SGML stands for Standard Generalized Mark-up Language. It consists of a collection of syntax and parsing conventions for defining mark-up languages like HTML. Thus, one doesn't use SGML directly, and for this reason, it is termed a meta language.

The idea behind SGML is that the content, structure and layout of a document are all distinct. One uses SGML to define tags that can be used to "mark-up" the logical structure of a document.

The SGML definition of the tag set is called a DTD. Other programs can use the DTD to translate the tag syntax into their own internal data structures for processing. In this way, the same document can be rendered in a screen-specific way, in a print version, even in an executable version as in Scientific Workplace (using the Maple kernel) or Mathematica 3.0.

SGML has been used in proprietary ways for many years. For example, Boeing uses SGML for its maintenance history documents. Some good SGML tools are available in free versions. However, SGML viewers and print drivers are just beginning to appear.

Some External Links to SGML Software:

• SoftQuad -- SoftQuad makes a freely available viewer called Panorama that functions as a helper application for SGML documents. Basic Math support in accordance with the ISO 12083 standard DTD for mathematics. Good background info.
• Arbortext -- Arbortext has high quality equation editing and typesetting software. Excellent TeX support.
• An online guide to SGML.
• (Oops, lost the link for:
  Perl SGML programs -- there is a free parser and some authoring stuff.)
• Microsoft -- Word has SGML support. Dare you to find it...