Variable: gnus-invalid-group-regexp
gnus-invalid-group-regexp is a variable defined in gnus.el.gz.
Value
"[: `'\"/]\\|^$"
Documentation
Regexp matching invalid groups.
Source Code
;; Defined in /usr/src/emacs/lisp/gnus/gnus.el.gz
(defvar gnus-invalid-group-regexp "[: `'\"/]\\|^$"
"Regexp matching invalid groups.")