Legal analysis: after the parties are fully authorized, they can sign the contract on their behalf, and the contract signed by them has the same legal effect. A contract signed without the authorization of the parties may be ratified by the parties, and the contract has the same effect, but if the parties refuse to recognize it, the contract is invalid and has no legal effect on the parties. Persons with limited capacity and persons without civil capacity may sign contracts on their behalf by their legal representatives.

Legal basis: Article 165 of the Civil Code of People's Republic of China (PRC).

If the power of attorney is in written form, the power of attorney shall specify the agent's name, agency matters, authority and time limit, and shall be signed or sealed by the principal.