Web Accessibility

Bernie D. Davenport & A. Craig DixonSeptember 26, 2007

Web Accessibility Defined

Web accessibility refers to making web resources utile for all users, regardless of disability.The cardinal rule of web accessibility is that all users must be able to use the parts of the site that are essential to its message and function.Making web sites accessible requires some knowledge of the various kinds of assistive technologies used by people with disabilities to access the Web.Making web sites accessible often has the beneficial side effect of adding ease of use or additional functionality for users without disabilities.

Types of Disabilities

Web Accessibility in Mind (WebAIM) defines five types of disabilities of which web designers should be cognizant.

VisualAuditoryMotorCognitiveSeizure

Visual Disabilities

Visual disabilities include blindness, low vision, and colorblindness.Low vision users may utilize screen magnifiers or high contrast color schemes in order to see the information on the page more clearly.Blind users may utilize screen reader technologies that audibly read the contents of the page to the user.Because some users may be colorblind, page designers should never use color alone to convey a piece of information.

Auditory Disabilities

Auditory disabilities include deafness and hardness of hearing.Audio content that is critical to the message or function of the web resource should be captioned or transcribed.Audio content should be clear and free from background noise so it can be easily perceived by users who are hard of hearing.

Motor Disabilities

Motor disabilities include limited range of motion, slowness of motor response, and lack of fine motor control. These disabilities may be the result of bone or neuromuscular diseases, broken bones, or amputation.Users with motor disabilities often find using the keyboard preferable to using the mouse. Care should be taken to ensure that all page functions can be performed independent of the user’s input device.Time-sensitive tasks should also be avoided. If time-sensitive tasks are necessary, the user must easily be able to request more time to complete the task.

Cognitive Disabilities

Cognitive disabilities include learning disabilities, high susceptibility to distraction, an inability to process large amounts of information, and short-term memory loss.Many of the design principles for dealing with cognitive disabilities overlap with general principles of good web design. For example, writing to the lowest reading level appropriate for the intended audience.Because a user’s reading level often affects the speed at which they can read and process information, scrolling or marquee text should be avoided. If scrolling or marquee text is used, mechanisms for controlling its speed should be utilized.Often, graphics, diagrams, tables, etc. are useful in addressing cognitive disabilities. Care must be taken to make these visual aides as simple and understandable as practical, and the designer must account for visually-impaired users when including these elements in the page’s design.

Seizure Disabilities

Some people are subject to photoepileptic seizures when viewing content that flashes, strobes, flickers, or blinks at a certain frequency.Content that blinks or flashes can also be distracting, making it a potential problem for those with cognitive disabilities as well. Because of this, blinking or flashing content should be avoided.If the content cannot be avoided, the user must be warned in advance about the presence of blinking or flashing content and possibility of triggering a seizure.

Accessibility Goals

WebAIM further defines four accessibility goals for web content. These are referred to by the acronym POUR.

PerceivableOperableUnderstandableRobust

Perceivability

Perceivability refers to the ability of a user to access critical content via one of the senses that he or she has sufficient use of.

For blind users, this could be audio perception.For deaf users, this could be visual perception.For deaf-blind users, this could be tactile perception via a Braille output device.

The most efficient way to achieve accessibility is to ensure that content is transformable from one form to another.

Text is the most transformable medium.Content must be separated from presentation.

Operability

Operability refers to the ability of a user to locate and interact with the critical content of the page.Some disabilities render users unable to use a mouse. Others make it preferable for the user to use a keyboard. Keyboard accessibility is one of the most crucial concepts in web accessibility.Efficient navigation is also a part of operability. Users should be able to skip parts of the page that are not relevant to them.

In this way, site indices and search functions are components of good operability.Proper heading structures and good organization of information and links is also important.

Understandability

Understandability refers to the user being able to process the content and respond accordingly.Use of appropriate reading level and use of supplemental charts, graphics, etc. are important aspects of understandability.Understandability is also important in complex, multi-step processes like filling out a form or placing an order.Consistent design can be a major boost to understandability. Users quickly learn where to find the elements of your site (navigation controls, branding information, etc.) and are able to focus their attention on the content itself.

Robustness

Robustness refers to the ability of the user to get a consistent experience from the web resource regardless of the technology used to access it.Designers should account for differences in operating systems, browsers, browser versions, and settings and ensure that the web resource behaves the same way in as many configurations as possible.Designers should only require users to download additional resources such as plug-ins when expressing the content in another way is not practical.The user’s connection speed plays a role in robustness as well. Tasks that require large downloads may be considered inaccessible for users that do not have broadband Internet connections.

World Wide Web Consortium (WC3)

Created in October 1994Mission – “…to lead the World Wide Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability.”450 member organizations worldwide

Developed the Web Accessibility Initiative (WAI) team

To promote a “high degree of usability for people with disabilities.”Developed Web Content Accessibility Guidelines

W3C Guidelines

Provides guidance on accessibility of Web sitesContain 14 Guidelines for accessibility designProvides Checkpoints for each GuidelineMakes pages more accessible to all users

Priorities and Conformance Levels

Priorities are assigned to each CheckpointPriority 1 = developer must satisfyPriority 2 = developer should satisfyPriority 3 = developer may satisfy

Conformance LevelsSingle-A = Priority 1 accessibleDouble-A = Priority 1 & 2 accessibleTriple-A = Priority 1,2, & 3 accessible

WC3 Guidelines

Why?To remove barriers from Web sites that prevent people with disabilities from accessing Web based informationTo remove barriers in the “user agents”

BrowsersMultimedia playersAssistive Technologies

W3C GuidelinesCommon Web Page Problems

Images without alternative textImage Maps or Hotspots without alternative textMisleading use of structural elements such as tablesUncaptioned AudioUn-described Video

Lack of alternative information for users who cannot access frames or scriptsTables that are difficult to decipher when linearizedPoor color contrasts and color choices

W3C Guidelines

The following section provides information concerning:The 14 W3C GuidelinesThe Related Checkpoints

Priority 1 P1 – Required by Jan 1, 2004Priority 2 P2 – Should IncorporatePriority 3 P3 – May Incorporate

W3C Guidelines

Guideline 1 of 14Provide equivalent alternatives to auditory and visual content

1.1 P1 – Provide a text equivalent for every non-text element. 1.2 P1 – Provide redundant text links for each active region of a server-side image map. 1.3 P1 – Provide an auditory description of the important information of a visual track.1.4 P1 – Synchronize alternatives of a visual track with the presentation.1.5 P3 – Provide redundant text links for each active region of a client-side image map.

W3C Guidelines

Guideline 2 of 14Don’t rely on Color alone

2.1 P1 – All information conveyed with color must also be available without color. 2.2 P2, P3 – All foreground and background color combinations must provide sufficient contrast when viewed on a black and white screen.

W3C Guidelines

Guideline 3 of 14Use markup and style sheets and do so properly

3.1 P2 – Use markup rather than images to convey information. 3.2 P2 – Validate to published formal grammars.3.3 P2 – Use style sheets to control layout and presentation3.4 P2 – Use relative rather than absolute units.3.5 P2 – Use Header elements to convey document structure.3.6 P2 – Mark up lists and list items properly.3.7 P2 –Mark up quotations.

W3C Guidelines

Guideline 4 of 14Clarify natural language used

4.1 P1 – Clearly identify changes in the documents natural language. 4.2 P3 – Specify the expansion of each abbreviation or acronym in a document where it first occurs. 4.3 P3 – Identify the primary natural language of a document.

W3C Guidelines

Guideline 5 of 14Create tables that transform gracefully

5.1 P1 – Identify row and column headers for data tables. 5.2 P1 – Use mark up to associate data cells and header cells. 5.3 P2 – Do not use table for layout unless they make sense when linearized.5.4 P2 – If a table is used for layout, do not use any structural markup for the purpose of visual formatting.5.5 P3 – Provide summaries for tables.5.6 P3 – Provide abbreviations for header labels.

W3C Guidelines

Guideline 6 of 14Ensure that pages featuring new technologies transform gracefully

6.1 P1 – Organize documents so that they may be read without style sheets. 6.2 P1 – Equivalents for dynamic content must be updated whenever the dynamic content changes. 6.3 P1 – Ensure that pages are usable when scripts, applets, etc are turned off or not supported.6.4 P2 – Ensure that event handlers are input device independent.6.5 P2 – Ensure that dynamic content is accessible or provide an alternative.

W3C Guidelines

Guideline 7 of 14Ensure user control of time-sensitive content changes

7.1 P1 – Avoid causing the screen to flicker. 7.2 P2 – Avoid causing the content to blink. 7.3 P2 – Avoid movement in pages.7.4 P2 – Do not create periodically refreshing pages.7.5 P2 – Do not use mark up to redirect pages automatically.

W3C Guidelines

Guideline 8 of 14Ensure direct accessibility of embedded user interfaces

8.1 P1, P2 – Make programmatic elements such as scripts and applets directly accessible or compatible with assistive technologies.

W3C Guidelines

Guideline 9 of 14Design for device-independence

9.1 P1 – Provide client-side image maps instead of server-side image maps. 9.2 P2 – Ensure that any element that has its own interface can be operated in a device independent manner. 9.3 P2 – Specify logical event handlers (on mouse over, on click, etc).9.4 P3 – Create a logical tab order through links, form controls and objects.9.5 P3 – Provide keyboard shortcuts to important links.

W3C Guidelines

Guideline 10 of 14Use interim solutions (so that older browsers and assistive technologies will operate correctly)

10.1 P2 – Do not cause pop-ups, new windows, or change in current window to occur without informing the user. 10.2 P2 – Ensure explicit associations between labels and form controls. 10.3 P3 – Provide a linear text alternative for tables that layout text in parallel, word-wrapped columns.10.4 P3 – Place holding characters in edit boxes and text areas.10.5 P3 – Include non-link printable characters, (surrounded by spaces) between adjacent links.

W3C Guidelines

Guideline 11 of 14Use W3C technologies and guidelines

11.1 P2 – Use W3C technologies when they are available and appropriate for a task (HTML 4.0). 11.2 P2 – Avoid depreciated features of W3C technologies. 11.3 P3 – Provide information so that users may receive documents according to their preference.11.4 P1 – If after best efforts, you cannot create an accessible page, provide a link to an alternative page.

W3C Guidelines

Guideline 12 of 14Provide context and orientation information (to help users understand complex pages or elements)

12.1 P1 – Title each frame to facilitate frame identification and navigation. 12.2 P2 – Describe the purpose of frames and how they relate to each other. 12.3 P2 – Divide large blocks of information into more manageable groups.

12.4 P2 – Associate labels explicitly with their controls in a form.

W3C Guidelines

Guideline 13 of 14Provide clear navigation mechanisms

13.1 P2 – Clearly identify the target of each link. 13.2 P2 – Provide metadata to pages and sites. 13.3 P2 – Provide information about the general layout of a site.13.4 P2 – Use navigation mechanisms in a consistent manner.13.5 P3 – Provide navigation bars to provide access to the navigation mechanism.More!

W3C Guidelines

Guideline 13 of 14Provide clear navigation mechanisms

13.6 P3 – Group related links and provide a method to bypass the group. 13.7 P3 – If a search is provided, enable different types of searches. 13.8 P3 – Place distinguishing information at the beginning of headings, paragraphs, lists, etc.13.9 P3 – Provide information about document collections (documents comprising multiple pages).13.10 P3 – Provide a means to skip over multi-line ASCII art.

W3C Guidelines

Guideline 14 of 14Ensure that documents are clear and simple

14.1 P1 – Use the clearest and simplest language appropriate for the site’s content. 14.2 P3 – Supplement text with graphic or auditory presentations where they will facilitate the comprehension of the page. 14.3 P3 – Create a style of presentation that is consistent across pages.

WCAG 2.0 DRAFT

Applies to a wider range of current, future, and non-W3C Web technologiesRequirements are more testableTechniques are more comprehensiveBased upon Principles vs. CheckpointsAlthough more comprehensive, most Web sites that meet current WCAG 1.0 guidelines should be able to pass the majority of WCAG 2.0 principle requirements

What is KCTCS doing about web

accessibility?The Web Services Peer Team was formed last year to develop standards regarding web properties. Part of that charge includes drafting accessibility standards.The Peer Team is consulting with KCTCS legal to determine the minimum level of compliance required by law.From there, the Content and Accessibility sub-team will make further recommendations regarding compliance.Your input is welcome!

Web Accessibility Resources

http://www.section508.gov/http://www.webaim.org/http://www.w3.org/TR/WAI-WEBCONTENT/