Legal basis: subscription book, power of attorney, appointment book, etc. as stipulated in Article 495 of People's Republic of China (PRC) Civil Code. If the parties agree to conclude a contract within a certain period of time in the future, it constitutes an appointment contract. If one party fails to perform the obligation of concluding a contract as stipulated in the appointment contract, the other party may require it to bear the responsibility for violating the appointment contract.