Carsten Dominik <carsten.dominik@gmail.com> writes:

> Hi Baoqiu and Mario,
>
> clearly, writing =double[3][3]= is the correct solution to this problem.
>
> As for the behavior of [3][3], this is not clearly defined.  Neither
> the LaTeX
> nor the HTML exporter handle this case gracefully, as in producing
> meaningful output.
>
> Maybe the right thing would be to have them both treated as a footnote
> reference, but that would also require changes to org-footnote.el.
> These changes are not entirely
> trivial, as far as I can see now.
>
> So uness you are willing to dig into org-footnote.el to changes this,
> the
> easy solution would be to simply catch the problem we have now in the
> docbook exporter, so that it does not crash.

Thanks for the suggestion, Carsten.

Attached below please find the patch for the easy solution for the
DocBook exporter (HTML and LaTeX exporters do not report any visible
errors).  Note that this patch also includes another fix that I had in
my local branch to avoid empty "<listitem></listitem>" caused by inline
tasks.