fn

Use footnote (<fn>) to annotate text with notes that are not appropriate for inclusion in line or to indicate the source for facts or other material used in the text.

Footnote content is always skipped at the place where it was entered, and reproduced elsewhere, according to these rules:

A footnote with no given id attribute is a single-use footnote. Upon output, it generates a number as a superscript "callout" that is linked to the placement of the footnote, usually at the bottom of the immediate printed page or at the end of the Web article. Subsequent footnotes in the same topic will have the next number in sequence for their callouts. If you enter a particular character in the callout attribute for the footnote, that character will be used as the superscript "callout" that is linked to the placement of the footnote.
A footnote entered with an id attribute is a use-by-reference footnote. Upon output, it does not appear anywhere unless it has been referenced using an <xref> with the type attribute set to "fn". The same callout behaviors will apply.
Ordinarily, a footnote in one topic can't be referenced in another topic. The previous behaviors are local to each topic. But by using the <conref> mechanism, you can instance another topic's footnote into the local topic where it will then follow those behaviors:
- If you use <fn conref="thatid"></fn> all by itself, the result will be the same as the single-use footnote entered literally in the same location.
- If you use <fn conref="thatid" id="thisid"></fn>, then <xref href="thisid" type="fn"/>, the result will be the same as the use-by-reference model described before.

Example

The first example uses a simple fn element, with no ID and no callout attribute. In that case, markup such as the following:

The memory storage capacity of the computer is 
2 GB<fn>A GB (gigabyte) is equal to 
1000 million bytes</fn> with error correcting support.

may produce output similar to the following:

The memory storage capacity of the computer is 2 GB¹ with error correcting support.

......

¹ A GB (gigabyte) is equal to 1000 million bytes

----- [bottom of page] -----------------------------------------------------------------

The second example uses a callout attribute. It is marked up as follows:

The memory storage capacity of the computer is 
2 GB<fn callout="#">A GB (gigabyte) is equal to 
1000 million bytes</fn> with error correcting support.

That DITA markup may produce output similar to the following:

The memory storage capacity of the computer is 2 GB^# with error correcting support.

......

^# A GB (gigabyte) is equal to 1000 million bytes

----- [bottom of page] -----------------------------------------------------------------

The third example uses an ID on a footnote, and then references that ID multiple times. The DITA markup looks like this:

I like pets. <fn id="reuse-fn">This is the name of an animal.</fn>
At my house, I have a dog<xref href="#topic/reuse-fn"/>, a
cat<xref href="#topic/reuse-fn"/>, and a llama<xref href="topic/reuse-fn"/>.

and may produce output similar to the following:

I like pets. At my house, I have a dog¹, a cat¹, and a llama¹.

......

¹This is the name of an animal.

----- [bottom of page] -----------------------------------------------------------------

Note: Footnote support may vary between different output types, depending on conventions and capabilities. For example, PDF output may lack support for the callout attribute, or footnotes may be collected as endnotes for certain types of Web publications.

Contains

Doctype	Content model
ditabase, topic, task, reference, concept	( text data or ph or codeph or synph or filepath or msgph or userinput or systemoutput or b or u or i or tt or sup or sub or uicontrol or menucascade or term or xref or cite or q or boolean or state or keyword or option or parmname or apiname or cmdname or msgnum or varname or wintitle or tm or p or lq or note or dl or parml or ul or ol or sl or pre or codeblock or msgblock or screen or lines or fig or syntaxdiagram or imagemap or image or object or data or data-about or foreign or unknown) (any number)
map, bookmap	( text data or ph or term or xref or cite or q or boolean or state or keyword or tm or p or lq or note or dl or ul or ol or sl or pre or lines or fig or image or object or data or data-about or foreign or unknown) (any number)

Doctype

Content model

ditabase, topic, task, reference, concept

( text data or ph or codeph or synph or filepath or msgph or userinput or systemoutput or b or u or i or tt or sup or sub or uicontrol or menucascade or term or xref or cite or q or boolean or state or keyword or option or parmname or apiname or cmdname or msgnum or varname or wintitle or tm or p or lq or note or dl or parml or ul or ol or sl or pre or codeblock or msgblock or screen or lines or fig or syntaxdiagram or imagemap or image or object or data or data-about or foreign or unknown) (any number)

map, bookmap

( text data or ph or term or xref or cite or q or boolean or state or keyword or tm or p or lq or note or dl or ul or ol or sl or pre or lines or fig or image or object or data or data-about or foreign or unknown) (any number)

Contained by

Doctype	Parents
bookmap	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, organizationname
map	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry
ditabase	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, prereq, context, cmd, info, tutorialinfo, stepxmp, choice, choptionhd, chdeschd, choption, chdesc, stepresult, result, postreq, refsyn, proptypehd, propvaluehd, propdeschd, proptype, propvalue, glossdef, screen, codeblock, pd
topic	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, screen, codeblock, pd
task	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, prereq, context, cmd, info, tutorialinfo, stepxmp, choice, choptionhd, chdeschd, choption, chdesc, stepresult, result, postreq, screen, codeblock, pd
concept	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, screen, codeblock, pd
reference	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, refsyn, proptypehd, propvaluehd, propdeschd, proptype, propvalue, screen, codeblock, pd
glossary	p, note, lq, sli, li, itemgroup, dd, fig, figgroup, pre, lines, ph, stentry, entry, abstract, section, example, glossdef, screen, codeblock, pd

Inheritance:

- topic/fn

Attributes

Name	Description	Data Type	Default Value	Required?
callout	Specifies what character is used for the footnote link, for example a number or an alpha character. The attribute may also specify a short string of characters. When no callout value is specified, footnotes are numbered.	CDATA	#IMPLIED	No
%univ-atts; (%select-atts;, %id-atts;, %localization-atts;)	A set of related attributes, described at %univ-atts;	parameter entity	PE not applicable	Not applicable
%global-atts; (xtrf, xtrc)	A set of related attributes, described at %global-atts;	parameter entity	PE not applicable	Not applicable
class, outputclass	Common attributes described in Other common DITA attributes.