Variable: rmail-re-abbrevs
rmail-re-abbrevs is a customizable variable defined in rmail.el.gz.
Value
"\\(RE\\|رد\\|回复\\|回覆\\|SV\\|Antw\\|VS\\|REF\\|AW\\|ΑΠ\\|ΣΧΕΤ\\|השב\\|Vá\\|R\\|RIF\\|BLS\\|RES\\|Odp\\|YNT\\|ATB\\)"
Documentation
Regexp with localized 'Re:' abbreviations in various languages.
This variable was added, or its default value changed, in Emacs 28.1.
Probably introduced at or before Emacs version 28.1.
Source Code
;; Defined in /usr/src/emacs/lisp/mail/rmail.el.gz
;; Note: this is matched with case-fold-search bound to t.
(defcustom rmail-re-abbrevs
"\\(RE\\|رد\\|回复\\|回覆\\|SV\\|Antw\\|VS\\|REF\\|AW\\|ΑΠ\\|ΣΧΕΤ\\|השב\\|Vá\\|R\\|RIF\\|BLS\\|RES\\|Odp\\|YNT\\|ATB\\)"
"Regexp with localized 'Re:' abbreviations in various languages."
:version "28.1"
:type 'regexp)