bingofan is correct. The factory technican that knots the hair on a lace base (or injects it into a skin base) can control the direction of the hair according to your order instructions. So if you want a comb back unit the hair would be directed towards the back. If you want a left part the hair would be 'ventilated' or 'directed' in that fashion. Most orders are for 'freestyle' venting which means that the hair is directed in no particilar direction. 'Freestyle' venting can be styled in any way.
Regards,
John