Hello I have been trying to find out how the data for the atomic mass of different isotopes is processed. I am vaguely familiar with mass spectrometry and other techniques used for the measurements and I know that the experimental results are coordinated by the Atomic Mass Data Centre. I am particularly interested in atomic hydrogen but how is the data processed? What measurements are needed and how is the data processed to calculate the mass of hydrogen in, for example, its ground state. I think I know the answer but I would like confirmation. I have a rather large paper on the subject of mass measurement coordination but I find it a very heavy read and I think it assumes a lot of prior metrological knowledge on the part of the reader. Thank you.