<programming> (Or "released version", "baseline") A version of
	a piece of software which has been made public (as opposed to
	a version that is in development, or otherwise unreleased).

	A release is either a {major release}, a {revision}, or a
	{bugfix}.

	Pre-release versions may be called {alpha test}, or {beta
	test} versions.

	See {change management}.

	(1996-08-04)

1. Not operating.  "The up escalator is down" is considered a
	humorous thing to say, and "The elevator is down" always
	means "The elevator isn't working" and never refers to what
	floor the elevator is on.  With respect to computers, this
	term has passed into the mainstream; the extension to other
	kinds of machine is still hackish.

	2. "go down" To stop functioning; usually said of the
	{system}.  The message from the {console} that every hacker
	hates to hear from the operator is "System going down in 5
	minutes".

	3. "take down", "bring down" To deactivate purposely, usually
	for repair work or {PM}.  "I'm taking the system down to work
	on that bug in the tape drive."  Occasionally one hears the
	word "down" by itself used as a verb in this sense.

	See {crash}; opposite: {up}.

	[{Jargon File}]

	(1994-12-07)

In {object-oriented programming} sending a message to an
	{object} (to invoke a {method}) is equivalent to calling a
	{procedure} in traditional programming languages, except that
	the actual code executed may only be selected at run time
	depending on the {class} of the object.  Thus, in response to
	the message "drawSelf", the method code invoked would be
	different if the target object were a circle or a square.

	(1995-02-16)

<data> A data structure holding many values, possibly of
	different types, which is usually accessed sequentially,
	working from the head to the end of the tail - an "ordered
	list".  This contrasts with a (one-dimensional) {array}, any
	element of which can be accessed equally quickly.

	Lists are often stored using a cell and pointer arrangement
	where each value is stored in a cell along with an associated
	pointer to the next cell.  A special pointer, e.g. zero, marks
	the end of the list.  This is known as a (singly) "linked
	list".  A doubly linked list has pointers from each cell to
	both next and previous cells.

	An unordered list is a {set}.

	(1998-11-12)

1. <file format> A single file containing one or (usually)
	more separate files plus information to allow them to be
	extracted (separated) by a suitable program.

	Archives are usually created for software distribution or
	{backup}.  {tar} is a common format for {Unix} archives, and
	{arc} or {PKZIP} for {MS-DOS} and {Microsoft Windows}.

	2. <operating system> To transfer files to slower, cheaper
	media (usually {magnetic tape}) to free the {hard disk} space
	they occupied.  This is now normally done for long-term
	storage but in the 1960s, when disk was much more expensive,
	files were often shuffled regularly between disk and tape.

	3. <networking> {archive site}.

	(1996-12-08)

1. <database> See {data dictionary}.

	2. <programming> The core of a {CASE} tool, typically a {DBMS}
	where all development documents are stored.

	(1999-04-27)

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)

<programming> One of a sequence of copies of a program, each
	incorporating new modifications.  Each version is usually
	identified by a number, commonly of the form X.Y where X is
	the major version number and Y is the release number.
	Typically an increment in X (with Y reset to zero) signifies a
	substantial increase in the function of the program or a
	partial or total re-implementation, whereas Y increases each
	time the progam is changed in any way and re-released.

	Version numbers are useful so that the user can know if the
	program has changed ({bugs} have been fixed or new functions
	added) since he obtained his copy and the programmer can tell
	if a bug report relates to the current version.  It is thus
	always important to state the version when reporting bugs.
	Statements about compatibility between different software
	components should always say which versions they apply to.

	See {change management}.

	(1997-12-07)

<programming, library> A collection of {subroutines} and
	{functions} stored in one or more files, usually in compiled
	form, for linking with other programs.  Libraries are one of
	the earliest forms of organised {code reuse}.  They are often
	supplied by the {operating system} or {software development
	environment} developer to be used in many different programs.
	The routines in a library may be general purpose or designed
	for some specific function such as three dimensional animated
	graphics.

	Libraries are linked with the user's program to form a
	complete {executable}.  The linking may be {static linking}
	or, in some systems, {dynamic linking}.

	(1998-11-21)

<mathematics> A function f : A -> B is surjective or onto or a
	surjection if f A = B.  I.e. f can return any value in B.
	This means that its {image} is its {codomain}.

	Only surjections have {right inverses}, f' : B -> A where
	f (f' x) = x since if f were not a surjection there would be
	elements of B for which f' was not defined.

	See also {bijection}, {injection}.

	(1995-05-27)

<theory> The least defined element in a given {domain}.

	Often used to represent a non-terminating computation.

	(In {LaTeX}, bottom is written as {\perp}, sometimes with the
	domain as a subscript).

	(1997-01-07)

<World-Wide Web, project> A {open source} {HTTP} server for
	{Unix}, {Windows NT}, and other {platforms}.  Apache was
	developed in early 1995, based on code and ideas found in the
	most popular HTTP server of the time, {NCSA httpd} 1.3.  It
	has since evolved to rival (and probably surpass) almost any
	other {Unix} based HTTP server in terms of functionality, and
	speed.  Since April 1996 Apache has been the most popular HTTP
	server on the {Internet}, in May 1999 it was running on 57% of
	all web servers.

	It features highly configurable error messages, {DBM}-based
	{authentication} {databases}, and {content negotiation}.

	Latest version: 1.3.9, as of 1999-10-27.

	{Home (http://www.apache.org/httpd.html)}.

	{FAQ (http://www.apache.org/docs/misc/FAQ.html)}.

	(1999-10-27)