tags-apropos-additional-actions

tags-apropos-additional-actions is a variable defined in `etags.el'.
Its value is

nil

Documentation:
Specify additional actions for `tags-apropos'.

If non-nil, value should be a list of triples (TITLE FUNCTION
TO-SEARCH). For each triple, `tags-apropos' processes TO-SEARCH and
lists tags from it. TO-SEARCH should be an alist, obarray, or symbol.
If it is a symbol, the symbol's value is used.
TITLE, a string, is a title used to label the additional list of tags.
FUNCTION is a function to call when a symbol is selected in the
*Tags List* buffer. It will be called with one argument SYMBOL which
is the symbol being selected.

Example value:

'(("Emacs Lisp" Info-goto-emacs-command-node obarray)
("Common Lisp" common-lisp-hyperspec common-lisp-hyperspec-obarray)
("SCWM" scwm-documentation scwm-obarray))

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.