I am reading Class Field Theory from Milne's notes. I do not understand a couple of things from the following lemma about fundamental class: https://www.jmilne.org/math/CourseNotes/CFT.pdf#X.3.2.7 (the link will take you to the lemma)
In the proof of the lemma, the author says 
I think by kernal-cokernal lemma he refers to Snake lemma. I do not understand what is meant by applying this lemma on the rows and that the lemma is functorial. I hence do not get how one gets the second commutative diagram from the first. Also, if I assume somehow that we get the second diagram by applying snake lemma, how do we recognize the maps in the diagram as $Inf$ or $Res$? Apriori they are just the maps we get from snake lemma.
Any help is appreciated and feel free to give any reference.
No, by the kernel-cokernel lemma he means the kernel-cokernel lemma p.87.
Contrary to the comment by Chin, this does answer the question. OP was misreading the text. Once this is corrected, everything should be clear.