For me it's ESP and it's not even close. To me it's nonsense to dictate chemistry limits in a spec, especially one that results from a roomful of "experts" voting on something. It's as stupid as having rules like NFL QBs must be 6'4" tall at least (a rule that cause the Chargers to say goodbye to one Drew Brees, who it turns out could play QB at least as well as the taller Phillip Rivers who displaced him).
Absurd arbitrary limits are all around us, creating pretend differences of kind out of differences of degree. Yes, one could draw a line at 68F and say everything below it is "cold" and everything above it is "hot", but at the margin, 67F and 69F are only two degrees different. Yet the categorization implies they are as different as -20F and 120F, which also fall into the same separate categories.
Nature is analog and any perfectly round value is almost certainly manmade and arbitrary. This is why PI was discovered, not dictated. As was the golden ratio, Euler's number, avagadro's number, etc etc.
There is a place for abitrary limits-- mostly in politics. But in the apolitical arena of science and nature, limits should be discovered, not dictated.