An instrument that requires an indorsement for negotiation must contain a handwritten signature.

Indorsement

An act of signing one's name on the back of a check or other negotiable instrument, thereby transferring the rights to another party.

Negotiation

The process by which two or more parties aim to reach a mutual agreement through dialogue and compromise on various issues.

Handwritten Signature

A person's unique method of writing their name with pen and paper, often used for authorization or personal verification.