Variable: org-agenda-auto-exclude-function
org-agenda-auto-exclude-function is a customizable variable defined in
org-agenda.el.gz.
Value
nil
Documentation
A function called with a tag to decide if it is filtered on \ (org-agenda-filter-by-tag) RET.
The sole argument to the function, which is called once for each possible tag, is a string giving the name of the tag. The function should return either nil if the tag should be included as normal, "-<TAG>" to exclude the tag, or "+<TAG>" to exclude lines not carrying this tag. Note that for the purpose of tag filtering, only the lower-case version of all tags will be considered, so that this function will only ever see the lower-case version of all tags.
Source Code
;; Defined in /usr/src/emacs/lisp/org/org-agenda.el.gz
(defcustom org-agenda-auto-exclude-function nil
"A function called with a tag to decide if it is filtered on \
\\<org-agenda-mode-map>`\\[org-agenda-filter-by-tag] RET'.
The sole argument to the function, which is called once for each
possible tag, is a string giving the name of the tag. The
function should return either nil if the tag should be included
as normal, \"-<TAG>\" to exclude the tag, or \"+<TAG>\" to exclude
lines not carrying this tag.
Note that for the purpose of tag filtering, only the lower-case version of
all tags will be considered, so that this function will only ever see
the lower-case version of all tags."
:group 'org-agenda
:type '(choice (const nil) (function)))