gnus-decode-header-methods

gnus-decode-header-methods is a variable defined in `gnus-art.el'.
Its value is

(mail-decode-encoded-word-region)

Documentation:
List of methods used to decode headers.

This variable is a list of FUNCTION or (REGEXP . FUNCTION). If item
is FUNCTION, FUNCTION will be applied to all newsgroups. If item is a
(REGEXP . FUNCTION), FUNCTION will be only apply to the newsgroups
whose names match REGEXP.

For example:
(("chinese" . gnus-decode-encoded-word-region-by-guess)
mail-decode-encoded-word-region
("chinese" . rfc1843-decode-region))