4.1.1 Platform Accessibility Services

Here's the version of the SC we discussed on today's call, proposed Intent wording that merges the existing version with Jan's rewrite, an improved version of the existing Example, and updated and corrected list of Related Resources. (If we're changing "platform accessibility architecture" to "platform accessibility services" throughout the document, now would be a good time to do it.)

    4.1.1 Platform Accessibility Services: The user agent supports relevant platform accessibility services. (Level A)

    *Intent of Success Criteria 4.1.1:*

    The intent of this success criterion is to make user agent user interfaces more accessible to users who rely on assistive technologies, such as screen readers and speech recognition software. Most major operating environments provide platform accessibility services that allow applications (including user agents) and assistive technologies to work together more effectively, but these must be supported by the software on both sides. The requirement is stated generally because the specifics of what constitutes a platform accessibility service will differ on each platform, but basic features common to these services are addressed by other success criteria under Guideline 4.1.

    Assistive technologies often use a combination of methods to get information about and manipulate a user agent's user interface and the content it's rendering; some of these are addressed in other success criteria. However, platform accessibility services are particularly important because they provide common functionality across all the well-behaved applications running on the platform, reducing the amount of special-casing the assistive technology has to implement for each of the hundreds of applications it may need to support.

    Most web-based user agents will support this requirement automatically because they run inside host user agents, and the host is responsible for exposing all content, including nested user agents, via platform accessibility services. As long as the nested user agent's user interface is entirely web-based and complies with Web Content Accessibility Guidelines (e.g. providing alternative text and supporting WAI-ARIA where needed) the host will understand it well enough to provide a bridge between it and platform accessibility services.

    [NOTE: I've left this paragraph in, but it's not clear what Note it's referring to. If that can't be clarified it should be removed.] The note regarding documenting the platform accessibility service(s) that were implemented in the conformance claim should encourage developers to implement services that are well supported by assistive technologies.

    *Examples of Success Criterion 4.1.1:*

    *    A browser is developing a new type of button bar for their Microsoft Windows product. When coding the new component the developer includes support for the Microsoft Active Accessibility API (MSAA) so that assistive technologies can recognize it as representing a toolbar, and can identify, navigate, and activate the bar and its buttons on the user's behalf.

    *Related Resources for Success Criterion 4.1.1: *

    *    See 4.1.2 (Name, Role, State, Value, Description) and 4.1.6 (Expose Accessible Properties) for specific information that should be exposed through platform accessibility services.

    *    Microsoft Active Accessibility (MSAA) http://msdn.microsoft.com/en-us/library/ms971310.aspx

    *    Microsoft UI Automation http://msdn.microsoft.com/en-us/library/ms747327.aspx

    *    Gnome Accessibility Toolkit (ATK) http://library.gnome.org/devel/atk/

    *    Gnome Assistive Technology Service Provider Interface (AT-SPI) http://accessibility.gnome.org/developer/atk.php

    *    Accessibility Programming Guidelines for Mac https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Accessibility/

    *    Accessibility Programming Guide for iOS https://developer.apple.com/library/ios/#documentation/UserExperience/Conceptual/iPhoneAccessibility/

    *    Iaccessible2 http://www.linuxfoundation.org/collaborate/workgroups/accessibility/iaccessible2, http://www-03.ibm.com/able/open_computing/open_source_windows.html

    *    Accessibility API Cross reference http://www.mozilla.org/access/platform-apis.html