Accessibility supported technologies
Government websites must use technologies in ways that support accessibility and people using assistive technology.
The Web Content Accessbility Guidelines (WCAG) 2.0 that form the main requirement of the New Zealand Government Web Accessibility Standard come with five conformance requirements. The fourth of these is that
[o]nly accessibility-supported ways of using technologies are relied upon… to meet the WCAG 2.0 success criteria.
The concept of accessibility support is complex, but central to the application of WCAG 2.0.
A technology use is accessibility supported if it is
supported by users’ assistive technologies as well as the accessibility features in browsers and other user agents.
Accessibility support in the NZ Government context
Open versus closed environments
The audience for most New Zealand Government websites is the general public. With some websites, the audience might be a more specific subset of the general public, such as registered members of a special working group.
Unless the site owner has control of the browsers and assistive technologies being used by the people accessing the site, they need to assume that people will be using the site with all sorts of browsers, assistive technologies and operating systems. This means that the website will need be developed using technologies in ways that are accessibility supported by a broad range of user agents.
Where the site owner does have control of the environment in which people will be using the website, such as a department’s intranet, the specific browsers and assistive technologies available to users can be constrained. In this case, it is easier to use web technologies in ways that target the accessibility support of those known browsers and assistive technologies.
What is or isn’t accessibility supported?
Determining if a particular use of technology is accessibility supported can be tricky. As noted in Understanding WCAG 2.0,
[i]ndividual authors will not usually be able to do all of the testing necessary to determine which ways of using which Web technologies are actually supported by which versions of assistive technologies and user agents.
Using WCAG 2.0 sufficient techniques
WCAG 2.0 also covers a wide range of common failures that describe ways of using web technologies that will result in a lack of conformance with particular WCAG 2.0 success criteria. Web authors should ensure that they use web technologies in ways that do not replicate these common failures.
Not all sufficient techniques provide accessibility support
The WCAG 2.0 sufficient techniques include ways of using specific technologies that currently cannot be considered accessibility supported in the context of the typical New Zealand Government website. In particular, and for the time being, these include the sufficient techniques for PDF, Flash and Silverlight.
PDF, Word, Flash and Silverlight
Common ways of using these technologies are not accessibility supported in the user agents that a site’s visitors can be reasonably expected to be using.
Specifically, unless a government organisation has control over its users’ operating system and assistive technologies, all but the very simplest uses of PDF, Microsoft Word, Flash and Silverlight cannot be relied upon to meet a variety of basic WCAG 2.0 success criteria. This is because these technologies have variable and, in some cases, very limited accessibility support on the Mac OS and Linux platforms for screen reader users.
The situation is very similar on the Linux platform, as it is with technologies such as Flash and Silverlight.
As the accessibility support for these technologies improves, it should become permissable to rely on them for the delivery of web content in the context of most New Zealand Government websites.