Glossary

Introduction

This glossary is produced to help you understand the many terms–and in particular the myriad of acronyms–that can be encountered on this topic.

To keep this document reasonably small we have deliberately omitted common terms. In addition, the definitions have been kept brief. We recommend that you consult the glossaries found in other sources (see below) for more comprehensive definitions.

You are invited to submit words which you think should be included in future editions.

Glossary

abstract syntax: A description of a data structure that is independent of machine-oriented structures and encodings.
ACSE: Association Control Service Element. The method used in OSI for establishing a call between two applications. Checks the identities and contexts of the application entities, and could apply an authentication security check.

address mask: A bit mask used to select bits from an Internet address for subnet addressing. The mask is 32 bits long and selects the network portion of the Internet address and one or more bits of the local portion. Sometimes called subnet mask.

address resolution: A means for mapping Network Layer addresses onto
media-specific addresses. See ARP.

ADMD: Administration Management Domain. An X.400 Message Handling
System public service carrier. Examples: MCImail and ATTmail in the
U.S., British Telecom Gold400mail in the U.K. The ADMDs in all
countries worldwide together provide the X.400 backbone. See PRMD.

agent: In the client-server model, the part of the system that
performs information preparation and exchange on behalf of a client
or server application. See NMS, DUA, MTA.

ANSI: American National Standards Institute. The U.S.
standardization body. ANSI is a member of the International
Organization for Standardization (ISO)

AOW: Asia and Oceania Workshop. One of the three regional OSI
Implementors Workshops, equivalent to OIW and EWOS.

API: Application Program Interface. A set of calling conventions
defining how a service is invoked through a software package.

Application Layer: The top-most layer in the OSI Reference Model
providing such communication services as electronic mail and file
transfer.

ARP: Address Resolution Protocol. The Internet protocol used to
dynamically map Internet addresses to physical (hardware) addresses
on local area networks. Limited to networks that support hardware
broadcast.

ARPA: Advanced Research Projects Agency. Now called DARPA, the U.S.
government agency that funded the ARPANET.

ARPANET: A packet switched network developed in the early 1970s. The
“grandfather” of today’s Internet. ARPANET was decommissioned in
June 1990.

ASN.1: Abstract Syntax Notation One. The OSI language for describing
abstract syntax. See BER.

attribute: The form of information items provided by the X.500
Directory Service. The directory information base consists of
entries, each containing one or more attributes. Each attribute
consists of a type identifier together with one or more values. Each
directory Read operation can retrieve some or all attributes from a
designated entry.

Autonomous System: Internet (TCP/IP) terminology for a collection of
gateways (routers) that fall under one administrative entity and
cooperate using a common Interior Gateway Protocol (IGP). See
subnetwork.

backbone: The primary connectivity mechanism of a hierarchical
distributed system. All systems which have connectivity to an
intermediate system on the backbone are assured of connectivity to
each other. This does not prevent systems from setting up private
arrangements with each other to bypass the backbone for reasons of
cost, performance, or security.

Bart Simpson (R): Internet and OSI cult hero.

baseband: Characteristic of any network technology that uses a single
carrier frequency and requires all stations attached to the network
to participate in every transmission. See broadband.

BER: Basic Encoding Rules. Standard rules for encoding data units
described in ASN.1. Sometimes incorrectly lumped under the term
ASN.1, which properly refers only to the abstract syntax description
language, not the encoding technique.

big-endian: A format for storage or transmission of binary data in
which the most significant bit (or byte) comes first. The reverse
convention is called little-endian.

BITNET: Because It’s Time NETwork. An academic computer network
based originally on IBM mainframe systems interconnected via leased
9600 bps lines. BITNET has recently merged with CSNET, The
Computer+Science Network (another academic computer network) to form
CREN: The Corporation for Research and Educational Networking. See
CSNET.

BOC: Bell Operating Company. More commonly referred to as RBOC for
Regional Bell Operating Company. The local telephone company in each
of the seven U.S. regions.

bridge: A device that connects two or more physical networks and
forwards packets between them. Bridges can usually be made to filter
packets, that is, to forward only certain traffic. Related devices
are: repeaters which simply forward electrical signals from one cable
to another, and full-fledged routers which make routing decisions
based on several criteria. In OSI terminology, a bridge is a Data
Link Layer intermediate system. See repeater and router.

broadband: Characteristic of any network that multiplexes multiple,
independent network carriers onto a single cable. This is usually done using frequency division multiplexing. Broadband technology
allows several networks to coexist on one single cable; traffic from
one network does not interfere with traffic from another since the
“conversations” happen on different frequencies in the “ether,”
rather like the commercial radio system.

broadcast: A packet delivery system where a copy of a given packet is
given to all hosts attached to the network. Example: Ethernet.

BSD: Berkeley Software Distribution. Term used when describing
different versions of the Berkeley UNIX software, as in “4.3BSD
UNIX.”

catenet: A network in which hosts are connected to networks with
varying characteristics, and the networks are interconnected by
gateways (routers). The Internet is an example of a catenet. See
IONL.

CCITT: International Consultative Committee for Telegraphy and
Telephony. A unit of the International Telecommunications Union
(ITU) of the United Nations. An organization with representatives
from the PTTs of the world. CCITT produces technical standards,
known as “Recommendations,” for all internationally controlled
aspects of analog and digital communications. See X Recommendations.

CCR: Commitment, Concurrency, and Recovery. An OSI application
service element used to create atomic operations across distributed
systems. Used primarily to implement two-phase commit for
transactions and nonstop operations.

client-server model: A common way to describenetwork services and the
model user processes (programs) of those services. Examples include
the name-server/name-resolver paradigm of the DNS and file-
server/file-client relationships such as NFS and diskless hosts.

CLNP: Connectionless Network Protocol. The OSI protocol for
providing the OSI Connectionless Network Service (datagram service).
CLNP is the OSI equivalent to Internet IP, and is sometimes called
ISO IP.

CLTP: Connectionless Transport Protocol. Provides for end-to-end
Transport data addressing (via Transport selector) and error control
(via checksum), but cannot guarantee delivery or provide flow
control. The OSI equivalent of UDP.

CMIP: Common Management Information Protocol. The OSI network
management protocol.

CMOT: CMIP Over TCP. An effort to use the OSI network management
protocol to manage TCP/IP networks.

connectionless: The model of interconnection in which communication
takes place without first establishing a connection. Sometimes
(imprecisely) called datagram. Examples: LANs, Internet IP and OSI
CLNP, UDP, ordinary postcards.

connection-oriented: The model of interconnection in which
communication proceeds through three well-defined phases: connection
establishment, data transfer, connection release. Examples: X.25,
Internet TCP and OSI TP4, ordinary telephone calls.

core gateway: Historically, one of a set of gateways (routers)
operated by the Internet Network Operations Center at BBN. The core
gateway system forms a central part of Internet routing in that all
groups must advertise paths to their networks from a core gateway,
using the Exterior Gateway Protocol (EGP). See EGP, backbone.

COS: Corporation for Open Systems. A vendor and user group for
conformance testing, certification, and promotion of OSI products.

COSINE: Cooperation for Open Systems Interconnection Networking in
Europe. A program sponsored by the European Commission, aimed at
using OSI to tie together European research networks.

CREN: See BITNET and CSNET.

CSMA/CD: Carrier Sense Multiple Access with Collision Detection. The
access method used by local area networking technologies such as
Ethernet.

CSNET: Computer+Science Network. A large computer network, mostly in
the U.S. but with international connections. CSNET sites include
universities, research labs, and some commercial companies. Now
merged with BITNET to form CREN. See BITNET.

DARPA: Defense Advanced Research Projects Agency. The U.S.
government agency that funded the ARPANET.

Data Link Layer: The OSI layer that is responsible for data transfer
across a single physical connection, or series of bridged
connections, between two Network entities.

DCA: Defense Communications Agency. The government agency
responsible for the Defense Data Network (DDN).

DCE: Distributed Computing Environment. An architecture of standard
programming interfaces, conventions, and server functionalities
(e.g., naming, distributed file system, remote procedure call) for
distributing applications transparently across networks of
heterogeneous computers. Promoted and controlled by the Open
Software Foundation (OSF), a consortium led by HP, DEC, and IBM. See
ONC.

DDN: Defense Data Network. Comprises the MILNET and several other
DoD networks.

DECnet: Digital Equipment Corporation’s proprietary network
architecture.

DNS: Domain Name System. The distributed name/address mechanism used
in the Internet.

domain: In the Internet, a part of a naming hierarchy.
Syntactically, an Internet domain name consists of a sequence of
names (labels) separated by periods (dots), e.g., “tundra.mpk.ca.us.”
In OSI, “domain” is generally used as an administrative partition of
a complex distributed system, as in MHS Private Management Domain
(PRMD), and Directory Management Domain (DMD).

dotted decimal notation: The syntactic representation for a 32-bit
integer that consists of four 8-bit numbers written in base 10 with
periods (dots) separating them. Used to represent IP addresses in
the Internet as in: 192.67.67.20.

DSA: Directory System Agent. The software that provides the X.500
Directory Service for a portion of the directory information base.
Generally, each DSA is responsible for the directory information for
a single organization or organizational unit.

DUA: Directory User Agent. The software that accesses the X.500
Directory Service on behalf of the directory user. The directory
user may be a person or another software element.

EARN: European Academic Research Network. A network using BITNET
technology connecting universities and research labs in Europe.

EGP: Exterior Gateway Protocol. A reachability routing protocol used
by gateways in a two-level internet. EGP is used in the Internet
core system. See core gateway.

encapsulation: The technique used by layered protocols in which a
layer adds header information to the protocol data unit (PDU) from
the layer above. As an example, in Internet terminology, a packet

would contain a header from the physical layer, followed by a header
from the network layer (IP), followed by a header from the transport
layer (TCP), followed by the application protocol data.

end system: An OSI system which contains application processes
capable of communicating through all seven layers of OSI protocols.
Equivalent to Internet host.

entity: OSI terminology for a layer protocol machine. An entity
within a layer performs the functions of the layer within a single
computer system, accessing the layer entity below and providing
services to the layer entity above at local service access points.

ES-IS: End system to Intermediate system protocol. The OSI protocol
by which end systems announce themselves to intermediate systems.

EUnet: European UNIX Network.

EUUG: European UNIX Users Group.

EWOS: European Workshop for Open Systems. The OSI Implementors
Workshop for Europe. See OIW.

FARNET: Federation of American Research NETworks.

FDDI: Fiber Distributed Data Interface. An emerging high-speed
networking standard. The underlying medium is fiber optics, and the
topology is a dual-attached, counter-rotating Token Ring. FDDI
networks can often be spotted by the orange fiber “cable.”

FIPS: Federal Information Processing Standard.

flame: To express strong opinion and/or criticism of something,
usually as a frank inflammatory statement in an electronic message.

FNC: Federal Networking Council. The body responsible for
coordinating networking needs among U.S. Federal agencies.

fragmentation: The process in which an IP datagram is broken into
smaller pieces to fit the requirements of a given physical network.
The reverse process is termed reassembly. See MTU.

FRICC: Federal Research Internet Coordinating Committee. Now
replaced by the FNC.

FTAM: File Transfer, Access, and Management. The OSI remote file
service and protocol.

FTP: File Transfer Protocol. The Internet protocol (and program)
used to transfer files between hosts. See FTAM.

gateway: The original Internet term for what is now called router or
more precisely, IP router. In modern usage, the terms “gateway” and
“application gateway” refer to systems which do translation from some
native format to another. Examples include X.400 to/from RFC 822
electronic mail gateways. See router.

GOSIP: Government OSI Profile. A U.S. Government procurement
specification for OSI protocols.

IAB: Internet Activities Board. The technical body that oversees the
development of the Internet suite of protocols (commonly referred to
as “TCP/IP”). It has two task forces (the IRTF and the IETF) each
charged with investigating a particular area.

ICMP: Internet Control Message Protocol. The protocol used to handle
errors and control messages at the IP layer. ICMP is actually part
of the IP protocol.

IESG: Internet Engineering Steering Group. The executive committee
of the IETF.

IETF: Internet Engineering Task Force. One of the task forces of the
IAB. The IETF is responsible for solving short-term engineering
needs of the Internet. It has over 40 Working Groups.

IGP: Interior Gateway Protocol. The protocol used to exchange
routing information between collaborating routers in the Internet.
RIP and OSPF are examples of IGPs.

IGRP: Internet Gateway Routing Protocol. A proprietary IGP used by
cisco System’s routers.

INTAP: Interoperability Technology Association for Information
Processing. The technical organization which has the official
charter to develop Japanese OSI profiles and conformance tests.

intermediate system: An OSI system which is not an end system, but
which serves instead to relay communications between end systems.
See repeater, bridge, and router.

internet: A collection of networks interconnected by a set of routers
which allow them to function as a single, large virtual network.

Internet: (note the capital “I”) The largest internet in the world
consisting of large national backbone nets (such as MILNET, NSFNET,
and CREN) and a myriad of regional and local campus networks all over
the world. The Internet uses the Internet protocol suite. To be on
the Internet you must have IP connectivity, i.e., be able to Telnet
to–or ping–other systems. Networks with only e-mail connectivity
are not actually classified as being on the Internet.

Internet address: A 32-bit address assigned to hosts using TCP/IP.
See dotted decimal notation.

IONL: Internal Organization of the Network Layer. The OSI standard
for the detailed architecture of the Network Layer. Basically, it
partitions the Network layer into subnetworks interconnected by
convergence protocols (equivalent to internetworking protocols),
creating what Internet calls a catenet or internet.

IP: Internet Protocol. The network layer protocol for the Internet
protocol suite.

IP datagram: The fundamental unit of information passed across the
Internet. Contains source and destination addresses along with data
and a number of fields which define such things as the length of the
datagram, the header checksum, and flags to say whether the datagram
can be (or has been) fragmented.

IRTF: Internet Research Task Force. One of the task forces of the
IAB. The group responsible for research and development of the
Internet protocol suite.

ISDN: Integrated Services Digital Network. An emerging technology
which is beginning to be offered by the telephone carriers of the
world. ISDN combines voice and digital network services in a single
medium making it possible to offer customers digital data services as
well as voice connections through a single “wire.” The standards
that define ISDN are specified by CCITT.

IS-IS: Intermediate system to Intermediate system protocol. The OSI
protocol by which intermediate systems exchange routing information.

ISO: International Organization for Standardization. You knew that,
right? Best known for the 7-layer OSI Reference Model. See OSI.

ISODE: ISO Development Environment. A popular implementation of the
upper layers of OSI. Pronounced eye-so-dee-eee.

JANET: Joint Academic Network. A university network in the U.K.

JUNET: Japan UNIX Network.

KA9Q: A popular implementation of TCP/IP and associated protocols for
amateur packet radio systems.

Kermit: A popular file transfer and terminal emulation program.

little-endian: A format for storage or transmission of binary data in
which the least significant byte (bit) comes first. See big-endian.

mail exploder: Part of an electronic mail delivery system which
allows a message to be delivered to a list of addressees. Mail
exploders are used to implement mailing lists. Users send messages
to a single address (e.g., hacks@somehost.edu) and the mail exploder
takes care of delivery to the individual mailboxes in the list.

mail gateway: A machine that connects two or more electronic mail
systems (especially dissimilar mail systems on two different
networks) and transfers messages between them. Sometimes the mapping
and translation can be quite complex, and generally it requires a
store-and-forward scheme whereby the message is received from one
system completely before it is transmitted to the next system after
suitable translations.

Martian: Humorous term applied to packets that turn up unexpectedly
on the wrong network because of bogus routing entries. Also used as
a name for a packet which has an altogether bogus (non-registered or
ill-formed) Internet address.

MHS: Message Handling System. The system of message user agents,
message transfer agents, message stores, and access units which
together provide OSI electronic mail. MHS is specified in the CCITT
X.400 series of Recommendations.

MIB: Management Information Base. A collection of objects that can
be accessed via a network management protocol. See SMI.

MILNET: MILitary NETwork. Originally part of the ARPANET, MILNET was
partitioned in 1984 to make it possible for military installations to
have reliable network service, while the ARPANET continued to be used
for research. See DDN.

MTA: Message Transfer Agent. An OSI application process used to
store and forward messages in the X.400 Message Handling System.
Equivalent to Internet mail agent.

MTU: Maximum Transmission Unit. The largest possible unit of data
that can be sent on a given physical medium. Example: The MTU of
Ethernet is 1500 bytes. See fragmentation.

multicast: A special form of broadcast where copies of the packet are
delivered to only a subset of all possible destinations. See
broadcast.

multi-homed host: A computer connected to more than one physical data
link. The data links may or may not be attached to the same network.

name resolution: The process of mapping a name into the corresponding
address. See DNS.

NetBIOS: Network Basic Input Output System. The standard interface
to networks on IBM PC and compatible systems.

Network Address: See Internet address or OSI Network Address.

Network Layer: The OSI layer that is responsible for routing,
switching, and subnetwork access across the entire OSI environment.

NFS(R): Network File System. A distributed file system developed by
Sun Microsystems which allows a set of computers to cooperatively
access each other’s files in a transparent manner.

NIC: Network Information Center. Originally there was only one,
located at SRI International and tasked to serve the ARPANET (and
later DDN) community. Today, there are many NICs, operated by local,
regional, and national networks all over the world. Such centers
provide user assistance, document service, training, and much more.

NIST: National Institute of Standards and Technology. (Formerly
NBS). See OIW.

NMS: Network Management Station. The system responsible for managing
a (portion of a) network. The NMS talks to network management
agents, which reside in the managed nodes, via a network management
protocol. See agent.

NOC: Network Operations Center. Any center tasked with the
operational aspects of a production network. These tasks include
monitoring and control, trouble-shooting, user assistance, and so on.

NSAP: Network Service Access Point. The point at which the OSI
Network Service is made available to a Transport entity. The NSAPs
are identified by OSI Network Addresses.

NSF: National Science Foundation. Sponsors of the NSFNET.
NSFNET: National Science Foundation NETwork. A collection of local,
regional, and mid-level networks in the U.S. tied together by a
high-speed backbone. NSFNET provides scientists access to a number
of supercomputers across the country.

OIW: Workshop for Implementors of OSI. Frequently called NIST OIW or
the NIST Workshop, this is the North American regional forum at which
OSI implementation agreements are decided. It is equivalent to EWOS
in Europe and AOW in the Pacific.

ONC(tm): Open Network Computing. A distributed applications
architecture promoted and controlled by a consortium led by Sun
Microsystems.

OSI: Open Systems Interconnection. An international standardization
program to facilitate communications among computers from different
manufacturers. See ISO.

OSI Network Address: The address, consisting of up to 20 octets, used
to locate an OSI Transport entity. The address is formatted into an
Initial Domain Part which is standardized for each of several
addressing domains, and a Domain Specific Part which is the
responsibility of the addressing authority for that domain.

OSI Presentation Address: The address used to locate an OSI
Application entity. It consists of an OSI Network Address and up to
three selectors, one each for use by the Transport, Session, and
Presentation entities.

OSPF: Open Shortest Path First. A “Proposed Standard” IGP for the
Internet. See IGP.

PCI: Protocol Control Information. The protocol information added by
an OSI entity to the service data unit passed down from the layer
above, all together forming a Protocol Data Unit (PDU).

PDU: Protocol Data Unit. This is OSI terminology for “packet.” A
PDU is a data object exchanged by protocol machines (entities) within
a given layer. PDUs consist of both Protocol Control Information
(PCI) and user data.

Physical Layer: The OSI layer that provides the means to activate and
use physical connections for bit transmission. In plain terms, the
Physical Layer provides the procedures for transferring a single bit
across a Physical Media.

Physical Media: Any means in the physical world for transferring
signals between OSI systems. Considered to be outside the OSI Model,
and therefore sometimes referred to as “Layer 0.” The physical
connector to the media can be considered as defining the bottom
interface of the Physical Layer, i.e., the bottom of the OSI

Reference Model.

ping: Packet internet groper. A program used to test reachability of
destinations by sending them an ICMP echo request and waiting for a
reply. The term is used as a verb: “Ping host X to see if it is up!”

port: The abstraction used by Internet transport protocols to
distinguish among multiple simultaneous connections to a single
destination host. See selector.

POSI: Promoting Conference for OSI. The OSI “800-pound gorilla” in
Japan. Consists of executives from the six major Japanese computer
manufacturers and Nippon Telephone and Telegraph. They set policies
and commit resources to promote OSI.

PPP: Point-to-Point Protocol. The successor to SLIP, PPP provides
router-to-router and host-to-network connections over both
synchronous and asynchronous circuits. See SLIP.

Presentation Address: See OSI Presentation Address.

Presentation Layer: The OSI layer that determines how Application
information is represented (i.e., encoded) while in transit between
two end systems.

PRMD: Private Management Domain. An X.400 Message Handling System
private organization mail system. Example: NASAmail. See ADMD.

protocol: A formal description of messages to be exchanged and rules
to be followed for two or more systems to exchange information.

proxy: The mechanism whereby one system “fronts for” another system
in responding to protocol requests. Proxy systems are used in
network management to avoid having to implement full protocol stacks
in simple devices, such as modems.

proxy ARP: The technique in which one machine, usually a router,
answers ARP requests intended for another machine. By “faking” its
identity, the router accepts responsibility for routing packets to
the “real” destination. Proxy ARP allows a site to use a single IP
address with two physical networks. Subnetting would normally be a
better solution.

PSN: Packet Switch Node. The modern term used for nodes in the
ARPANET and MILNET. These used to be called IMPs (Interface Message
Processors). PSNs are currently implemented with BBN C30 or C300
minicomputers.

RARE: Reseaux Associes pour la Recherche Europeenne. European
association of research networks.

RARP: Reverse Address Resolution Protocol. The Internet protocol a
diskless host uses to find its Internet address at startup. RARP
maps a physical (hardware) address to an Internet address. See ARP.

RBOC: Regional Bell Operating Company. See BOC.

repeater: A device which propagates electrical signals from one cable
to another without making routing decisions or providing packet
filtering. In OSI terminology, a repeater is a Physical Layer
intermediate system. See bridge and router.

RFC: Request For Comments. The document series, begun in 1969, which
describes the Internet suite of protocols and related experiments.
Not all (in fact very few) RFCs describe Internet standards, but all
Internet standards are written up as RFCs.

RFS: Remote File System. A distributed file system, similar to NFS,
developed by AT&T and distributed with their UNIX System V operating
system. See NFS.

RIP: Routing Information Protocol. An Interior Gateway Protocol
(IGP) supplied with Berkeley UNIX.

RIPE: Reseaux IP Europeenne. European continental TCP/IP network
operated by EUnet. See EUnet.

rlogin: A service offered by Berkeley UNIX which allows users of one
machine to log into other UNIX systems (for which they are
authorized) and interact as if their terminals were connected
directly. Similar to Telnet.

ROSE: Remote Operations Service Element. A lightweight RPC protocol,
used in OSI Message Handling, Directory, and Network Management
application protocols.

router: A system responsible for making decisions about which of
several paths network (or Internet) traffic will follow. To do this
it uses a routing protocol to gain information about the network, and
algorithms to choose the best route based on several criteria known
as “routing metrics.” In OSI terminology, a router is a Network
Layer intermediate system. See gateway, bridge and repeater.

RPC: Remote Procedure Call. An easy and popular paradigm for
implementing the client-server model of distributed computing. A
request is sent to a remote system to execute a designated procedure,

using arguments supplied, and the result returned to the caller.
There are many variations and subtleties, resulting in a variety of
different RPC protocols.

RTSE: Reliable Transfer Service Element. A lightweight OSI
application service used above X.25 networks to handshake application
PDUs across the Session Service and TP0. Not needed with TP4, and
not recommended for use in the U.S. except when talking to X.400
ADMDs.

SAP: Service Access Point. The point at which the services of an OSI
layer are made available to the next higher layer. The SAP is named
according to the layer providing the services: e.g., Transport
services are provided at a Transport SAP (TSAP) at the top of the
Transport Layer.

selector: The identifier used by an OSI entity to distinguish among
multiple SAPs at which it provides services to the layer above. See
port.

Session Layer: The OSI layer that provides means for dialogue control
between end systems.

SGMP: Simple Gateway Management Protocol. The predecessor to SNMP.
See SNMP.

SLIP: Serial Line IP. An Internet protocol used to run IP over
serial lines such as telephone circuits or RS-232 cables
interconnecting two systems. SLIP is now being replaced by PPP. See
PPP.

SMDS: Switched Multimegabit Data Service. An emerging high-speed
networking technology to be offered by the telephone companies in the
U.S.

SMI: Structure of Management Information. The rules used to define
the objects that can be accessed via a network management protocol.
See MIB.

SMTP: Simple Mail Transfer Protocol. The Internet electronic mail
protocol. Defined in RFC 821, with associated message format
descriptions in RFC 822.

SNA: Systems Network Architecture. IBM’s proprietary network
architecture.

SNMP: Simple Network Management Protocol. The network management
protocol of choice for TCP/IP-based internets.

SPAG: Standards Promotion and Application Group. A group of European
OSI manufacturers which chooses option subsets and publishes these in
a “Guide to the Use of Standards” (GUS).

SQL: Structured Query Language. The international standard language
for defining and accessing relational databases.

subnet mask: See address mask.

subnetwork: A collection of OSI end systems and intermediate systems
under the control of a single administrative domain and utilizing a
single network access protocol. Examples: private X.25 networks,
collection of bridged LANs.

TCP: Transmission Control Protocol. The major transport protocol in
the Internet suite of protocols providing reliable, connection-
oriented, full-duplex streams. Uses IP for delivery. See TP4.

Telnet: The virtual terminal protocol in the Internet suite of
protocols. Allows users of one host to log into a remote host and
interact as normal terminal users of that host.

three-way-handshake: The process whereby two protocol entities
synchronize during connection establishment.

TP0: OSI Transport Protocol Class 0 (Simple Class). This is the
simplest OSI Transport Protocol, useful only on top of an X.25
network (or other network that does not lose or damage data).

TP4: OSI Transport Protocol Class 4 (Error Detection and Recovery
Class). This is the most powerful OSI Transport Protocol, useful on
top of any type of network. TP4 is the OSI equivalent to TCP.

transceiver: Transmitter-receiver. The physical device that connects
a host interface to a local area network, such as Ethernet. Ethernet
transceivers contain electronics that apply signals to the cable and
sense collisions.

Transport Layer: The OSI layer that is responsible for reliable end-
to-end data transfer between end systems.

UA: User Agent. An OSI application process that represents a human
user or organization in the X.400 Message Handling System. Creates,
submits, and takes delivery of messages on the user’s behalf.

UDP: User Datagram Protocol. A transport protocol in the Internet
suite of protocols. UDP, like TCP, uses IP for delivery; however,
unlike TCP, UDP provides for exchange of datagrams without
acknowledgements or guaranteed delivery. See CLTP.

UUCP: UNIX to UNIX Copy Program. A protocol used for communication
between consenting UNIX systems.

XDR: eXternal Data Representation. A standard for machine-
independent data structures developed by Sun Microsystems. Similar
to ASN.1.

X/Open: A group of computer manufacturers that promotes the
development of portable applications based on UNIX. They publish a
document called the X/Open Portability Guide.

X Recommendations: The CCITT documents that describe data
communication network standards. Well-known ones include: X.25
Packet Switching standard, X.400 Message Handling System, and X.500
Directory Services.

The X Window System (TM): A popular window system developed by MIT
and implemented on a number of workstations.

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A

 

Application Profile
The DCMI Abstract Model (DCAM) [1] is a specification which defines an abstract syntax for metadata records that is independent of, but mappable to, a diversity of concrete implementation syntaxes such as HTML/XHTML, XML, and any of the concrete syntaxes defined for RDF. The DCAM was developed as a basis for defining validatable metadata records, in a variety of popular implementation syntaxes, whose contents could straightforwardly be exposed as RDF triples.
Appropriate Literal (archaic)
In the late 1990s, when work began on the Resource Description Framework, the notion was introduced that resolvable URIs should be used as metadata values. The notion of “appropriate literal” captured the requirement to present consumers of metadata not just with URIs, but with readable text strings or other appropriate literals, such as dates or classification numbers, for the purpose of resource discovery. The ambiguity of whether Dublin Core properties were intended to be used with strings or URIs as values was not properly addressed until the assignment of domains and ranges in 2008.
DCMI Abstract Model
The Dublin Core Abstract Model (DCAM) specifies the components and constructs used in Description Sets (metadata records). DCAM provides an information model independent of any particular encoding syntax and a clear mapping to RDF triples. It is designed to be used in conjunction with the Description Set Profile constraint language and DCAM-conformant syntax specifications in the construction of application profiles. Developed between 2003 and 2008, DCAM was in 2010 the subject of a critical review. DCAM and related specifications are not currently the object of further development and testing.
DCMI (Dublin Core Metadata Initiative) Ltd
The Dublin Core Metadata Initiative (DCMI) is a public, not-for-profit organization, incorporated in Singapore, with a mission to develop interoperable metadata standards for a broad range of purposes and business models. DCMI is hosted by the National Library Board of Singapore and supported by institutional members and sponsors. From its start in 1995 with a workshop at OCLC in Dublin, Ohio, through incorporation in Singapore in 2009, the Dublin Core Metadata Initiative was managed as an activitiy within OCLC’s Office of Research. DCMI publishes metadata specifications, holds annual conferences, and hosts numerous discussion forums.
DCMI Metadata Terms
The RDF Properties, Classes, Vocabulary Encoding Schemes, and Datatypes declared and maintained by the Dublin Core Metadata Initiative are collectively referred to as DCMI Metadata Terms. Of the four types of terms, Properties, Classes, and Datatypes (Syntax Encoding Scheme) are defined exactly as in RDF. The notion of a Vocabulary Encoding Scheme is unique to DCMI, though it is similar to — arguably, formally indistinguishable from — the notion of a Concept Scheme in Simple Knowledge Organization System (SKOS).
AACR2
See Anglo-American Cataloguing Rules
administrative metadata
Metadata used in managing and administering information resources, e.g., location or donor information. Includes rights and access information, data on the creation and preservation of the digital object.
AGLS
See AGLS (Australian Government Locator Service)
Anglo-American Cataloguing Rules (AACR2)
The dominant bibliographic standard regulating cataloging in the English-speaking world.  AACR2 represents a set of rules for the standard description of and access to all materials which a library holds or to which it has access.
American Standard Code for Information Interchange (ASCII)
A scheme that provides standard numeric values to represent letters, numbers, punctuation marks and other characters.  The use of standard values allows computers and computer programs to exchange data.
application profile
In DCMI usage, an application profile is a declaration of the metadata terms an organization, information resource, application, or user community uses in its metadata. In a broader sense, it includes the set of metadata elements, policies, and guidelines defined for a particular application or implementation. The elements may be from one or more element sets, thus allowing a given application to meet its functional requirements by using metadata elements from several element sets including locally defined sets. For example, a given application might choose a specific subset of the Dublin Core elements that meets its needs, or may include elements from the Dublin Core, another element set, and several locally defined elements, all combined in a single schema. An application profile is not considered complete without documentation that defines the policies and best practices appropriate to the application.
Appropriate values
Best practice for a particular Element or Qualifier may vary by context. Definitions may provide some guidance; other information may be found in “Using Dublin Core”.
ASCII
See American Standard Code for Information Interchange
Audience
Dublin Core element to record a class of entity for whom the resource is intended or useful. A class of entity may be determined by the creator or the publisher or by a third party. See also “Using Dublin Core”.
Author
See Creator
authority control
A set of rules or procedures that assist in the maintenance of consistent forms of names or terms within a database.
authority file
A collection o
f authority records.
authority record
A record that registers the preferred form of a personal or corporate name, geographic region or subject term. It may indicate variant forms of the established heading, biographical or cultural information associated with the heading, as well as related headings.

B

Basic Semantics Register
An ISO Standard ISO/TS 16668:2000 which identifies and defines semantic components for use in data exchange.
best practice
Guidance and documentation to describe and standardize the use of metadata elements that best support a community’s needs.
BSR
See Basic Semantics Register

C

case-sensitive
Lower and upper case letters are not treated as if they were interchangeable; e.g. ‘a’ is not the same as ‘A’.
CEN
European Committee for Standarization (Comité Européen de Normalisation; Europäisches Komitee für Normung) “CEN is contributing to the objectives of the European Union and European Economic Area with voluntary technical standards which promote free trade, the safety of workers and consumers, interoperability of networks, environmental protection, exploitation of research and development programmes, and public procurement.” http://www.cenorm.be/cenorm/index.htm
classification
A logical scheme for arrangement of knowledge, usually by subject. Classification schema are alpha and/or numeric; for example, Library of Congress Classification, Dewey Classification, Universal Decimal Classification.
controlled vocabulary
A prescribed set of consistently used and carefully defined terms.
Contributor
The Dublin Core element used to designate the entity responsible for making contributions to the content of the resource. Examples of a Contributor include a person, an organization or a service. Typically, the name of a Contributor should be used to indicate the entity. See also “Using Dublin Core”.
Coverage
The Dublin Core element used to designate the extent or scope of the content of the resource. Coverage will typically include spatial location (a place name or geographic co-ordinates), temporal period (a period label, date, or date range) or jurisdiction (such as a named administrative entity). Recommended best practice is to select a value from a controlled vocabulary, and that, where appropriate, named places or time periods be used in preference to numeric identifiers such as sets of co-ordinates or date ranges. See also “Using Dublin Core”.
Creator
The Dublin Core element used to designate the entity primarily responsible for making the content of the resource. Examples of a Creator include a person, an organization, or a service. See also “Using Dublin Core”.
Crosswalk
A table that maps the relationships and equivalencies between two or more metadata schemes. Crosswalks or metadata mapping support the ability of search engines to search effectively across heterogeneous databases.

D

Date
The Dublin Core element used to designate the date associated with an event in the life cycle of the resource. Typically, Date will be associated with the creation or availability of the resource. See also “Using Dublin Core”.
DCAPS
Dublin Core Application Profile ” is a declaration specifying which metadata terms an organization, information provider, or user community uses in its metadata. By definition, a DCAP identifies the source of metadata terms used – whether they have been defined in formally maintained standards such as Dublin Core, in less formally defined element sets and vocabularies, or by the creator of the DCAP itself for local use in an application. Optionally, a DCAP may provide additional documentation on how the terms are constrained, encoded, or interpreted for application-specific purposes.” See http://www.ukoln.ac.uk/metadata/dcmi/dc-elem-prop/
DCMES
Dublin Core Metadata Element Set. See Dublin Core.
DCMI
See Dublin Core Metadata Initiative
DCMI recommendation
A DCMI recommendation is a human-readable document that may define one or more DCMI terms.
DCMI term
A DCMI term is a DCMI element, a DCMI qualifier or term from a DCMI-maintained controlled vocabulary. Each DCMI term is defined in a DCMI recommendation and is identified by a Uniform Resource Identifier (URI) within a DCMI namespace.
DCMI term declaration
A DCMI term declaration is the machine-processable representation of one or more DCMI terms, expressed in a schema language.
Description
The Dublin Core element used to designate a textual description of the content of the resource. See also “Using Dublin Core”.
DCSV
See Dublin Core Structured Value
descriptive metadata
Metadata that supports the discovery of an object.
digital tourist
An inexperienced searcher in the digital environment who does not possess knowledge of community- specific vocabularies. The Dublin Core provides a rudimentary vocabulary, or “pidgin language” for information discovery when exploring new digital territories. Coined by Ricky Erway at the Metadata Workshop on Metadata for Networked Images, September 24-25, 1996.
discovery software
A computer application designed to simplify, assist and expedite the process of finding information resources.
Digital Object Identifier
DOI was developed by the International DOI Foundation as a system for identifying and exchanging intellectual property in the digital environment. It provides a mechanism to link a searcher to digital content and facilitates copyright management.
Document Type Definition (DTD)
In SGML or XML, a formal description of the components of a specific document or class of documents. DTDs provide a formal grammar used for machine processing (parsing) of documents expressed in SGML or XML. A DTD description includes:

  • The containers or elements that make up the document; e.g., paragraphs, headings, list items, figures, tables, etc.
  • The logical structure of the document; e.g., chapters containing sections, etc.
  • Additional information associated with elements (known as attributes); e.g., identifiers, date stamps, etc.
document-like object (DLO)
Originally defined as an entity that resembles a document from the standpoint that it is substantially text-based and shares other properties of a document; e.g., electronic mail messages or spreadsheets. The definition was expanded at the 3rd DC workshop to refer to any discrete information resource that are characterized by being fixed (i.e., having identical content for each user). Examples include text, images, movies, and performances.
DOI
see Digital Object Identifier
dot.syntax
A mechanism for refining the meaning of the element in HTML; for example, <META NAME=”DC.Title.Alternative” CONTENT=”Title“>
DTD
See Document Type Definition
Dublin Core
The Dublin Core is a metadata element set. It includes all DCMI terms (that is, refinements, encoding schemes, and controlled vocabulary terms) intended to facilitate discovery of resources. The Dublin Core has been in development since 1995 through a series of focused invitational workshops that gather experts from the library world, the networking and digital library research communities, and a variety of content specialties. See the Dublin Core Web Site for additional information.
Dublin Core Metadata Initiative
The Dublin Core Metadata Initiative is the body responsible for the ongoing maintenance of Dublin Core. DCMI is currently hosted by the OCLC Online Computer Library Center, Inc., a not-for-profit international library consortium. The work of DCMI is done by contributors from many institutions in many countries. DCMI is organized into Communities and Task Groups to address particular problems and tasks (see the DCMI Work structure page). Participation in DCMI is open to all interested parties. Instructions for joining can be found at the DCMI web site on the DCMI Contact information page.
Dublin Core Simple
See Simple Dublin Core
Dublin Core Structured Values
DCSV recognizes two types of substrings: labels and values. A label is the name of the type of a value, and a value is the data itself. A value that is comprised of components, i.e. a value which has its own label and value, is called a structured value. Punctuation supports the parsing of the DCSV.
Dublin Core Terms
See DCMI term
Dumb-down Principle
The qualification of Dublin Core Elements is guided by a rule known colloquially as the Dumb-Down Principle. According to this rule, a client should be able to ignore any qualifier and use the value as if it were unqualified. While this may result in some loss of specificity, the remaining term value (minus the qualifier) must continue to be generally correct and useful for discovery. Qualification is therefore supposed only to refine, not extend the semantic scope of an Element.

E

EAD
see EAD (Encoded Archival Description)
electronic information resource
An information resource that is maintained in electronic, or computerized format, and may be accessed, searched and retrieved via electronic networks or other electronic data processing technologies (e.g., CD-ROM)
element
An element is a property of a resource. As intended here, “properties” are attributes of resources — characteristics of a resource, such as a Title, Publisher, or Subject. Elements are formally defined terms which are used to describe attributes and properties of a resource.
element refinement (qualifier)
Qualifiers make the meaning of an element narrower or more specific. An element refinement is a property of a resource which shares the meaning of a particular DCMI Element but with narrower semantics. In some application environments (notably HTML-based encodings), Element refinements are used together with elements in the manner of natural-language “qualifiers” (i.e., adjectives) . However, since element refinements are properties of a resource (like elements), element refinements can alternatively be used in metadata records independently of the properties they refine. In DCMI practice, an Element refinement refines just one parent DCMI property.
embedded metadata
Metadata that is maintained and stored within the object it describes; the opposite of stand-alone metadata.
Encoded Archival Description
An SGML DTD that represents a highly structured way to create digital finding aids for a grouping of archival or manuscript materials. The standard is maintained in the Network Development and MARC Standards Office of the Library of Congress (LC) in partnership with the Society of American Archivists. For more information see http://lcweb.loc.gov/ead/.
encoding scheme
An encoding scheme provides contextual information or parsing rules that aid in the interpretation of a term value. Such contextual information may take the form of controlled vocabularies, formal notations, or parsing rules. If an encoding scheme is not understood by a client or agent, the value may still be useful to a human reader. There are two types of encoding schemes: Vocabulary Encoding Schemes and Syntax Encoding Schemes
extensible
Having the potential to be expanded in scope, area or size. In the case of Dublin Core, the ability to extend a core set of metadata with additional elements.
Extensible Markup Language (XML)
A subset of Standard Generalized Markup Language (SGML), a widely used international text processing standard. XML is being designed to bring the power and flexibility of generic SGML to the Web, while maintaining interoperability with full SGML and HTML. For more information, see http://www.w3.org/XML/

F

Format
The Dublin Core element used to designate the physical or digital manifestation of the resource. See also “Using Dublin Core”.
FRBR
Functional Requirements for Bibliographic Records is a conceptual model to describe bibliographic entities, their relations and attributes within IFLA (International Federation of Library Associations). The complete work is available at http://www.ifla.org/VII/s13/frbr/frbr.htm and a presentation at http://www.loc.gov/catdir/cpso/frbreng.pdf

G

GIF
See Graphics Interchange Format
GILS
See GILS (Global Information Locator Service)
glossary
An alphabetized list of terms with definitions often created by an organization to reflect its needs. Normally lacks hierarchical arrangement or cross references. Also known as a term list.
Graphics Interchange Format (GIF)
The dominant graphics format on the Web, limited to 256 colors. GIFs provide sharper black & white images than JPEGs.
granularity
The level of detail at which an information object or resource is viewed or described.

H

Harvester
A harvester is a client application that issues OAI-PMH requests. A harvester is operated by a service provider as a means of collecting metadata from repositories. (http://www.openarchives.org/OAI/openarchivesprotocol.html#harvester)
HayStack
An MIT project to develop to personal management systems that would all individuals to organize their information objects, such as email, web pages, documents, images, calendars. The information can be categorize and create relationships that are meaningful for themselves. See http://haystack.lcs.mit.edu/
HTML
See Hypertext Markup Language
Hypertext Markup Language (HTML)
The standard text-formatting language for documents on the World Wide Web. HTML text files contain content that is rendered on a computer screen and markup, or tags, that can be used to tell the computer how to format that content. HTML tags can also be used to encode metadata and to tell the computer how to respond to certain user actions, such as a mouse click. For more information, see http://www.w3.org/MarkUp/.

I

Identifier
The Dublin Core element that is an unambiguous reference to the resource within a given context. Recommended best practice is to identify the resource by means of a string or number conforming to a formal identification system. See also “Using Dublin Core”.
IETF
See Internet Engineering Task Force
IEEE LOM
See IEEE LOM (Institute of Electrical and Electronics Engineers. Learning Object Metadata)
IMS
See IMS Instructional Management Systems
IMT
See Internet Media Type
INDECS
See INDECS ( Interoperability of Data in D-Commerce Systems)
indexing
The process of evaluating information entities and creating terms that aid in finding and accessing the entity. Index terms may be in natural language or controlled vocabulary or a classification notation.
indexing program
Computer software used to order things; frequently used to refer to software that alphabetizes some or all of the terms in one or more electronic documents.
information resource
Any entity, electronic or otherwise, capable of conveying or supporting intelligence or knowledge; e.g. a book, a letter, a picture, a sculpture, a database, a person. See also DLO
instantiation
An identifiable occurrence or occasion of something; in the case of Dublin Core, a specific occurrence of an information resource.
International Organization for Standardization
ISO was established in 1947 as a worldwide federation of national standards bodies from some 130 countries.
Internet Commons
The global Internet environment, collection of information-bearing repositories whose data can be accessed through the Internet.
Internet Engineering Task Force (IETF)
The IETF is responsible for solving short-term engineering needs of the Internet. It has over 40 Working Groups.
Internet Media Type (IMT)
A set of terms that describe types of resources on the Internet. Used as an encoding scheme for the Format element in Dublin Core. http://www.isi.edu/in-notes/iana/assignments/media-types/media-types
interoperability
The ability of different types of computers, networks, operating systems, and applications to work together effectively, without prior communication, in order to exchange information in a useful and meaningful manner. There are three aspects of interoperability: semantic, structural and syntactical.
Interoperability Qualifiers
Additional metadata used either to refine the semantics of a Dublin Core metadata element’s value, or to provide more information about the encoding scheme used for the value.
ISO
See International Organization for Standardization

J

Joint Photographic Experts Group (JPEG)
A standard for compressing digital images. The advantage of JPEG is that it uses compression to make graphics files smaller, making them faster to transfer and view over the World Wide Web. More than 16 million color hues are available. Better than GIF for color photographs. The disadvantage is some loss of image quality due to data loss during compression. For more information see http://www.jpeg.org/
JPEGs
See Joint Photographic Experts Group

K

Keywords
See Subject

L

Language
The Dublin Core element used to designate the language of the intellectual content of the resource. Recommended best practice for the values of the Language element is defined by RFC 3066. See also “Using Dublin Core”.
literal
A literal or “appropriate literal” is the value of any given metadata entity that can be either a hyperlink or a string value (literal). A literal affords a great deal of flexibility and power, but increases complexity. Metadata should as well include an appropriate literal that reflects the base value of the metadata entity. For example, in these fragments: creator = “Public, John Q.” creator = ” http://authority.org/public-john-q-1234″ the first has a value expressed as an appropriate literal whereas the second has a (hypothetical) link to an authority structure. It is not entirely clear what a person or application will find at the end of the link, so the metadata should contain an appropriate literal for simple discovery purposes.

M

mapping metadata
See crosswalk
MARC
See MARC (Machine-Readable Cataloging Record)
META tag
The HTML element used to demarcate metadata on a Web page. <META> </META>.
metadata
In general, “data about data;” functionally, “structured data about data.” Metadata includes data associated with either an information system or an information object for purposes of description, administration, legal requirements, technical functionality, use and usage, and preservation. . In the case of Dublin Core, information that expresses the intellectual content, intellectual property and/or instantiation characteristics of an information resource. See Section 1.1 of this guide. For a history of the term See Caplan,pp. 1-3.
metadata record
A syntactically correct representation of the descriptive information (metadata) for an information resource. In the case of Dublin Core, a representation of the Dublin Core elements that has been defined for the resource. The majority of metadata records and record fragments in this document are presented in HTML syntax.
metadata schema registry
A publicly accessible system that records the semantics, structure and interchange formats of any type of metadata. A formal authority, or agency, maintains and manages the development and evolution of a metadata registry. The authority is responsible for policies pertaining to registry contents and operation. See also http://www.dlib.org/dlib/may02/wagner/05wagner.html
METS (Metadata Encoding & Transmission Standard
See METS (Metadata Encoding & Transmission Standard
MIME
See Multipurpose Internet Mail Extensions
MODS
See MODS (Metadata Object Description Schema)
Multipurpose Internet Mail Extensions
The standard for attaching files to Internet e-mail messages. Attached files may be text, graphics, spreadsheets, documents, sound files, etc.

N

National Information Standards Organization
NISO, accredited by ANSI, develops and promotes technical standards used in a wide variety of information services.
namespace
A DCMI namespace is a collection of DCMI terms. Each DCMI namespace is identified by a URI. An XML namespace [XML-NAMES] is a collection of names, identified by a URI reference [RFC2396], that are used in XML documents as element types and attribute names. The use of XML namespaces to uniquely identify metadata terms allows those terms to be unambiguously used across applications, promoting the possibility of shared semantics. DCMI adopts this mechanism for the identification of all DCMI terms. For example, the namespace for Dublin Core elements and qualifiers would be expressed respectively in XML as:

xmlns:dc = “http://purl.org/dc/elements/1.1/
xmlns:dcterms = “http://purl.org/dc/terms/

The use of namespaces allows the definition of an element to be unambiguously identified with a URI, even though the label “title” alone might occur in many metadata sets. In more general terms, one can think of any closed set of names as a namespace. Thus, a controlled vocabulary such as the Library of Congress Subject Headings, a set of metadata elements such as DC, or the set of all URLs in a given domain can be thought of as a namespace that is managed by the authority that is in charge of that particular set of terms.
networked resource
An object that is available electronically via a network.
NISO
See National Information Standards Organization

O

OAI
See Open Archives Initiative
OAI-PMH
See Open Archives Initiative Protocol for Metadata Harvesting
OCLC
See Online Computer Library Center
ONIX
See ONIX (ONline InformationeXchange)
Ontology
A hierarchical structure that formally defines the semantic relationship of a set of concepts. Used to create structured / controlled vocabularies for the discovery or exchange of information. A thesaurus, like the AAT is an example.
Online Computer Library Center (OCLC)
The major source of cataloging data for libraries around the world; located in Dublin, Ohio, US. For more information, see http://www.oclc.org/.
Open Archives Initiative
“Develops and promotes interoperability standards that aim to facilitate the efficient dissemination of content. The Open Archives Initiative has its roots in an effort to enhance access to e-print archives as a means of increasing the availability of scholarly communication” For more information see http://www.openarchives.org/organization/index.html.
OpenURL
A method for describing resources and associated resources that are referenced in a network environment. It defines the mentods for transporting these descriptions between networked systems. NISO standard NISO Z39.88-2003 (still in draft). The Standard has been issued in two parts and it available for comment through California Institute of Technology http://library.caltech.edu/openurl/Public_Comments.htm
Open Archives Initiative Protocol for Metadata Harvesting
The Protocol “provides an application-independent interoperability framework based on metadata harvesting. There are two classes of participants in the OAI-PMH framework: Data Providers administer systems that support the OAI-PMH as a means of exposing metadata; and Service Providers use metadata harvested via the OAI-PMH as a basis for building value-added services. ” For more information see http://www.openarchives.org/organization/index.html.
OWL
Web ontology language http://www.w3.org/TR/owl-features/. OWL is a language for describing ontologies and schema. It can specify concepts and their relationships. OWL/XDD (XML declaration description) allows a means to express complex rules and constraints.

P

parsing
Parsing may be divided into parts: lexical analysis and semantic parsing. Lexical analysis divides strings into components based on punctuation or tagging. Semantic parsing then attempts to determine the meaning of the string.
Persistent Uniform Resource Locator
An approach to the URL permanence problem proposed by OCLC. A PURL is a public alias for a document. A PURL remains stable, while the document’s background URL will change as it is managed (e.g. moved) over time. A PURL is created by a Web administrator who is registered as a PURL “owner” and who maintains a mapping of the PURL to a current and functioning URL. A PURL is a form of URN.
POI (PURL-based Object Identifier)
A specification for resource identifiers that are described by metadata ‘items’ in OAI-compliant repositories. POI are based on the PURL system [POI]. “Because POIs conform to the URI specification, they can be used unmodified in DC metadata and LOM.” See http://www.ukoln.ac.uk/metadata/dcmi-ieee/identifiers/ and http://www.ukoln.ac.uk/distributed-systems/poi/
Property
A property is a specific aspect, characteristic, attribute, or relation used to describe a resource. Dublin Core metadata elements are properties http://dublincore.org/documents/2003/04/02/dc-xml-guidelines/
Provenance
Dublin Core element used for making statements of any changes in ownership and custody of the resource since its creation that are significant for its authenticity, integrity and interpretation. The statement may include a description of any changes successive custodians made to the resource. See also “Using Dublin Core”.
Publisher
The Dublin Core element used to designate the entity responsible for making the resource available. Examples of a Publisher include a person, an organization, or a service. Typically, the name of a Publisher should be used to indicate the entity. See also “Using Dublin Core”.
PURL
See Persistent Uniform Resource Locator

Q

qualifier
“Qualifiers” is the generic heading traditionally used for terms now usually referred to specifically as Element Refinements or Encoding Schemes. A qualifier must follow the Dumb-Down Principle. There are two broad categories of qualifiers: Encoding schema and Element refinement.
Qualified Dublin Core
Qualified Dublin Core includes an additional element, Audience, as well as a group of element refinements (also called qualifiers) that refine the semantics of the elements in ways that may be useful in resource discovery

R

RDF
See Resource Description Framework.
RDF Site Summary
RSS was created and popularized by Netscape for their personalized portal site. Rich Site Summary (RSS) is a lightweight XML application designed to exchange headline metadata between news content providers and portals.
record
A record is some structured metadata about a resource, comprising one or more properties and their associated values. http://dublincore.org/documents/2003/04/02/dc-xml-guidelines/
registry
A system to provide management of metadata elements. See also metadata schema registry The DCMI Registry Working Group (WG) is the development of a metadata registry providing authoritative information regarding the DCMI vocabulary and the relationship between terms in that vocabulary.
Relation
The Dublin Core element used to designate A reference to a related resource. Recommended best practice is to reference the resource by means of a string or number conforming to a formal identification system. See also “Using Dublin Core”.
Request for Comment (RFC)
A Request for Comment (RFC) is the process of establishing a standard on the Internet. Discussion of the proposed standard on the Internet is facilitated by the Internet Engineering Task Force (IETF). Once approved, the standard receives a unique number which identifies it; e.g., RFC See http://www.isi.edu/rfc-editor/. and http://www.ietf.org/rfc.html
resource
A resource is anything that has identity. Familiar examples include an electronic document, an image, a service (e.g., “today’s weather report for Los Angeles”), and a collection of other resources. Not all resources are network “retrievable”; e.g., human beings, corporations, and bound books in a library can also be considered resources. http://dublincore.org/documents/2003/04/02/dc-xml-guidelines/
Resource Description Framework (RDF)
The basic language for writing metadata; a foundation which provides a robust flexible architecture for processing metadata on the Internet. RDF will retain the capability to exchange metadata between application communities, while allowing each community to define and use the metadata that best serves their needs. For more information see http://www.w3.org/RDF/
resource discovery
The process through which one searches and retrieves an information resource.
Resource Type
See Type.
Resource Description
See Description.
Resource Identifier
See Identifier
RFC
See Request for Comment
Rights
The Dublin Core element used to provide a link to information about rights held in and over the resource. Typically a Rights element will contain a rights management statement for the resource, or reference a service providing such information. Rights information often encompasses Intellectual Property Rights (IPR), Copyright, and various Property Rights. If the rights element is absent, no assumptions can be made about the status of these and other rights with respect to the resource. See also “Using Dublin Core”.
RightsHolder
Dublin Core element used to record a person or organization owning or managing rights over the resource. Recommended best practice is to use the URI or name of the Rights Holder to indicate the entity. See also “Using Dublin Core”.
Rights Management
See Rights
ROADS
Resource Organisation And Discovery in Subject based services. A UK funded project whose aim is to develop discovery software for Internet resources.
RSS
See RDF Site Summary .

S

schema or scheme(plurals schemas or schemata; schemes)
In general terms, any organization, coding, outline or plan of concepts. In terms of metadata, a systematic, orderly combination of elements or terms. In terms of DCMI term declarations represented in XML or RDF schema language, schemas are machine-processable specifications which define the structure and syntax of metadata specifications in a formal schema language. In terms of an encoding scheme, is a set of rules for encoding information that supports a specific community of users. See also Encoding scheme.
scheme
See schema
SCORM
See SCORM (Sharable Content Object Reference Model)
search engine
A utility capable of returning references to relevant information resources in response to a query.
semantic interoperability
Ability to search for digital information across heterogeneous distributed databases whose metadata schemas have been mapped to one another. It is achieved through agreements about content description standards; for example, Dublin Core, Anglo-American Cataloging Rules.
Semantic Web
A term coined by Tim Berners-Lee which views the future Web as a web of data, like a global database. The infrastructure of the Semantic Web would allow machines as well as humans to make deductions and organize information. The architectural components include semantics (meaning of the elements), structure (organization of the elements), and syntax (communication). http://www.w3.org/DesignIssues/Semantic.html
semantics
Significance or meaning. In the case of Dublin Core, the significance or intended meaning of individual metadata elements and their components.
SGML
See Standard Generalized Markup Language
SICI
Serial Item and Contribution Identifier (ANSI/NISO Z39.56-1996 Vers. 2) A numeric notation to identify serial issues and articles uniquely regardless of their distribution medium (paper, electronic, microform).
Simple Dublin Core
The fifteen Dublin Core elements used without qualifiers, that is without element refinement or encoding schemes. Sometimes referred to as Dublin Core simple.
SOAP
A protocol that uses XML for the exchange of structured information, that is messages, in a distributed environment. See http://www.w3.org/TR/soap12-part1/
software agent
A computer program that carries out tasks on behalf of another entity. Frequently used to reference a program that searches the Internet for information meeting the specified requirements of an individual user.
Source
The Dublin Core element used to designate a reference to a resource from which the present resource is derived. The present resource may be derived from the Source resource in whole or part. Recommended best practice is to reference the resource by means of a string or number conforming to a formal identification system. See also “Using Dublin Core”.
spatial
An element refinement of Coverage. Spatial characteristics of the intellectual content of the resource.
Standard Generalized Markup Language (SGML)
A non-proprietary language/enabling technology for describing information. Information in SGML is structured like a database, supporting rendering in and conversion between different formats. Both XML and later versions of HTML are instances of SGML. For more information see http://www.w3.org/MarkUp/SGML/.
stand-alone metadata
Metadata that is created, maintained and stored independently of the object it describes. The opposite of embedded metadata.
structured value
See Dublin Core Structured Value
structural interoperability
Is achieved through data models for specifying semantic schemas in a way that they can be shared; for example, RDF.
structural metadata
Structural metadata defines the digital object’s internal organization and is needed for display and navigation of that object.
sub-element
See element refinement
Subject
The Dublin Core element used to describe the content of the resource. The element may use controlled vocabularies or keywords or phrases that describe the subject or content of the resource. See also “Using Dublin Core”.
Subject Headings
An alphabetical list of words or phrases that represent a concept that is under authority control, e.g., the Library of Congress Subject Headings.
surrogate content
Metadata as a substitute for an actual resource.
switching language
A mediating language used to establish equivalencies among various indexing languages. Dublin Core has been viewed as a switching “language” between various metadata schemas.
syntactic interoperability
Achieved by marking up our data in a similar fashion so we can share the data and so that our machines can understand and take the data apart in sensible ways; for example, XML, EAD and MARC.
syntax
The form and structure with which metadata elements are combined. In the case of Dublin Core, the form and structure of how metadata elements and their components are combined to form a metadata record.
Syntax Encoding Schemes
Syntax Encoding Schemes indicate that the value is a string formatted in accordance with a formal notation, such as “2000-01-01” as the standard expression of a date.

T

TAP
A project developed at Stanford, TAP seeks to create a web of “machine-readable” (XML, RDF) data, not just human readable (HTML) data. A server which is queried for information about people or subjects, will collocate documents about people and concepts. See http://tap.stanford.edu/
taxonomy
In general terms, systematic classification according to principles or general laws. In digital terms, automated classification of documents in a hierarchy based on information gathered by a metacrawler. May refer to a classification of DCMI terms. A classification system such as Library of Congress Classification is an example of a taxonomy.
technical metadata
Metadata that documents the creation and the digital characteristics of the files.
TEI
See Text Encoding Initiative
temporal
An element refinement of coverage. Temporal characteristics of the intellectual content of the resource.
term
See DCMI term
Text Encoding Initiative (TEI)
An international project to develop guidelines for the preparation and interchange of electronic texts for scholarly research as well as a broad range of other language industry uses. The TEI DTD is an SGML Document Type Definition for encoding literary works. For more information, seehttp://www.tei-c.org/
thesaurus
A structured vocabulary make up of names, words, and other information, typically including synonyms and/or hierarchical relationships for the purpose of cross-referencing in order to organize a collection of concepts for reference and retrieval. See the ANSI/NISO Standard for thesaurus construction Z39.19-2003 (R1998; ISO 2788). A controlled vocabulary of terms or concepts that are structured hierarchically (parent/child relationships) or as equivalences (synonyms), and related terms (associative). See also Subject headings and glossary. A thesaurus is a taxonomy.
Thesaurus of Geographic Names
The TGN is a controlled vocabulary containing around 1,000,000 names and other information about places. It includes physical features and administrative entities, such as cities and nations. The emphasis in TGN is on places important for art and architecture.
Title
The Dublin Core element used to designate the name given to the resource. Typically, a Title will be a name by which the resource is formally known. See also “Using Dublin Core”.
tokens
The means to denote the status of an element or qualifier within a registry; e.g., proposed, recommended, conforming (to the namespace), obsolete, or local.
Type
The Dublin Core element used to designate the nature or genre of the content of the resource. Type includes terms describing general categories, functions, genres, or aggregation levels for content. Recommended best practice is to select a value from a controlled vocabulary. See also “Using Dublin Core”.

U

ULAN
See Union List of Artist Names
Unicode
A universal encoding scheme designed to allow interchange, processing and display of the world’s principal languages, as well as many historic and archaic scripts. Unicode supports and fosters a multilingual computing world community by allowing computers using one language to “talk” to computers using a different language. A registered trademark of Unicode, Inc.
Unicode Transformation Format, 8-bit (UTF-8)
A temporary form of Unicode that is well suited for routing data through systems that are not designed for Unicode, such as some email servers and Web clients. UTF-8 is an attractive way of storing multilingual data on the Internet, without requiring full Unicode compliance.
Uniform Resource Identifier (URI)
The syntax for all names/addresses that refer to resources on the World Wide Web. For information about Internet addressing, see http://www.w3.org/Addressing/Addressing.html.
Uniform Resource Locator (URL)
A technique for indicating the name and location of Internet resources. The URL specifies the name and type of the resource, as well as the computer, device and directory where the resource may be found. The URL for Dublin Core Metatdata Initiative is <http://dublincore.org/>. For information about Internet addressing, see http://www.w3.org/Addressing/Addressing.html.
Uniform Resource Name (URN)
A URI (name and address of an object on the Internet) that has some assurance of persistence beyond that normally associated with an Internet domain or host name. For information about Internet addressing, see http://www.w3.org/Addressing/Addressing.html.
Union Lists of Artists’ Names (ULAN)
Union List of Artist Names. A controlled vocabulary of artists’ names and biographical and bibliographic information produced by the Getty Vocabulary Program.
URI
See Uniform Resource Identifier
URL
See Uniform Resource Locator
URN
See Uniform Resource Name
USMARC
See MARC
UTF-8
See Unicode Transformation Format, 8-bit.

V

value qualifier
Value qualifier refers to either an encoding rule or controlled vocabulary that aids in the interpretation of the value within the metatag. See encoding scheme.
vCard
A standard for storing information about individuals or corporations; an electronic business card.
For more information, check the Internet Mail Consortium page on personal data exchange.
Vocabulary Encoding Schemes
Vocabulary Encoding Schemes indicate that the value is a term from a controlled vocabulary, such as the value “China – History” from the Library of Congress Subject Headings.
Vocabulary Terms
The Usage Board maintains the DCMI Type Vocabulary — a general, cross-domain list of recommended terms that may be used as values for the Resource Type element to identify the genre of a resource. The member terms of the DCMI Type Vocabulary are called Vocabulary Terms.

W

Warwick Framework
An architecture for the interchange of metadata packages, or “containers”; designed to satisfy the need for competing, overlapping, and complementary metadata models. For more information, see http://www.dlib.org/dlib/july96/07weibel.html.
World Wide Web (WWW)
The panoply of Internet resources (text, graphics, audio, video, etc.) that are accessible via a Web browser.
World Wide Web Consortium (W3C)
An international industry consortium founded in October 1994 to lead the World Wide Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. For additional information see http://www.w3.org/Consortium/.
WWW
See World Wide Web
W3C
See World Wide Web Consortium

X

XML
See Extensible Markup Language

Y

Z

Z39.50
A NISO standard for an application layer protocol for information retrieval which is specifically designed to aid retrieval from distributed servers. http://lcweb.loc.gov/z3950/agency
Aadministrative metadata
Metadata used in managing and administering information resources, e.g., location or donor information. Includes rights and access information, data on the creation and preservation of the digital object.
Source: Dublin Core Metadata Initiative (DCMI) – Glossaryapplication profile
A set of metadata elements, policies, and guidelines defined for a particular application. The elements may be from one or more element sets, thus allowing a given application to meet its functional requirements by using metadata from several element sets including locally defined sets. For example, a given application might choose a subset of the Dublin Core that meets its needs, or may include elements from the Dublin Core, another element set, and several locally defined elements, all combined in a single schema. An Application profile is not complete without documentation that defines the policies and best practices appropriate to the application.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

Application profiles may be defined as schemas comprised of “data elements taken from one or more namespaces, combined together by implementors, and optimised for a particular local application.”
Source: “Application profiles: mixing and matching metadata schemas” by Rachel Heery and Manjula Patel

 

C

Contributor
The Dublin Core element used to designate the entity responsible for making contributions to the content of the resource. Examples of a Contributor include a person, an organization or a service. Typically, the name of a Contributor should be used to indicate the entity.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

controlled element
An element in which the content is in a specific form, or comes from a specified list of acceptable values, such as a thesaurus.
Source: Common Look and Feel Metadata Standard Definitions and HTML Examples

Coverage
The Dublin Core element used to designate the extent or scope of the content of the resource. Coverage will typically include spatial location (a place name or geographic co-ordinates), temporal period (a period label, date, or date range) or jurisdiction (such as a named administrative entity). Recommended best practice is to select a value from a controlled vocabulary, and that, where appropriate, named places or time periods be used in preference to numeric identifiers such as sets of co-ordinates or date ranges.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

Creator
An entity primarily responsible for making the content of the resource. Examples of a Creator include a person, an organization or a service. Typically, the name of a Creator should be used to indicate the entity.
Source: Common Look and Feel Metadata Standard Definitions and HTML Examples

Crosswalk
A table that maps the relationships and equivalencies between two or more metadata formats. Crosswalks or metadata mapping support the ability of search engines to search effectively across heterogeneous databases, i.e. crosswalks help promote interoperability.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

D

Date
A date associated with an event in the life cycle of the resource. Typically, Date will be associated with the creation or availability of the resource. Recommended best practice for encoding the date value is defined in a profile of ISO 8601 [W3CDTF] and follows the YYYY-MM-DD format.
Source: Common Look and Feel Metadata Standard Definitions and HTML Examples

Description
The Dublin Core element used to designate a textual description of the content of the resource.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

descriptive metadata
Metadata that supports the discovery of a digital object.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

Document-Like Object (DLO)
Originally defined as an entity that resembles a document from the standpoint that is substantially text-based and shares other properties of a document, e.g. electronic mail messages or spreadsheets. The definition was expanded at the 3rd DC workshop to refer to any discrete information resource that are characterized by being fixed (i.e., having identical context for each user). Examples include text, images, movies, and performances.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

dot.syntax
A mechanism for refining the meaning of the element in HTML; for example, <META NAME=”DC.Title.Alternative” CONTENT=”Title”>
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

Dublin Core
Dublin Core Metadata Element Set consists of 15 descriptive data elements relating to content, intellectual property and instantiation. The elements are title, creator, publisher, subject, description, source, language, relation, coverage, date, type, format, identifier, contributor and rights. They are to be supplied by the producer of the resource. The Warwick Framework set out a conceptual approach to implementing the Dublin Core, one of which is embedding the data in an HTML document using the META tag. DC is being widely discussed and there is a growing corpus of implementation projects in over 10 countries. There is a Dublin Core-USMARC mapping.
Source: National Library of Canada – A Glossary of Digital Library Standards, Protocols and Formats

Dublin Core Metadata Initiative (DCMI)
The body responsible for the ongoing maintenance of Dublin Core. DCMI is currently hosted by the OCLC Online Computer Library Center, Inc., a not-for-profit international library consortium. The work of DCMI is done by contributors from many institutions in many countries. DCMI is a consensus-driven organization organized into working groups to address particular problems and tasks. DCMI working groups are open to all interested parties. Instructions for joining can be found at the DCMI web site under Working Groups.
Source: Dublin Core Metadata Initiative (DCMI) – Glossary

Dublin Core Structured Values (DCSV)
DCSV recognizes two types of substrings: labels and values. A label is the name of the type of a value, and a value is the data itself. A value that is comprised of components, i.e. a value which has its own label and value, is called a structured value. Punctuation supports the parsing of the DCSV.

Dublin Core Projects

Related Metadata Standards

AGLS (Australian Government Locator Service)
A set of 19 descriptive elements based on the Dublin Core which the Australian government departments and agencies can use to improve the visibility and accessibility of their services and information over the Internet.
EAD (Encoded Archival Description)
An SGML DTD that represents a highly structured way to create digital finding aids for a grouping of archival or manuscript materials. The standard is maintained in the Network Development and MARC Standards Office of the Library of Congress (LC) in partnership with the Society of American Archivists. For more information see http://lcweb.loc.gov/ead/.
GILS (Global Information Locator Service)
GILS embraces open standards to implement interoperable searching across diverse, decentralized information ‘locators’ to return references to all kinds of electronic and non-electronic information resources. Locators are implemented as common semantics for characterizing information resources, i.e. common metadata semantics. Formally known as Government Information Locator Service
IEEE LOM (Institute of Electrical and Electronics Engineers. Learning Object Metadata)
Standard jointly developed by IMS, IEEE, ARIADNE, and ADL/SCORM for describing, exchanging and managing, locating and evaluating learning objects, that is, instructional content, in a digital or non-digital format. The Draft standard dated 15 July 2002 includes nine categories for the metadata: general, life-cycle, meta-metadata, educational, technical, rights, relation, annotation and classification. Includes a mapping to Dublin Core Simple (Annex B, p. 44)
IMS (Instructional Management Systems)
A specification developed by EDUCAUSE (formerly EDUCOM), a consortium of U.S. institutions of higher learning and vendors, for for the discovery and description of learning objects. The specification covers a wide range of e-learning related activities, e.g. vocabulary markup, learning design, content packaging, learner information. It became the basis for the IEEE Learning Object Meta-Data (LOM). The specification includes the element names, definitions, datatypes, and field lengths and defines a conceptual structure for the metadata.
INDECS ( Interoperability of Data in D-Commerce Systems)
Standard that addresses the management of intellectual property rights and rights transactions for all media. Elements designed to faciliate the exchange of rights information between domain-specific standards.
MARC (Machine-Readable Cataloging Record)
The MARC formats are standards for the representation and communication of bibliographic and related information (authority, holdings, classification, community information) in machine-readable form. MARC 21 grew out of the harmonization of USMARC and CAN/MARC, formerly national standards, and has emerged as an international standard. MARC21 is an implementation of the American National Standard, Information Interchange Format (ANSI Z39.2) and its international counterpart, Format for Information Exchange (ISO 2709). UniMARC was originally designed for conversion between national formats but now has been adopted by some countries as their national standard.
METS (Metadata Encoding & Transmission Standard
“A standard for encoding descriptive, administrative, and structural metadata regarding objects within a digital library, expressed using the XML schema language of the World Wide Web Consortium. The standard is maintained in the Network Development and MARC Standards Office of the Library of Congress, and is being developed as an initiative of the Digital Library Federation.”
MODS (Metadata Object Description Schema)
“Intended to be able to carry selected data from existing MARC 21 records as well as to enable the creation of original resource description records. It includes a subset of MARC fields and uses language-based tags rather than numeric ones, in some cases regrouping elements from the MARC 21 bibliographic format.”
ONIX (ONline Information eXchange)
Developed by book publisher for the exchange of book trade information between publishers and wholesalers, e-tail and retail booksellers, other publishers, and anyone else involved in the supply chain. Standards are also being developed by publishers for serials. Mapping between ONIX and MARC exists to facilitate the exchange of content from publishers to library cataloging agencies. Consists of more than 236 elements.
SCORM (Sharable Content Object Reference Model)
eLearning metadata standards supported by ADL (Advanced Distributive Learning Initiative). See IEEE LOM
Application profile
A declaration of the metadata terms an organisation, information resource, application or user community uses in its metadata. This includes the set of metadata elements, policies and guidelines defined for a particular application or implementation.

B

Box
DCMI Box Encoding Scheme, a Syntax Encoding Scheme for identifying a region of space using its geographic limits.

C

Class
A group containing members that have attributes, behaviours, relationships or semantics in common; a kind of category.

D

DCMES
Dublin Core Metadata Element Set. See Dublin Core.
DCMI
Dublin Core Metadata Initiative. See Dublin Core.
DCMI Abstract Model
A set of components and constructs used in Dublin Core metadata, providing an information model independent of any encoding syntax.
DCMIType
DCMI Type Vocabulary. A generic controlled vocabulary for the type property.
DCSV
Dublin Core Structured Values. A syntax for writing a list of labelled values in a text string.
Described resource
A resource that is described by a description.
Description
One or more statements about a resource.
Description set
A set of one or more descriptions, each of which describes a resource.
DOI
Digital Object Identifier. A system for identifying and exchanging intellectual property in the digital environment.
Domain
A relationship between a property and a class which indicates that if the property is part of a property/value pair, then it follows that the
described resource is an instance of that class.
Dublin Core (DC)
An internationally recognised core set of metadata properties on which AGLS is based. More information is available from the Dublin Core Metadata Initiative website.

E

EdNA
Education Network Australia is a network of education information and services. The EdNA metadata standard is based on the Dublin Core set.
Element
See property.
Element refinement
A synonym for property. The word element is also commonly used to refer to a structural markup component within an XML document.
Embedded metadata
Metadata that is stored and maintained within the resource or object it describes.
Encoding scheme
See Vocabulary Encoding Scheme and Syntax Encoding Scheme.

G

GOLD
Government Online Directory of Australian Commonwealth government agencies and employees.

H

HTML
HyperText Markup Language.
HTML META Tag
An approach to encoding metadata in HTML documents.

I

IANA
Internet Assigned Numbers Authority, the coordinator for the assignment of unique parameter values for Internet protocols.
IETF
Internet Engineering Task Force, the international community of network designers, operators, vendors and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. See http://www.ietf.org/
IMT
Internet Media Types.
ISBN
International Standard Book Number.
ISO
International Organization for Standardization.
ISO 639
Codes for the representation of names of languages.
ISO 3166
Codes for representations of names of countries and their subdivisions.
ISO 8601
Data elements and interchange formats – Information interchange – Representation of dates and times.
ISO 15386
Information and documentation – The Dublin Core metadata element set. A PDF copy is available from the National Information Standards Organization (NISO) website.
ISO 15924
Codes for the representation of names of scripts.
ISO 19115
International Standard: Geographic Information – Metadata.
ISSN
International Standard Serial Number.

L

LCSH
Library of Congress Subject Headings is a thesaurus of subject headings maintained by the United States Library of Congress for use in
bibliographic records.
Literal
The value of a metadata property that can be either a hyperlink (URI) or a string value (free text).

M

MESH
Medical Subject Headings is a thesaurus of medical subject terms developed by the United States National Library of Medicine.
Metadata
Structured, machine-processible information that describes and/or enables finding, managing, controlling, understanding or preserving other information over time.
Metadata record
A syntactically correct representation of the descriptive information (metadata) for an information resource.

N

Namespace
A logical grouping of metadata terms. Namespaces allow unique identification of metadata terms to allow those terms to be unambiguously used across applications.

P

Period
DCMI Period Encoding Scheme is a Syntax Encoding Scheme for indicating a single time interval.
Point
DCMI Point Encoding Scheme, a Syntax Encoding Scheme for identifying a point in space using its geographic coordinates.
Property
A specific aspect, characteristic, attribute or relation used to describe a resource (previously called ‘elements’). Dublin Core and AGLS
metadata terms are properties.
Property/Value Pair
The combination of a property and a value, used to describe a characteristic of a resource.

Q

Qualifier
See property, Vocabulary Encoding Scheme and Syntax Encoding Scheme.

R

Range
A relationship between a property and a class which indicates that if the property is part of a property/value pair, then it follows that the value is an instance of that class.
RDF
Resource Description Framework for metadata syntax and interoperability.
Resource
Anything that has an identity. Examples include an electronic document, an image, a service and a collection of other resources. Not all resources are network retrievable; humans, corporations, physical objects and electronic documents on portable media are also resources.
RFC
Request For Comment, the process of establishing a standard on the Internet. More information is available at the Internet Engineering Task Force website.
RFC 2119
Key Words for Use in RFCs to Indicate Requirement Levels.
RFC 3986
Uniform Resource Identifiers (URI): Generic Syntax.
RFC 4646
Tags for Identifying Languages.

S

Schema
A machine-processible specification that defines the structure and syntax of metadata in a formal schema language.
Service
A service exists where a relationship exists between a business function of an organisation and the identified needs of an individual client or a group of clients.
Sub-property
A property of a resource which shares the meaning of another property but with narrower semantics (previously called ‘element refinements’).
Syntax Encoding Scheme
Indicates that the value is a string formatted in accordance with a formal notation or externally defined standard.

U

URI
Uniform Resource Identifier is a syntax for all names/addresses for resources on the World Wide Web, includes Uniform Resource Locator (URL) and Uniform Resource Name (URN). See also Naming and Addressing: URIs, URLs, … and RFC 3986.
URL
Uniform Resource Locator is a technique for indicating the name and location of Internet resources. See also Naming and Addressing: URIs, URLs, …
URN
Uniform Resource Name, a technique for indicating the name and location of Internet resources that has some assurance of persistence
beyond that normally associated with an Internet domain or host name. More information is available at the World Wide Web Consortium website.
UUID
Universally Unique Identifier is a unique, persistent identifier capable of being generated on demand without requiring a central registration process. UUIDs consist of 32 hexadecimal digits in the form 8-4-4-4-12, eg 6ba7b810-9dad-11d1-80b4-00c04fd430c8. UUIDs are a form of URN. More information is available in RFC 4122.

V

Value
The content of a metadata property providing information about a characteristic of a resource.
Vocabulary Encoding Scheme
Indicates that the value is a term from a controlled vocabulary.

W

W3C
World Wide Web Consortium is the international consortium that develops web standards, guidelines and protocols.

X

XHTML
eXtensible HyperText Markup Language. A reformulation of HTML 4.01 conforming to XML syntax. See also XHTML™ 1.0 The Extensible HyperText Markup Language (Second Edition).
XML
eXtensible Markup Language.
Agent In Dublin Core terms, the super-property of Creator, Contributor and Publisher. A person or corporate body.
AHDS Arts and Humanities Data Service. UK service funded by JISC to collect, describe, and preserve the electronic resources which result from research and teaching in the humanities.
Ariadne A parallel web and print journal for librarians and information specialists funded by JISC under eLib.
ASF Advanced Search Facility.
Attribute/value pair The combination of a metadata property and its value.
Broker A network service that provides a single interface to multiple (often remote) network services.
Bureau A third party serving metadata descriptions, e.g. a PICS label bureau.
Checksum A computed value which depends on the contents of a ‘block of data’.
CIMI Computer Interchange of Museum Information. CIMI records are a SGML-based metadata format developed for museum information.
CLD Collection Level Description
CNI Coalition for Networked Information.
CNRI Corporation for National Research Initiatives.
CORBA Common Object Request Broker Architecture.
CURL Consortium of University Research Libraries.
DASL DAV Searching and Locating. See also: WebDAV.
DC See: Dublin Core.
DCMI See: Dublin Core.
DC-dot A program for creating Dublin Core metadata which can be pasted into the headers of Web pages.
DN Distinguished Name. An X.500 or LDAP object name.
DOI Digital Object Identifier.
DSig Digital Signatures Initiative. Work co-ordinated by W3C to develop a trust mechanism for the Web. Will be based on RDF.
DSTC Distributed Systems Technology Centre.
DTD Document Type Definition. An application program defining document types in a SGML context.
Dublin Core A metadata format defined on the basis of international consensus which has defined a minimal information resource description, generally for use in a WWW environment.
EAD Encoding Archival Description. A SGML-based metadata format developed for the description of archives.
EDI Electronic Data Interchange. The exchange of structured data messages to enable automated transactions between application systems.
FGDC Federal Geographic Data Committee. Organisation that defined FGDC Content Standards for Digital Geospatial Metadata.
FRBR Functional Requirements for Bibliographic Records.
GCL A controlled vocabulary for UK government categories.
GILS Government Information Locator Service. Metadata format created by the US Federal Government in order to provide a means of locating information generated by government agencies.
Handle System A distributed system developed by CNRI which resolves identifiers into the information necessary to locate and access resources.
Harvest A system providing a software architecture for gathering, indexing and accessing Internet information. Uses SOIF.
Hash Function See: Checksum.
HTML Hypertext Mark-up Language. The standard language used for creating Web documents.
HTTP HyperText Transfer Protocol. The client-server protocol used for the exchange of HTML. See also: TCP/IP.
IAFA templates Internet Anonymous FTP Archive templates. Metadata format designed for Anonymous FTP archives, now adapted for use in ROADS project.
ICE Internet Content Exchange.
ICPSR Inter-university Consortium for Political and Social Research. Organisation that developed the ICPSR SGML Codebook Initiative – a structured metadata format to describe social science data sets.
IETF Internet Engineering Task Force.
IFLA International Federation of Library Associations and Institutions.
IMesh An international ‘community’ of subject gateway service providers.
IMesh-Toolkit A JISC/NSF funded project to develop a distributed architecture and software toolkit for developing subject gateways.
IMS Instructional Management System.
INDECS Interoperability of Data in E-Commerce Systems. A European funded project.
ISAAC The Isaac Network: Information Seeker’s Avenue to Authoritative Content.
ISBN International Standard Book Number.
ISSN International Standard Serial Number.
ISO 8601 A date format endorsed by the W3C for use by Web-applications.
LDAP Lighweight Directory Access Protocol. Internet standard for directory services.
LOM IEEE Learning Object Metadata – a part of the IMS specification.
MARC MAchine Readable Cataloguing. A family of formats based on ISO 2709 for the exchange of bibliographic and other related information in machine readable form. For example, USMARC, UKMARC and UNIMARC.
MD5 A one-way hash function typically used within cryptography.
MeSH Medical Subject Headings.
Metadata Structured data about a resource.
METS Metadata Encoding and Transmission Standard.
MODS Metadata Object Description Schema.
NISO National Information Standards Organization.
OAI Open Archives Initiative
OAI-PMH Open Archives Initiative Protocol for Metadata Harvesting
OCLC On-line Computer Library Center.
PICS Platform for Internet Content Selection. Internet content filtering infrastructure.
PII Publisher Item Identifier.
Portal A Web-based gateway to Internet resources, often with other value-added services such as free email accounts.
PURL Persistent Uniform Resource Locator.
Push technology New Web technologies based on pushing information to end user.
RDF Resource Description Framework. RDF is currently under development within the W3C and provides a framework for metadata in different application areas, e.g. resource discovery, content ratings and intellectual property.
RDN Resource Discovery Network.
RDN Relative Distinguished Name. An X.500 or LDAP object name.
RDNC Resource Discovery Network Centre.
Reggie A Java-based metadata editor.
ROADS Resource Organisation And Discovery in Subject based services. eLib funded project developing software for use by Internet subject services. ROADS templates are a metadata format and are a development of IAFA templates.
RSS Rich Site Summary – a metadata format for syndicating web site headlines. It was created and popularised by Netscape for their personalised portal site.
SBIG Subject-Based Information Gateway. See: Subject Service.
SGML (ISO 8879) Standard Generalised Mark-up Language. An international standard for the description of marked-up electronic text.
SHHTP HTTP secured using SSL.
SICI Serial Item and Contribution Identifier.
SiRPAC RDF-XML parser developed by W3C.
SOIF Summary Object Interchange Format. A metadata format developed for use with the Harvest architecture.
SSI Server Side Include. Mechanism for dynamically generating parts of Web pages.
SSL Secure Socket Layer. A method for end-to-end network encryption.
stuff A neutral term for ‘resource’ (which absolves you from any need to define what you are talking about).
Subject Service Internet subject services or gateways. Typically give access to selected Internet resources based on subject coverage and quality criteria. For example: Social Science Information Gateway (SOSIG).
Unicode A standard for international character encoding.
TCN See: Transparent Content Negotiation.
TCP/IP Transmission Control Protocol/Internet Protocol. The Internet transport-level protocols, often used to refer to the entire collection of Internet protocols.
TEI Text Encoding Initiative. An attempt to define the encoding of literary and linguistic texts in electronic form. TEI headers are a SGML-based metadata format for the documentation of these electronic texts.
TERENA Trans-European Research and Education Networking Association.
TF-CHIC TERENA Task Force – Cooperative Heirarchical Indexing Coordination.
Transparent Content Negotiation Transparent Content Negotiation. Mechanism for transparent selection of content type – by format, language, etc.
UDDI Universal Description, Discovery and Integration
URC Uniform Resource Characteristics.
URI Uniform Resource Identifier. The super-set of URNs, URLs and URCs.
URL Uniform Resource Locator. The standard way to give the address of a source of information on the WWW. For example: http://www.ukoln.ac.uk/metadata/publications.html
URN Uniform Resource Name. Persistent identification for Web resources.
Warwick Framework An architecture for the exchange of distinct metadata packages involving the aggregation of metadata packages into containers.
Web robot A software robot which trawls the WWW, generating all-encompassing Web indexes. Also known as Web crawlers or Web spiders.
WebDAV Web Distributed Authoring and Versioning. An IETF Working Group.
Whois++ An Internet directory services protocol.
World Wide Web Consortium Organisation currently responsible for the development of Web protocols.
WWW World Wide Web.
W3C See: World Wide Web Consortium
XML Extensible Markup Language. A lightweight version of SGML designed for use on the Internet.
Z39.50 A NISO standard for an applications layer protocol for information retrieval which is specifically designed to aid retrieval from distributed servers.
ZNG Z39.50 Next Generation – a proposal to evolve Z39.50 to a more mainstream protocol based on XML, URI, SOAP (RPC), and HTTP.

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Glossary

AACR (Anglo-American Cataloguing Rules)
A data content standard for describing bibliographic materials. http://www.aacr2.org/.

algorithm
A formula or procedure for solving a problem or carrying out a task. An algorithm is a set of steps in a very specific order, such as a mathematical formula or the instructions in a computer program.

application profile
A set of metadata elements, policies, and guidelines defined for a particular application or community. The elements may be from one or more element sets, thus allowing a given application to meet its functional requirements by using metadata from several element sets, including locally defined elements.

authentication
A human or machine process that verifies that an individual, computer, or information object is who or what it purports to be.

authority file
A file, typically electronic, that serves as a source of standardized forms of names, terms, titles, and so on. Authority files should include references or links from variant forms to preferred forms. For example, in the Library of Congress Name Authority File (LCNAF), “Schiavone, Andrea” is the preferred name form for a Dalmatian artist active in Italy during the sixteenth century, while “Medulic\xB4, Andrija,” “Lo Schiavone,” and several other forms are listed as variant names. Authority files regulate usage but also provide additional access points, thus increasing both the precision and the recall of many searches.

back-end database
A database that contains and manages data for an information system, distinct from the presentation or interface components of that system.

CCO (Cataloging Cultural Objects)
A data content standard for describing works of art, architecture, and material culture. http://www.vraweb.org/ccoweb/cco/index.html.

CDWA (Categories for the Description of Works of Art)
A set of metadata categories and recommendations that may be used to design information systems and to do cataloging for art, architecture, objects of material culture, and archaeological and archival materials. http://www.getty.edu/research/conducting_research/standards/cdwa/.

CDWA Lite
An XML schema for core records for art, architecture, and material culture designed to work with the OAI-PMH; the elements are based on a subset of the full element set of Categories for the Description of Works of Art (CDWA). http://www.getty.edu/research/conducting_research/standards/cdwa/cdwalite.html.

CGI script
A computer program, most frequently written in C, Perl, or a shell script, that uses the Common Gateway Interface (CGI) standard and provides an interactive interface between a user or an external computer application and a World Wide Web server. CGI scripts are most commonly used to develop forms that allow users to submit information to a Web server.

CIDOC CRM (CIDOC Conceptual Reference Model)
An object-oriented ontology for the mediation and interchange of heterogeneous cultural heritage information. http://cidoc.ics.forth.gr/.

client
An application that retrieves and/or renders resources or resource manifestations. Often used to denote a computer or other kinds of devices connected to a network, equipped with software that enables users to access resources available on another computer connected to the same network, called a server. See also server.

conceptual data model
An abstract model or representation of data for a particular domain, business enterprise, field of study, etc., independent of any specific software or information system. Usually expressed in terms of entities and relationships. See also logical data model.

crosswalk
A chart or table (visual or virtual) that represents the semantic mapping of fields or data elements in one data standard to fields or data elements in another standard that has a similar function or meaning. Crosswalks make it possible to convert data between databases that use different metadata schemes and enable heterogeneous databases to be searched simultaneously with a single query as if they were a single database (semantic interoperability). Also known as field mapping. See also metadata mapping.

DACS (Describing Archives: A Content Standard)
A data content standard for describing archival collections. http://www.archivists.org/catalog/pubDetail.asp?objectID=1279.

data content standard
Rules that determine the vocabulary, syntax, or format of content entered into data fields or metadata elements, for example, Anglo-American Cataloguing Rules (AACR), ISO 8601 (rules for recording date and time), Describing Archives: A Content Standard (DACS), Cataloging Cultural Objects (CCO).

data provider (OAI nomenclature)
An organization that exposes metadata records in one or more repositories (specially configured servers) for harvesting by service providers.

Deep Web
See Hidden Web.

default values
Values that are assumed or supplied automatically, for example, by a computer system, if a value is not specified.

digital signatures
A form of electronic authentication of a digital document. Digital signatures are created and verified using public key cryptography and serve to tie the document being signed to the signer.

digital surrogate
A digital “copy” of an original work or item, for example, a JPEG or TIFF image of a painting or sculpture or a PDF file of an article or book. In OAI nomenclature, digital surrogates are often referred to as “resources.”

DTD (Document Type Definition)
A collection of markup declarations that define the structure, elements, and attributes that can be used in encoding certain type of documents in SGML or, more commonly, in XML. Examples of DTDs include the EAD DTD, the HTML DTD, and the TEI DTD. XML DTDs are gradually being replaced by the newer XML schemas.

Dublin Core Metadata Element Set (DCMES)
A set of 15 metadata elements that can be assigned to information resources, optimized for resource discovery on the World Wide Web. Also often used as a “lowest common denominator” in metadata mapping. http://dublincore.org/documents/dces/.

dynamically generated
Refers to a Web page, metadata record, or other information object that is generated on demand, typically from content stored in a database, and usually either in response to a user’s input or from dynamic data sources that are refreshed periodically. The expression “on the fly” is often used in relation to dynamically generated content.

EAD (Encoded Archival Description)
A data structure standard for encoding archival finding aids in SGML or XML according to the EAD DTD or EAD XML schema, making it possible for the semantic contents of a hierarchically structured finding aid to be machine processed. http://www.loc.gov/ead/.

encryption
An encoding mechanism used to prevent nonauthorized users from reading digital information and also for user and document authentication. Only designated users or recipients have the capability to decode encrypted materials.

entity-relationship model
A type of conceptual data model that represents structured data in terms of entities and relationships. An entity-relationship diagram can be used to represent information objects and their relationships visually. Because the constructs used in the entity-relationship model can easily be transformed into relational tables, this type of model is often used in database design.

EXIF (Exchangeable Image File Format)
A specification for an image file format for digital cameras that provides the ability to attach image metadata to JPEG, TIFF, and RIFF images. As of this writing, EXIF is not maintained by any industry or standards organization but is widely used by camera manufacturers. http://www.exif.org/.

field mapping
See crosswalk.

FTP (File Transfer Protocol)
A TCP/IP protocol that allows data files to be copied directly from one computer to another over the Internet.

finding aid
A descriptive tool widely used in archives. Finding aids typically take the form of hierarchical narrative descriptions of cohesive groups of archival records or collections of manuscript materials. Finding aids traditionally were paper documents; EAD is a structured way of expressing finding aids as machine-readable data.

FRBR (Functional Requirements for Bibliographic Records)
A set of requirements and a conceptual entity-relationship model developed by the International Federation of Library Associations and Institutions (IFLA) to support bibliographic access and control. http://www.ifla.org/VII/s13/frbr/frbr.htm.

FRBRoo
A joint initiative of the International Federation of Library Associations and Institutions (IFLA) and the International Council of Museums–International Documentation Committee (ICOM-CIDOC) to create an object-oriented ontology that both captures the semantics of bibliographic information and harmonizes those concepts in common with the CIDOC CRM, thus facilitating information interchange between the museum and library communities. http://cidoc.ics.forth.gr/frbr_inro.html. folksonomy
An assemblage of concepts, represented by terms and names (called “tags”), the result of social tagging. Note that a folksonomy is not a true taxonomy. See also social tagging, taxonomy.

Google Sitemap
Metadata about the content of a Web site that assists the Googlebot Web crawler to index a site more efficiently and comprehensively. www.google.com/webmasters/sitemaps/.

granularity
The level of detail at which an information object or resource is viewed or described.

harvester (OAI nomenclature)
A computer system that sends OAI-PMH requests to OAI data providers’ repositories and harvests metadata records from them.

header metadata
Metadata embedded in the header part of a digital file.

Hidden Web (also known as Deep Web, Invisible Web)
The sum of the Web pages that are not accessible to Web crawlers, usually because they are either dynamically generated by a user querying a database or password-protected or subscription-based.

hostname
An identifier for a specific machine on the Internet. The hostname identifies not only the machine but also its subnet and domain, for example, www.getty.edu. See also domain name.

HTML (HyperText Markup Language)
An SGML-derived markup language used to create documents for World Wide Web applications. HTML has evolved to emphasize design and appearance rather than the representation of document structure and metadata elements.

HTTP
HyperText Transfer Protocol, the standard protocol that enables users with Web browsers to access HTML documents and related media.

hyperlink
An abbreviated reference to a “hypertext link,” a method of creating nonlinear pathways between related digital documents or to link to related objects such as image or audio files.

information object
A digital item or group of items referred to as a unit, regardless of type or format, that a computer can address or manipulate as a single discrete object.

Internet
A global collection of computer networks that exchange information by the TCP/IP suite of networking protocols.

Internet directory
A thematically organized list of descriptive links to Internet sites, often created by humans who have classified sites by their content. Yahoo! provides numerous such directories. interoperability
The ability of different information systems to work together, particularly in the correct interpretation of data semantics and functionality. See also semantic interoperability.

Invisible Web
See Hidden Web.

legacy system
An information system that has been developed and modified over a period of time and has become outdated and difficult and costly to maintain but that holds important information and involves processes that are deeply ingrained in an organization. Legacy systems usually are eventually replaced by a new hardware and software configuration.

link resolver
Software that uses the OpenURL standard to automatically redirect a user’s request to the most appropriate copy of a networked digital object. Typically, link resolvers are used by libraries to direct their patrons from bibliographic records or abstracts to licensed subscription-based resources such as full-text electronic versions of articles and books. http://www.niso.org/standards/standard_detail.cfm?std_id=783.

logical data model
A data model that includes all entities and the relationships among them based on the structures identified in a conceptual data model and that specifies all attributes for each entity. The data is described in as much detail as possible, without regard to how it will be physically implemented in a specific database.

MARC (Machine-Readable Cataloging format)
A set of standardized data structures for describing bibliographic materials that facilitates cooperative cataloging and data exchange in bibliographic information systems. http://www.loc.gov/marc/.

markup language
A formal way of annotating a document or collection of digital data using embedded encoding tags to indicate the structure of the document or datafile and the contents of its data elements. This markup also provides a computer with information about how to process and display marked-up documents. HTML, XML, and SGML are examples of standardized markup languages.

memory institution
A generic term used to describe an institution that has a responsibility to collect, care for, and provide access to the human record—for example, museums, libraries, and archives.

metadata mapping
A formal identification of equivalent or nearly equivalent metadata elements or groups of metadata elements within different metadata schemas, carried out in order to facilitate semantic interoperability.

metadata mining
The automated extraction of metadata from electronic documents.

metasearch
Searching of diverse databases on diverse platforms with diverse metadata in real time by means of one or more protocols. The NISO MetaSearch Initiative defines metasearch as “search and retrieval to span multiple databases, sources, platforms, protocols, and vendors at once.” Metasearch enables users to enter search criteria once and access several search engines simultaneously. With metasearch, fresh records are always available, because searching is in real time, in a distributed environment. http://www.niso.org/committees/MS_initiative.html.

META tag
An HTML tag that enables metadata to be embedded invisibly on Web pages, for example, Description, Keywords.

META tag spamming
The deliberate misuse of meta tags in order to attract traffic to a site, for example, by boosting its ranking in search results.

METS (Metadata Encoding Transmission Schema)
A standard for encoding descriptive, administrative, and structural metadata relating to objects in a digital library, expressed in XML. METS enables the “packaging” of complex digital objects that include a range of metadata as well as related digital surrogates. http://www.loc.gov/standards/mets/

MODS (Metadata Object Description Schema)
An XML schema for bibliographic records, developed and maintained by the Library of Congress. http://www.loc.gov/standards/mods/.

namespace
The set of unique names used to identify objects within a well-defined domain, particularly relevant for XML applications. An XML Namespace is a W3C recommendation for providing uniquely named elements and attributes in an XML instance. A namespace is declared using the reserved XML attribute xmlns, the value of which must be a URI (Uniform Resource Identifier) reference. For example, the Dublin Core Metadata Element Set, Version 1.1 (original 15 elements) has the approved DCMI namespace URI as http://purl.org/dc/elements/1.1/.

nesting
The way in which subelements may be contained within larger elements, resulting in multiple levels of metadata.

network bandwidth
Derived from the term used to describe the size or “width” of the frequencies used to carry analog communications such as television and radio. For Internet purposes, bandwidth is generally (and incorrectly) used to refer to the rate of data transfer.

OAI-PMH (Open Archives Initiative Protocol for Metadata Harvesting)
A protocol used to harvest or collect metadata records from data providers. http://www.openarchives.org/pmh/.

object-oriented
A programming or data modeling methodology that utilizes the notion of classes and their properties. Members (or instances) of a class share the same propeties—for example, color or weight (however, note that although members of a class all share the same properties, the values of those properties do not need to be the same). Classes can contain subclasses, members of which inherit the properties of the parent or “superclass.”

ontology
A formal, machine-readable specification of a conceptual model, in which concepts, properties, relationships, functions, constraints, and axioms are all explicitly defined.

OPAC (Online Public Access Catalog)
A computerized inventory of a library’s holdings.

Open WorldCat
A subset of the WorldCat union bibliographic database made available by OCLC to certain Web search engines and online book retailers. http://www.oclc.org/worldcat/open/.

PageRank™ (Google)
A proprietary link-analysis algorithm developed by Google founders Larry Page and Sergey Brin to assign a numerical score to each document in a set of hypertext documents based on the number of referring links. The algorithm also takes into account the rank of the referring page, such that a link from a high-ranking page counts more than a link from a low-ranking page. http://www.google.com/technology/.

precision
A measure of search effectiveness expressed as the ratio of relevant records or documents retrieved from a database to the total number retrieved in response to the query; for example, in a database containing 100 records relevant to the topic “book history,” a search retrieving 50 records, 25 of which are relevant to the topic, would have 50 percent precision (25/50). (Definition from ODLIS, Online Dictionary for Library and Information Science, http://lu.com/odlis/.) See also recall.

protocol
A specification—often a standard—that describes how computers communicate with each other, for example, the TCP/IP suite of communication protocols or the OAI-PMH.

RDF (Resource Description Framework)
An application of XML that enables the creation of rich, structured, machine-readable resource descriptions. http://www.w3.org/RDF/.

RDF schema
A set of semantics within a defined namespace for use with specific applications of RDF.

recall
A measure of the effectiveness of a search expressed as the ratio of the number of relevant records or documents retrieved in response to the query to the total number of relevant records or documents in the database; for example, in a database containing 100 records relevant to the topic “book history,” a search retrieving 50 records, 25 of which are relevant to the topic, would have 25 percent recall (25/100). (Definition from ODLIS, Online Dictionary for Library and Information Science, http://lu.com/odlis/.) See also precision.

relevance
The extent to which information retrieved in a search of a library collection or other resource, such as an online catalog or a bibliographic database, is judged by the user to be applicable to (“about”) the subject of the query. Relevance depends on the searcher’s subjective perception of the degree to which the document fulfills the information need, which may or may not have been expressed fully or with precision in the search statement. Measures of the effectiveness of information retrieval, such as precision and recall, depend on the relevance of search results. (Definition from ODLIS, Online Dictionary for Library and Information Science, http://lu.com/odlis/.)

relevance ranking
The algorithmic process, a feature of many search software applications, by which results in a result set are sorted or ranked according to their relevance. In OPACs, for example, relevance is computed based upon the number of occurrences of the search term in the record that is retrieved, and the weight assigned to the field(s) in which the search term appears. (Definition from ODLIS, Online Dictionary for Library and Information Science, http://lu.com/odlis/.) Google’s PageRank™ is an example of a relevance ranking algorithm.

resource discovery
The process of searching for specific information objects on the Web.

robot
See Web crawler.

schema
A set of rules for encoding information that supports specific communities of users. Also called “scheme.” The plural forms of the word schema are schemas and schemata. See also XML schema.

schema registry
An authoritative source of names, semantics, and syntaxes for one or more schemas.

screen scraping
A technique in which display data (usually unstructured) is automatically retrieved and extracted, for example, from a Web page.

search engine
A computer program that allows users to search electronic resources. In the context of the World Wide Web, the term usually refers to a program that searches a large index of Web pages generated by an automated Web crawler. See also Web search engine.

semantic interoperability
The ability of different agents, services, and applications to communicate data while ensuring accuracy and preserving the meaning of the data (definition based on Marcia Bates and Mary Niles Maack, Encyclopedia of Library and Information Sciences, 3rd ed. [New York: Marcel Dekker, forthcoming]).

Semantic Web
An evolving, collaborative effort led by the W3C whose goal is to provide a common framework that will allow data to be shared and reused across various applications as well as across enterprise and community boundaries. It derives from W3C director and inventor of the World Wide Web Sir Tim Berners-Lee’s vision of the Web as a universal medium for data, information, and knowledge exchange.

server
An application that supplies resources or resource manifestations. Often used to refer to a networked computer that acts as a source of data and/or applications used by multiple client computers or devices. See also client.

service provider (OAI nomenclature)
An institution or organization that harvests metadata from data providers and uses the aggregated metadata as a basis for building value-added services.

SGML (Standard Generalized Markup Language)
International Standards Organization standard ISO/IEC 8879:1986; a markup language first used by the publishing industry, for defining, specifying, and creating digital documents that can be delivered, displayed, linked, and manipulated in a system-independent manner. XML and HTML are derived from SGML.

social bookmarking
The decentralized practice and method by which individuals and groups create, classify, store, discover, and share Web bookmarks or “favorites” in an online “social” environment.

social tagging
The decentralized practice and method by which individuals and groups create, manage, and share terms, names, and so on (called tags), to annotate and categorize digital resources in an online “social” environment. A folksonomy is the result of social tagging. Also referred to as collaborative tagging, social classification, social indexing, mob indexing, folk categorization. See also folksonomy, tagging.

spamming
Used in reference to meta tags. The abuse of metadata that creators include in the HTML header area of their Web pages in order to increase the number of visitors to a Web site. Keyword spamming entails repeating keywords multiple times in order to appear at the top of search engine result listings or listing keywords that are irrelevant to the site in order to attract visitors under false pretenses.

spider
See Web crawler.

SRU/SRW (Search and Retrieve via URL/Search and Retrieve Web Service)
Companion protocols for Web search queries utilizing the CQL Common Query Language. http://www.loc.gov/standards/sru/.

surrogate
See digital surrogate.

tagging
In the context of the Web, the act of associating terms (called tags) with an information object (e.g., a Web page, an image, a streaming video clip), thus describing the item and enabling keyword-based classification and retrieval. Tags—a form of user-generated metadata—from communities of users can be aggregated and analyzed, providing useful information about the collection of objects with which the tags have been associated. See also social tagging.

taxonomy
An orderly classification that explicitly expresses the relationships, usually hierarchical (e.g., genus/species, whole/part, class/instance), between and among the things being classified.

TCP/IP (Transmission Control Protocol/ Internet Protocol)
The ISO standardized suite of network protocols that enables information systems to communicate with other information systems on the Internet, regardless of their computer platforms.

TEI (Text Encoding Initiative)
An international cooperative effort to develop guidelines for standard encoding schemes (i.e., the TEI and TEI Lite DTDs) for literary and linguistic texts. http://www.tei-c.org/.

URI (Uniform Resource Identifier)
A short string that uniquely identifies a resource such as an HTML document, an image, a downloadable file, or a service. URLs and URNs are types of URIs.

URL (Uniform Resource Locator)
A type of URI consisting of an Internet address that tells users how and where to locate a specific file on the World Wide Web. A URL includes not only the name of a file but also the name of the host computer, the directory path to get to that file, and the protocol needed in order to use it (e.g., http://www.getty.edu/research/conducting_research/standards/intrometadata/intro.html specifies that the hypertext transfer protocol “http” should be used to retrieve the document intro.html from the host www.getty.edu in the directory research/conducting_research/standards/intrometadata.

URN (Uniform Resource Name)
A type of URI consisting of a unique, location-independent identifier of a file available on the Internet. The file remains accessible by its URN regardless of changes that might occur in its host and directory path. For example, urn:issn:0167-6423 is the URN for the journal Science of Computer Programming.

Visible Web
The subset of the World Wide Web that is visible to Web browsers and indexable by search engines’ Web crawlers. To be accessible to Web crawlers, the pages must be accessible simply by following links (i.e., not generated dynamically in response to user input) and not protected by a password.

VRA Core 4.0
An XML schema for describing works of art and architecture and their visual surrogates. http://www.vraweb.org/projects/vracore4/index.html

W3C (World Wide Web Consortium)
The main international standards organization for the World Wide Web.

Web 2.0
A phrase used loosely by the Web development community to refer to a perceived “second generation” of Web technologies and applications. Wikis, folksonomies, gaming, podcasting, blogging, and so on, are all considered Web 2.0 applications.

Web browser
A software application that enables users to view and interact with information and media files on the Web. Internet Explorer, Mozilla Firefox, and Netscape Navigator are examples of Web browsers.

Web crawler (robot, spider)
A software program that systematically traverses the Web, either for the purpose of generating a searchable index of Web content or to gather statistics.

Web server
A computer that is able to respond to HTTP requests from clients known as Web browsers and return the appropriate HTTP responses—most typically serving an HTML page.

Web search engine/Internet search engine
A software program that collects data taken from the content of files available on the Web and puts them in an index or database that Web users can search in a variety of ways. The search results provide links back to the pages matching the user’s search in their original location.

wiki
A collaborative Web site that contains pages that any authorized user can edit. Wikis typically retain all former versions of each page, allowing the revision history of a page to be tracked and for unwanted revisions to be reversed.

Wikipedia
A free, collaborative, volunteer-driven Web-based encyclopedia that utilizes wiki software to allow anyone to edit articles. http://en.wikipedia.org/wiki/.

World Wide Web
A vast distributed wide-area client-server architecture for retrieving hypermedia documents over the Internet.

XHTML (Extensible HyperText Markup Language)
A reformulation of HTML in XML.

XML (Extensible Markup Language)
A simple, flexible markup language derived from SGML. Originally designed for large-scale electronic publishing, XML is now playing an increasingly important role in the publication and exchange of a wide variety of data on the Web.

XML schema
A machine-readable definition of the structure, elements, and attributes allowed in a valid instance of a conforming XML document. XML schemas are expressed using the XML Schema Definition language, a W3C standard. http://www.w3.org/TR/xmlschema-0/.

XMP (Extensible Metadata Platform)
A markup language, based on RDF, for recording and embedding metadata about digital assets. Developed by Adobe Systems and supported across the company’s range of software products and file formats. http://www.adobe.com/products/xmp/index.html.

Main Sources: http://dublincore.org/documents/usageguide/glossary.shtml, http://www.ukoln.ac.uk/metadata/glossary/, Introduction to Metadata (Getty),

Glossary

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