Requirements for multimedia markup and style sheets on the World Wide Web

The unequivocal acceptance of Cascading Style sheets by all major browser vendors clearly indicates the need for separating content and style issues in HTML documents. However, in search of ever-richer content, providers rely on platform-specific plug-ins and browser-specific extensions such as dynamic HTML and scripting to achieve the desired (multimedia) functionality. We consider such an ad-hoc approach to delivering multimedia content as inadequate, and henceforth propose a multimedia document markup language (SMIL, which has recently been submitted to W3C) and discuss the requirements for an associated style sheet language supporting temporal and spatial constraints, hyperlinking among continuous media objects and adaptivity with respect to Quality of Service. In this paper we propose extensions to current style sheet languages to meet the requirements imposed by the capability to specify the presentation of multimedia content in a declarative manner.