So let's sum things up: The LOI and similar documentary terms, are non standard, confusing, and lead to ambiguity. Documentary ambiguity is referred to in trade law as a condition "The Battle of the Forms" in which confusion from contradictory and ambiguous forms and documents damages the transaction. This should be avoided. To seasoned corporate traders and bankers, using terms like "Letter of Intent" is the mark of amateurs. What you properly want is an RFQ, request for quotation, from a seller or supplier. The seller may then reply to your RFQ with a quote OR full offer if they wish.
The lawyers add that: "This is the legal problem with a Letter of Intent _ you can't legally state you agree to something and then state that you don't in the same document." Famous Case of a Letter of Intent Gone Bad: Court Case of GETTY OIL vs. PENNZOIL