E+ Shading:Overhang Object: What is Depth?

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So I am trying to figure out what the depth of shade in the Input/Ouput Reference in Energy+ for the Shading:Overhang Object is actually referring to. Initially I thought it was the net-distance between the wall and the end of the shade rather than the shade length itself but some sensitivity analysis is giving me some weird results making me question my initial thought. So it the field referring to shade length or what I initially thought?

Thanks,