Flipping threads

Ever wondered where this button is used for in the Thread dialog?

The button does not have a tooltip. So let's call it the <flip button> for now.

I was under the impression that it allowed users to decide on which side of the face the thread would be applied.

However the side the thread will be applied to is unambiguously determined by the pick location and not by the flip button.

In below image the pick location is illustrated by the orange diamond.

Thread as a result of picking on left side of face	Thread as a result of picking on right side of face

So what is the purpose of the flip button then? 
The flip button is used in very particular situations (like keyways), to obtain the result that you want.

Default thread located close to keyway	Thread after toggling the flip button

Hope this tip clarifies Inventor's behavior in this area.
Cheers
Bob