XML

XML (eXtensible Markup Language) is a universal method for the textual representation of structured data according to a standardized syntax. XML was designed to enable data to be exchanged and stored independently of the programs or processes that produce it, and to be produced independently of the programs or processes that use it.

The notion of representation in textual form, i.e. in the sequential form of a tagged stream of characters, is opposed here to that of binary representation. XML has been developed under the aegis of the World Wide Web Consortium (W3C) since late 1996; the XML language, i.e. the set of syntax rules governing the tagged representation of information, is defined very precisely in a W3C recommendation [1] , version 1.0 of which was dated 10/02/98. (A second edition of this specification, correcting certain editorial errors, was published on 6/10/00).

By convention, we call the result of this representation an XML document, even in cases where the marked-up text stream has no narrative character and is in no way intended to be apprehended by a human reader after it has been formatted on a medium. While XML has many applications in the documentary world, inherited from its ancestor SGML [2] , it is also applicable to a wide variety of problems concerning the representation, exchange and processing of structured data outside the documentary field. XML can be used to represent a database extract, a spreadsheet, all the configuration parameters of a computer application, the data flows exchanged during financial transactions, the complex data of a geographic information system, graphics, and so on. XML is destined to become the universal exchange format for structured data flows on the World Wide Web, in ever-increasing volumes.