The common term is metric. SI is short for system international (actually the french words). While there have been attempts to force it on the U. S., the public has overwhelmingly rejected it. It has crept in to some places. The car industry is mostly metric and we buy 2 liter bottles of soda but people are too used to the English system to change quickly. I've never understood the whole ton/BTU thing. You've got a unit in your house. The bottom part delivers heat in BTUs and the top part takes away heat in Tons. Oh well, thats what those nifty calculators are for.
