I read on NIST CODATA that electron mass is a fundamental constant. I take from this that proton mass is not fundamental. I also read it is possible that proton-electron mass ratio may vary. So I wonder how proton mass is measured or derived. I have no training in physics, however in studying a way to describe electron and proton as superconducting electric current shells I find a ratio of 1860.308707, and this ratio makes possible an equation describing elementary charge (q). From what I read the possible ratio variation is not that large, but it makes me wonder.