Multimedia interchange using SGML/HyTime. I. Structures

HyTime is a standard neutral markup language for representing hypertext, multimedia, hypermedia and time-based documents in terms of their logical structure. Documents represented in HyTime conform fully to the ISO Standard Generalized Markup Language (SGML). In effect, HyTime extends SGML by adding certain syntactic conventions called SGML architectural forms, with which it represents certain semantic constructs. HyTime cannot be understood or evaluated without understanding, at least to some extent, the significance and usefulness of the SGML standard on which it is based. This article examines the structure of the two standards. HyTime places unprecedented demands on document processing systems-demands which they have yet to meet. For example, a full implementation of HyTime would allow one to create a hyperlink to whatever happens to be going on at a particular time and/or place in a finite coordinate space (FCS), even if the event, location and time are not yet known, because of binding-time issues. HyTime allows a document to specify where and/or when the results of traversing a hyperlink will be rendered. HyTime provides constructs for specifying how events scheduled in one FCS are to be “projected” onto another, e.g. from a 3D FCS to a 2D FCS, or from a virtual measurement domain to a real one