Variable: org-open-link-functions
org-open-link-functions is a variable defined in ol.el.gz.
Value
(org-ctags-find-tag
org-ctags-ask-rebuild-tags-file-then-find-tag
org-ctags-ask-append-topic)
Documentation
Hook for functions finding a plain text link.
These functions must take a single argument, the link content. They will be called for links that look like [[link text][description]] when LINK TEXT does not have a protocol like "http:" and does not look like a filename (e.g. "./blue.png").
These functions will be called *before* Org attempts to resolve the link by doing text searches in the current buffer - so if you want a link "[[target]]" to still find "<<target>>", your function should handle this as a special case.
When the function does handle the link, it must return a non-nil value. If it decides that it is not responsible for this link, it must return nil to indicate that Org can continue with other options like exact and fuzzy text search.
Source Code
;; Defined in /usr/src/emacs/lisp/org/ol.el.gz
(defvar org-open-link-functions nil
"Hook for functions finding a plain text link.
These functions must take a single argument, the link content.
They will be called for links that look like [[link text][description]]
when LINK TEXT does not have a protocol like \"http:\" and does not look
like a filename (e.g. \"./blue.png\").
These functions will be called *before* Org attempts to resolve the
link by doing text searches in the current buffer - so if you want a
link \"[[target]]\" to still find \"<<target>>\", your function should
handle this as a special case.
When the function does handle the link, it must return a non-nil value.
If it decides that it is not responsible for this link, it must return
nil to indicate that Org can continue with other options like
exact and fuzzy text search.")