<fn>
- A footnote with no specified @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, such as at the bottom of the immediate printed page or at the end of an online article. If a character is specified in the @callout attribute for the footnote, that character is used as the superscript "callout" that is linked to the placement of the footnote.
- A footnote that specifies 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".
- 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 create
a new
copy of another topic's footnote within the local topic where it will then follow
these behaviors:
- If you use
<fn conref="file.dita#topic/thatid"></fn>all by itself, the result will be the same as the single-use footnote entered literally in the same location. That is, it creates a local copy of the footnote with no local @id attribute, so it uses the behavior from the first bullet above. - If you use
<fn conref="file.dita#topic/thatid" id="thisid"></fn>, followed by<xref href="#thistopic/thisid" type="fn"/>, the result will be the same as the use-by-reference model described in the second bullet. That is, the <fn> element creates a local copy of the footnote with an id of "thisid"; that local copy is then referenced by the <xref> element.
- If you use
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
----- [bottom of page] -----------------------------------------------------------------
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.