Making footnotes accessible in PDFs (and other PDF accessibility fixes)
1 January 2010
Summary
Many people visit this site looking for information on making footnotes accessible in PDFs. In response, this article explains how to do so, using a technique that can also be applied to fix many other common PDF accessibility problems.
The problem defined
Normally the eye can jump from a footnote reference (often a superscript number or letter) to the footnote itself and back with ease, in the jargon, "randomly accessing" a page. By contrast, the experience of screen reader or other assistive technology users is a little like viewing a document through a thin tube, one word at a time, and in a linear manner only. It is not possible to jump from place to place randomly as a sighted person might. For this reason, footnotes need special treatment to ensure that they are accessible.
Editorial considerations
Before getting into the detail of how to fix PDF footnotes it is important to note that effective web copy is, generally speaking, short and to the point. But footnotes are the opposite, they provide fine detail. Leaving them out altogether or working them into the main body of content can improve readability significantly. They should be used as sparingly as possible.
Creating footnotes in Word 2007
If you are using Microsoft Word 2007 to create your source document you won’t have a problem – it just works. Insert your footnotes in the normal way in Word and then generate a tagged PDF. Any footnote text will be read out by a screen reader immediately after its reference as if it were inserted inline rather than positioned at the bottom of the page.
However, if you are using any other program for your source document you will need to edit the tag tree of the PDF (using Acrobat Professional) in order to make any footnotes accessible.
Creating footnotes in Word 2003
When you create a footnote in Word 2003 and then generate a tagged PDF, the footnote reference is automatically linked to the footnote. Using a screen reader the link can usually be followed easily enough and the footnote read.
However, there are still problems. Firstly, it is often hard for screen reader users to tell where a footnote ends, and therefore all too easy to continue into the next page (or the next footnote) without realising it. Secondly, even if it is possible to determine where the footnote ends, there is no easy way of getting back to where you came from in the main body of text. Either situation is likely to be highly confusing.
Use a destination?
It is possible to use a PDF "destination" (an in-page link much like an HTML anchor) to create a link from the footnote back to its reference point. However, doing so creates two new problems.
- Sighted users don't need the additional link text and may well be confused by it.
- Using destinations often causes unexpected changes in page zoom settings that can be disorientating for sighted users.
A much better solution is to use Acrobat's highly versatile alternate text property, available via its tag tree.
Editing the tag tree
Changes to a PDF's tag tree affect only the output of the document that screen reader users receive (or the contents of any text only (.txt) version); they have no impact on the document as viewed on screen or when printed.
The process
The following tag tree edits will: remove the link from the footnote reference to the footnote; remove the footnote text from the bottom of the page; re-insert the footnote text in the same position as its reference. This will enable screen reader users to hear the footnote text in its correct context in the same way that they would with a Word 2007-generated document. For sighted users, of course, the footnote will remain at the foot of the page.
The method
- Open the PDF in Acrobat Professional.
- Highlight the footnote text and copy it (Ctrl + C).
- Open the tags panel () and locate the
<Link>tag associated with the footnote reference. The<Link>tag will have two child tags – a content container for the footnote reference and aLink – OBJRtag (see figure). - Delete the
Link – OBJRtag. This tag just makes the link screen reader accessible, but because we about to delete the link, theLink – OBJRtag is not needed. - Click three times slowly inside the
<Link>tag to edit it. Change it to a<Span>tag by deleting the word "Link" and typing "Span" in its place. - Right-click the new
<Span>tag and from the context menu select . Paste the footnote text into the Alternate Text field of the TouchUp Properties dialogue box. - In order to make it clear that this is a note rather than a continuation of the main text, type "Note:" before the footnote text and "(end of note)." after it. Close the TouchUp Properties dialogue box.
- In the tag tree, locate and delete the original footnote tag so that it isn't read a second time at the foot of the page.
The result
As alternative text takes precedence over "normal" content, the footnote will now be read by screen readers instead of the reference and in the right place. Screen reader users will get at least as good as an experience as they would from PDF footnotes generated in Word 2007. Arguably the experience will be better given the explicit identification of the note via the additional "note" and "(end of note)" text, as well as the absence of potentially confusing footnote reference numbers.
Creating footnotes InDesign
As of this writing, it is not possible to tag a footnote in InDesign (CS4). Attempting to do so generates a pop-up stating that "tagging of footnote text is not supported."
InDesign originated footnotes will need to be
fixed as above in Acrobat Professional except there
will be no Link OBJR or <Link> tags.
The footnote reference is likely to be contained already
in a <Span> tag, but if not, edit
it as described above.
Fixing other common problems
The above explains specifically how to make PDF footnotes accessible. However, as mentioned at the outset, the same technique can be used to fix a host of other PDF accessibility problems including incorrectly voiced abbreviations and acronyms, incomprehensible URLS, and much more. Virtually any text based element that isn't working properly (for whatever reason) can be replaced with alternate text using this method.
Testing
Testing for this article was with JAWS (9), Window-Eyes (7) and NVDA screen readers.
Ted Page Director PWS
PDF accessibility services
For further information please see our Accessible PDFs or PDF accessibility training pages, or contact us on 01932 355 222 or 07918 952 874.
RSS (subscribe)