SGML

SGML (Standard Generalized Markup Language)
SGML is both a language (or rather a meta-language) and an ISO standard (ISO 8879:1086) for describing information embedded within a document. It defines the structure of a document and the logical relationship of its parts.

Hyper Text Mark-Up Language (HTML) is a subset of Standard Generalized Mark-Up Language (SGML) for electronic publishing, the specific standard used for the World Wide Web was invented by Tim Berners-Lee.

XML is derived from SGML and now outperforms SGML in terms of breadth of application.

Literature:

Burnard, Lou & Sperberg-McQueen, C. M. (eds.). (1993). Guidelines For the Encoding and Interchange of Machine-Readable Texts. Document Number: TEI PI. Chicago & Oxford: Text Encoding Initiative, ACH, ACL, ALLC. Draft Version 1.1. October 1990. Draft version 2, Part 1-2, May 1993.

ISO 8879, 1986.

Wikipedia, the free encyclopedia. (2006). Standard Generalized Markup Language. http://en.wikipedia.org/wiki/Standard_Generalized_Markup_Language