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)

1. <programming, operating system> A formal name used in
	{source code} to refer to a {variable}, {function},
	{procedure}, {package}, etc. or in an {operating system} to
	refer to a {process}, {user}, {group}, etc.

	Each different type of entity may have a different range of
	valid identifiers or "name space".  For example, an identifier
	in {C} is a series of one or more letters, digits and
	{underscores} that does not begin with a digit.  An identifier
	has a type, e.g. integer variable, {hash}, {variant} and a
	{scope}, e.g. {block}, {global}.

	(2006-05-29)

	2. <database> (id) A {primary key}.  The column containing a
	table's primary key is frequently named after the table with
	"_id" appended, e.g. "customer_id".

	(2006-05-29)

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)

<operating system> A character string which tells a program to
	perform a specific action.  Most commands take {arguments}
	which either modify the action performed or supply it with
	input.  Commands may be typed by the user or read from a file
	by a {command interpreter}.  It is also common to refer to
	menu items as commands.

	(1997-06-21)

1. <hardware> An electrical conductor.  For distances larger
	than a breadbox, a single line may consist of two electrical
	conductors in twisted, parallel, or concentric arrangement
	used to transport one logical signal.

	By extension, a (usually physical) medium such as an {optical
	fibre} which carries a signal.

	(1995-09-29)

A message sent to a {newsgroup} or {mailing list} (may also be
	called "a post") or the act of sending it.  Distinguished from
	a "letter" or ordinary {electronic mail} message by the fact
	that it is broadcast rather than point-to-point.  It is not
	clear whether messages sent to a small mailing list are
	postings or e-mail; perhaps the best dividing line is that if
	you don't know the names of all the potential recipients, it
	is a posting.

	[{Jargon File}]

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

	(1997-11-20)

<hardware> A {SCSI} device that executes a command from a
	{SCSI initiator} to perform some task.  Typically the target
	is a SCSI peripheral device but the {host adapter} can also be
	a target.

	(1999-02-10)

<file system> An element of data storage in a {file system}.

	The history of computing is rich in varied kinds of files and
	{file systems}, whether ornate (e.g., {Macintosh file system}
	for a well-known case) or deficient (e.g., many simple
	pre-1980s file systems don't allow {directories}).

	However, the prototypical file has these characteristics:

	* It is a single sequence of bytes (but consider {Macintosh}
	{resource forks}).

	* It has a finite length, unlike, e.g. a {Unix} {device}.

	* It is stored in a {non-volatile storage} medium (but see
	{ramdrive}).

	* It exists (nominally) in a {directory}.

	* It has a name that it can be referred to by in file
	operations, possibly in combination with its {path}.

	Additionally, a file system may associate other information
	with a file, such as {permission} bits or other {file
	attributes}; timestamps for file creation, last revision, and
	last access; revision numbers (a` la VMS), and other kinds of
	{magic}.

	Compare: {document}.

	(1997-04-08)

<programming> In {subject-oriented programming}, a subject is
	a collection of {classes} or class fragments whose {class
	hierarchy} models its domain in its own, subjective way.  A
	subject may be a complete application in itself, or it may be
	an incomplete fragment that must be composed with other
	subjects to produce a complete application.  Subject
	composition combines class hierarchies to produce new subjects
	that incorporate functionality from existing subjects.

	(1999-08-31)