<fn>

The <fn> element is a footnote used to annotate text with notes that are inappropriate for inline inclusion. It is also used to indicate the source for facts or other material used in the text.

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

The details of footnote processing and styling are implementation and/or stylesheet dependent. For example, a tool that renders DITA as PDF might lack support for the @callout attribute, or footnotes might be collected as endnotes for certain types of publications.

Content models

See appendix for information about this element in OASIS document type shells.

Inheritance

- topic/fn

Example

The first example is of a single-use footnote. It 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.
might 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

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The second example is a single-use footnote that 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 might 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 is a use-by-reference footnote. It 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" type="fn"/>, a
cat<xref href="#topic/reuse-fn" type="fn"/>, and a 
llama<xref href="#topic/reuse-fn" type="fn"/>.
and might 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] -----------------------------------------------------------------

Attributes

The following attributes are available on this element: Universal attribute group, outputclass, and the attribute defined below.

@callout
Specifies what character is used for the footnote link, for example a number or an alpha character. The attribute can also specify a short string of characters. When no @callout value is specified, footnotes are typically numbered.
@datatype
Available for describing the type of data contained in the value attribute for this metadata element. The default value is the empty string "".