Tools to Increase Accessibilityof the Web
Clare SoDepartment of Computer Science
University of Western OntarioLondon, Ontario. N6A 5B7
OUCC 2004 - May 16-18, 2004
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Aim of this Talk
• What is accessible Web?
• Who are obligated to provide accessible Web?
• Many FREE tools available!
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Outline
• Clare
– Goals of accessibility
• Mark
– Obligations
• Stephen
– Accessibility mechanisms
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In a Perfect World
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In Reality
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What is Web Accessibility?
• Viewable and useful for target population
• ”Able to get something out of it!”
Why Making the Web Accessible?
• More than showing good ethics!
• Legal obligations
• Increase clients
– Pages can be read using different technologies (example: phone)
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What is a Web site?
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What is a Web site?
• Not just an aesthically pleasing page!
• Consist of more than text and pictures
– Math
– Music (score, sound clip)
– Chemistry formulae
• Accomodate a wide variety of
– Users (students, professors, public)
– Knowledge
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How to Make the Web Inaccessible?
• Imaged text
– Enlarging fonts?
– Searching for keywords?
• No “alt” text in <img>
– Text browsers
– Exception: Put email address in an image without “alt” text → spam list
• Non-standard HTML
– Displaying pages using different browsers?
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Free Tools - Markup Validation Service
• Offer by World Wide Web Consortium
• Point out HTML markup that does not conform to the standard
– Example: missing ”alt” attribute in images
• http://validator.w3.org/
Free Tools - HTML Tidy
• Clean up improper markup
– Example: missing closing tag
• Give suggestions to improve accessibility
• Version for many OSs available
• http://tidy.sourceforge.net/
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Free Tools - WAI Checklists
• Offer by Web Accessibility Initiative (WAI),World Wide Web Consortium
• Three different level of conformance
– Priority 1 - Basic requirement
– Priority 2 - Remove significant barriers
– Priority 3 - Bells and whistle
• Some criteria are to be checked manually
• http://www.w3.org/WAI/
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Free Tools - Some of WAI Quick Tips
• Images & animations: Use the alt attribute to describe the function of eachvisual.
• Multimedia. Provide captioning and transcripts of audio, and descriptionsof video.
• Hypertext links. Use text that makes sense when read out of context. Forexample, avoid ”click here.”
• Page organization. Use headings, lists, and consistent structure. UseCSS for layout and style where possible.
• Scripts, applets, & plug-ins. Provide alternative content in case activefeatures are inaccessible or unsupported.
• Check your work. Validate. Use tools, checklist, and guidelines athttp://www.w3.org/TR/WCAG
(c) W3C (MIT, INRIA, Keio) 2001/01
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Demo - UWO Library Homepage
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Demo - Validating UWO Library Homepage
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Demo - Tidying UWO Library Homepage
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What Do These Error Messages Mean?
• Markup Validation Service gives 67 errors such as
– Line 5, column 42: there is no attribute ”TYPE”<link rel="icon" href="favicon.ico" type="image/x-icon">
– Line 250, column 8: there is no attribute ”ID”<div id="headerdiv" z-index=2>
– Line 272, column 66: required attribute ”ALT” not specified...T COORDS="17,77,139,115" HREF="/crcatalogues.shtml">
• HTML Tidy gives 90 warnings such as
– line 77 column 1 - Warning: <script> inserting ”type” attribute
– line 245 column 1 - Warning: <div> proprietary attribute ”z-index”
– line 260 column 540 - Warning: <area> lacks ”alt” attribute
– line 320 column 1 - Warning: <table> lacks ”summary” attribute
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What Do These Error Messages Mean?
• ”alt” text missing
• Authoring tools that do not conform to Web standard
• Web page may not be rendered meaningfully in a text-based browser
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