©2006 IBM Corporation Accessibility Web Coding Techniques

©2006 IBM Corporation

Accessibility Web Coding Techniques


Learning objectives.

By the end of this training session, you should be able to:

Identify standards and guidelines that govern accessibility.Explain checklist items from accessibility guidelines.Locate accessibility resources.


Accessibility laws and regulations


Standards and legislation appearing worldwide.

United StatesSection 508 of Rehabilitation Act requires federal

agencies to purchase electronic and information technology that is accessible to people with disabilities.

States are enacting similar legislation.

Litigation and legal inquiries triggered by legislation in the United States

State of Arkansas: New state accounting system built on SAP technology is inaccessible to blind employees.

Commonwealth of Pennsylvania: Web portal inaccessible to blind. SAP software is the source of the problem; IBM is providing integration services.

Metro Atlanta Mass Transit: Web site schedule and services inaccessible.Southwest Airline: Reservations and ticketing are inaccessible.Connecticut: Attorney General’s office investigates Web-based tax filing services.Bank of America: inaccessible Web sites and A TMs.America Online: Software incompatible with screen readers.

CanadaCanadian Human Rights ActOntarians with Disabilities Act – 2001Common Look & Feel Web guidelines – 2001

EuropeMany countries have enacted legislation or national standards:

UK – Web accessibility, 2002Germany – Barrier Free Decree, 2002 Italy – ICT accessibility & government procurement, 2004Switzerland – Public sector Web accessibility, 2004European Union – Procurement of accessible I T, 2004Spain – Accessibility for computer platforms, 1998 Ireland – I T accessibility guidelines, 2002Netherlands – Web accessibility, 2003Sweden – Guidelines for computer accessibility, 1998

ChinaLaw of the PRC on the Protection of

Disabled Persons – Provisions on employment, public services, transportation, and legal sanctions, 1991

JapanJIS standards

Australia / New Zealand Disability Discrimination Act passed – 1996 Australian Bankers’ Association endorsed e-

commerce standards – 2000 Australian Communications Industry Forum's

(ACIF) Guidelines – 2001


Accessibility standards are not all the same.

USSection

508

W3C/Web Accessibility Initiative (WAI) AccessibilityGuidelines


W3C/WAI is for the Web only; Section 508 covers all electronic and information technology.

Section 508 W3C Web AccessibilityInitiative

Software 1194.21 Software applications and operating systems

ATAG: Authoring tools UAAG: User agent

Web Content 1194.22 Internet and intranet content and applications

WCAG: Web content

Printers, Copiers, Kiosks, etc. 1194.25 Self-contained closed products

Computer systems 1194.26 Desktop and portable computers

Documentation 1194.41 Information, documentation, and support

Telecommunications Products 1194.23 Telecommunications products

Video & Multimedia Products 1194.24 Video and multimedia products

Functional Performance Criteria

1194.31 Functional performance criteria


508 Web guidelines are different from W3C WCAG priority 1s.508 Web Accessibility partSection 1194.22 Paragraphs

Web Content Accessibility Guidelines (WCAG 1.0)Priority 1 & 2s

Identical (Declared in 508 preamble)

a. Alternatives for non-textb. Multimedia

c. Color independent d. Style sheets not requirede. Server-side image mapf. Client-side image mapg. Column and row headingsh. Complex tablesi. Titles for framesj. Avoid flickerk. Text-only if necessary

1.1 p1 Alternatives for non-text elements 1.4 p1 Synchronized captions and descriptions 1.3 p1 Provide auditory description of video 2.1 p1 Color independent 6.1 p1 Style sheets not required 1.2 p1 Server-side image map 9.1 p1 Client-side image map 5.1 p1 Column and row headings 5.2 p1 Complex tables12.1 p1 Titles for frame 7.1 p1 Avoid flicker11.4 p1 Text-only if necessary 6.2 p1 Update dynamic content equivalents

Different l. Accessible JavaScript OKm. Applets, plug-ins, and other OK if 508 software compliant n. Electronic forms

o. Skip navigation linksp. Timed responses

6.3 p1 Turning off scripts required (p2 otherwise)6.3 p1 Turning off applets/plug-ins required (p2 otherwise)

10.2 p2 Position labels on forms12.4 p2 Explicitly label form controls

13.6 p3 Group and provide method to skip

Additional W3C Priority 1s and 2s

4.1 p1 Identify changes in language (rare access issue)14.1 p1 Clearest and simplest language appropriate for site (subjective)and an additional 28 priority 2s


Most additional WCAG priority 2 requirements increase usability; many are solved by browser + assistive technology.

There are 23 additional priority 2 requirements shown on the next two charts. Section 508 Web Accessibility Section 1194.22. Paragraphs a

through p do NOT map to any of these W3C WCAG priority 2s.

Web Content Accessibility Guidelines (WCAG 1.0) Priority 2's

Impact to developer Workaround supported in A T or browsers

2.2 Background and foreground contrast M Yes

3.1 Use markup when appropriate (i.e., SMIL) H

3.2 Validate markup L Yes

3.3 Use style sheets to control layout/presentation H Yes

3.4 Use relative sizes H Yes

3.5 Use heading levels in document structure M Yes

3.6 Use list markup correctly M

3.7 Use quotation correctly L

5.3 Don't use layout tables that don't linearize H Yes

5.4 Don't use table markup in layout tables L

7.2 Avoid blinking M Yes

7.3 Avoid moving content M Yes

7.4 Don't auto refresh M Yes

7.5 Don't auto redirect M Yes


Most additional WCAG priority 2 requirements increase usability; many are solved by browser + assistive technology.

Web Content Accessibility Guidelines (WCAG 1.0) Priority 2's

Impact to developer

Workaround supported in A T or browsers

10.1 Don't spawn windows without notifying user M Yes

11.1 Use W3C technologies H Yes

11.2 Avoid deprecated W3C features M Yes

12.2 Describe purpose of frames M

12.3 Divide information into groups H Yes

13.1 Clearly identify target of link M

13.2 Add metadata L

13.3 Add site map and TOC L

13.4 Use consistent navigation M


Text equivalents for images, audio, and multimedia are key for Web checklist.

IBM Web Accessibility Checklist:http://www-03.ibm.com/able/guidelines/web/accessweb.html

Text equivalents Images and animations Image maps Graphs and charts Audio and multimedia

Accessible interfaces Scripts must be keyboard accessible. Applets and plug-ins must meet software (or Java TM) accessibility checklist. Forms must be usable with assistive technology.

Skip navigation Provide a method for allowing the user to skip over navigation links to the main content.

Frames Provide a title for each frame element and frame page. Provide accessible source for each frame.

Tables Use TH to mark up row and column header in data tables. Associate data cells with header cells in complex data tables.

CSS (Cascading Style Sheets) Pages should be readable without requiring associated style sheets.

Color and Contrast Ensure all information conveyed with color is also conveyed in the absence of color.

Blinking, Flickering Avoid causing content to blink, move, or flicker.

Timed Responses Functions that have a time limit on the user's response must provide a way for the user to ask for more time.

Text-only Page If accessibility cannot be achieved any other way, provide a text-only version of the page.


Software requirements drive the way that code is implemented.

IBM Software Checklist: http://www-03.ibm.com/able/guidelines/software/accesssoftware.html

Keyboard Access Provide keyboard equivalents for all actions.Do not interfere with keyboard accessibility features built into the operating systems.

Object Information

Provide visual keyboard focus programmatically exposed to assistive technology.Provide semantic information about user interface objects, including text for images.Associate labels with controls, objects, icons, and images. Use images consistently.Electronic forms must be usable with assistive technology.

Sounds & Multimedia

Provide an option to display a visual cue for all audio alerts.Provide accessible alternatives to significant audio and video.Provide an option to adjust the volume.

Display Provide text through standard system function calls or through an API that supports interaction with assistive technology.

Use color as an enhancement, not as the only way to convey information.Support system settings for high contrast for all user interface controls and client area content.When color customization is supported, provide a variety of color selections capable of producing a

range of contrast levels.Inherit system settings for font, font size, and color for all user interface controls.Provide an option to display animation in a non-animated presentation mode.

Timing Provide an option to adjust the response times on timed instructions or allow the instructions to persist.

Avoid the use of blinking text, objects, or other elements.


Documentation and support services are also covered; testing is required.

Documentation Provide documentation in an accessible format.Provide documentation on all accessibility features, including

keyboard access.

Support Support services must accommodate the communication needs of end users with disabilities.

Test Verify accessibility using available tools: - Assessment tools - Assistive technology - Manual verification for some items


A closer look at some Web coding techniques – based on WCAG & Section 508 guidelines


Common Web accessibility issues.

Web feature Accessibility issue

Images Screen readers cannot read images without text equivalents.If null alt text is used for important links, the links are skipped and

the site is not accessible – even though it might pass an accessibility checker.

Navigation Screen readers read Web pages sequentially.If Web sites that use frames do not have meaningful frame titles,

users cannot easily move to the content they want to read.If Web sites do not use frames, users must listen to all navigation

links unless a “skip to main” link has been added.

Data tables Screen readers cannot read row and column headings if the headings have not been coded properly by the Web developer.

Missing header labels make the table impossible to understand.

Forms Screen readers cannot read text labels on form elements if the labels have not been coded properly by the Web developer.


Provide a text equivalent for every non-text element.

Alternate text (alt text)• Use alt=“text description” to provide text equivalents for images, graphs, charts.

• Use null alt text (alt=“”) if images are unimportant or redundant.

• Do not use alt=“” for image links unless the links are redundant.

• Do not use alt=“ ” to implement null alt text.

• Accessibility checkers check for the presence of alt=“text” or alt=“”.

Add alt text for all image links (input type=“image”).

<img src=“sam.gif”alt=“Sam”>

Correct alt text for spacer images:<img src= “spacer.gif” alt=“”>

Incorrect alt text:<img src=“spacer.gif” alt=“spacer.gif”>

Correct alt text:<input type=“image”name=“Go” src=go.gif alt=“Go”>

Incorrect use of null alt text:<input ytpe=“image”Name=“Go” src=“go.gif alt=“”>


Provide a method to skip repetitive navigation links.

Provide a way to skip over navigation links to quickly get to main content.• Screen readers read Web pages sequentially, so users have to listen to all navigation links on

the page before they hear the main content.

• A “skip to main” link enables screen reader users to skip navigation links on every page.

Correct coding for skip link using an image link:<a href="#navskip">

<img src="http://spacer.gif.gif" alt="skip to main content" width="10" height="33" border="0">

</a>

…

<a name="navskip"></a>

<p>This is the main content on the page.</p>

Skip navigation links cannot be tested using checking tools. You must listen to the Web page with assistive technology to hear the link and verify that it works.


Give frames names that facilitate frame identification and navigation.

Provide a meaningful title attribute for each FRAME element.• Meaningful titles (for example, “Main Content”, “Navigation”, or ”Logo”) aid navigation of the Web

site.

• Accessibility checkers check for the existence of the Frame title attribute; they do not check whether the title is meaningful.

Correct coding for FRAME elements:<frame title=“Navigation” src=“bp_left.html">

<frame title=“Logo” name=“top” src=“bp_header.html">

<frame title=“Main Content” src=“maincontent.html">

Incorrect coding for FRAME elements:<frame src=“bp_left.html">

<frame name="top" src=“bp_header.html“>

<frame title="body_center" src=“maincontent.html">


Screen readers read frame titles. Use the screen reader command to list the frames on the page.

Select the frame you want to read.

Accessible frame titles:

Inaccessible frame titles:


Use forms to allow people using A T to access the functionality required to complete and submit the form.

Most form elements (for example, text fields, checkboxes, and radio buttons) require explicit labels so the elements can be read by assistive technology.

• Associate text labels using the LABEL element and the for attribute.

• Proximity is not sufficient to help assistive technology “see” field labels.

• Accessibility checkers check for the presence of the LABEL element.

Correct coding of a text field for accessibility:• <label for=“search”> Search</label><br> <input name=“yourname” id=“search”>

Incorrect coding of a text field for accessibility:• Missing LABEL element: Search<br> <input name=“yourname”>

• Missing id tag: <label for=“search”> Search</label> <br> <input name=“yourname”>

• Incorrect id tag: <label for=“search”>Search</label> <br> <input name=“yourname” id=“mine”>

• Implicit LABEL: <label>Search</label><br> <input name=“yourname”>


Screen readers read form labels.

Locator feature – tells where am I?Text entry

Labeled Search for

Form 1

At 28% of page

List of links.

Controls reading with arrow keys.Search for [Text]

Read title attribute.


Define row and column headers for data tables.

Row and column headers must be defined so they can be spoken.• Use the TH element to mark up heading cells.

• Use the scope attribute to identify row or column headings.

• Use the headers and id attribute to identify row or column headings on complex tables that use rowspan or colspan.

• Accessibility checkers identify “possible” errors for tables because distinguishing between data and layout tables is difficult.

The CAPTION element associates a title with the table.* • <caption>Computer Science Job Openings - November 2005</caption>

The summary attribute provides additional information about the table.*• <table summary="Table that summarizes federal job openings by date">

*Recommended technique, not required by Section 508 guidelines.


Identify row and column headers using the scope attribute.

Inaccessible table headers<tr> <td> </td> <td>Percentage with any disability</td> <td>Number with any disability</td></tr><tr> <td>Population 5-15 years</td> <td>5.8</td> <td>2,614,919</td></tr><tr> <td>Population 16-64 years</td> <td>18.6</td> <td>33,153,211</td></tr>……

Accessible table headers using scope<tr> <td> </td> <th scope=“col”>Percentage with any disability</th> <th scope=“col”>Number with any disability</th></tr><tr> <th scope=“row”>Population 5-15 years</th> <td>5.8</td> <td>2,614,919</td></tr><tr> <th scope=“row”>Population 16-64 years</th> <td>18.6</td> <td>33,153,211</td></tr>……


Identify row and column headers using headers / id attributes.Inaccessible table headers:<table summary=“Job openings by positioncaption=“Technical Job Openings as of Nov 1, 2003”><tr> <td>Job Position</td> <td> Level</td> <td>Location</td> <td>Agency</td></tr>…….<tr> <td>Computer Scientist</td> <td>GS-17</td> <td>US-MS-Vicksburg</td> <td>Army Research Lab</td></tr><tr><td>Army Corps of Engineers</td></tr><tr> <td>US-MD-Prince George County</td> <td>Army Research Lab</td></tr>……

Accessible table headers using headers tag<table summary=“Job openings by positioncaption=“Technical Job Openings as of Nov 1, 2003”><tr> <th id=“col1”>Job Position</th> <th id=“col2”>Level</th> <th id=“col3”>Location</th> <th id=“col4”>Agency</th></tr>…..<tr> <th headers=“col1” id=“compsci”>Computer Scientist</th> <th headers=“col2” id=“gs17”>GS-17</th> <td headers=“compsci gs17 col3”>US-MS-VicksBurg</td> <td headers=“compsci gs17 col4”>Army Research Lab</td></tr><tr> <td headers=“compsci gs17 col4”>Army Corps of Engineers</td></tr>……


Screen readers read table headers.

Table Jump reading

• Reads the CAPTION element, which gives your table a title.

• Reads the summary attribute of the TABLE element, which describes the overall structure of a table.

Table Navigation reading

• Reads table headers.

• Use TH to identify row and column headers for simple data tables. Use the scope attribute on TH cells, if needed, to further clarify header and data cell relationships.

• Use the headers attribute on data cells and the id attribute on header cells to identify headers for complex data tables.


Listening to table headers with a screen reader.

Listening to the table without headers – response varies based on A T used:Matriculated Students. College of Education. 523

or

Matriculated Students. Undergraduate. 523

or

Matriculated Students. College of Education. Undergraduate. 523

Listening to the table with headers – consistent and correct results:Matriculated Students. In state. College of Education. Undergraduate. 523


Summary of Web accessibility techniques.

Web feature Accessibility technique

Images Use alt text for important images (alt=“your text”).Use null alt text for unimportant or redundant images (alt=“”).

Navigation Use a visible or invisible link to skip to main content.Use the frame title attribute to add a meaningful name to your frame.

Data tables Use the TH element to identify row and column headers.Use headers and id attributes to identify row and column headers in

complex tables.Use the scope attribute on tables that don’t use rowspan or colspan.

Forms Use the LABEL element to associate text labels with form elements.


Additional resources for learning about accessibility.

IBM Human Ability and Accessibility Center•http://www.ibm.com/able

IBM Human Ability and Accessibility Checklists and Techniques•http://www.ibm.com/able/guidelines

IBM Home Page Reader•Test instructions: http://www.ibm.com/able/guidelines/web/webhprtest.html

•Trial Download: http://www.ibm.com/able/solution_offerings/hpr.html

Guide to Section 508 Standards for Electronic and Information Technology•http://www.access-board.gov/sec508/guide/

Web accessibility tutorials•http://www.jimthatcher.com/webcourse1.htm

•http://www.webaim.org

•http://www.section508.gov

Documents

©2006 IBM Corporation Accessibility Web Coding Techniques