Geometric normal pass - Usage?

[Ed]

The "Geometric normal pass" option in the Passes/Output tab renders a file named *_normals.exr

I know it can be used in a program like After Effects to relight the model using the Normality Plug-in:  http://www.3dcg.net/software/normality/

Is the Geometric normal pass intended to adjust lighting like this:  http://www.powercreative.com/blogs/node/94

Or is it intended to build your own textures using a 3D model?

Are there any KeyShot instructions or tutorials showing how to use the Geometric normal pass?

Ed