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3 Interchange Standards

Unlike linear documents which are static, generic, and structured, hypertext documents are unstructured and can be dynamic. Hence, current structured document standards are not sufficient to represent hypertext networks. A tree based hierarchy is relevant but NOT sufficient for hypertext. There should be a hierarchical framework with a system of typed links to cover the cross-references of structured documents and the links of hypertext. The current forms of ODA and SGML are not sufficient enough for the representation and exchange) of hypertext. These need extensions to provide a proper typed-link mechanism. SGML does not specify layout or presentation information (which is important for hypertext) or how to handle images and graphics. ODA does address these issues but it is not sufficient.

At the same time, a single standard may not be enough due to the diversity of usage of hypertext applications – large volume hypertext systems are different from highly interactive systems. While the former require highly efficient search capabilities (and standards), the latter require better individualized responses and navigational tools. Hence, these two may require different standards.

In this section, we discuss specific limitations of SGML and ODA and research efforts to extend them to handle hypertext [Newcomb et al., 1991]. Some researchers are also interested in combining the best of ODA and SGML and extending them to form a comprehensive hypermedia standard.