What is the official name of the vehicle's main document?

[McTaylor]

The 'main document' of a car refers to the Motor Vehicle Registration Certificate. Here is relevant information: 1. Registration Certificate: This certificate serves as the legal proof of vehicle ownership, kept by the vehicle owner and does not need to be carried in the vehicle. It is required for any vehicle registration procedures such as transfer of ownership or change of registration, and records the vehicle's details, functioning as the vehicle's 'household register'. 2. Important Notes: Vehicles registered before October 8, 2001, do not have a Motor Vehicle Registration Certificate. Vehicles registered after this date do have one, but for about a month after registration, the certificates were not issued immediately. Owners can collect them directly from the original vehicle management office where the registration was processed.