X

X.509
A standard format for digital certificates, defined by the International Telecommunication Union.

XML - extensible markup language
XML is a pared-down version of SGML, which is designed especially for Web documents. Symbian OS provides a framework for parsing XML.

XML style sheets
The CS Help compiler provides XML style sheets that allows a representation of the help file to be viewed in an XML enabled browser.

XOFF
Flow control character used to signal to a transmitter that it should suspend data transmission. The character is configurable, with the industry standard being decimal 19.
See also: high water mark

XON
Flow control character used to signal to a transmitter that it should resume data transmission. The character is configurable, with the industry standard being decimal 17.
See also: low water mark