Page 1 The Link vs. the Event: Activating and Deactivating Elements in Time-Based Hypermedia Lynda Hardman CWI, Amsterdam, The Netherlands (e-mail: Lynda.Hardman@cwi.nl) Patrick Schmitz Microsoft BARC, San Francisco, CA, USA (e-mail: pschmitz@microsoft.com) Jacco van Ossenbruggen CWI, Amsterdam, The Netherlands (e-mail: Jacco.van.Ossenbruggen@cwi.nl) Warner ten Kate Philips Research, Eindhoven, The Netherlands (e-mail: warner.ten.kate@philips.com) Lloyd Rutledge CWI, Amsterdam, The Netherlands (e-mail: Lloyd.Rutledge@cwi.nl) Abstract Activation and deactivation of media items plays a fundamental role in the playing of multimedia and time-based hypermedia presentations. Activation and deactivation information thus has to be captured in an underlying document format. In this paper we show that a number of aspects of activation and deactivation information can be captured using both link structures and events in time-based hypermedia. In particular, we discuss how deactivation and activation can be specified, how the activations and deactivations can be initiated and potential (synchronization) relationships between the elements involved. We first introduce the notions of time-based scheduling and event-based scheduling and then present a short summary of linking. We discuss the similarities between event-based scheduling and linking. We describe a number of aspects of activation and deactivation that can be specified within a document. We then discuss how activation and deactivation information can be recorded in link structures and events. 1. Introduction An informal notion of hypertext is that a piece of information is linked to another piece of information and, when a reader clicks on the first item, a second item comes into view. In contrast, an informal notion of multimedia is that a number of items play on the screen, and the items playing change with time. These views of hypertext and multimedia class the interactions into two different and unconnected worlds, thus restricting the potential for specifying