Variable: find-tag-default-function
find-tag-default-function is a customizable variable defined in
etags.el.gz.
Value
nil
Documentation
A function of no arguments used by M-x find-tag (find-tag) to pick a default tag.
If nil, and the symbol that is the value of major-mode
has a find-tag-default-function property (see put), that is used.
Otherwise, find-tag-default is used.
Source Code
;; Defined in /usr/src/emacs/lisp/progmodes/etags.el.gz
;;;###autoload
(defcustom find-tag-default-function nil
"A function of no arguments used by \\[find-tag] to pick a default tag.
If nil, and the symbol that is the value of `major-mode'
has a `find-tag-default-function' property (see `put'), that is used.
Otherwise, `find-tag-default' is used."
:type '(choice (const nil) function))