Which of the following is NOT a type of military correspondence?

Military correspondence typically includes various formal means of communication that are used within the military context to convey orders, information, and reports. A personal diary, on the other hand, is not a formal type of military correspondence. It is a private collection of thoughts, experiences, and reflections that an individual keeps for personal use. It does not follow the established formats or protocols associated with military documentation.

In contrast, standard letters, emails, and memorandums are all recognized forms of communication within military operations. They are used to ensure clarity, maintain a record of communications, and adhere to the formalities expected in military environments. These formats also carry official significance and are governed by specific guidelines, which is not the case with a personal diary.