About
This report explores the suitability of Standard Generalized Markup Language (SGML) as a framework for building, managing, and providing access to digital libraries, with special emphasis on preservation and access issues. SGML is an international standard (ISO 8879) designed to promote text interchange. It is used to define markup languages, which can then encode the logical structure and content of any so-defined document. The connection between SGML and the traditional concerns of preservation and access may not be immediately apparent, but the use of descriptive markup tools such as SGML is crucial to the quality and long-term accessibility of digitized materials. Beginning with a general exploration of digital formats for preservation and access, the report provides a staged technical tutorial on the features and uses of SGML. The tutorial covers SGML and related standards, SGML Document Type Definitions in current use, and related projects now under development. A tiered metadata model is described that could incorporate SGML along with other standards to facilitate discovery and retrieval of digital documents. Endnotes and a bibliography provide further resources. Appendices include: a discussion of practical concerns related to the uses of SGML in conversion and authoring projects, descriptions of markup format and SGML tools, and a vendor's look at cost metrics. The report concludes that SGML meets current preservation and access requirements for digital libraries and that SGML solves the widest range of archival database problems today: SGML is a standard; it is non-proprietary and platform-independent; and it allows rich, full access to content-based digital documents. The SGML framework should be seriously considered when planning digital library projects.