<programming> To add {features} to a program, especially
	through the use of {hooks}.

	"Extend" is very often used in the phrase "extend the
	{functionality} of a program."

	{Plug-ins} are one form of extension.

	(1997-06-21)

<standard> Standards are necessary for {interworking},
	{portability}, and {reusability}.  They may be {de facto
	standards} for various communities, or officially recognised
	national or international standards.

	{Andrew Tanenbaum}, in his Computer Networks book, once said,
	"The nice thing about standards is that there are so many of
	them to choose from", a reference to the fact that competing
	standards become a source of confusion, division,
	obsolescence, and duplication of effort instead of an
	enhancement to the usefulness of products.

	Some bodies concerned in one way or another with computing
	standards are {IAB} ({RFC} and {STD}), {ISO}, {ANSI}, {DoD},
	{ECMA}, {IEEE}, {IETF}, {OSF}, {W3C}.

	(1999-07-06)

<character> (Or "ctrl", "^") One (or a pair) of {modifier
	keys} found on all modern {keyboards}.  If the control key is
	held down while pressing and releasing certain other keys then
	a "{control character}" is generated, e.g. holding control and
	hitting "A" generates control-A ({ASCII} code 1).  The ASCII
	code for the control character is generally 64 less than that
	for the unmodified character.

	The control key does not generate any character on its own but
	most modern keyboards and {operating systems} allow a program
	to tell whether each of the individual keys on the keyboard
	(including modifier keys) is pressed at any time.

	Control characters mostly have some kind of "non-printing"
	effect on the output such as ringing the bell (Control-G) or
	advancing to the next line (Control-J).  Most have alternative
	names suggesting these functions (Bell, Line Feed, etc.).

	See {ASCII character table}.

	(1997-07-10)

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

	See also {dry run}.

	(1996-05-13)

<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)

<specification, business, programming> (EJB) A {server}-side
	{component architecture} for writing reusable {business logic}
	and {portable} {enterprise} applications.  EJB is the basis of
	{Sun}'s {Java 2 Platform, Enterprise Edition} (J2EE).

	Enterprise JavaBean components are written entirely in {Java}
	and run on any EJB compliant server.  They are {operating
	system}, {platform}, and {middleware} independent, preventing
	vendor {lock-in}.

	EJB servers provide system-level services (the "plumbing")
	such as {transactions}, security, {threading}, and
	{persistence}.

	The EJB architecture is inherently transactional,
	{distributed}, {multi-tier}, {scalable}, secure, and {wire
	protocol} neutral - any {protocol} can be used: {IIOP},
	{JRMP}, {HTTP}, {DCOM} etc.  EJB 1.1 requires {RMI} for
	communication with components.  EJB 2.0 is expected to require
	support for RMI/IIOP.

	EJB applications can serve assorted clients: {browsers}, Java,
	{ActiveX}, {CORBA} etc.  EJB can be used to wrap {legacy
	systems}.

	EJB 1.1 was released in December 1999.  EJB 2.0 is in
	development.

	Sun claims broad industry adoption.  30 vendors are shipping
	server products implementing EJB.  Supporting vendors include
	{IBM}, {Fujitsu}, {Sybase}, {Borland}, {Oracle}, and
	{Symantec}.

	An alternative is Microsoft's MTS ({Microsoft Transaction
	Server}).

	{Home (http://java.sun.com/products/ejb/)}.

	{FAQ (http://java.sun.com/products/ejb/faq.html)}.

	(2000-04-20)

<file system> (Or "file mode") The ability to access (read,
	write, execute, traverse, etc.) a {file} or {directory}.
	Depending on the {operating system}, each file may have
	different permissions for different kinds of access and
	different users or groups of users.

	{chmod} ("change mode") is the {UNIX} command to change
	permissions.

	(2000-12-07)

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)

1. <language> An English-like query language used in the
	{Pick} {operating system}.

	2. <database, product> {Microsoft Access}.

	(1994-11-08)

1. <data, graphics> Data representing a two-dimensional scene.
	A digital image is composed of {pixels} arranged in a
	rectangular array with a certain height and width.  Each pixel
	may consist of one or more {bits} of information, representing
	the brightness of the image at that point and possibly
	including colour information encoded as {RGB} triples.

	{Images} are usually taken from the real world via a {digital
	camera}, {frame grabber}, or {scanner}; or they may be
	generated by computer, e.g. by {ray tracing} software.

	See also {image formats}, {image processing}.

	(1994-10-21)

	2. <mathematics> The image (or range) of a {function} is the
	set of values obtained by applying the function to all
	elements of its {domain}.  So, if f : D -> C then the set f(D)
	= \{ f(d) | d in D \} is the image of D under f.  The image is
	a subset of C, the {codomain}.

	(2000-01-19)

1. <programming> An {address}, from the point of view of a
	programming language.  A pointer may be typed, with its {type}
	indicating the type of data to which it points.

	The terms "pointer" and "reference" are generally
	interchangable although particular programming languages often
	differentiate these two in subtle ways.  For example, {Perl}
	always calls them references, never pointers.  Conversely, in
	C, "pointer" is used, although "a reference" is often used to
	denote the concept that a pointer implements.

	{Anthony Hoare} once said:

	Pointers are like jumps, leading wildly from one part of the
	data structure to another.  Their introduction into high-level
	languages has been a step backward from which we may never
	recover.

	[C.A.R.Hoare "Hints on Programming Language Design", 1973,
	Prentice-Hall collection of essays and papers by Tony Hoare].

	2. <operating system> (Or "mouse pointer") An {icon}, usually
	a small arrow, that moves on the screen in response to
	movement of a {pointing device}, typically a {mouse}.  The
	pointer shows the user which object on the screen will be
	selected etc. when a mouse button is clicked.

	(1999-07-07)