<data> To read data that is not in the native format of the
	application.  For example, a {web browser} will have its own
	way of storing {bookmarks} but it will usually provide a
	function to import bookmarks from {Internet Explorer}.  The
	alternative is to provide an independent external conversion
	utility but this is usually less convenient for the user.

	(2004-11-15)

1. <programming> The prototype for an {object} in an
	{object-oriented language}; analogous to a {derived type} in a
	{procedural language}.  A class may also be considered to be a
	set of objects which share a common structure and behaviour.
	The structure of a class is determined by the {class
	variables} which represent the {state} of an object of that
	class and the behaviour is given by a set of {methods}
	associated with the class.

	Classes are related in a {class hierarchy}.  One class may be
	a specialisation (a "{subclass}") of another (one of its
	"{superclasses}") or it may be composed of other classes or it
	may use other classes in a {client-server} relationship.  A
	class may be an {abstract class} or a {concrete class}.

	See also {signature}.

	2. <programming> See {type class}.

	3. <networking> One of three types of {Internet addresses}
	distinguished by their most significant bits.

	3. <language> A language developed by the {Andrew Project}.
	It was one of the first attempts to add {object-oriented}
	features to {C}.

	(1995-05-01)

<World-Wide Web> A {Java} program which can be distributed as
	an attachment in a {World-Wide Web} document and executed by a
	Java-enabled {web browser} such as Sun's {HotJava},
	{Netscape Navigator} version 2.0, or {Internet Explorer}.

	Navigator severely restricts the applet's file system and
	network access in order to prevent accidental or deliberate
	security violations.  Full Java applications, which run
	outside of the browser, do not have these restrictions.

	Web browsers can also be extended with {plug-ins} though these
	differ from applets in that they usually require manual
	installation and are {platform}-specific.  Various other
	languages can now be embedded within {HTML} documents, the
	most common being {JavaScript}.

	Despite Java's aim to be a "write once, run anywhere"
	language, the difficulty of accomodating the variety of
	browsers in use on the Internet has led many to abandon
	client-side processing in favour of {server}-side Java
	programs for which the term {servlet} was coined.

	Merriam Webster "Collegiate Edition" gives a 1990 definition:
	a short application program especially for performing a simple
	specific task.

	(2002-07-12)

1. See {multithreading}.

	2. See {threaded code}.

	3. {topic thread}.

	[{Jargon File}]

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)

<programming> The name given in {Smalltalk} and other
	{object-oriented languages} to a procedure or routine
	associated with one or more {classes}.  An {object} of a
	certain class knows how to perform actions, e.g. printing
	itself or creating a new instance of itself, rather than the
	function (e.g. printing) knowing how to handle different types
	of object.

	Different classes may define methods with the same name
	(i.e. methods may be {polymorphic}).  The term "method" is used
	both for a named operation, e.g. "PRINT" and also for the code
	which a specific class provides to perform tha
	t operation.

	Most methods operate on objects that are instances of a
	certain class.  Some object-oriented languages call these
	"object methods" to distinguish then from "{class methods}".

	In {Smalltalk}, a method is defined by giving its name,
	documentation, temporary local variables and a sequence of
	expressions separated by "."s.

	(2000-03-22)

<library, networking> {Berkeley} {Unix} networking {socket}
	library routine to satisfy a connection request from a remote
	{host}.  A specified socket on the local host (which must be
	capable of accepting the connection) is connected to the
	requesting socket on the remote host.  The remote socket's
	socket address is returned.

	{Unix manual pages}: accept(2), connect(2).

	(1994-11-08)

1. <programming> A collection of identically typed data items
	distinguished by their indices (or "subscripts").  The number
	of dimensions an array can have depends on the language but is
	usually unlimited.

	An array is a kind of {aggregate} data type.  A single
	ordinary variable (a "{scalar}") could be considered as a
	zero-dimensional array.  A one-dimensional array is also known
	as a "{vector}".

	A reference to an array element is written something like
	A[i,j,k] where A is the array name and i, j and k are the
	indices.  The {C} language is peculiar in that each index is
	written in separate brackets, e.g. A[i][j][k].  This expresses
	the fact that, in C, an N-dimensional array is actually a
	vector, each of whose elements is an N-1 dimensional array.

	Elements of an array are usually stored contiguously.
	Languages differ as to whether the leftmost or rightmost index
	varies most rapidly, i.e. whether each row is stored
	contiguously or each column (for a 2D array).

	Arrays are appropriate for storing data which must be accessed
	in an unpredictable order, in contrast to {lists} which are
	best when accessed sequentially.

	See also {associative array}.

	2. <architecture> A {processor array}, not to be confused with
	an {array processor}.

	(1995-01-25)

<programming> (Or "parameter") A name in a {function} or
	{subroutine} definition that is replaced by, or bound to, the
	corresponding {actual argument} when the function or
	subroutine is called.  In many languages formal arguments
	behave like {local variables} which get initialised on entry.

	See: {argument}.

	(2002-07-02)

<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)

<programming> (Or "computer program", "program", "code") The
	instructions executed by a computer, as opposed to the
	physical device on which they run (the "{hardware}").

	The term was coined by the eminent statistician, {John Tukey}.

	Programs stored on {non-volatile storage} built from
	{integrated circuits} (e.g. {ROM} or {PROM}) are usually
	called {firmware}.

	Software can be split into two main types - {system software}
	and application software or {application programs}.  System
	software is any software required to support the production or
	execution of application programs but which is not specific to
	any particular application.  Examples of system software would
	include the {operating system}, {compilers}, editors and
	sorting programs.

	Examples of application programs would include an accounts
	package or a {CAD} program.  Other broad classes of
	application software include {real-time} software, {business
	software}, scientific and engineering software, {embedded
	software}, personal computer software and {artificial
	intelligence} software.

	Software includes both {source code} written by humans and
	executable {machine code} produced by {assemblers} or
	{compilers}.  It does not usually include the data processed
	by programs unless this is in a format such as {multimedia}
	which depends on the use of computers for its presentation.
	This distinction becomes unclear in cases such as {spread
	sheets} which can contain both instructions (formulae and
	{macros}) and data.  There are also various intermediate
	compiled or {semi-compiled}, forms of software such as
	{library} files and {byte-code}.

	Some claim that {documentation} (both paper and electronic) is
	also software.  Others go further and define software to be
	programs plus documentation though this does not correspond
	with common usage.

	The noun "program" describes a single, complete and
	more-or-less self-contained list of instructions, often stored
	in a single {file}, whereas "code" and "software" are
	uncountable nouns describing some number of instructions which
	may constitute one or more programs or part thereof.  Most
	programs, however, rely heavily on various kinds of {operating
	system} software for their execution.  The nounds "code" and
	"software" both refer to the same thing but "code" tends to
	suggest an interest in the implementation details whereas
	"software" is more of a user's term.

	(2002-07-21)

1. {application program}.

	2. {function application}.

<operating system, programming> The process of carrying out
	the {instructions} in a computer program by a computer.

	See also {dry run}.

	(1996-05-13)

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)

<programming> The multiple kilograms of macerated, pounded,
	steamed, bleached, and pressed trees that accompany most
	modern software or hardware products (see also {tree-killer}).
	Hackers seldom read paper documentation and (too) often resist
	writing it; they prefer theirs to be terse and {on-line}.  A
	common comment on this predilection is "You can't {grep} dead
	trees".

	See {drool-proof paper}, {verbiage}, {treeware}.

	[{Jargon File}]

	(2003-10-25)

<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)

1. <file system> {hard link} or {symbolic link}.

	2. <hypertext> {hyperlink}.

	(1997-10-22)

<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)

<storage> A {byte}, {word} or other small unit of storage
	space in a computer's {main memory} that is identified by its
	starting {address} (and size).

	(1999-04-19)

1. <tool, compression> To extract files from an archive
	created with {PKWare}'s {PKZIP} archiver.

	2. <tool, compression> A program to list, test, or extract
	files from a {ZIP} archive, commonly found on {MS-DOS}
	systems.  zip, creates ZIP archives; both programs are
	compatible with archives created by {PKWARE}'s {PKZIP} and
	{PKUNZIP} for {MS-DOS}.

	(1995-03-06)

<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)

<networking> (Note: not capitalised) Any set of networks
	interconnected with {routers}.  The {Internet} is the biggest
	example of an internet.

	(1996-09-17)