As @DogMan said, the coefficient is a number (ratio) that allows the mods chip to "measure" how resistance changes in the atomiser wire correlate to its temperature. Kanthal does not change resistance to a large enough degree to measure this well (at least at the scale of vaping), and thus is cannot be used in TC. SS, Ni and Ti all change resistance differently as power is applied, and they therefore need a different coefficient to measure how this relates to temperature changes. I agree with you in that TC has limitations that make for a not as satisfying vape as standard VV/VW vaping. Cutoffs, having to set up power curves etc etc etc.... Too much hassle and not enough payoff. Formaldehyde studies are flawed. They are based on conditions emulating dry hits. I highly doubt that anyone could vape under those conditions to have enough of a concentrated hit of formaldehyde to be dangerous. Vapes know when they are approaching a dry hit (particularly drippers).... Its a mistake you try to only make once!