A short-term permit for running in a state you are not registered in.
Covers a single trip when you do not hold apportioned plates or a fuel-tax licence for that jurisdiction.
Cheaper than full registration for occasional runs, and a fine if you skip it. The decision is worth making before the state line, not at the scale.
Related
Inteleri works out what a load actually pays you once things like this land. See how it works.