= X =
=====

X: /X/ n. 1. 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 80186, 80286 80386 or 80486 (note that 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. [after the name of an earlier
   window system called `W'] An over-sized, over-featured,
   over-engineered and incredibly over-complicated window system
   developed at MIT and widely used on UNIX systems.

XOFF: /X'of/ n. Syn. {control-s}.

xor: /X'or/, /kzor/ conj. Exclusive or.  `A xor B' means
   `A or B, but not both'.  "I want to get cherry pie xor a
   banana split."  This derives from the technical use of the term as
   a function on truth-values that is true if exactly one of its two
   arguments is true.

xref: /X'ref/ vt., n. Hackish standard abbreviation for
   `cross-reference'.

XXX: /X-X-X/ n. A marker that attention is needed.
   Commonly used in program comments to indicate areas that are kluged
   up or need to be.  Some hackers liken `XXX' to the notional
   heavy-porn movie rating.

xyzzy: /X-Y-Z-Z-Y/, /X-Y-ziz'ee/, /ziz'ee/, or /ik-ziz'ee/
   [from the ADVENT game] adj.  The {canonical} `magic word'.
   This comes from {ADVENT}, in which the idea is to explore an
   underground cave with many rooms and to collect the treasures you
   find there.  If you type `xyzzy' at the appropriate time, you can
   move instantly between two otherwise distant points.  If, therefore,
   you encounter some bit of {magic}, you might remark on this
   quite succinctly by saying simply "Xyzzy!"  "Ordinarily you
   can't look at someone else's screen if he has protected it, but if
   you type quadruple-bucky-clear the system will let you do it
   anyway."  "Xyzzy!"  Xyzzy has actually been implemented as an
   undocumented no-op command on several OSes; in Data General's
   AOS/VS, for example, it would typically respond "Nothing
   happens", just as {ADVENT} did if the magic was invoked at the
   wrong spot or before a player had performed the action that enabled
   the word.  See also {plugh}.