I am learning the Sweep feature in SW2016. There are Profile Orientation options and Profile Twist options for the Sweep feature. For the profile twist, the help documents explains

<p>"None"  (For 2D paths only.) Aligns the profile normal to the path. No correction is applied.      </p>

How is the profile normal to the path? Does anyone know the detail of the options and please help to explain it. Thanks a lot.