[2]_ will be "2" (manually numbered),
[#]_ will be "3" (anonymous auto-numbered), and
[#label]_ will be "1" (labeled auto-numbered).

.. [2] This footnote is labeled manually, so its number is fixed.

.. [#label] This autonumber-labeled footnote will be labeled "1".
   It is the first auto-numbered footnote and no other footnote
   with label "1" exists.  The order of the footnotes is used to
   determine numbering, not the order of the footnote references.

.. [#] This footnote will be labeled "3".  It is the second
   auto-numbered footnote, but footnote label "2" is already used.

