(forgive me if this is unnecessary review. hazard of message board communication) My understanding is that up until now they've been using a reference kilogra

(forgive me if this is unnecessary review. hazard of message board communication) My understanding is that up until now they've been using a reference kilogram (Si sphere or, for the watt balance, a reference object) to measure Planck's Constant. Now that they are getting repeatable, converging results for Planck's constant they can turn the process around; define Planck's constant and then use the apparatus to generate a reference kilogram. And so the beauty of it is that any sufficiently motivated team could assemble the equipment (either apparatus!) and manufacture a reference kilogram that would be just as good as anyone else's. Unlike the present state of affairs, where no matter how hard anyone wants to try, they simply can't manufacture a reference kilogram better than the one in Paris.