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> An {object} adhering to a {component
	architecture}.

	(1997-11-20)

1. <hardware> {monitor}.

	2. <language> A vector of pointers to {activation records}.
	The Nth element points to the activation record containing
	variables declared at {lexical depth} N.  This allows faster
	access to variables from outer {scopes} than the alternative
	of linked activation records (but most variable accesses are
	either local or global or occasionally to the immediately
	enclosing scope).  Displays were used in some {ALGOL}
	implementations.

	(1996-02-22)

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> (CSS) An extension to {HTML} to allow styles,
	e.g. colour, {font}, size to be specified for certain elements
	of a {hypertext} document.  Style information can be included
	in-line in the HTML file or in a separate CSS file (which can
	then be easily shared by multiple HTML files).  Multiple
	levels of CSS can be used to allow selective overriding of
	styles.

	{Home (http://www.w3.org/Style/CSS/)}.

	(2000-07-26)

1. <data, programming> One of the items of data in an {array}.

	2. <language, text> One kind of node in an {SGML}, {HTML}, or
	{XML} {document} {tree}.  An SGML element is typically
	represented by a start {tag} ("<p>") and an end tag ("</p>").
	In some SGML implementations, some tags are omissible, as with
	"</p>" in {HTML}.

	The start tag can contain {attributes} ("<p lang="en-UK"
	class='stuff'>"), which are an unordered set of key-value
	bindings for that element.  Both the start tag and end tag for
	an element typically contain the "tag name" (also called the
	"{GI}" or generic identifier) for that element.

	In {XML}, an element is always represented either by an
	explicit start tag and end tag, or by an empty element tag
	("<img src='thing.{png}' alt='a dodad' />").

	Other kinds of SGML node are: a section of character data
	("foo"), a comment ("<!-- bar -->"), a markup declaration
	("<!ENTITY reg CDATA '&#174'>"), or a processing instruction
	("<?xml-stylesheet href="shop-english.xsl" type="text/xsl"
	?>").

	(2001-01-30)

<programming> A special value used in several languages to
	represent the thing referred to by an uninitialised pointer.

	<database> A special value that may be stored in some database
	columns to represent an unknown, missing, not applicable, or
	undefined value.  Nulls are treated completely differently
	from ordinary values when evaluating SQL expressions and there
	are several SQL constructs for dealing with nulls.

	(2003-06-17)

<data, database> An area of a {database} {record}, or
	{graphical user interface} {form}, into which a particular
	item of data is entered.

	Example usage: "The telephone number field is not really a
	numerical field", "Why do we need a four-digit field for the
	year?".

	A {database} {column} is the set of all instances of a given
	field from all records in a {table}.

	(1999-04-26)

<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)