I have a document from intel named "Strain Measurement Methodology for Circuit Board Assembly: Guide." In it there is an image referencing three strain gage locations also discussed in this document. There is the POR location, ALT1 location, and ALT2 location. I would like to know what is the difference between these strain gage placement locations in the amount of strain they measure. Do they measure the same amount of strain occuring at the corner of the BGA component? Or, do they measure some slight difference in the amount of strain on the corner of the BGA component?