American civilian curious about something. I'm sorry if this isn't appropriate for the subreddit, but I don't know of a better one.
If I remember right, at least two Robert Heinlein science-fiction books has a military character requiring that an order be put in writing and signed. Heinlein had been in the U. S. Navy, and he had some interest in accuracy there. Also, the instances that I can remember were not in the field (one in a mess hall, one during a long trip on a ship). Also also, Heinlein's biography mentions on p. 156 that he had done just that in early 1932.
On the other hand, he was writing science fiction, and more than that, he had some, um, unique notions. And the biography does have occasional errors.
So: in the US's armed forces, is there anything at all pertaining to requiring that an order be put in writing? If so, do you have a source that says it's possible? I did try a Google search, but I can't find anything particularly pertinent.