The order that references appear in the reference block of a naval letter is based on which factor?

The correct approach for ordering references in the reference block of a naval letter is based on the order in which they appear in the text. This means that the first reference cited in the letter should be the first listed in the reference block, followed by subsequent references in the same sequence they are mentioned. This method allows for clarity and ease of understanding, as it directly correlates the references to their usage within the content of the letter.

Ordering by other factors like an assigned number, title length, or numerical listing does not align with the standard practices for formatting naval communications. Such practices ensure that readers can quickly find and verify the references as they relate to the information presented in the document.