The upper case of the IOU is 50,000 yuan, and the lower case is 500 million yuan. Such an IOU has legal effect.

If the capital letters and lower letters of the IOU are inconsistent, the capital letters shall prevail. The lower letters are a clerical error and have the same legal effect.

An IOU is a document written by an individual or unit to the relevant unit or individual when they owe money or property. IOUs are also called "white notes" today. IOUs are also common written documents in daily life that are written to prove that one party owes another party property. It is a type of voucher application style.

IOUs generally consist of three parts: title, body, and payment.

(1) Title. The title of an IOU generally consists of the name of the genre, that is, the word "IOU" is written in a larger font in the middle of the text above the text. Some also write the words "arrears" or "owe now" as the title in this position, but the text of this title is written in the top box of the next line.

(2) Text. The text of the IOU should state clearly who or what unit is owed, what the amount is, and the date of repayment should be noted.

(3) Signing. The payment must be signed with the name of the debtor's unit and the signature of the person handling it. If the IOU is issued by an individual, the name of the individual who owes the debt must be signed. And also sign the date of the IOU. The unit's official seal must be stamped, and the individual's private seal must be stamped.