board. Riding stance is part of riding, not part of the standing up or board start process.