Good question, I debated that with a relative until I reminded him I once worked for a heating oil company.

It's for any use OTHER THAN a vehicle registered to operate on any road or highway supported by federal or state tax monies. It CAN be used in farm equipment, generator/welders, construction equipment, boats, furnaces, etc. The rule of thumb is - if it requires a license plate, inspection and insurance to be legally operated on a public road you are not supposed to burn off road fuel in it. Some locales (including here in NC) have a provision for off road gasoline BUT it's more complicated than just asking a farm supplier for it. At least when I saw it last, the buyer had to have a business tax number (and an actual farm) and do a bit of paperwork before buying it.