HTML and XHTML.
This failure relates to:
Screen reader support for navigating data tables with and without correct header mark-up varies.
JAWS has many keyboard shortcuts to navigate between data cells and read associated header information. The default behavior for JAWS with version 12 and later is to read only headers that have been properly marked as headers by the author of a table.
Window-Eyes has different customization options for row and column announcement: both column and row headers, just column or just row headers, just the header that changes, and even defining a specific row or column to compensate for missing markup. For example, "R 1, C 1" would be the first row and column of the table.
VoiceOver announces column headers when traversing a table horizontally. It does not currently read row headers even when they are marked up, though it will identify the row number.
NVDA has shortcuts for moving between table cells horizontally or vertically, reading the header that changes when navigating. When moving through data cells vertically, NVDA (2011.3 with Firefox 11) will read the first cell of a row even when it is not marked up as header. However, when moving through data cells horizontally, it will only read out the cells in the first row as column headers if they are correctly marked up.
This failure occurs when data tables do not use header elements (th) or other appropriate table mark-up (the scope attribute, headers and id or the ARIA roles columnheader / rowheader) to make the headers programatically determinable from within table content. Making headers programmatically determinable is especially important when data cells are only intelligible together with header information. When screen reader users navigate through the table content horizontally or vertically, the headers that change can be read out to provide the necessary context for the information in the data cells.
This table does not use th (or other appropriate header markup) for headers. Instead, it uses td elements for all cells. Navigating cell by cell, screen readers will often fail to read the header cells associated with content.
Example Code:
<table>
<tr>
<td>Name</td>
<td>Age</td>
<td>Height (cm)</td>
<td>Weight (kg)</td>
</tr>
<tr>
<td>Linda</td>
<td>33</th>
<td>169</th>
<td>59</th>
</tr>
<tr>
<td>Jack</td>
<td>37</td>
<td>184</td>
<td>74</td>
</tr>
<tr>
<td>Kira</td>
<td>8</td>
<td>120</td>
<td>21</td>
</tr>
<tr>
<td>Daniel</td>
<td>3</td>
<td>79</td>
<td>14</td>
</tr>
</table>
For all data tables, check if table headers can be correctly programmatically determined by use of one of the following mechanisms:
headers marked up with table header (th) elements, optionally with scope attributes
headers and data cells associated using headers and id attributes
headers marked up as td elements with the scope attribute
headers marked up with ARIA role attributes rowheader or columnheader
If all checks #1 - #4 are false, then this failure condition applies and the content fails the Success Criterion.
Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.