In this article, we explain what an enclosure is and how to cite one, and we provide an example of an enclosure in a business letter. Add an enclosure notation after your signature at the end of the letter, and abbreviate it with "Enc." or "Encl.13. Enclosures. An enclosure can prevent a letter from becoming too detailed. The Coast Guard uses "enclosure" to supplement additional material sent with correspondence either in paper or electronic format. I would appreciate a reply at your earliest convenience. •. An early reply would be appreciated. A cover letter enclosure is a document you include with a physical cover letter, such as a resume or letter of recommendation. Permit Application Originals complete. Notarized signatures. 2. This is a Request for Proposal (RFP) for THE INSTALLATION AND DISCONNECTION OF. PORTABLE CLASSROOMS AND FOR SUPPORT SERVICES to the School District of Palm.