1. A discrepancy between a computed, observed, or measured
	value or condition and the true, specified, or theoretically
	correct value or condition.

	2. <programming> A mental mistake made by a programmer that
	may result in a program {fault}.

	3. (verb) What a program does when it stops as result of a
	programming error.

	(2000-03-28)

<programming> (Or "procedure") A sequence of {instructions}
	for performing a particular task.  Most programming languages,
	including most {machine languages}, allow the programmer to
	define subroutines.  This allows the subroutine code to be
	called from multiple places, even from within itself (in which
	case it is called {recursive}).  The programming language
	implementation takes care of returning control to (just after)
	the calling location, usually with the support of call and
	return instructions at {machine language} level.

	Most languages also allow {arguments} to be passed to the
	subroutine, and one, or occasionally more, {return values} to
	be passed back.

	A {function} is often very similar to a subroutine, the main
	difference being that it is called chiefly for its return
	value, rather than for any {side effects}.

	(1996-10-01)

1. A program which provides some service to other ({client})
	programs.  The connection between client and server is
	normally by means of {message passing}, often over a
	{network}, and uses some {protocol} to encode the client's
	requests and the server's responses.  The server may run
	continuously (as a {daemon}), waiting for requests to arrive
	or it may be invoked by some higher level daemon which
	controls a number of specific servers ({inetd} on {Unix}).

	There are many servers associated with the {Internet}, such as
	those for {HTTP}, {Network File System}, {Network Information
	Service} (NIS), {Domain Name System} (DNS), {FTP}, {news},
	{finger}, {Network Time Protocol}.  On Unix, a long list can
	be found in /etc/services or in the {NIS} database "services".
	See {client-server}.

	2. A computer which provides some service for other computers
	connected to it via a network.  The most common example is a
	{file server} which has a local disk and services requests
	from remote clients to read and write files on that disk,
	often using {Sun}'s {Network File System} (NFS) {protocol} or
	{Novell Netware} on {PCs}.  Another common example is a {web
	server}.

	[{Jargon File}]

	(2003-12-29)

<language, database, standard> /S Q L/ An industry-standard
	language for creating, updating and, querying {relational
	database management systems}.

	SQL was developed by {IBM} in the 1970s for use in {System R}.
	It is the {de facto standard} as well as being an {ISO} and
	{ANSI} {standard}.  It is often embedded in general purpose
	programming languages.

	The first SQL standard, in 1986, provided basic language
	constructs for defining and manipulating {tables} of data; a
	revision in 1989 added language extensions for {referential
	integrity} and generalised {integrity} {constraints}.  Another
	revision in 1992 provided facilities for {schema} manipulation
	and {data administration}, as well as substantial enhancements
	for data definition and data manipulation.

	Development is currently underway to enhance SQL into a
	computationally complete language for the definition and
	management of {persistent}, complex objects.  This includes:
	generalisation and specialisation hierarchies, {multiple
	inheritance}, user defined {data types}, {triggers} and
	{assertions}, support for {knowledge based systems},
	{recursive query expressions}, and additional data
	administration tools.  It also includes the specification of
	{abstract data types} (ADTs), object identifiers, {methods},
	{inheritance}, {polymorphism}, {encapsulation}, and all of the
	other facilities normally associated with object data
	management.

	The emerging {SQL3} standard is expected to be complete in
	1998.

	According to Allen G. Taylor, SQL does _not_ stand for
	"Structured Query Language".  That, like "SEQUEL" (and its
	pronunciation /see'kw*l/), was just another unofficial name
	for a precursor of SQL.  However, the IBM SQL Reference manual
	for DB2 and Craig Mullins's "DB2 Developer's Guide" say SQL
	_does_ stand for "Structured Query Language".

	{SQL Standards (http://www.jcc.com/sql_stnd.html)}.

	{An SQL parser
	(ftp://ftp.ora.com/published/oreilly/nutshell/lexyacc/)} is
	described in "Lex & Yacc", by Levine, Mason & Brown published
	by O'Reilly.

	{The 1995 SQL Reunion: People, Projects, and Politics
	(http://www.mcjones.org/System_R/SQL_Reunion_95/)}.

	["A Guide to the SQL Standard", C.J. Date, A-W 1987].

	["SQL for Dummies", Allen G. Taylor, IDG Books Worldwide].

	(2005-11-17)

<database, programming> (JDBC) Part of the {Java Development
	Kit} which defines an {application programming interface} for
	{Java} for standard {SQL} access to {databases} from Java
	{programs}.

	{Home
	(http://java.sun.com/products/jdk/1.1/docs/guide/jdbc/index.html)}.

	{FAQ (http://www.yoyoweb.com/Javanese/JDBC/FAQ.html)}.

	See also {Open Database Connectivity}.

	(1997-09-04)

<operating system> See {Microsoft Windows}, {Windows NT}.

	(1997-11-23)

<security> The verification of the identity of a person or
	process.  In a communication system, authentication verifies
	that messages really come from their stated source, like the
	signature on a (paper) letter.

	(2001-03-16)

<security> The {authentication} system of {MIT}'s Project
	{Athena}.  It is based on {symmetric key cryptography}.
	Adopted by {OSF} as the basis of security for {DME}.

	(1997-02-04)

<database> A collection of {records} in a {relational database}.

	(1997-06-04)

1. <operating system> {device driver}.

	2. <programming> The {main loop} of an event-processing
	program; the code that gets commands and dispatches them for
	execution.

	3. <tool> In the {TeX} world and the computerised typesetting
	world in general, a program that translates some
	device-independent or other common format to something a real
	device can actually understand.

	[{Jargon File}]

<networking, programming> Work performed (or offered) by a
	{server}.  This may mean simply serving simple requests for
	data to be sent or stored (as with {file servers}, {gopher} or
	{http} servers, {e-mail} servers, {finger} servers, {SQL}
	servers, etc.); or it may be more complex work, such as that
	of {irc} servers, print servers, {X Windows} servers, or
	process servers.

	E.g. "Access to the finger {service} is restricted to the
	local {subnet}, for security reasons".

	(1997-09-11)

<company> The biggest supplier of {operating systems} and
	other software for {IBM PC} compatibles.  Software products
	include {MS-DOS}, {Microsoft Windows}, {Windows NT},
	{Microsoft Access}, {LAN Manager}, {MS Client}, {SQL Server},
	{Open Data Base Connectivity} (ODBC), {MS Mail}, and {SNA
	Server} for Windows NT.

	Microsoft was founded as "Micro-soft" in 1975 by {Bill Gates}
	(now CEO) and his high school pal Paul Allen.  Their first
	product was a version of {BASIC} for the new {Altair} computer
	[which one?].  In 1980, {IBM} chose Microsoft to supply the
	{operating system} for the {IBM PC}.

	On the UK television program "The Net" in May 1994, {Bill
	Gates} said he was betting his company on the {information
	highway}".

	Quarterly sales $1293M, profits $362M (Aug 1994).

	{Home (http://www.microsoft.com/)}.
	{(ftp://ftp.microsoft.com/)}.

	{Interesting Info and Other Microsoft WWW Servers
	(http://www-drg.microsoft.com/devinfo.htm)}.

	{Microsoft Windows Developer Information
	(http://www-drg.microsoft.com/devinfo.htm)}.

	{Microsoft Research Group Information
	(http://www.research.microsoft.com)}.

	{Win_News
	(http://www.microsoft.com/chicago/ms-www/ms-intro.htm)}.
	maintained by the Personal Operating Systems Division to
	distribute information on {Microsoft Windows}, {MS-DOS} and
	{Windows 95}.

	(1998-11-06)

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

	See also {dry run}.

	(1996-05-13)

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

	See also {dry run}.

	(1996-05-13)

1. <messaging> One point-to-point transmission in a series
	required to get a message from point A to point B on a {store
	and forward} network.  On such networks (including {UUCPNET}
	and {FidoNet}), an important inter-machine metric is the hop
	count of the shortest path between them.  This can be more
	significant than their geographical separation.

	Each {exclamation mark} in a {bang path} represents one hop.

	2. <networking> One direct host-to-host connection forming
	part of the route between two hosts in a {routed} {network}
	such as the {Internet}.  Some {protocols} place an upper limit
	on the hop count in order to detect routing loops.

	3. <jargon, networking> To {log in} to a {remote} computer,
	especially via {rlogin} or {telnet}.  "I'll hop over to foovax
	to FTP that."

	[{Jargon File}]

	(1997-06-25)

<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)

<World-Wide Web, database, tool> {Allaire Corporation}'s
	commercial {database} application development tool that allows
	{databases} to have a {World-Wide Web} {interface}, so a
	database can be queried and updated using a {web browser}.

	The ColdFusion Server application runs on the {web server} and
	has access to a {database}.  ColdFusion files on the web
	server are {HTML} pages with additional ColdFusion commands to
	{query} or {update} the database, written in {CFML}.  When the
	page is requested by the user, the {web server} passes the
	page to the Cold Fusion application, which executes the {CFML}
	commands, places the results of the {CFML} commands in the
	{HTML} file, and returns the page to the {web server}.  The
	page returned to the {web server} is now an ordinary {HTML}
	file, and it is sent to the user.

	Examples of ColdFusion applications include order entry, event
	registration, catalogue search, directories, calendars, and
	interactive training.  ColdFusion applications are robust
	because all database interactions are encapsulated in a single
	industrial-strength {CGI} script.  The formatting and
	presentation can be modified and revised at any time (as
	opposed to having to edit and recompile {source code}).

	ColdFusion Server can connect with any database that supports
	{ODBC} or {OLE DB} or one that has a native database driver.
	Native database drivers are available for {Oracle} and
	{Sybase} databases.

	ColdFusion is available for {Windows}, {Solaris}, and {HP-UX}.
	A {development environment} for creating ColdFusion files,
	called ColdFusion Studio, is also available for {Windows}.

	Current version: MX(6), as of 2003-07-11.

	The {filename extension} for ColdFusion files is .cfm

	{Home (http://www.coldfusion.com/)}.

	(2003-07-27)

<standard, database> (ODBC) A {standard} for accessing
	different {database} systems.  There are interfaces for
	{Visual Basic}, {Visual C++}, {SQL} and the ODBC driver pack
	contains drivers for the {Access}, {Paradox}, {dBase}, Text,
	{Excel} and {Btrieve} databases.

	An application can submit statements to ODBC using the ODBC
	flavor of SQL.  ODBC then translates these to whatever flavor
	the database understands.

	ODBC 1.0 was released in September 1992.

	ODBC is based on {Call-Level Interface} and was defined by the
	{SQL Access Group}.  {Microsoft} was one member of the group
	and was the first company to release a commercial product
	based on its work (under {Microsoft Windows}) but ODBC is not
	a Microsoft standard (as many people believe).

	ODBC drivers and development tools are available now for
	{Microsoft Windows}, {Unix}, {OS/2}, and {Macintosh}.

	[On-line document?]

	["Unix Review", Aug 1995].

	(1996-05-27)

After-sale handholding; something many software vendors
	promise but few deliver.  To hackers, most support people are
	useless - because by the time a hacker calls support he or she
	will usually know the software and the relevant manuals better
	than the support people (sadly, this is *not* a joke or
	exaggeration).  A hacker's idea of "support" is a tte--tte
	or exchange of {electronic mail} with the software's designer.

	[{Jargon File}]

	(1995-02-15)

<jargon> To transfer data from one computer to another.
	Downloading usually refers to transfer from a larger "host"
	system (especially a {server} or {mainframe}) to a smaller
	"client" system, especially a {microcomputer} or specialised
	peripheral, and "{upload}" usually means from small to large.

	Others hold that, technically, download means "receive" and
	upload means "send", irrespective of the size of the systems
	involved.

	Note that in communications between ground and space,
	space-to-earth transmission is always "down" and the reverse
	"up", regardless of size.  So far the in-space machines have
	invariably been smaller; thus the upload/download distinction
	has been reversed from its usual sense.

	[{Jargon File}]

	(2003-11-04)

<protocol> {Transmission Control Protocol} over
	{Internet Protocol}.

	The {de facto} {standard} {Ethernet} {protocols} incorporated
	into {4.2BSD} {Unix}.  TCP/IP was developed by {DARPA} for
	{internetworking} and encompasses both {network layer} and
	{transport layer} protocols.  While {TCP} and {IP} specify two
	protocols at specific {protocol layers}, TCP/IP is often used
	to refer to the entire {DoD} {protocol} suite based upon
	these, including {telnet}, {FTP}, {UDP} and {RDP}.

	See also {ICMP}, {SMTP}, {SNMP}.

	(1995-03-17)

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}]

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)

<jargon> A {marketroid} term for something he wants to sell
	you without bothering you with the often dizzying distinctions
	between {hardware}, {software}, {services}, {applications},
	{file formats}, companies, brand names and {operating
	systems}.

	"{Flash} is a perfect image-streaming solution."  "What is
	it?"  "Um...  about a thousand dollars."

	See also: {technology}.

	(1998-07-07)

<programming> One of a sequence of copies of a program, each
	incorporating new modifications.  Each version is usually
	identified by a number, commonly of the form X.Y where X is
	the major version number and Y is the release number.
	Typically an increment in X (with Y reset to zero) signifies a
	substantial increase in the function of the program or a
	partial or total re-implementation, whereas Y increases each
	time the progam is changed in any way and re-released.

	Version numbers are useful so that the user can know if the
	program has changed ({bugs} have been fixed or new functions
	added) since he obtained his copy and the programmer can tell
	if a bug report relates to the current version.  It is thus
	always important to state the version when reporting bugs.
	Statements about compatibility between different software
	components should always say which versions they apply to.

	See {change management}.

	(1997-12-07)

<World-Wide Web> (URL, previously "Universal") A {standard}
	way of specifying the location of an object, typically a {web
	page}, on the {Internet}.  Other types of object are described
	below.  URLs are the form of address used on the {World-Wide
	Web}.  They are used in {HTML} documents to specify the target
	of a {hyperlink} which is often another HTML document
	(possibly stored on another computer).

	Here are some example URLs:

	 http://www.w3.org/default.html
	 http://www.acme.co.uk:8080/images/map.gif
	 http://www.foldoc.org/?Uniform+Resource+Locator
	 http://www.w3.org/default.html#Introduction
	 ftp://wuarchive.wustl.edu/mirrors/msdos/graphics/gifkit.zip
	 ftp://spy:secret@ftp.acme.com/pub/topsecret/weapon.tgz
	 mailto:fred@doc.ic.ac.uk
	 news:alt.hypertext
	 telnet://dra.com

	The part before the first colon specifies the access scheme or
	{protocol}.  Commonly implemented schemes include: {ftp},
	{http} (World-Wide Web), {gopher} or {WAIS}.  The "file"
	scheme should only be used to refer to a file on the same
	host.  Other less commonly used schemes include {news},
	{telnet} or mailto ({e-mail}).

	The part after the colon is interpreted according to the
	access scheme.  In general, two slashes after the colon
	introduce a {hostname} (host:port is also valid, or for {FTP}
	user:passwd@host or user@host).  The {port} number is usually
	omitted and defaults to the standard port for the scheme,
	e.g. port 80 for HTTP.

	For an HTTP or FTP URL the next part is a {pathname} which is
	usually related to the pathname of a file on the server.  The
	file can contain any type of data but only certain types are
	interpreted directly by most {browsers}.  These include {HTML}
	and images in {gif} or {jpeg} format.  The file's type is
	given by a {MIME} type in the HTTP headers returned by the
	server, e.g. "text/html", "image/gif", and is usually also
	indicated by its {filename extension}.  A file whose type is
	not recognised directly by the browser may be passed to an
	external "viewer" {application}, e.g. a sound player.

	The last (optional) part of the URL may be a query string
	preceded by "?" or a "fragment identifier" preceded by "#".
	The later indicates a particular position within the specified
	document.

	Only alphanumerics, reserved characters (:/?#"<>%+) used for
	their reserved purposes and "$", "-", "_", ".", "&", "+" are
	safe and may be transmitted unencoded.  Other characters are
	encoded as a "%" followed by two {hexadecimal} digits.  Space
	may also be encoded as "+".  Standard {SGML} "&<name>;"
	character entity encodings (e.g. "&eacute;") are also accepted
	when URLs are embedded in HTML.  The terminating semicolon may
	be omitted if &<name> is followed by a non-letter character.

	{The authoritative W3C URL specification
	(http://www.w3.org/hypertext/WWW/Addressing/Addressing.html)}.

	(2000-02-17)

1. The {supervisor} program or {operating system} on a
	computer.

	2. The entire computer system, including input/output devices,
	the {supervisor} program or {operating system} and possibly
	other {software}.

	3. Any large program.

	4. Any method or {algorithm}.

	[{Jargon File}]

1. <networking> A {bang path} or explicitly routed {Internet
	address}; a node-by-node specification of a link between two
	machines.

	2. <file system> {pathname}.

	3. <operating system>  The list of directories the kernel
	(under {Unix}) or the command interpreter (under {MS-DOS})
	searches for {executables}.  It is stored as part of the
	{environment} in both operating systems.

	Other, similar constructs abound under Unix; the {C}
	{preprocessor}, for example, uses such a search path to locate
	"#include" files.

	[{Jargon File}]

	(1996-11-21)

See also {complete graph}, {complete inference system},
	{complete lattice}, {complete metric space}, {complete partial
	ordering}, {complete theory}.

	[1. or 2. or both?]

	(1996-04-24)