My old roommate (he-who-used-to-be-an-oblate-monk) hailed from Corvallis, Oregon. He would add to this discussion that "soda" comes from "sodium," and where he grew up the custom was to order a "lime phosphate," as opposed to our "lime soda." Different mineral in the water. Tasted different, too, he said.

Anyone else ever come across this variation? I know I haven't, not since that one mention.