I’m a little confused about what the “Upv Reference Array” is supposed to do.
I thought it was a way to set a custom positioned polevector for the IK, but components still seem to build their own controls for the polevector.
It simply allows you to change the parent space of the polevector control. So you can set your elbow PV to be “parented” the body control or something else like the hand. In short it works like any other reference array. 
Hope this answers your question.
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Ohh, I see. That actually makes sense now. Thanks @Lucas_Brown.
I guess if you wanted custom placement of the polevectors you’d need to make your own components or post-script?
Yes I believe that is correct.