Variable: mail-hist-header-ring-alist
mail-hist-header-ring-alist is a variable defined in mail-hist.el.gz.
Value
nil
Documentation
Alist of form (header-name . history-ring).
Used for knowing which history list to look in when the user asks for previous/next input.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/mail-hist.el.gz
(defvar mail-hist-header-ring-alist nil
"Alist of form (header-name . history-ring).
Used for knowing which history list to look in when the user asks for
previous/next input.")