I wanted this to be separate from the flatten everything discussion even though I think I reference this idea in there.

In Pro-E and other programs (like geometry works) you can create complex geometry by using this method:

     Take a section of a complex surface and "flatten" it.

     Then use that surface as a sketch plane to build other geometry.

     Once the geometry is created the user can "bend it back" and the solids on the falattened face a re-mapped to the initial face.

This is really powerful.  The most obvious use case is putting logos onto surfaces of complex molded parts.

Allso I have seen it used to make ribs along complex faces and anything else where you want solid geometry to follow the curvature of a complex surface.

It is like wrap but so much more pwoerful

Wrap is very unpredictable and you can't control how the geometry will be attached to the wrapp surface.  (also obviously it only supports conic surfaces)

What is nice here is you can create relations to the edges of the unfolded surface so when it is bent back you will have clean edges.