The 'CC' marking often contains the names of those to whom copies are distributed. You might sometimes mention their addresses as well. The 'enclosure(s)' notation is used at the beginning of a letter when there are more than one document attached. The word 'enclosure' means any item given with a letter, note, or other communication that is sent through the mail. For example, if you were sending John and Jane Doe two documents through the mail, you would put "Enclosures: Documents 1 and 2" on the face of the letter. The person receiving the letter can read what's written on the outside covering the letter and know that there are enclosed items. But most people don't open letters like this one so as not to break the seal before reading the contents. Sending many small documents in one package reduces postage costs. In this case, you should write "Enclosures: Document 1, Document 2, etc." on the face of the letter so the sender doesn't have to bother counting them out loud before sealing the letter. People use different methods when filing letters. Some keep each enclosure in its own file folder with a label indicating what's inside.