Most modern biographies and history books that aim to include non-scholarly readers use an end note style that is indexed using short snippets of the text, rather than numbers within the text. That is, the note reads:
“John had lost his spectacles” - Letter to R.H. Numbnuts, 9/16/54.
Is there a name for this style, and do any of the standard style guides outline the format and style? (I have only an older CMS here…)