Citations sometimes get truncated in a different way. Readers of law review articles will be familiar with a citation practice unknown elsewhere: "on file with the xyz law review," or "on file with author." Twice I have tried to consult such sources, and contacted an author and a law review about them. Both times the sources could not be located.
I suspect that both sorts of citation practices are often used to save space. A press might ask an author to cut down the length of endnotes. Fewer pages mean lower publishing costs, of course. Sometimes law review editors try to streamline cites, without realizing that those pesky record group numbers and unwieldy file names are a precise road map to the author's source material.
So what's an author to do when faced with an editor's effort to trim your citations? For starters: just say no. And to back yourself up: most archives have guidelines for how to cite to their materials, like the guidelines from the National Archives of the U.S., and the Canadian Library and Archives.
Please. Your colleagues will love you for it.
Images 1 and 2.