Accessibility verification of WWW documents by an automatic guideline verification tool

Since the World Wide Web (WWW) is currently the principal infrastructure used by the general public, Web site creators are required to build universally accessible sites. Accessibility guidelines such as the Web content accessibility guidelines (WCAG) show the creators how to make accessible Web pages. Also, tools which automatically verify whether or not a given web page complies with the guidelines are provided. Although those tools are useful, applying them to any document format other than HTML or any guidelines other than WCAG is difficult, since these tools assume a fixed set of guidelines (e.g., WCAG) and a fixed document format (e.g., HTML). That is, changing the built-in guidelines (e.g., verifying whether a given document complies with the guidelines defined by their organization) requires modifying the tool. This paper proposes a simple and clear language for specifying guidelines, and discusses a verification tool which has the following characteristics: a guideline specification is separated from the tool and can be easily modified; an arbitrary XML document can be verified; and the tool can be used not only for accessibility guideline verification but also for complex syntactic checking. We also present the verification results conducted on about 3,000 Web pages of forty major organizations in the U.S.A. and Japan using our verification tool.