Summary

Identifying notes and placing them at logical breaks in the text minimizes their impact on the reading of the primary text.

Techniques

Examples

Example 1 — Footnotes in the body

Note that the doc-footnote role is used on an aside. Do not apply it to list items, as it will break the lists they belong to. Use doc-endnote to group notes into lists.

<p>
   In that
   year<a href="#ft2f" role="doc-noteref" epub:type="noteref">2</a>
   there were 67 mills engaged in the manufacture of
   cotton goods …
</p>

<aside id="ft2f" role="doc-footnote" epub:type="footnote">
   <p>
     2 The manufacturing statistics for 1900 which
     follow are not those given in the Twelfth
     Census, but are taken from the 
     <em>Census of Manufactures</em> …
   </p>
</aside>

<p>…</p>
Example 2 — Grouped notes at the end of a section/work

Note that the doc-endnotes and doc-endnote roles are used on the section and list items, respectively. The doc-endnotes role cannot be used on lists.

<section epub:type="endnotes" role="doc-endnotes"> 
   <h2>End Notes</h2>
   <ol>
     <li role="doc-endnote">
       According to the usual nomenclature, the
       branch flowing S.W. is called the Chattooga;
       this unites with the Tallulah to form the 
       Tugaloo, which …
     </li>
     …
   </ol>   
</section>
Example 3 — CSS to superscript note references

Note the use of the CSS ~= selector. If the roleattribute contains more than one value (i.e., a fallback role) this selector ensures a match will still occur. See attribute selectors in CSS 2 for more information.

a[role~='doc-noteref'] {
   vertical-align: super;
   line-height: normal;
   font-size: smaller;
}
Example 4 — Backlink from footnote

The backlink precedes the note text so that the user will be aware that such a link is available.

<aside role="doc-footnote">
   <p><a href="#ref" role="doc-backlink" title="Go to note reference">1.</a> According to the usual nomenclature, the …</p>
</aside>
Example 5 — Backlink from endnote

The backlink follows the note text to avoid any conflicts with automatic list numbering. The link is placed in its own element so that the user does not have to listen to the note before being able to activate it.

<li role="doc-endnote">
   <p>According to the usual nomenclature, the …</p>
   <p><a href="#ref" role="doc-backlink">Go to note reference</a></p>
</li>

Explanation

Footnotes and endnotes have proven an impediment to the reading experience because they interrupt the narrative flow. When footnotes are placed immediately following the paragraph that references them, users had to manually navigate past them each time, as they are typically indistinguishable from text content. Even endnotes, grouped at the end of the section, require the user to jump past them.

The HTML5 structural elements, together with the role attribute, provide a means of alleviating this problem, by clearly marking individual footnotes and endnotes, and sections of them. Not only does this allow accessible user agents to ignore the notes except when followed from their referents, but it allows any user agent to handle them more intelligently (e.g., as pop-ups).

Notes placed within the primary narrative should be tagged using the HTML5 aside element (see Example 1). This usage ensures that even if their semantics are not recognized, the notes will still be treated as secondary content due the nature of the HTML5 aside element.

Notes that are grouped at the end of a section do not need to be individually tagged as aside, but should be grouped using the appropriate footnotes or endnotes semantic (see Example 2). Lists are an effective means of representing groups of notes in these sections, as they allow users to move through them more effectively (e.g., each list item number will typically correspond sequentially to the contained note number, and users should have the ability to jump through more than one list item at a time when there are many notes).

Notes in Tables

If notes occur in a table, avoid placing them in a tfoot element, as it is intended for summaries of the columns. Footnotes can follow the table or can be grouped together with the table inside a figure. See the Tables section for an example.

Note References

Note references must be tagged using the HTML5 a element.

Do not use the sup element to superscript note references, as it is redundant presentational tagging. The CSS vertical-align property can be set to superscript the a elements (see Example 3).

Back Referencing

Although not specifically required to be accessible, it is good practice to backlink groups of notes to their referent locations in the text (see Example 4). If a user is surveying the notes, backlinks will allow them to quickly find the text the note refers to.

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