Completion mechanism for headlines when creating a link between 2 Org files?

[Alain.Cochard@unistra.fr]

Hello.  For internal links, the manual states that

   To insert a link targeting a headline, in-buffer completion can be
   used.  Just type a star followed by a few optional letters into the
   buffer and press ‘M-<TAB>’.  All headlines in the current buffer
   are offered as completions."

Is there a similar mechanism for links from one Org file to a headline
of another Org file?  In the 'Handling Links' section of the manual:

   C-c C-l (org-insert-link)

       [...]

       Completion support

	   Completion with TAB helps you to insert valid link prefixes
	   like ‘http’ or ‘ftp’, including the prefixes defined
	   through link abbreviations (see Link Abbreviations). If you
	   press RET after inserting only the prefix, Org offers
	   specific completion support for some link types.

but, after I complete for a given file, I cannot find a way to further
complete for a specific (sub)headline.  Is there a way that I missed,
even after searching the Internet a bit?

If not, I am making it a feature request.  Indeed it would be great,
especially if one does not really remember where, in a (known) file,
the headline is, nor --even more importantly-- what its name exactly
is.

(In my naive view, as the completion mechanism already exists for
internal files, it should be easy to extend it for external files...)

Regards