See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.0 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.0.
HTML and XHTML
This failure relates to:
This document describes a failure that occurs when the tab order does not follow logical relationships and sequences in the content.
Focusable elements like links and form elements have a tabindex
attribute. The elements receive focus in ascending order of the value of the
tabindex attribute. When the values of the
tabindex attribute are assigned in a different order than the
relationships and sequences in the content, the tab order no longer follows
the relationships and sequences in the content.
One of the most common causes of this failure occurs when editing a page
where tabindex has been used. It is easy for the tab order and
the content order to fall out of correspondence when the content is edited
but the tabindex attributes are not updated to reflect the
changes to the content.
The following example incorrectly uses tabindex to specify an alternative tab order:
Example Code:
<ol>
<li><a href="main.html" tabindex="1">Homepage</a></li>
<li><a href="chapter1.html" tabindex="4">Chapter 1</a></li>
<li><a href="chapter2.html" tabindex="3">Chapter 2</a></li>
<li><a href="chapter3.html" tabindex="2">Chapter 3</a></li>
</ol>
If this list is navigated by the tab key, the list is navigated in the order Homepage, chapter 3, chapter 2, chapter 1, which does not follow the sequence in the content.
The tab order has been set explicitly in a Web page by providing
tabindex attributes for all fields. Later, the page
is modified to add a new field in the middle of the page, but the
author forgets to add a tabindex attribute to the new
field. As a result, the new field is at the end of the tab
order.
Resources are for information purposes only, no endorsement implied.
HTML 4.01 Tabbing navigation
If tabindex is used, check that the tab order
specified by the tabindex attributes follows
relationships in the content.
If check #1 is false, then this failure condition applies and content fails the Success Criterion.