Scribe, GML and SGML
The first language to make a clear and clean distinction between structure and presentation was Scribe, developed by Brian Reid and described in his doctoral thesis in 1980.[6] Scribe was revolutionary in a number of ways, not least that it introduced the idea of styles separated from the marked up document, and of a grammar controlling the usage of descriptive elements. Scribe influenced the development of Generalized Markup Language (later SGML) and is a direct ancestor to HTML and LaTeX.
In the early 1980s, the idea that markup should be focused on the structural aspects of a document and leave the visual presentation of that structure to the interpreter led to the creation of SGML. The language was developed by a committee chaired by Goldfarb. It incorporated ideas from many different sources, including Tunnicliffe’s project, GenCode. Sharon Adler, Anders Berglund, and James A. Marke were also key members of the SGML committee.
SGML specified a syntax for including the markup in documents, as well as one for separately describing what tags were allowed, and where (the Document Type Definition (DTD) or schema). This allowed authors to create and use any markup they wished, selecting tags that made the most sense to them and were named in their own natural languages. Thus, SGML is properly a meta-language, and many particular markup languages are derived from it. From the late ’80s on, most substantial new markup languages have been based on SGML system, including for example TEI and DocBook. SGML was promulgated as an International Standard by International Organization for Standardization, ISO 8879, in 1986.
SGML found wide acceptance and use in fields with very large-scale documentation requirements. However, it was generally found to be cumbersome and difficult to learn, a side effect of attempting to do too much and be too flexible. For example, SGML made end tags (or start-tags, or even both) optional in certain contexts, because it was thought that markup would be done manually by overworked support staff who would appreciate saving keystrokes[citation needed].