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Tech Review #3: by Shelley Rygg |
SGML Standard Generalized Markup Language
SGML stands for: Standard Generalized Markup Language. It is a set of rules used to organize and tag elements of a document. SGML is actually a metalanguage formalism that facilitates the definition of descriptive markup languages for the purpose of electronic information encoding and interchange. It is an international standard for the definition of device-independent, system-independent methods of representing texts in electronic form and was developed and standardized by the International Organization for Standards (ISO) in 1986.
SGML itself is not a mark-up scheme - it does not define mark-up tags nor does it provide a template for a particular type of document - rather it denotes a way of describing any mark-up scheme. By using SGML, many mark-up schemes can be developed, one for each document type or class. This is both a strength and weakness for SGML.
Perhaps the largest set of SGML encoded files are those used on the World Wide Web. HTML, the hypertext mark-up language used in Web documents, is an application of SGML. Thus, the relationship that HTML has to SGML is that HTML uses the SGML concepts to define the structure or mark-up which allows the publishing of the content.
An SGML document normally consists of three items: the SGML Declaration, the DTD and the text of the document itself. The SGML Declaration tells the computer which codes it should use to identify the start and end of mark-up sequences. The DTD or Document Type Definition are the mark-up tags which surround the content and define each structural element. DTDs can include provisions for graphics files, SPDL or PostScript printing, or special processing codes for mathematics. The text of the document is up to the author.
Hyperlinks for Further Research:
SGML and the Web:
http://www-tei.uic.edu/orgs/tei/sgml/teip3sg/SG.htm.
The source of this information is the TEI guidelines. A must-read for folks new to SGML.
http://www.oasis-open.org/cover/sgml-xml.html.
The SGML Web Page offers a comprehensive set of links to archives, user groups, software, projects, industry-specific applications, and standards.
http://www.pineapplesoft.com/reports/sgml/basic.html.
This document summarizes key facts on SGML for the technically inclined reader.
http://www.geocities.com/Athens/2694/sgml.html.
The site contains links to conversion tools, documents, standards, verification utilities, and general information help.
http://www.isgmlug.org/whatsgml.htm.
Answers general questions about SGML and contains links to overviews, vendors, standards, and related resources.
Page last updated on 05/30/2000.