XML

https://developer.mozilla.org/en-US/docs/Web/XML

XML: Extensible Markup Language The Extensible Markup Language is a strict serialisation of the Document Object Model.

XML IndexFound 4 pages:

XML introductionXML is a markup language similar to HTML. It stands for Extensible Markup Language and is a W3C recommended specification as a general purpose markup language. This means, unlike other markup languages, XML is not predefined so you must define your own tags. The primary purpose of the language is the sharing of data across different systems, such as the Internet.

xml:basexml:base is like the HTML BaseElement but can specify the base URI per element as well as the entire document.