<operating system> A list from which the user may select an
	operation to be performed.  This is often done with a {mouse}
	or other pointing device under a {graphical user interface}
	but may also be controlled from the keyboard.

	Menus are very convenient for beginners because they show what
	commands are available and make experimentating with a new
	program easy, often reducing the need for user documentation.
	Experienced users however, often prefer keyboard commands,
	especially for frequently user operations, because they are
	faster to use.  In situations such as text entry where the
	keyboard must be used anyway, having to move your hand to the
	mouse to invoke a menu operation is slow.

	There are many different ways of presenting menus but the most
	common are the {menu bar} (with {pull-down menus}) and the
	{context-sensitive menu}.

	The term "menu" tends to be reserved for a list of actions or
	global options, whereas a "{list box}" or other graphical
	{widget} might present any kind of choice.

	See also {menuitis}.

	(1994-12-02)

1. <mathematics> {Base} two.  A number representation
	consisting of zeros and ones used by practically all computers
	because of its ease of implementation using digital
	electronics and {Boolean algebra}.

	2. <file format> {binary file}.

	3. <programming> A description of an {operator} which takes
	two {arguments}.  See also {unary}, {ternary}.

	(2005-02-21)

1. Executable code, especially a "pure code" portion shared
	between multiple instances of a program running in a
	{multitasking} {operating system}.

	Compare {English}.

	2. Textual material in the mainstream sense; data in ordinary
	{ASCII} or {EBCDIC} representation (see {flat ASCII}).  "Those
	are text files; you can review them using the editor."

	These two contradictory senses confuse hackers too.

	[{Jargon File}]

	(1995-03-16)

To change a {bit} from whatever state it is in to the other
	state; to change from 1 to 0 or from 0 to 1.  This comes from
	"toggle switches", such as standard light switches, though the
	word "toggle" actually refers to the mechanism that keeps the
	switch in the position to which it is flipped rather than to
	the fact that the switch has two positions.  There are four
	things you can do to a bit: set it (force it to be 1), clear
	(or zero) it, leave it alone, or toggle it.

	[{Jargon File}]

	(1994-12-12)

<software> (Or "option", "flag", "switch", "option switch") An
	argument to a command that modifies its function rather than
	providing data.  Options generally start with "-" in {Unix} or
	"/" in {MS-DOS}.  This is usually followed by a single letter
	or occasionally a digit.

	Some commands require each option to be a separate argument,
	introduced by a new "-" or "/", others allow multiple option
	letters to be concatenated into a single argument with a
	single "-" or "/", e.g. "ls -al".  A few Unix commands
	(e.g. {ar}, {tar}) allow the "-" to be omitted.  Some options
	may or must be followed by a value, e.g. "cc prog.c -o prog",
	sometimes with and sometimes without an intervening space.

	{getopt} and {getopts} are commands for parsing command line
	options.  There is also a {C} library routine called getopt
	for the same purpose.

	(1996-12-11)

<computer> 1. A computer; especially in the construction "foo
	box" where foo is some functional qualifier, like "graphics",
	or the name of an {operating system} (thus, "{Unix} box",
	"{MS-DOS} box", etc.)  "We preprocess the data on Unix boxes
	before handing it up to the {mainframe}."  The plural
	"{boxen}" is sometimes seen.

	2. Without qualification in an {IBM} {SNA} site, "box" refers
	specifically to an {IBM} {front-end processor}.

	[{Jargon File}]

	(1994-11-29)

<hardware> To press and release a {button} on a {mouse} or
	other {pointing device}.  This generates an {event}, also
	specifying the screen position, which is processed by the
	{window manager} or {application program}.  On a mouse with
	more than one button, the unqualified term usually implies
	pressing the left-most button (with the right index finger),
	other buttons would be qualified, e.g. "{right-click}".
	{Keyboard} modifiers may also be used, e.g. "shift-click",
	meaning to hold down the shift key on the keyboard while
	clicking the mouse button.

	If the mouse moves while the button is pressed then this is a
	{drag}.

	(1995-03-14)

1. <electronics> {push-button}.

	2. <operating system> A graphical representation of an
	electrical {push-button} appearing as part of a {graphical
	user interface}.  Moving the {mouse pointer} over the
	graphical button and pressing one of the physical mouse
	buttons starts some software action such as closing a window
	or deleting a file.

	See also {radio button}.

	(1997-07-07)

<electronics> The quantity of {charge} per unit time, measured
	in Amperes (Amps, A).  By historical convention, the sign of
	current is positive for currents flowing from positive to
	negative {potential}, but experience indicates that electrons
	are negatively charged and flow in the opposite direction.

	(1995-10-05)

A language proposed by Cii {Honeywell-Bull} to meet the DoD
	{Ironman} requirements which led to {Ada}.  This language won
	in 1979.

	["On the GREEN Language Submitted to the DoD", E.W. Dijkstra,
	SIGPLAN Notices 13(10):16-21 (Oct 1978)].

	(1994-12-02)

<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)