org-map-entries

org-map-entries is a compiled Lisp function in `org.el'.

(org-map-entries FUNC &optional MATCH SCOPE &rest SKIP)

Call FUNC at each headline selected by MATCH in SCOPE.

FUNC is a function or a lisp form. The function will be called without
arguments, with the cursor positioned at the beginning of the headline.
The return values of all calls to the function will be collected and
returned as a list.

The call to FUNC will be wrapped into a save-excursion form, so FUNC
does not need to preserve point. After evaluation, the cursor will be
moved to the end of the line (presumably of the headline of the
processed entry) and search continues from there. Under some
circumstances, this may not produce the wanted results. For example,
if you have removed (e.g. archived) the current (sub)tree it could
mean that the next entry will be skipped entirely. In such cases, you
can specify the position from where search should continue by making
FUNC set the variable `org-map-continue-from' to the desired buffer
position.

MATCH is a tags/property/todo match as it is used in the agenda tags view.
Only headlines that are matched by this query will be considered during
the iteration. When MATCH is nil or t, all headlines will be
visited by the iteration.

SCOPE determines the scope of this command. It can be any of:

nil The current buffer, respecting the restriction if any
tree The subtree started with the entry at point
region The entries within the active region, if any
region-start-level
The entries within the active region, but only those at
the same level than the first one.
file The current buffer, without restriction
file-with-archives
The current buffer, and any archives associated with it
agenda All agenda files
agenda-with-archives
All agenda files with any archive files associated with them
(file1 file2 ...)
If this is a list, all files in the list will be scanned

The remaining args are treated as settings for the skipping facilities of
the scanner. The following items can be given here:

archive skip trees with the archive tag
comment skip trees with the COMMENT keyword
function or Emacs Lisp form:
will be used as value for `org-agenda-skip-function', so
whenever the function returns a position, FUNC will not be
called for that entry and search will continue from the
position returned

If your function needs to retrieve the tags including inherited tags
at the *current* entry, you can use the value of the variable
`org-scanner-tags' which will be much faster than getting the value
with `org-get-tags-at'. If your function gets properties with
`org-entry-properties' at the *current* entry, bind `org-trust-scanner-tags'
to t around the call to `org-entry-properties' to get the same speedup.
Note that if your function moves around to retrieve tags and properties at
a *different* entry, you cannot use these techniques.