Footprints are signed in the lower left corner or the lower right corner of the document. The corner sign is in the lower right corner of the copy of ID card. The function of foot sign is mainly to show attitude or make demands. When signing a document, you usually sign it with a foot stamp in the lower left corner or the lower right corner to prove the authenticity and legality of the document. The main function of the corner mark is to indicate which unit the ID card is provided to, what the purpose is, and other purposes are invalid.