X-Y

x-axis

The horizontal plane in a chart on which data is graphically represented. Also called the category axis .

XE

An index entry field code that defines the text and page number for an index entry and other options, such as a subentry text. See also index entry .

XML

See Extensible Markup Language.

XML schema

A description of a document s structure.

y-axis

The vertical plane in a chart on which data is graphically represented. Also called the value axis .