1. <mathematics> (Or "map", "mapping") If D and C are sets
	(the domain and codomain) then a function f from D to C,
	normally written "f : D -> C" is a subset of D x C such that:

	1. For each d in D there exists some c in C such that (d,c) is
	an element of f.  I.e. the function is defined for every
	element of D.

	2. For each d in D, c1 and c2 in C, if both (d,c1) and (d,c2)
	are elements of f then c1 = c2.  I.e. the function is uniquely
	defined for every element of D.

	See also {image}, {inverse}, {partial function}.

	2. <programming> Computing usage derives from the mathematical
	term but is much less strict.  In programming (except in
	{functional programming}), a function may return different
	values each time it is called with the same argument values
	and may have {side effects}.

	A {procedure} is a function which returns no value but has
	only {side-effects}.  The {C} language, for example, has no
	procedures, only functions.  {ANSI C} even defines a {type},
	{void}, for the result of a function that has no result.

	(1996-09-01)

1. One of a fixed set of symbols built into the syntax of a
	language.  Typical keywords would be if, then, else, print,
	goto, while, switch.  There are usually restrictions about
	reusing keywords as names for user-defined objects such as
	variables or procedures.  Languages vary as to what is
	provided as a keyword and what is a library routine, for
	example some languages provide keywords for input/output
	operations whereas in others these are library routines.

	2. A small set of words designed to convey the subject of a
	technical article.  Some publications specify a fixed set of
	keywords from which those for a particular article should be
	chosen.

<data, database, programming> An {ordered set} of {fields},
	usually stored contiguously.  The term is used with similar
	meaning in several different contexts.  In a file, a "record"
	probably has some fixed length, in contrast to a "line" which
	may have any length and is terminated by some {End Of Line}
	sequence).  A {database} record is also called a "row".  In a
	{spreadsheet} it is always called a "row".  Some programming
	languages use the term to mean a type composed of fields of
	several other types ({C} calls this a "{struct}").

	In all these cases, a record represents an entity with certain
	field values.

	Fields may be of a fixed width ({bits} or {characters}) or
	they may be separated by a {delimiter} character, often
	{comma} ({CSV}) or {HT} ({TSV}).

	In a database the list of values of a given field from all
	records is called a column.

	(2002-03-22)

<data> A named value or relationship that exists for some or
	all {instances} of some {entity} and is directly associated
	with that instance.

	Examples include the {href} attribute of an {HTML} {anchor}
	element, the columns of a database table considered as
	attributes of each row, and the {members} ({properties} and
	{methods} of an {object} in {OOP}.  This contrasts with the
	contents of some kind of container (e.g. an array), which are
	typically not named.  The contents of an {associative array},
	though they might be considered to be named by their key
	values, are not normally thought of as attributes.

	(2001-02-04)

<language, text> An {SGML}, {HTML}, or {XML} {token}
	representing the beginning (start tag: "<p ...>") or end (end
	tag: "</p>") of an {element}.  In normal SGML {syntax} (and
	always in {XML}), a tag starts with a "<" and ends with an
	">".

	In {HTML} jargon, the term "tag" is often used for an
	"{element}".

	(2001-01-31)

(TOP) An {applications layer} {network} {application} and
	{protocol stack} for {office automation} developed by {Boeing}
	following the {OSI model}.  This {protocol} is very similar to
	{MAP} except at the lowest levels, where it uses {Ethernet}
	({IEEE} {802.3}) rather than {Token Bus} ({IEEE} {802.4}).

Not working properly (of programs).

1. <chat> {Unix}'s simple {talk} command and {protocol}.
	write has been largely superseded by {talk} and then {irc}.

	An enhancement, {RWP}, has been proposed.

	2. <tool> A simple {text editor} for {Windows}.

	(1998-04-28)

A group G is a non-empty {set} upon which a {binary} operator
	* is defined with the following properties for all a,b,c in G:

	  Closure:     G is closed under *,  a*b in G
	  Associative: * is associative on G, (a*b)*c = a*(b*c)
	  Identity:    There is an identity element  e  such that
		       a*e = e*a = a.
	  Inverse:     Every element has a unique inverse a' such that
		       a * a' = a' * a = e.  The inverse is usually
		       written with a superscript -1.

	(1998-10-03)

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)