Formally, you would refer to the enclosed things in the body of your letter, followed by "enclosed," and then, at the conclusion, under your signature, you would add "Enclosures (x)," where x is the number of enclosures. As a result, you'd write: "... my ID card" (enclosed).
However, as long as they are attachments that are not part of your main message, we think it's OK to call them "enclosures." In fact, many people find this term to be more accurate than "attachment." We agree. An attachment is something that is attached to another document or piece of information. Enclosures are additional pieces of information that are sent with a letter.
In addition, there are two types of enclosures: substantive and procedural. Substantive enclosures are ones that provide relevant information about the recipient. For example, if you are writing a letter of recommendation for someone, you might include their photo identification card, certificate of achievement, and copy of newspaper article about their success story. These items of information would all be considered substantive enclosures. Procedural enclosures are ones that serve only to notify the recipient of their availability; for example, a list of acceptable filing methods or offices within the organization. They should not be included with any other documents because they cannot provide any useful information to the recipient.
Finally, there is no specific number of enclosures you can send with your letter.
Type "enclosure:" or "attachment:" under your name and title to indicate that you've added other papers. Provide a short explanation of the contents on the next line.
Simply list the document's title, followed by the description in parenthesis. "Enclosures: Birth certificate (original plus two copies)," for example. If you've attached original papers that you'll need returned, make a note of it in the body of the letter.
Take note of the attachments. For example, if you were sending Jane's resume in order to evaluate her for a job opening, you would type "Enclosure: Google" after her first name and before her last name.
Always state the purpose of an attachment or attachments anywhere in the body of the message or after the signature or initials. In the body of your letter, talk about the attachment or the topic it covers. For example, you may include a particular reference to a document that you wish the letter recipient to see. You can also attach files in email.
Type "CC" under your signature and leave two to four spaces between your signature and the CC line. Enter the names of everyone who will be copied on this letter now.
"Please find attached," or its shortened version, "PFA," will suffice. Enclosed refers to physical mail in which envelopes are utilized. Don't be perplexed. This usage is common and accepted.