Additional information tied to a particular location in the text, which is not considered to be part of the body of the text, but is a note instead of, in addition to, as a source for, or as a commentary on either some body text or on an element in the metadata such as an author. It is best practice to place a footnote at the site of the first reference.
In print, footnotes are traditionally displayed at the bottom of a printed page or in a list at the end of the article; each footnote reference is marked by a number or symbol, and the text of the footnote is prefixed by the same number or symbol to help the reader associate the text with its reference(s). On screen, footnotes may appear as clickable icons, in a separate pop-up window, in a list with links at the end of an article, or in a separate footnote area.
A reference to a <fn> is made with the <xref> element.
To describe a footnote that is not in the same language as the original document (for example, a Latin or Greek footnote for a document in English), use the @xml:lang attribute on the footnote.
<!ELEMENT fn %fn-model; >
<aff>, <article-title>, <attrib>, <bold>, <chem-struct>, <def-head>, <fn-group>, <italic>, <license-p>, <monospace>, <named-content>, <overline>, <p>, <product>, <roman>, <sc>, <speaker>, <strike>, <styled-content>, <sub>, <subtitle>, <sup>, <table-wrap-foot>, <td>, <term>, <term-head>, <th>, <title>, <trans-title>, <underline>
In the footer of a table:
... <table-wrap id="TN0.170"> <caption><p>Numbers of patients receiving institutional care at the end of scheduled follow up and use of hospital beds among those allocated to day hospital or alternative services</p></caption> <table> ... </table> <table-wrap-foot> <fn id="TF1-150"><p>Data not available for 1 trial.</p></fn> <fn id="TF1-151"><p>P&#x003C;0.05 (random effects model).</p></fn> </table-wrap-foot> </table-wrap> ...
In an article’s title:
... <article-meta> <title-group> <article-title>Adaptins<fn id="FN206"> <p>Online version of this essay contains supplemental tabular material.</p> </fn> </article-title> <subtitle>The Final Recount</subtitle> </title-group> <contrib-group> <contrib contrib-type="editor"> <name><surname>Pollard</surname> <given-names>Thomas D.</given-names></name> <author-comment> <p>This essay constitutes the second article in the “Genome Annotation Series” initiated by Thomas D. Pollard, Essay Editor. The first essay, by J.S. Berg, B.C. Powell, and R.E. Cheney, appeared in the April 2001 issue of <italic>Molecular Biology of the Cell</italic> (Vol. 12, Issue 4, pp 780–794).</p> </author-comment> </contrib> ... </contrib-group> ... </article-meta> ...