Legal subjectivity:

If Party B does not sign the contract, but has a seal or fingerprint, the contract is valid. If Party B does not sign, but one party has performed its main obligations and the other party has accepted the other party's performance, the contract is valid. Except for the above circumstances, the contract is invalid. Legal objectivity:

Article 490 of the Civil Code: If the parties conclude a contract in the form of a contract, the contract is established when both parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it. Laws and administrative regulations stipulate or the parties agree that a contract should be concluded in written form. If the parties do not use written form but one party has performed its main obligations and the other party accepts it, the contract is established.