May 31st, 2003, 06:31 PM
The history of markup
SGML: the father of markup
The Standard Generalized Markup Language (SGML) was developed in the
sixties when IBM had problems while exchanging documents from one OS
to another. The first try was General Markup Language (GML), a productspecific
language for IBM. The designers of GML - Charles Goldfarb and Ray Lorie -
realised a few years later they created a solution for making easy
transportable documents that would work everywhere, not just at IBM.
GML became a standard in the eighties.
Not much later the Department of Defense used SGML as their official
Every supplier was obligated to deliver all documentation in SGML-markup
so exchanging information was easier and compability was guaranteed.
Although SGML is a powerful language it is also complex and expensive to
implement and maintain. SGML is not suited to describe simple documents
and designing DTD's with it is not easy.
HTML: SGML for the world
At the end of the eighties Tim Berners-Lee went to the European Lab
for fysics (CERN) with the purpose to go study there.
When he was there, he noticed a problem: a lot of people came to CERN
for short periods of 3 to 5 years. Every person used another method to
save/view his data so it was very difficult for new professors to use other's
Tim started working to design a system that was platform-independent and
easy to use. The result was HTML.
HTML is a markup-language that is not dependent of any kind of machine
or platform. It is based on hypertext -a way to link documents and to
use them by clicking on text that leads to another one.
The problem with HTML is that is was not designed to describe complex documents
XML makes the bridge
The last years the W3C began to realise HTML wasn't suited for its
current task. They needed an extensible markupsystem that allowed
documentcreators to create markup that suited their content.
SGML could be used but wasn't handy. Their answer was XML.
It gives developers the opportunity to write their own DTD's.
There are rumors HTML will die now XML is there. But I think
HTML will probably become a DTD in the XML gallery of vocabularies.
May 31st, 2003, 06:54 PM
May 31st, 2003, 07:04 PM
FYI: XHTML is an XML schema which is very similar to HTML, and is intended to replace it. Current browsers support it.
I notice you seem to be living in the year 1999, having not mentioned XML schemas, still referring to the long-deprecated DTDs.