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.


fn-type Type of Footnote
id Identifier
xml:lang Language

Related Elements

A footnote <fn> usually contains material that cannot stand alone; the material must be related to a word, phrase, or paragraph already in the basic textual material. Supplementary material that stands on its own, that is related to but not directly tied to a particular place in the text, should be tagged using the <boxed-text> element.

Model Information

Content Model

<!ELEMENT  fn           %fn-model;                                   >


Any one of:

This element may be contained in:

<aff> Affiliation; <article-title> Article Title; <attrib> Attribution; <bold> Bold; <chem-struct> Chemical Structure (Display); <def-head> Definition List: Definition Head; <italic> Italic; <monospace> Monospace Text (Typewriter Text); <named-content> Named Special (Subject) Content; <overline> Overline; <p> Paragraph; <product> Product Information; <related-article> Related Article Information; <sc> Small Caps; <speaker> Speaker; <strike> Strike Through; <sub> Subscript; <subtitle> Article Subtitle; <sup> Superscript; <table-wrap-foot> Table Wrapper Footer; <td> Table Data Cell (XHTML table model); <term> Definition List: Term; <term-head> Definition List: Term Head; <th> Table Header Cell (XHTML table model); <title> Title; <trans-title> Translated Title; <underline> Underline

Tagged Examples

Example 1

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 
<td>No comprehensive care (3 trials)</td> 
<td align="center">37/411</td> 
<td align="center">&amp;#x2002;66/403</td> 
<td align="center">0.50<xref ref-type="table-fn" rid="TF1-151"></xref>
(0.26 to 0.96)</td> 
<fn id="TF1-150"><p>Data not available for 1 trial.</p></fn> 
<fn id="TF1-151"><p>P&amp;#x003C;0.05 (random effects model).</p></fn>

Example 2

In an article’s title:

<article-title>Adaptins<fn id="FN206">
<p>Online version of this essay contains
supplemental tabular material.</p>
<subtitle>The Final Recount</subtitle>
<contrib contrib-type="editor">
<given-names>Thomas D.</given-names></name>
<p>This essay constitutes the second article in the
&#x201C;Genome Annotation Series&#x201D; 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&#x2013;794).</p>