F90: Failure of Success Criterion 1.3.1 for incorrectly associating table headers and content via the headers and id attributes

One way for authors to explicitly associate header cells to data cells is by using the id and headers attributes. These allow the author to associate multiple header cells to a particular data cell, which can be necessary when complex data tables with more than one level of heading are used.

The failure occurs when the relationship between data cells and corresponding header cells cannot be programmatically determined correctly because the association of id and headers attributes is faulty. This can happen, for example, when copying code within tables and forgetting to update the code.

Examples

Failure Example 1: Table content not correctly associated to nested headers

In this example, nested headers are used, but the content cells are incorrectly associated via the id and headers attributes. All cells reference top level header 'Exams' (id="e") - this isn't correct for the last three columns which should reference header 'Projects'. Also, the referencing of the second level column headers has been accidentally swapped even though in this example this makes no difference as the contents (1, 2, Final) are repeated.

Example Code:


<table>
   <tr>
     <th rowspan="2" id="h">Homework</th>
     <th colspan="3" id="e">Exams</th>
     <th colspan="3" id="p">Projects</th>
   </tr>
   <tr>
     <th id="e1" headers="e">1</th>
     <th id="e2" headers="e">2</th>
     <th id="ef" headers="e">Final</th>
     <th id="p1" headers="p">1</th>
     <th id="p2" headers="p">2</th>
     <th id="pf" headers="p">Final</th>
   </tr>
   <tr>
     <td headers="h">15%</td>       
     <td headers="e p1">15%</td>  // should be "e e1"
     <td headers="e p2">15%</td>  // should be "e e2"
     <td headers="e pf">20%</td>  // should be "e ef"
     <td headers="e e1">10%</td>  // should be "p p1"
     <td headers="e e2">10%</td>  // should be "p p2"
     <td headers="e ef">15%</td>  // should be "p pf"
   </tr>
</table>

Failure example of table incorrectly associating headers attributes in table content (td) to table headers (th).

Related Techniques

Tests

Procedure

For tables that associate data cells to header cells via the id and headers attributes, check that the programmatic association is correct.

Expected Results

If check #1 is false, then this failure condition applies and the content fails the Success Criterion.

Techniques are Informative

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.