[fn:m])A footnote is started by a footnote marker in square brackets in
column 0, no indentation allowed. It ends at the next footnote definition, headline, or
after two consecutive empty lines. The footnote reference is simply the marker in
square brackets, inside text. Markers always start with fn:.
Footnote Example:
The Org homepage[fn:1] now looks a lot better than it used to. ... [fn:1] The link is: https://orgmode.org
Footnotes may also be named footnotes: [fn:name] (name must be unique).
Footnames may also be inline footnotes: [fn:inline definition]. This is basically a
LaTeX-like anonymous footnote where the definition is given directly at the reference point.
Finally, a hybrid footnote with both a label and an in-line definition, allowing further references to the same footnote.
[fn:name:a definition]