This section provides instructions for FDCs on how to complete the SBLGP Conditional. A letter of instruction is an important document used to help navigate the process of estate planning.Otherwise known as a letter of intent. The letter of credit obligates the bank to guarantee or stand as surety for the benefit of a third party. How do I fill this out? To fill out the bank reference letter, gather all necessary financial details including account balances and loan information. Details of documents enclosed: (please tick all that are relevant). This document provides detailed instructions for completing a Banker's Guarantee application form. Before you schedule your financial center appointment. If approved, your bank essentially transfers its credit rating to your company, so the supplier company can rely on it for payment.