Selle Italia ID Match - Low/High Pelvic Rotation

[Valbrona]

What is the low/medium/high pelvic rotation referred to by Selle Italia in its ID Match system? If you are 'low' does it mean you are young and flexible and can crumple yourself up. And if you are 'high' does it mean you are like a Chris Horner type and ride in an upright position? Or have I got that back to front?

Thanks.