So you see, the response requested is indicated in the very form and name of the document itself. The Letter of Intent has no established place in International trade law. Where they are used _ rarely _ is in some small niche internal markets and trades. The RFQ, Request for Quotation, a standard protocol in the business world, is what most brokers actually want when they err in using an LOI.
Letters of intent may be advanced in the world of commercial real estate. In some specific domestic markets (for example in principal to principal deals between upstream Petroleum traders and producers in the same country, or certain Joint venture projects) they may be found. But there is no underlying and supported standard international application for the Letter of Intent.