Letter of Intent

document that details a person's intention to act in a certain way or perform a certain task

A letter of intent or LOI is a document outlining an agreement between two or more parties before the agreement is finalized.LOIs resemble written contracts, but are usually not binding upon the parties in their entirety. Many LOIs, however, contain provisions that are binding, such as non-disclosure agreements, a covenant to negotiate in good faith, or a "stand-still" or "no-shop" provision promising exclusive rights to negotiate. A LOI may also be interpreted as binding the parties if it too closely resembles a formal contract.
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Noun
1. any letter expressing an intention to take (or forgo) some action
(hypernym) letter, missive
(hyponym) investment letter

An assurance by a mutual fund shareholder that a certain amount of money will be invested monthly, in exchange for lower sales charges. In mergers, a preliminary merger agreement between companies after significant negotiations.