Technique H73:Using the summary attribute of the table element to give an overview of data tables

Applicability

HTML 4.01, XHTML 1.x

This technique relates to 1.3.1: Info and Relationships (Sufficient when used with Making information and relationships conveyed through presentation programmatically determinable using the following techniques: ).

Description

The objective of this technique is to provide a brief overview of how data has been organized into a table or a brief explanation of how to navigate the table. The summary attribute of the table element makes this information available to people who use screen readers; the information is not displayed visually.

The summary is useful when the table has a complex structure (for example, when there are several sets of row or column headers, or when there are multiple groups of columns or rows). The summary may also be helpful for simple data tables that contain many columns or rows of data.

The summary attribute may be used whether or not the table includes a caption element. If both are used, the summary should not duplicate the caption.

In HTML5 the summary attribute is obsolete. Assistive technologies may or may not continue to support the attribute. Authors should consider alternatives and only use with caution.

Although WCAG 2 does not prohibit the use of layout tables, CSS-based layouts are recommended in order to retain the defined semantic meaning of the HTML table elements and to conform to the coding practice of separating presentation from content. However, if a layout table is used, then the summary attribute is not used or is null. The purpose of a layout table is simply to control the placement of content; the table itself is “transparent" to the user. A summary would “break" this transparency by calling attention to the table. A null summary (summary="") on layout tables is acceptable. See F46 for details.

Examples

Example 1: A data table with a `summary` but no `caption`

This example shows a bus schedule. The route number and direction are included in the summary along with information on how to use the schedule.

<table summary="Schedule for Route 7 going downtown. Service begins 
at 4:00 AM and ends at midnight. Intersections are listed in the top row. 
Find the intersection closest to your starting point or destination, then read 
down that column to find out what time the bus leaves that intersection.">
  <tr>
    <th scope="col">State & First</th>
    <th scope="col">State & Sixth</th>
    <th scope="col">State & Fifteenth</th>
    <th scope="col">Fifteenth & Morrison</th>
  </tr>
  <tr>
    <td>4:00</td>
    <td>4:05</td>
    <td>4:11</td>
    <td>4:19</td>
  </tr>
  …
</table>

Example 2: A data table with both a `summary` and a `caption`

In this example both a summary attribute and a caption element are used. The caption identifies the bus route. The summary helps users who are blind understand how to use the schedule. Screen readers read the caption, followed by the summary.

<table summary="Intersections are listed in row 1. 
Find the intersection closest to your starting point 
or destination, then read down that column to find 
out what time the bus leaves that intersection.  
Service begins at 4:00 AM and ends at midnight.">
  <caption>Route 7 Downtown (Weekdays)</caption>
…
</table>

Other sources

No endorsement implied.

HTML 4.01 summary attribute

Tests

Procedure

For each data table:

If a summary is present, check that the summary attribute describes the table's organization or explains how to use the table
If both a summary attribute and a caption element are present for the data table, check that the summary does not duplicate the caption.

Expected Results

#1 and #2 are true.