DRAFT DOCUMENT

This is a draft document supplied by the WCAG Techniques Task Force. It in no way represents a WCAG Working Group consensus or agreement and is provided for informational and discussion purposes only. The accessibility test listed below should not be construed as required for conformance with the proposed WCAG2.

HTML Test Suite for WCAG 2.0
Test 8 - A long description (`longdesc`) file is used for each `img` element that does not have Alt text and/or body text conveying the same information as the image.

W3C Editor's Draft 2005-08-11

Editors:: Chris Ridpath, ATRC, University Of Toronto; Jenae Andershonis, Microsoft Inc.

Abstract

This test case was created by the ATRC at the University Of Toronto. It should not be construed as required for conformance with the proposed WCAG2.

The complete list of tests may be found at http://www.w3.org/WAI/GL/WCAG20/tests/

Comments on this test may be made to the WCAG mailing list.

Status Of This Test

As part of the conformance test process, this test has a status of 'accepted'.

WCAG2 Guideline

Guideline: 1.1 - Provide text alternatives for all non-text content.
Success Criteria: 1. For all non-text content that is used to convey information, text alternatives identify the non-text content and convey the same information. For multimedia , provide a text-alternative that identifies the multimedia. Refer to guideline 1.2 for requirements for synchronized alternatives for multimedia. How to provide text alternatives for content that conveys information . (Informative)

Level 1

The WCAG2 has 3 priority levels for making Web content accessible. This test has a priority of 'Level 1'.

Techniques

The WCAG Working Group has created techniques that describe how Web content may be made accessible. The following techniques are related to this test:

Long descriptions of images

Prerequisite Tests

The following tests must be run before running this test. If any of the prerequisite tests fail then this test is invalid and should not be run.

All img elements have an alt attribute.

Test Process

Procedure

For each img element, view the associated image and Alt text.
View the text content of the content.
Check if there is a longdesc attribute for the img element.
Determine if the Alt text and body text convey the same information as the image.

Expected Results

A long description (longdesc) file is used for each img element that does not have Alt text and/or body text conveying the same information as the image.

Fail Instructions

Add a valid longdesc attribute or describe the image within the content.

Pass Instructions

Any accessibility check may be performed after this test.

Test Files

These test files contain examples of the accessibility problem detectable by this test. They may also contain more accessibility problems than the one described in this test. Please ignore any extraneous accessibility problems in these files.

8-1.html Will fail the test. (Image is not fully described in Alt text or content text and image is missing a longdesc attribute.)

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>OAC Testfile - Check #8 - Positive</title> </head> <body> <p><img src="chart.gif" alt="a complex chart" /></p> </body> </html>
8-2.html Will pass the test. (Image is not fully described in Alt text or content text but image has a longdesc attribute.)

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>OAC Testfile - Check #8 - Negative</title> </head> <body> <p><img src="chart.gif" alt="a complex chart" longdesc="chart.html"/></p> </body> </html>