XML is the Extensible Markup Language. While XML is not itself an encoding scheme, it is a framework within which encoding schemes (tag sets) may be developed. Because multiple tag sets may be used in the same texts, XML-based encoding schemes can easily support a diversity of opinions about the basic text features to be tagged. XML is device-independent and is supported by software products from an increasing number of vendors. It can handle any natural language for which an electronic representation exists and is by design application-independent. This means that it enables the same text base to be used for many different applications in different environments.
Robin Cover's XML Home Page.
CETH's LatinML Page.