The fingerprints of ten fingers are legally binding, but it is customary to press the fingerprints with the index finger of the right hand.

Legally speaking, whether it is signature, seal or handprint, it is an effective form to prove a person's identity. If there is no special agreement between the two parties, the three have the same effect. Everyone has a name, which is a representative symbol of citizens and reflects a person's identity. Signing, stamping or fingerprinting on the paper indicates his approval of the contract.