* The seller can also reply with a pro forma invoice. In fact a pro forma invoice can serve as quote and offer, becoming a more or less binding purchase order upon buyer acceptance and signing. Pro formas are used more in smaller FCL trades, and not in larger bulk trades.
In the business world letters of intent are often used to prove to potential investors that a potential deal or merger may take place. Without such proof, investors may not be so willing to loan out the much needed money. While letters of intent are common in the business world there are also other instances where letters of intent are used.