Traders are better off NOT using documents like LOI, ICPO, FCO, etc. Even if and when they rarely are used in internal trades, on a restricted level within specific industries, they have no legal or customary basis in International Trade whatsoever. In fact the presence of many of these terms are considered to be signs of Advance Fee Fraud, by knowledgeable players and law enforcement.
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