X (redirected from XES)

X, 24th letter of the alphabet. In English it has no peculiar sound, but stands for the combination ks as in fox, or gz as in exempt, or, initially, for the sound of z as in xenia. In words from Greek, x transliterates the 14th Greek letter, xi, a letter perhaps quite unrelated to the Roman x in form. The formal Greek correspondent of x was chi, hence it is used in phonetics to represent a velar fricative like ch in loch. As the initial of the name Christ, X has become a symbol for it, e.g., in Xmas and in the monogram XP (chi rho). In Roman numerals X stands for 10.

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x

(1) The exit (close) button on an application window or popup message. Clicking the X closes the window or message. In Windows, clicking the red X at the top right side of the title bar closes the entire application and all related open windows. In the Mac, clicking the red X at the top left side of the application closes all related open windows, but the application remains open.

(2) In programming, a symbol used to identify a hexadecimal number. For example, "0x0A" and "\x0A" specify the hex number 0A. See also X Window and MDI-X port.

(3) A performance rating for CD-ROM and DVD drives, based on rotation speed (RPM) of the platter. Each "x" means "times the speed of the first drive." Thus 10x means 10 times as fast as the original drive. See CD-ROM drives and DVD drives.

(4) (x-) The prefix used to describe a MIME type. For example, x-pdf and x-gzip refer to PDF and Gnu ZIP file formats, respectively. See MIME type.

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X

(spectroscopy)

siegbahn

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1.	(convention)	X - Used in various speech and writing contexts (also in lowercase) in roughly its algebraic sense of "unknown within a set defined by context" (compare N). Thus, the abbreviation 680x0 stands for 68000, 68010, 68020, 68030 or 68040, and 80x86 stands for Intel 80186, Intel 80286, Intel 80386 or Intel 80486. A Unix hacker might write these as 680[0-4]0 and 80[1-4]86 or 680?0 and 80?86 respectively; see glob.
2.	(graphics)	X - An alternative name for the X Window System.
3.	(storage)	X - A suffix for the speed of a CD-ROM drive relative to standard music CDs (1x). 32x is common in September 1999.