Dynamic Accessibility Nick Poole ICT Adviser Resource The

Dynamic Accessibility Nick Poole ICT Adviser Resource: The Council for Museums, Archives and Libraries

Contents • • • Introduction Static-page accessibility Dynamic accessibility - key concepts XHTML 1. 1 Cascading Style Sheets XML accessibility New technologies - SMIL, VRML, SVG e-Books and TTS Contact details

Introduction • What is accessibility? • Technological accessibility – browsers, platforms, operating systems, plugins, screen resolutions • Intellectual accessibility – navigation, language, structure, search tools, URL • Physical accessibility – design, layout, contrast, font size, text versions of animated/interactive information

Static-page accessibility • Proper use of existing accessibility features in HTML • Separation of content from presentation CSS and ‘graceful transformation’ • Logical in-page reading order • Logical in-site navigational structure • Thinking about visual presentation - contrast, layout etc • http: //www. w 3 c/prg/WAI

Dynamic accessibility - key concepts • Very similar. . . • Separation of style from content • Enabling dynamic re-flowing of content to address different platforms and technologies • Clean code properly implemented • The benefits and dangers of XML • Making use of existing accessibility features • Validate wherever possible • Universal design and user-oriented publishing

XHTML 1. 1 • ‘The Extensible Hyper. Text Markup Language (XHTML™) is a family of current and future document types and modules that reproduce, subset, and extend HTML, reformulated In XML. ’ • 3 ‘flavours’: – strict - clean structural markup – transitional - XHTML elements plus support for backwards-compatibility – frameset - for creating pages subdivided into frames

XHTML 1. 1 and Accessibility • Well-formed XHTML pages follow a strict set of rules and avoid the use of non-standard markup • XHTML supports graceful transformation between platforms - eg PC, PDA, braille • Strict rule-based approach ensures better compatibility across browsers • Imposes uniformity on document structure • Keep pace with tech development • Migrate existing documents from HTML using HTMLTidy - http: //www. w 3. org

Cascading Style Sheets • CSS separates document structure (content) from presentation (style) • Prevents the use of structural HTML tags to define layout • Positioning properties avoid further use of markup to define layout • Allows the user to override the server-side CSS with their own preferences • Supports features which help orientation • Support for Aural Style Sheets (ACSS) • Better presentation of ALT content

XML Accessibility • ‘An XML schema is accessible if it enables, and indeed actively promotes, the creation of accessible documents’ • …and • ‘A document is accessible if it can be equally understood by its target audience regardless of the device used to access it’ ‘XML Accessibility Guidelines’ http: //www. w 3. org/TR/xag. html

XML Accessibility • 2 key concepts: • Semantic-rich schema that support accessibility • Device independence - write once, deliver through different channels

XML Accessibility • Facilitate the provision of ALT descriptions for different types of content – Apply the ‘summary’ and ‘caption’ elements provided for tables in XHTML <table border=“ 1” summary=“This table provides a list of names, addresses, telephone numbers and email addresses for club members”> <caption><em>Contact details</em></caption> <tr><th></tr><td></tr></td> </table>

XML Accessibility • Standard mechanisms exist for linking and pointing in XML – Make use of XLink and Xpointer instead of creating your own mechanisms (which may not be recognised/supported) <crossref xmlns: xlink=“http: //www. w 3. org/1999/xlink” xlink: href=“http: //www. resource. gov. uk/file. xml”> Link text </crossref>

XML Accessibility • Using the flexibility of XML to define element types that identify important text content – Certain elements are more important than others in identifying and assessing the content of a document – When creating a tagset, include semantic tags which allow you to identify these important elements – In addition to identifying tags, include additional descriptive semantics

XML Accessibility • When identifying important descriptive elements, make use of standard mechanisms/namespaces where possible (eg Dublin Core/RDF) <rdf: RDF xmlns: rdf=“http: //www. w 3. org/1999/02/22 -rdf-syntax-ns#” xmlns: dc=“http: //www. purl. org/dc/elements/1. 1/”> <rdf: Description about =“http: //www. peoplesnetwork. gov. uk”> <dc: Title></dc. Title> <dc: Description></dc. Description>. . . etc. . .

XML Accessibility • Semantic consistency – Ensure that the same element contains the same content throughout the document - do not re-use elements for different purposes – When re-using modules from elsewhere, ensure that you apply their elements as intended

XML Accessibility • Using XML to design for platformindependence – Provide default style-sheets for output to different platforms/devices (CSS or XSLT) – Create element types that allow classification and grouping into logical, navigable document structures – Provide ways of interacting with the document that are device-independent – Allow the user to control the timeframe within which events occur

XML Accessibility • Final points…. – Document the semantics and structure of your XML – Provide a machine-understandable way of retrieving this documentation (eg. by using the xsi: schema. Location attribute) – Provide human-understandable definitions for the semantics of your XML elements (eg. by using the xsd: annotation attribute) – Where accessible elements have been provided, ensure that these are documented

New technologies - SMIL • Synchronised Multimedia Integration Language • Specific issues: – Alternative equivalent content – Alternatives have to be synchronised with primary media – Multiple sensory channels (sight, hearing, touch) – Content changes without user interaction leading to disorientation

New Technologies - SMIL • Alternative equivalent content – Text transcription - alt, title, abstract, longdesc – Auditory descriptions – Synchronised captions - textstream, systemcaptions (where enabled) – Multilinguality - textstream captions in one language, overdub audio descriptions in another – Use of the ‘switch’ element to allow the user to select their preferred channel

New Technologies - SMIL • Use SMIL in conjunction with CSS to provide screen layouts that transform (eg. percentage areas for onscreen captioning) • Use the ‘title’ attribute to describe the nature of all SMIL elements • Consider providing a ‘temporal’ navigation bar to enable user interaction with timedependent content • Use the ‘system-’ test attributes to re-purpose content to user preferences

New Technologies - VRML • Range of built-in features to enhance access: – 2 levels of alternative textual description - ‘Worldinfo’ and ‘Anchor’ nodes – audio cues including spoken descriptions, proximitysensitive effects and trigger/viewpoint-specific events – mapping to external input devices to facilitate navigation • Utilities available to enable access: – show. VP, add. Snd. To. Vrml and speak. World. Info – essentially providing context/viewpoint info to assist the user – http: //ovrt. nist. gov/projects/VRMLaccess/

New Technologies - SVG • Scalable Vector Graphics • XML-based image format • Range of accessibility features: – scalable! – Includes a text description for each logical component of an image – images are encoded as plain text – SVG images can be encoded into XML documents – Can also call images from other documents using x. Link – Images can be re-flowed to suit different media – Improved support for metadata

e-Books and Text-to-Speech • Conflict between XML encoding and Digital Rights Management information • XML encoding supports user-controlled textto-speech delivery (Open e-Books Publication Structure) • DRM protection blocks delivery through these channels • Ongoing debate at: http: //www. openebook. org

Contact: Nick Poole ICT Adviser Resource: The Council for Museums, Archives and Libraries 16 Queen Anne’s Gate London SW 1 H 9 AA Email: nick. poole@resource. gov. uk Web: http: //www. peoplesnetwork. org. uk Telephone: 020 7273 1410