Tables

WCAG Criteria

Techniques

H43:Using id and headers attributes to associate data cells with header cells in data tables

Description

The objective of this technique is to associate each data cell (in a data table) with the appropriate headers. This technique adds a headers attribute to each data cell (td element). It also adds an id attribute to any cell used as a header for other cells. The headers attribute of a cell contains a list of the id attributes of the associated header cells. If there is more than one id, they are separated by spaces.

This technique is used when data cells are associated with more than one row and/or one column header. This allows screen readers to speak the headers associated with each data cell when the relationships are too complex to be identified using the th element alone or the th element with the scope attribute. Using this technique also makes these complex relationships perceivable when the presentation format changes.

This technique is not recommended for layout tables since its use implies a relationship between cells that is not meaningful when tables are used for layout.

Examples

Table with multiple rows of headers

<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 e1">15%</td>
    <td headers="e e2">15%</td>
    <td headers="e ef">20%</td>
    <td headers="p p1">10%</td>
    <td headers="p p2">10%</td>
    <td headers="p pf">15%</td>
   </tr>
 </table>

Homework	Exams			Projects
Homework	1	2	Final	1	2	Final
15%	15%	15%	20%	10%	10%	15%