Must be returned, 1, as long as it is the expression of the true meaning of the parties and the content is legal and signed by the parties, it is legally binding and does not need special format; 2. Even if there are formal defects in the IOUs or IOUs signed by the parties, it will not affect the court's trial of the case; 3. The court will, in combination with other evidence, determine whether there is a loan relationship between "IOUs" or "receipts" with defects in form. At the same time, for cash delivery loans, we can comprehensively judge whether there is a legal and true creditor-debtor relationship between the two parties according to the delivery voucher, payment ability, trading habits, loan amount, the relationship between the parties and the transaction details stated by the parties.