Variable: gnus-read-mark
gnus-read-mark is a customizable variable defined in gnus-sum.el.gz.
Value
82
Documentation
Mark used for read articles.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/gnus-sum.el.gz
(defcustom gnus-read-mark ?R
"Mark used for read articles."
:group 'gnus-summary-marks
:type 'character)