The Department of Land Transport says TC plates are for pre-production prototype vehicles (permit valid 180 days) and QC plates are for quality-test samples taken before sale (permit valid 90 days). Either way, a copy of the permit must stay in the vehicle during testing, insurance proof is required, and the driver's licence must match the vehicle type. Breaking these conditions carries a fine of up to 2,000 baht. Relevant mainly to car and motorcycle makers, importers, or anyone dealing with test vehicles.