SGML

The "Standard Generalised Mark-up Language" is an ISO standardised derivative of an earlier IBM "GML". It allows the structure of a document to be defined, and the logical relationship of its parts. This structure can be checked for validity against a " Document Type Definition ", or DTD. The SGML standard defines the syntax for the document, and the syntax and semantics of the DTD. See books -- Eric van Herwijnen's "Practical SGML" and Charles Goldfarb's "SGML Handbook". Some of the points generally broght up in (frequent) discussions of SGML follow.

High level markup

An SGML document is marked up in a way which says nothing about the representation of the document on paper or a screen. A presentation program must marge the document with style information in order to produce a printed copy. This is invaluable when it comes to interchange of documents between different systems, providing different views of a document, extracting information about it, and for machine processing in general. However, some authors feel that the act of communication includes the entire design of the document, and if this is done correctly the formatting is an essential part of authoring. They resist any attempts to change the representation used for their documents.

Syntax

The SGML syntax is sufficient for its needs, but few would say that it is particularly beautiful. The language shows its origins in systems where text was the principle content and markup was the exception, so a document which contains a lot of SGML is clumsy. There is always, of course, an element of personal taste to syntax.

Tools

For many years, SGML was generated by hand, by people editing the source. This has lead to a hatred of SGML among those who prefer their own mark-up language which may have been quicker, more powerful, or more familiar. The advent of WYSIWYG editors and solid SGML applications should improve that facet of SGML.

SGML

High level markup

Syntax

Tools

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