Legal analysis: The IOU number refers to the number of the IOU, which is a written certificate indicating the relationship between creditor and debt. It is usually written and signed by the debtor, indicating that the debtor has owed the creditor the amount specified in the IOU.

Legal basis: "The People's Republic of China and the Civil Code"

Article 667: The loan contract means that the borrower borrows money from the lender, and returns the loan and pays when due interest contract.

Article 668: A loan contract shall be in written form, unless otherwise agreed upon for a loan between natural persons. The content of a loan contract generally includes terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Article 669: When entering into a loan contract, the borrower shall provide the true situation of business activities and financial status related to the loan as required by the lender.