What are the functions of the 'Norm''Power', and button on shifter?

Yes, I will buy a manual, until then if someone can answer the question(s) I'd appreciate it. I had an older Toyota (Corolla)years before, but, I really never quite figured out the button functionality - so I left them alone, I think the power  button (pushed in the down position) is for pulling a load, climbing a grade, and the over-load down shifts for more power at low speed. Thank you.
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