Links to, and provides a link from, footnote or endnote references using {{user:mdswbkq/original ref|note#}}, where note# is alphanumeric (no symbols, please).
Usage is "{{user:mdswbkq/sandbox/original note|note#}} Footnote text.", which results in "note#.↑ Footnote text."
The corresponding reference in text is inserted using {{user:mdswbkq/sandbox/original ref}}.