• X-ray

High frequency electromagnetic ray of short wave-length, capable of penetrating most solid substances.

• X.25

International standard of the CCITT for packet switching.

• X.400

A CCITT recommendation designed to facilitate international message and information exchange between subscribers of computer based store-and-forward services and office information systems in association with public and private data networks.

• X.500

The CCITT now ITU recommendations (ISO9594) for the structure of directories for the maintenance of addresses used in electronic mail.

• XML

Extensible mark-up language is an official recommendation by the World Wide Web Consortium as a successor of HTML (Hyper Text Mark-up language) it can be used to convey documents layout and contents from one computer application to another. XML is a subset of SGML.

• XML / EDI

The exchange of structured information over the Internet using XML as the syntax.