On Offer acceptance there is either a contract generated or a pro forma invoice generated. Since the offer is binding once accepted, the offer if well enough detailed and advised can and often does take the place of the contract. Customarily in Real Estate transactions the purchase offer itself is generally also the contract for purchase as well. The offer becomes a binding contract once accepted.
In fact, some experts have called the LOI a document whose use is primarily advocated or promoted only by amateurs and marginal dealers or "joker_broker" types in the crude trade business, especially the overzealous sellers' agents and brokers in a desperate hurry to land some buyers. Mr. Ziad K. Abdelnour, President & CEO of Blackhawk Partners, Inc, a New York_based advisory firm to traders and suppliers of metals, minerals and crude oil commodities, calls the LOI document something that is primarily "used out on the Internet by inexperienced traders," and by "inexperienced 'intermediary seller' who is claiming to be the supplier."