Strain Again

I am looking at the Anderson Loop as a possible solution for strain measurement and am interested in the 4 sensor circuit on page 13 of the pdf document at https://www.electro-tech-online.com/custompdfs/2003/04/im.pdf. The IC's next to the INA114's are not labelled but I am told, are probably OPA4277's - the quad version of the OPA177. What I don't understand is why these components, which seems to fullfill exactly the same function on each separate gauge circuit, utilises different pins [13,12/9,10/2,3/6,5].

I would be grateful if somebody could explain.

Thankyou

Having just tried, clicking the link in the post produces an error message that the page cannot be found but it does work if pasted into the address window of my browser.

https://www.electro-tech-online.com/custompdfs/2003/04/im-1.pdf

I don't know anyting on this topic but this is what the address is suppost to be...