Extensible Markup Language, or SGML done right. It depends on whether you actually used IBM stuff or not.
See SOAP, HTML, XHTML, RSS, and just about anything else related to data handling these days.
Oddities:
- WBXML - one of my recurring nightmares.
- VTD-XML - "The initial design goal of VTD-XML is to significantly improve the processing performance of XML so that network switches and routers can inspect XML content at very high speed.". Fear.
Rui Carmo