Today's Style Sheet Standards: The Gread Vision Blinded

, attribute the Web's continuing development crisis to the failure of commercial browsers to fully implement agreed-upon standards. This is an important issue: Nonconfor-mant and incomplete implementations have been a nightmare for Web developers. However, there is a deeper issue— one that has had little public discussion: Will these standards actually provide the envisioned benefits for the Web? Style sheets, which specify how documents are presented to users, are expected to play a critical role in the Web's architecture. Through the use of style sheets, future Web documents will be easier to author and will be accessible everywhere, from PCs to TVs to palm devices to cellular phones. Unfortunately, the current standards appear to impede this grand vision of the Web. Visionaries foresee a Web in which pages have rich semantics that enhance users' understanding and also facilitate searching with automated tools. In this grand vision, a huge variety of devices can view these semantically dense pages in innumerable styles tuned to users' diverse tastes, needs, and interests. This improved Web will offer total accessibility , with users listening to Web pages through aural browsers that speak or feeling them through Braille devices. Style sheets are a critical part of this vision. The Extensible Markup Language (XML), which is expected to replace HTML, allows Web documents to contain much richer semantic information than is possible with HTML. However, unlike HTML, XML doesn't specify anything about a document's appearance. Browsers get this missing information from style sheets, which are separate appearance specifications. Because the style sheets are separate, it should be possible to mix and match them with documents to provide a variety of display and playback styles. An author only has to create a single version of a page, and users can apply appropriate style sheets to adapt the page to their devices and needs. This vision of Web accessibility imposes a number of requirements. First, style sheet languages and systems must support the complete separation of content (XML) and presentation (style sheets) so that it isn't necessary to change content to suit the presentation's needs. Second, users must have final say over how style sheets are applied because they know their own needs best. This implies that final control over the style sheets will reside on the client side. Third, to have control over presentation, end users must be able to write at least the more simple style sheets …