Final answer:
In a letter, the abbreviation "ENC." stands for enclosure, indicating additional materials included with the letter.
Step-by-step explanation:
In a letter, the abbreviation "ENC." indicates an enclosure. When you send a letter and include additional items within the same package, you should list these items separately under the heading 'Enclosures.' This could include various documents such as a resume, a writing sample, or any other supplementary material. It's important to note that if the enclosed items contain work done for a company, permission to share these materials should be obtained in advance. 'Enclosures' tells the recipient to look for these additional items in the package.