A collection of objects, known as the elements of the set,
	specified in such a way that we can tell in principle whether
	or not a given object belongs to it.  E.g. the set of all prime
	numbers, the set of zeros of the cosine function.

	For each set there is a {predicate} (or property) which is
	true for (possessed by) exactly those objects which are
	elements of the set.  The predicate may be defined by the set
	or vice versa.  Order and repetition of elements within the
	set are irrelevant so, for example, {1, 2, 3} = {3, 2, 1} =
	{1, 3, 1, 2, 2}.

	Some common set of numbers are given the following names:

	N = the {natural numbers} 0, 1, 2, ...

	Z = the {integers} ..., -2, -1, 0, 1, 2, ...

	Q = the {rational numbers} p/q where p, q are in Z and q /= 0.

	R = the {real numbers}

	C = the {complex numbers}.

	The empty set is the set with no elements.  The intersection
	of two sets X and Y is the set containing all the elements x
	such that x is in X and x is in Y.  The union of two sets is
	the set containing all the elements x such that x is in X or x
	is in Y.

	See also {set complement}.

	(1995-01-24)

1. <programming, operating system> A simple item of data that
	identifies a resource.  For example, a {Unix} file handle
	identifies an open file and associated data such as whether it
	was opened for read or write and the current read/write
	position.  On the {Macintosh}, a handle is a pointer to a
	pointer to some dynamically-allocated memory.  The extra level
	of indirection allows on-the-fly {memory compaction} or
	{garbage collection} without invalidating application program
	references to the allocated memory.

	2. <jargon> An alias used intended to conceal a user's true
	identity in an electronic message.  The term is common on
	Citizen's Band and other amateur radio but, in that context
	usually means the user's real name as {FCC} rules forbid
	concealing one's identity.

	Use of grandiose handles is characteristic of {crackers},
	{weenies}, {spods}, and other lower forms of network life;
	true hackers travel on their own reputations.

	Compare {nick}.

	[{Jargon File}]

	(2004-07-20)