The court won't judge the plaintiff's case just by an IOU or IOU. The court will also examine the facts of borrowing or owing money. Moreover, carbon paper is not the original, it can be forged, and it is more difficult to get support.

IOU is a kind of documentary application written to the relevant unit or individual when an individual or unit owes money or things. White stripes are also called "IOUs" today. IOU is also a common written document in daily life to prove that one party owes money to the other, and it is an application style of credentials.