3G
3G is an ITU specification for the third generation (analog cellular was the first generation, digital PCS the second) of mobile communications technology. 3G promises increased bandwidth, up to 384 Kbps when a device is stationery or moving at pedestrian speed, 128 Kbps in a car, and 2 Mbps in fixed applications. 3G will work over wireless air interfaces such as GSM, TDMA, and CDMA. The new EDGE air interface has been developed specifically to meet the bandwidth needs of 3G.

10Base2
Also called Thin Ethernet, it uses a thin COAXIAL CABLE and daisy chain configuration for 10 Mbps.

10Base5
Thick Ethernet, or 10Base5, uses a large COAXIAL CABLE to achieve 10 Mbps.

10Base-T
A 10 Mbps Ethernet LAN that runs over TWISTED-PAIR wiring. This network interface was originally designed to run over ordinary twisted-pair (phone wiring) but is predominantly used with CATEGORY 3 or CATEGORY 5 cabling.

100Base-T
A 100 Mbps LAN that maintains backward compatibility with 10 BASE-T networks running at 10 Mbps.

1000Base-T
Also called Gigabit Ethernet, this is a new standard that is being defined to carry 1 Gigabit per second traffic a total distance of 100 meters using CAT5 TWISTED-PAIR cable.

ADSL (Asymmetric Digital Subscriber Line)
A technology that delivers data faster downstream than upstream; therefore the use of the term ADSL. The fastest downstream rate is 8 Mbps, while the fastest upstream rate is 640 Kbps. The ADSL standard is governed by the ITU and ANSI standards bodies. The two most common implementations of ADSL are full-rate ADSL, governed by ITU G.992.1 and ANSI T1.413, and the lower-speed ADSL, governed by ITU G.992.2. There is no ANSI specification for G.LITE.

Many operators providing DSL service drop ship the customer premises equipment to the SUBSCRIBER, for self-installation. The equipment typically consists of the DSL modem/router, NIC card and filters to filter out high-frequency signals so that both the voice and data can share common inside wiring.

AMR (Automated Meter Reading)
The remote collection of consumption data from customers? utility meters using telephony, RF, powerline, and satellite communications technologies.

API (Application Programming Interface)
A generic term for the routines, features, and associated rules which allow computer programmers to build APPLICATIONS, and, APPLICATIONS which exchange data with one another.

For example, when an operator?s VOD SUBSCRIBER elects to watch a movie on demand, the video server and TV APPLICATION SERVER will exchange information with the subscriber billing system based on the use of the two systems? APIs, so the fee for the viewing of the movie can be billed to the SUBSCRIBER. The API ensures that the data is presented from one system to the other in a format that the receiving system can interpret or act upon.

Applications
Computer programs designed for use by end users and SUBSCRIBERs. Examples include IPGs, VOD, electronics spreadsheets, and word processing.

Application Server
Also called an appserver. A program that handles all application operations between users and an organizations? backend business applications or databases. Application servers are typically used for complex transaction-based applications. To support high-end needs, an application server has to have built-in redundancy, monitors for high-availability, high-performance distributed application services and support for complex database access.

ASIC (Application Specific Integrated Circuit)
A chip designed for a specific application. Examples of an ASIC application can be SDSL or other broadband solutions.

ATM (Asynchronous Transfer Mode)
A high-bandwidth, low-delay, connection-oriented packet-like switching and multiplexing technique. Usable capacity is segmented into 53-byte fixed-size cells; each cell is presented to the network on a start-stop basis, thus asynchronous. ATM is designed for use in high-speed communications frameworks such as OC-3, OC-12 and SONET.

ATSC (Advanced Television Systems Committee)
The ATSC is a U.S.-based industry organization chartered to establish digital broadcasting standards used in the U.S.

Bluetooth
A technology named after Harald Bluetooth, a 10th-century Viking King who united Denmark under Christianity. This short-range RF solution (10 centimeters to 10 meters) operates on a bandwidth of 2.4 GHz, an unlicensed frequency worldwide. It is viewed primarily as a cable replacement technology to link such devices as laptop computers and personal digital assistants and mobile phones to headsets.

Broadband Network Operator
The business entity that provides information and entertainment services to SUBSCRIBERs via a broadband network. These entities can be TELCOS or independent private network providers utilizing the Telco?s network. An operator may also choose to implement a network that is separate and parallel to the public telephone network. Property management firms that operate MDUs can also be broadband network operators.

Broadcast
A simultaneous analog or digital transmission sent to all the receivers in a network.

Bundle
A combination of more than one package of services, sold for a single rate (price) by the BROADBAND NETWORK OPERATORS.

CA (Conditional Access)
A means of modifying a media stream, through encryption, scrambling or other techniques, so that the SUBSCRIBER can view only the services authorized by the operator for viewing by that SUBSCRIBER.

CableLabs
The dominant industry association for the U.S. cable television industry. CableLabs has provided a number of reference specifications to the industry, some of which have been adopted by international standards organizations.

CAP (Carrierless Amplitude Modulation)
A single-carrier transmission technique used by some implementations of ADSL.

Category 3 (Category 3 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for medium speed communications of up to 10 Megabits over distances of up to 100 meters. The FCC has specified the use of a minimum of CAT3 wiring for telephones in new home construction.

Category 4 (Category 4 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for medium speed communications of up to 16 Mbps over distances of up to 100 meters. It is not in general use as its introduction was soon followed by the development of CAT 5 cabling that provides greater throughput.

Category 5 (Category 5 Wiring)
Consists of 4 pairs of TWISTED-PAIR wires used for high-speed communications of up to 100 Mbps over distances of up to 100 meters.

CDMA (Code-Division Multiple Access)
A digital cellular technology that uses SPREAD-SPECTRUM techniques. Unlike competing systems, such as GSM, that use TDM, CDMA does not assign a specific frequency to each user. Instead, every channel uses the full available spectrum. Individual conversations are encoded with a pseudo-random digital sequence. CDMA is a military technology first used during World War II by the English allies to foil German attempts at jamming transmissions. The allies decided to transmit over several frequencies, instead of one, making it difficult for the Germans to pick up the complete signal. Because Qualcomm Inc. created communications chips for CDMA technology, it was privy to the classified information. Once the information became public, Qualcomm claimed patents on the technology and became the first to commercialize it.

CEBus (Consumer Electronics BUS?)
Known as EIA-600, it is a standard developed by the Electronics Industry Association. The CEBus effort was initiated in 1984 as a cross-industry effort among players in home controls, residential wiring, and consumer electronics. The standard specifies home control signals across a wide variety of network media.

Channel
The route by which a single stream of TV programming is distributed from its originator to the SUBSCRIBER. The originator distributes the content over a private network to the operator, which in turn, allocates it to an assigned set of its own encoding and distribution resources.

Channel Assignment
The logical address for a stream of television programming, assigned by the operator. In an IP TV deployment, channels are multicast to the edge of the network, where they are presented for joins and leaves by SUBSCRIBERS.

Circuit Switching
A switching system that establishes a dedicated physical communications connection between endpoints through the network, for the duration of a session. Contrasted with PACKET-SWITCHING in data communications transmissions.

CISC (Complex Instruction Set Computer)
Pronounced sisk. Most personal computers use a CISC architecture, in which the CPU supports as many as two hundred instructions. An alternative architecture, used by many workstations and also some personal computers, is RISC, which supports fewer instructions.

CLEC (Competitive Local Exchange Carrier)
A Local Exchange Carrier which is not the Incumbent (ILEC) or market-leading LEC. CLECs compete on a selective basis for local exchange service, and long distance, Internet access, and cable TV/video-on-demand. They build or rebuild their own loops (wired or wireless), and lease LOCAL LOOPs from ILECs at wholesale rates for resale to end-users. CLECs include cellular/PCS providers, ISPs, IXCs, CATV providers, CAPs, LMDS operators, and power utilities.

CO (Central Office)
The operations facility of a TELCO or BROADBAND NETWORK OPERATOR, which acts as the switching hub and nerve center for a local subscriber base. SUBSCRIBER lines are aggregated to the CO, for switching and routing to other subscribers, and, into regional and interexchange wide area telecommunications networks. In a television deployment, the CO may become the co-location of the Head End.

Coaxial Cable
This cable consists of a single insulated copper wire surrounded by a braided copper shield. Two types of coaxial cable are currently used in LANs: 50-ohm cable is used for digital signaling, and 75-ohm cable is used for analog and high-speed digital signaling. TIA-570-A (the ?standard? for residential structured wiring) calls for 75-ohm quad-shielded coaxial cabling.

CODEC
A contraction of the terms Encoder and Decoder, used for the compression of a media stream at the originating end and decompression at the receiving end. This process enables more streams to be passed through a given network path, simultaneously. Codecs are software algorithms that may be distributed as software, or as software embedded into a hardware chip or CONTENT PROCESSING SYSTEM.

Content-Processing System
A system of hardware and software which captures incoming analog, digital, and encrypted media streams, and readies them for distribution through the operator?s network. Among the processes done by a content processing system are encoding, packet-shaping, and analog-to-digital conversion.

Convergence
A term used to denote the combining of multiple communications media types, such as voice, data, TV, movies, and the Internet, into a single coordinated set of services for SUBSCRIBERs. Convergence is also used as an identifying term for the industry of technology providers and service operators collaboration to deliver multimedia services to SUBSCRIBERs through communications networks.

CPE (Customer Premises Equipment)
Networking devices such as modems, POTS splitters, and other devices, installed at a customer site, terminating the TELCO or BROADBAND NETWORK OPERATOR network. The terminating device passes communications streams into the SUBSCRIBER?s premises, to telephone sets, set-top boxes, personal computers, routers, and other devices that present the streams to the SUBSCRIBER for use.

Crosstalk
Interference on an analog line of an adjacent signal with the intended receive signal. Crosstalk makes it hard to hear just the intended signal, as there are multiple conversations on the line at once.

DAVIC (Digital Audio Video Council)
A worldwide association concerned with the interoperability of audio-visual equipment and standardized interfaces. It is the source of the DAVIC 1.3 specification, which incorporates the MHEG-5 content decoder prevalent in the UK, as well as the use of the JAVA? virtual machine, in a set-top box environment.

DECT (Digital Enhanced Cordless Telecommunications)
A digital wireless telephone technology expected to make cordless phones much more common in both businesses and homes in the future. Formerly called the Digital European Cordless Telecommunications standard because it was developed by European companies, DECT?s new name reflects its global acceptance. Like another important wireless standard, GSM, DECT uses TDMA to transmit radio signals to phones. Whereas GSM is optimized for mobile travel over large areas, DECT is designed especially for a smaller area with a large number of users, such as in cities and corporate complexes. A user can have a telephone equipped for both GSM and DECT (this is known as a dual-mode phone), and they can operate seamlessly.

DHCP (Dynamic Host Configuration Protocol)
ATCP/IP protocol that allocates IP addresses automatically to any DHCP client (any device attached to your network, such as your PC) so that addresses can be reused when the client no longer needs them.

DMT (Discrete Multitone)
A technique used to carry multiple streams of data, each stream being assigned a different frequency (subband), across a single carrier.

DOCSIS (Data Over Cable Service Interface Specification)
Now officially termed CableModem?, DOCSIS was developed by CABLELABS and approved by the ITU in March 1998. The DOCSIS defines interface standards for cable modems and supporting equipment. With certification from CABLELABS, manufacturers will be able to produce cable modems for retail, so consumers no longer have to depend on leased cable modems from their cable providers. Other devices that recognize and support the DOCSIS standard include HDTVs and Web-enabled set-top boxes for regular televisions. DOCSIS specifies downstream traffic transfer rates between 27 and 36 Mbps over a RF path in the 50 MHz to 750+ MHz range, and upstream traffic transfer rates between 320 Kbps and 10 Mbps over a RF path between 5 and 42 MHz. But, because data over cable travels on a shared loop, individuals will see transfer rates drop as more users gain access.

DSL (Digital Subscriber Line/Loop)
A digital communications technology that uses TELCO copper wiring to connect to the SUBSCRIBER. DSL uses a MODEM at each end of the connection, one at the CO (or field cabinet) and another at the subscriber premises. Subscriber DSL modems may be integrated devices that also have routing, built-in ETHERNET, and other home networking capabilities. Types of DSL listed elsewhere in this glossary are ADSL and VDSL. Other types include HDSL and RADSL, which are not widely used for television deployments.

DSLAM (DSL Access Multiplexer)
A system that aggregates multiple DSL SUBSCRIBER lines into a single high-speed connection, usually and OC-3 or OC-12 optical trunk, back to the operator?s facilities and the core network. The DSLAM can be physically located within the CO or in a field cabinet.

DSP (Digital Signal Processor/Processing)
Refers to manipulating analog information, such as sound or photographs, that has been converted into a digital form. DSP also implies the use of a data compression technique. When used as a noun, DSP stands for digital signal processor, a special type of coprocessor designed for performing the mathematics involved in DSP. Most DSPs are programmable, which means that they can be used for manipulating different types of information, including sound, images, and video.

DSSS (Direct-Sequence Spread Spectrum)
Wireless LAN products are available in three different technologies ? DSSS, FHSS, and infrared. DSSS and FHSS are SPREAD-SPECTRUM techniques that operate over the radio airwaves in the unlicensed ISM band (industrial, scientific, and medical). DSSS uses a radio transmitter to spread data packets over a fixed range of the frequency band.

DTG (Digital Television Group)
An organization dedicated to accelerating the deployment and acceptance of DTV in the UK.

DTV (Digital Television)
The transmission of television signals using digital rather than conventional analog methods.

DVB (Digital Video Broadcast)
A set of standards that defines digital broadcasting using existing satellite, cable, and terrestrial infrastructures, used worldwide, but not (yet) in the US. In the early 1990s, European broadcasters, consumer equipment manufacturers, and regulatory bodies formed the European Launching Group (ELG) to discuss introducing digital television (DTV) throughout Europe. The ELG realized that mutual respect and trust had to be established between members and later became the DVB Project. Today, the DVB Project consists of more than 220 organizations in more than 29 countries worldwide. DVB-compliant digital broadcasting and equipment is widely available and is distinguished by the DVB logo. Numerous DVB broadcast services are available in Europe, North and South America, Africa, Asia, and Australia. The term digital television is sometimes used as a synonym for DVB. However, the ATSC standard is the digital broadcasting standard used in the U.S.

DVD (Digital Versatile Disk)
ACD-sized laser disc used to store and playback high-quality audio and video.

DVR (Digital Video Recording/Recorder)
See PVR.

Dynamic IP Address
Requesting DHCP computers receive a dynamic IP address (think temporary phone number) for the duration of that Internet session or for some other specified amount of time. Once the user disconnects from the Internet, their dynamic IP address goes back into the IP address pool so it can be assigned to another user. Even if the user reconnects immediately, odds are they will not be assigned the same IP address from the pool. To keep our telephone analogy going, using a dynamic IP address is similar to using a pay phone. Unless there is a reason to receive a call, the user does not care what number he or she is calling from.

Ecosystem
A term used to convey the concept that a television delivery network is an end-to-end system in which all of the elements are interdependent and managed as a whole by the operator.

EDGE (Enhanced Data Rates for Global Evolution)
A technology that gives GSM and TDMA the capacity to handle services for the third generation of mobile telephony. EDGE was developed to enable the transmission of large amounts of data at a high speed, 384 Kbps. EDGE uses the same TDMA frame structure, logic channel, and 200kHz carrier bandwidth as today?s GSM networks, which allows existing cell plans to remain intact. (Definition courtesy of Ericsson)

EPG (Electronic Program Guide)
See IPG.

Ethernet
A LAN used to connect devices within a single building or campus. Within the OSI Reference Model, Ethernet is defined at layer one (physical) and layer two (data link). Based on Carrier Sense Multiple Access/Collision Detection (CSMA/CD), Ethernet works by simply checking the wire before sending data.

EPOC
An operating system from Psion Software designed specifically for mobile, ROMbased computing devices. EPOC16 is a 16-bit version of the operating system that has been available for several years and is embedded in many handheld devices. EPOC32 is a 32-bit operating system that supports preemptive multitasking. EPOC is competing head-to-head with Windows CE in the growing PDA market.

FHSS (Frequency-Hopping Spread Spectrum)
Wireless LAN products are available in three different technologies ? DSSS, FHSS, and infrared. DSSS and FHSS are SPREAD-SPECTRUM techniques that operate over the radio airwaves in the unlicensed ISM band (industrial, scientific, and medical). FHSS uses a technique by which the signal transmitted hops among several frequencies at a specific rate and sequence as a way of avoiding interference.

Firewall
A combination of software and hardware that filters or blocks traffic from a public network. A firewall renders parts of the private network inaccessible and invisible to the public network. It prevents unauthorized and/or unrecognized access.

Flash Memory
A special type of EEPROM that can be erased and reprogrammed in blocks instead of one byte at a time. Many modern PCs have their BIOS stored on a flash memory chip so that it can easily be updated if necessary. Such a BIOS is sometimes called a flash BIOS. Flash memory is also popular in MODEMs because it enables the modem manufacturer to support new protocols as they become standardized.

G.Lite
Also known as DSL Lite and Universal ADSL, G.Lite is expected to become the most widely installed form of DSL. It is essentially a smaller bandwidth flavor of DSL, providing a data rate from 128 Kbps to 1.544 Mbps downstream and from 128 Kbps to 384 Kbps upstream.

GPRS (General Packet Radio Service)
A standard for wireless communications which runs at speeds up to 150 Kbps, compared with current GSM systems? 9.6 kilobits. GPRS, which supports a wide range of bandwidths, is an efficient use of limited bandwidth and is particularly suited for sending and receiving small bursts of data, such as e-mail and Web browsing, as well as large volumes of data.

GSM (Global System for Mobile Communications)
One of the leading digital cellular systems. GSM uses narrowband TDMA, which allows eight simultaneous calls on the same RF. GSM was first introduced in 1991. As of the end of 1997, GSM service was available in more than 100 countries and has become the de facto standard in Europe and Asia.

HAVi (Home Audio Video Interoperability)
Announced in May 1998, HAVi is a consortium of consumer electronics to specifically focus on the transfer of digital Audio/Video (AV) content between HAVi devices as well as the processing (rendering, record, play back) of this content by HAVi devices. Typical examples of AV content are digital broadcasts received by a set-top box or content produced by HAVi devices in the consumer?s home such as a digital video recorder, a digital camera, or other devices via the IEEE-1394 ?FireWire? Interface. The HAVi 1.0 specification defines elements, roles and functions, and, ensures that their respective elements work together in a home network.

HDSL (High Data-Rate Digital Subscriber Line)
ADSL service delivering 1.544 mbps, upstream and downstream, via two copper twisted pairs. HDSL is used to provision T-1 services, and for PBX, DLC, Internet servers, private networking, and for interconnecting local and interexchange switches. Reach is limited to 12,000 feet.

HDTV (High-Definition Television)
A television display technology that provides picture quality similar to 35 mm movies with sound quality similar to that of a compact disc.

HFC (Hybrid Fiber Coax) Network
HFC network is a telecommunication technology in which optical fiber cable and COAXIAL CABLE are used in different portions of a network to carry broadband content (such as video, data, and voice). Using HFC, a local CATV company installs fiber-optic cable from the cable head-end (distribution center) to serving nodes located close to business and residential users and from these nodes uses coaxial cable to individual businesses and homes. An advantage of HFC is that some of the characteristics of fiber optic cable (high bandwidth and low noise and interference susceptibility) can be brought close to the user without having to replace the existing COAXIAL CABLE that is installed all the way to the home and business.

Home Network
An in-home network means that through the use of microprocessors and common software languages, different household products and systems will communicate with each other. The key in this definition is that devices are capable of true two-way signaling.

Home Plug & Play?
The Home Plug & Play standard allows CAL to be transported by multiple transport protocols, including IEEE 1394.

HomePlug Powerline Alliance
Officially launched on April 10, 2000, this alliance of companies is seeking to standardize a 10 Mbps home networking solution that will utilize electrical wiring.

HomePNA (Home Phoneline Networking Alliance)
Publicly announced in June 1998, HomePNA has launched two versions of a networking technology that utilizes the existing phonelines in the home to network PCs and other devices. The group endorsed a 1 Mbps technology from Tut Systems Inc. in 1998. In 1999, the consortium endorsed a 10 Mbps technology jointly proposed by Broadcom Corp. and Lucent Technologies Microelectronics Group. The alliance now totals more than 150 companies.

HomeRF
Publicly launched in March 1998, HomeRF has developed a technology called SWAP, or Shared Wireless Access Protocol. Utilizing the 2.4 GHz unlicensed bandwidth, first-generation HomeRF products will deliver wireless data and voice services between and among PCs, cordless telephone handsets, and other consumer electronics products at a throughput of 1.6 Mbps. Relying on FHSS technology, SWAP is a merger between wireless LAN technologies and DECT.

HTML (Hypertext Markup Language)
The language of the Internet?s World Wide Web, allowing publishing over the Internet using standardized instructions and methods for the presentations of text and graphics to the viewer. HTML is interpreted by Web browsers, which, although associated with personal computers, are widely used within television set-top boxes as the presentation environment for TV and WALLED GARDEN content. The specification for HTML is controlled by an open standards body called the W3C, the Worldwide Web Consortium.

IEEE (Institute of Electrical and Electronics Engineers)
A standards organization.

IEEE 1394
A technology that also goes by the name of FireWire? (Apple Computer) and i.LINK? (Sony), this high-speed hardware and software-based networking solution delivers data at rates of between 100 and 800 Mbps. Designed for technologies requiring isochronous data.

IEEE 802.3
See ETHERNET.

IEEE 802.11b
?High-Rate? radio frequency networking technology developed by the IEEE. Most wired networks conform to 802.3, the specification for CSMA/CD-based Ethernet networks, or 802.5, the specification for token ring networks. 802.11b utilizes the license-free bandwidth of 2.4 GHz, and most products utilize DSSS. Further 802.11 variants include:

• 802.11a: a 54 Mbps solution utilizing the 5 GHz space;
• 802.11e: an enhancement to the MAC for QoS; and
• 802.11g: OFDM-based variant that effectively doubles data throughput of 802.11b.

IGMP (Internet Group Management Protocol)
A set of rules governing the registration of users with a multicast group.

ILEC (Incumbent Local Exchange Carrier)
Not to be confused with Independent TELCOs, which were never part of the Bell system. An ILEC is a Local Exchange Carrier which, when competition begins (per the 1996 Telecommunications Act), has the dominant position in the market. In other words, the original carrier in the market prior to the entry of competition.

Information Appliance
A relatively low-cost, easy-to-use, reliable, special-purpose device that obtains and presents, captures and reports, and/or stores and manages various types of information in order to bring the benefits of the Internet to consumers.

IP (Internet Protocol)
A network layer protocol in the TCP/IP stack, provides features for addressing, type of service specification, fragmentation and reassembly, and security.

IPG (Interactive Program Guide)
A television user interface that allows SUBSCRIBERs to review and select programs to watch on TV using the remote control. The IPG data (METADATA) is housed at the head-end or CO, but is presented to the SUBSCRIBER visually via a program residing in the set-top box. IPG METADATA is obtained from licensors including Gemstar TV GUide, Tribune, TV Data and SourceMedia, from the content provider itself, or may be created by the operator. Some IPGs are designed to host data for programs as far as two weeks into the future, some are not.

IP Multicast (Internet Protocol Multicast)
A technique that lets a network simultaneously deliver a single stream of content (single copy of the data stream) to multiple locations over an IP network. Those that desire to receive this multicast join the multicast, leaving it when finished.

IP Multicast Address(es)
The IP devices which have joined an IP MULTICAST stream.

IP Multicast Group
An arbitrary collection of SUBSCRIBERs interested in receiving the same multicast stream. Those interested in receiving the stream join the stream via IGMP.

IP Telephony (Internet Protocol Telephony)
A general term for the technologies that use the IP?s packet-switched connections to exchange voice, fax, and other forms of information that have traditionally been carried over the dedicated circuit-switched connections of the public-switched telephone network (PSTN). Using the Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The challenge in IP telephony is to deliver the voice, fax, or video packets in a dependable flow to the user. Much of IP telephony focuses on this challenge.

IP Television
The offering of television and associated advanced media services using the same packet-based delivery system used for the Internet.

ISDN (Integrated Services Digital Network)
A communication protocol offered by telephone companies that permits telephone networks to carry data, voice, and other traffic. DSL is replacing ISDN because it can typically provide a faster connection. ISDN continues to be a popular technology in Europe and parts of the Pacific Rim.

ISO (International Organization for Standardization)
An international standards body based in Geneva, Switzerland. Best known for the seven-layer OSI REFERENCE MODEL.

Isochronous
From the Greek for ?equal? and ?time,? isochronous data transfer pertains to processes that require timing coordination to be successful, such as voice and digital video transmission.

ITU (International Telecommunications Union)
An international standards body based in Geneva, Switzerland. The ITU-T, formerly known as the CCITT, is the standardization sector which develops worldwide standards for telecommunications. ITU-R is the sector devoted to radio and television.

Java?
A high-level programming language developed by Sun Microsystems. Java was originally called OAK and was designed for handheld devices and set-top boxes. Oak was unsuccessful, so in 1995 Sun changed the name to Java and modified the language to take advantage of the burgeoning World Wide Web. Java is a general-purpose programming language with a number of features that make the language well suited for use on the World Wide Web. Small Java applications are called Java applets and can be downloaded from a Web server and run on your computer by a Java-compatible Web browser, such as Netscape Navigator or Microsoft Internet Explorer.

For television, a compact version of Java, called Personal Java, has been adopted within the DVB-MHP specification as its standard execution platform for television set-top boxes, and it is more widely used outside the US than within.

Jini?
Software from Sun Microsystems that seeks to simplify the connection and sharing of devices, such as printers and disk drives, on a network. Currently adding such devices to a computer or network requires installation and boot-up, but a device that incorporates Jini will announce itself to the network, provide some details about its capabilities, and immediately become accessible to other devices on the network. Under this technology it would be possible to create distributed computing, whereby capabilities are shared among the machines on a common network. This would allow users to access the power and features of any device on the network and would free the desktop computer from holding all the memory, storage, and processing power it needs for any job. For example, if a disk drive on a network had Jini capabilities, any computer on that network could use the drive as though it were its own. Because Jini has the potential to make operating systems incidental to the power of networks, some have seen Jini as an attempt to reduce the influence of Windows.

LAN (Local-Area Network)
A computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a WAN.

Latency
In networking, the time it takes a packet to travel from source to destination. Together, latency and bandwidth define the speed and capacity of a network.

Layer
Once upon a time, the ISO designed an OSI REFERENCE MODEL for all network developers on our planet. The seven ?layers? of the OSI model are:

• physical: electrical and mechanical functions;
• data link: detecting and correcting errors;
• network: routing processes;
• transport: initiating and releasing connections;
• session: handling transmission errors;
• presentation: formatting data; and
• application: interface with network services.

LMDS (Local Multipoint Distribution Service)
A form of broadband fixed wireless system that operates in the 27-31 GHz range.

Local Loop
A generic term for the connection between the customer premises (home or office) and the provider?s serving Central Office.

LONWORKS?
This home and building control standard was initiated by Echelon Corp. in the late 1980s. Like CEBus, the standard includes communication protocols that can be delivered over multiple media. The LONWORKS system includes all the components necessary to implement open interoperable control systems that can be easily and seamlessly integrated within a home ? and beyond. This LONWORKS system includes all the necessary hardware and software components for implementing complete end-to-end control systems. LONWORKS was approved as EIA-709 in 1998. Echelon has partnered with such Internet giants as Cisco Systems Inc. to initiate IP-based home control solutions.

MAC Address (Media Access Control)
A MAC (layer two) address is required for every port or device that connects to a LAN. MAC addresses allow framing and error detection. They are six bytes long and are also known as hardware addresses and physical addresses.

MDU (Multiple-Dwelling Unit)
A catch-all term that represents a collection of residential or business locations that can be served by broadband-based services. Examples of ?MDUs? include master-planned communities wherein the management company is also the provider of entertainment and communication services (i.e., TV and telephone services). Others are apartment complexes. In the broadest use of the definition, the term MDU can include hospitality businesses such as hotels, casinos, and cruise ships.

Metadata
Data about data. One example is the information about programming that goes into an IPG. Another example is the data that defines the format of billing information that is passed from a TV APPLICATION SERVER, to the SUBSCRIBER billing system, such as field definitions.

MHEG-5
A content presentation specification within the DAVIC API, which is widely adopted by operators in the UK.

MHP (Multimedia Home Project)
A specification developed by the DVB for interactive television set-top boxes. The execution environment uses Sun Microsystems? Java technology.

Middleware
A term used to describe separate products that serve as the glue between two APPLICATIONs. Middleware is sometimes called plumbing because it connects two sides of an APPLICATION and passes data between them.

MMDS (Multichannel Multipoint Distribution Service)
A form of broadband fixed wireless system that operates in the 2 GHz range. Also known as "wireless cable."

Modem
A term which is actually based on the function of the device itself ? a MOdulator/DEModulator. A modem converts analog waveforms into digital data and vice versa.

Modulation
The process whereby an electrical carrier wave is altered to facilitate the transmission of a signal.

MPEG (Motion Picture Experts Group)
This is an industry organization whose goal is to develop standards and specifications for the encoding, transmission, and decoding of video information over various media and network technologies.

MP3
Is the file extension for MPEG, audio layer 3. Layer 3 is one of three coding schemes (layer one, layer two, and layer three) for the compression of audio signals. The result in real terms is layer 3 shrinks the original sound data from a CD (with a bitrate of 1411.2 Kbps of stereo music) by a factor of 12 (down to 112-128 Kbps) without sacrificing sound quality.

MPEG1
Compression scheme for full-motion video. Compression algorithm introduced by MPEG in 1991, the common goal of MPEG is to compress 7.7 Megabytes down to about 150 Kilobytes. The MPEG1 is designed to provide a resolution of 352 by 240 pixels at 30 frames per second. It was designed for use with narrowband systems and CD-ROMs for progressive-scan moving pictures.

MPEG2
A digital moving picture format used for broadcast quality systems using variable bit rate encoding and interlacing. Typical MPEG2 rates are between 2.5 and 5 Mbps, with 3 Mbps being a typical frame of reference. Designed to provide a resolution of 720 by 480 pixels at 30 frames per second.

Multicast
A media (packet) stream that is copied and sent to multiple authorized SUBSCRIBERS (network addresses). Multicast addresses are group addresses. Typical uses include the updating of mobile personnel from a home office and the periodic issuance of online newsletters.

NAT (Network Address Translation)
The translation of an IP ADDRESS used within one network to a different IP ADDRESS known within another network. Reduces the need for globally unique IP ADDRESSes. NAT allows a business to use a single IP ADDRESS in its communication with the outside world.

Node
This refers to an endpoint of a network connection, or a junction common to two or more lines in a network. Nodes can be processors, controllers, or workstations.

"No-New-Wires"
A term commonly used to include any networking technology that doesn?t require new wiring to be installed into typical North American homes.

NVOD (Near-Video-On-Demand)
A television programming technique used by operators to devote multiple channels to a single movie, staggering the start times so the SUBSCRIBER need not wait as long for the next showing to start.

OSGi (Open Services Gateway Initiative)
Launched in early 1999, OSGi is an industry group working to define and promote an open standard for connecting the coming generation of smart consumer and small-business appliances with commercial Internet services. The Open Services Gateway specification will provide a common foundation for ISPs, network operators, and equipment manufacturers to deliver a wide range of e-services via gateway servers running in the home or remote office.

OSI (Open Systems Interconnection) Reference Model
An architectural conceptual model for communications networks, developed by the ISO in cooperation with the ITU. It consists of seven LAYERS, defining all aspects of a communications network, and the conveyance and control of communications-based services, over the network.

Packet Switching
The process of routing and transferring data by means of addressed packets so that a channel is occupied during the transmission of the packet only, and upon completion of the transmission, the channel is made available for the transfer of other traffic.

Parental Controls
A term used to connote the ability for programmers to shield viewers from inappropriate content. In the US, both movies and television programming are subject to content rating systems. Designers of TV delivery systems must factor these content rating systems into their systems and deployments, as SUBSCRIBERs have come to expect these systems. The content rating itself is a part of the METADATA used by IPGs and VOD systems.

PBX (Private Branch Exchange)
A private telephone network used within an enterprise. Users of the PBX share a certain number of outside lines for making telephone calls external to the PBX. Most medium-sized and larger companies use a PBX because it?s much less expensive than connecting an external telephone line to every telephone within the organization.

PCS (Personal Communications Service)
The U.S. Federal Communications Commission (FCC) term used to describe a set of digital cellular technologies being deployed in the U.S. PCS works over CDMA (also called IS-95), GSM, and North American TDMA (also called IS-136) air interfaces. Some of the most important distinguishing features of PCS systems are:

• They are completely digital;
• They operate at the 1900 MHz frequency range;
• They can be used internationally; and
• PCS is a second-generation mobile communications technology.

PLC (Powerline Carrier Communications)
Powerline carrier that uses the existing power cabling found in homes and commercial buildings to connect devices. Speeds range from 60 bps to over 10 Mbps. Depending on the technology, it is used for controls and data networking.

POTS (Plain Old Telephone Service)
This term commonly refers to standard telephony, as in placing and receiving telephone calls. This is more or less interchangeable with PSTN (Public Switched Telephone Network). APOTS splitter enables both DSL digital data and standard telephone analog transmissions to share a single connection.

PPV (Pay-Per-View) Programming
TV programming services, such as live events or pre-recorded programs, that are multicast only to those subscribers that have been authorized by the operator, usually meaning that the SUBSCRIBERs have paid for the right to view the event in advance. In order for the subscriber to place and confirm the order, a return-path is required back to the operator.

PVR (Personal Video Recording/Recorder)
Broadly speaking, PVR enables the subscriber to ?time-shift? the live television viewing experience in a way similar to the VCR, by pausing, rewinding, fast forwarding, and recording for later viewing. To do this, content must be stored. Storage can be client-side (stored on a hard disk in the set-top box), or, server-side (stored by a video server at the head-end that has been designed for this purpose). More sophisticated PVR offerings complement the viewing experience with an IPG and other enhancements. PVR is also a reference to the consumer electronics device that enables PVR service for the subscriber. Some PVRs are implemented within stand-alone devices, others are integrated within a multifunctional TV set-top box.

QoS (Quality of Service)
A networking term that specifies a guaranteed throughput level. One of the biggest advantages of ATM over competing technologies such as Frame Relay and Fast Ethernet is that it supports QoS levels. This allows ATM providers to guarantee to their customers that end-to-end LATENCY will not exceed a specified level.

RBOC (Regional Bell Operating Company)
An all-inclusive term for each of the seven telephone companies that were created after AT&T?s divestiture. Due to merger and acquisition activity, the original seven are currently four: SBC Communications (formerly Pacific Telesis, Southwestern Bell and Ameritech), BellSouth, Verizon (formerly NYNEX and BellAtlantic), and Qwest (formerly U S West).

RF (Radio Frequency)
Refers to alternating current (AC) having characteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications. These frequencies cover a significant portion of the electromagnetic radiation spectrum, extending from nine kilohertz (9 kHz), the lowest allocated wireless communications frequency (it?s within the range of human hearing), to thousands of gigahertz (GHz).

RG (Residential Gateway)
A residential gateway is a network interface device that terminates a WAN and connects to end-user devices directly or through a home network. In addition to features common to any gateway, it should include an embedded broadband modem, dynamic routing capacity, security features, and direct or indirect support for home networking.

Return Path
The return path is the communications connection carrying signaling from the SUBSCRIBER, back to the operator. A return path is required for true interactive television, and, for on-demand services such as PAY-PER-VIEW PROGRAMMING, VOD, and games.

For cable and satellite TV operators, the return path takes the form of a second connection to the set-top box (such as a telephone line); it is not an issue for broadband network operators and TELCOS using IP networks and/or xDSL, where a return path is inherent in the communications network.

RG59
RG59 is an older form of COAXIAL CABLE installed in most homes built before the 90s. It has a 20-gauge center conductor and is not as well shielded as RG6. It is also smaller in overall diameter. It uses an ?F? style connector.

RG6
RG6 cable is now specified for most new COAXIAL CABLING in homes. It uses an 18-gauge center conductor and typically is quad-shielded (4 shields: 2 foil and 2 braids). It uses an ?F? connector which can be connected to those used by RG59.

RISC (Reduced Instruction Set Computer)
Pronounced risk. A type of microprocessor that recognizes a relatively limited number of instructions. Until the mid-1980s, the tendency among computer manufacturers was to build increasingly complex CPUs that had ever-larger sets of instructions. At that time, however, a number of computer manufacturers decided to reverse this trend by building CPUs capable of executing only a very limited set of instructions. One advantage of reduced instruction set computers is that they can execute their instructions very quickly because the instructions are so simple. Another, perhaps more important advantage is that RISC chips require fewer transistors, which makes them cheaper to design and produce. Since the emergence of RISC computers, conventional computers have been referred to as CISCs. There is still considerable controversy among experts about the ultimate value of RISC architectures. Its proponents argue that RISC machines are both cheaper and faster, and are thus the machines of the future. Skeptics note that by making the hardware simpler, RISC architectures put a greater burden on the software, which is unnecessary because conventional microprocessors are becoming increasingly fast and cheap anyway. To some extent, the argument is becoming moot because CISC and RISC implementations are becoming more and more alike. Many of today?s RISC chips support as many instructions as yesterday?s CISC chips. And today?s CISC chips use many techniques formerly associated with RISC chips.

RJ-11
Six-conductor modular jack used with four-wire cabling. Most common phone jack in the world and is used commonly on phones, modems, and fax machines.

RJ-45
Eight-pin connector used to attach data transmission devices to standard telephone wiring. Commonly used in 10Base-T connections.

Router
A router is a network layer device that uses one or more algorithms to determine the optimal path along which data should be forwarded. Routers forward packets from one network to another based on network layer information. Routers are occasionally called gateways, but traditional gateways do not translate data.

SCP (Simple Control Protocol)
A lightweight network and control protocol for devices that have limited processing and memory resources and operate over limited bandwidth.

SDSL (Symmetrical Digital Subscriber Line)
A form of DSL, delivering 1.544 Mbps both downstream and upstream over a single copper pair. Range is up to 22,000 feet, depending on the gauge of the wiring.

Spread Spectrum
Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is deliberately varied ? this results in a much greater bandwidth than the signal would have if its frequency were not varied.

Splitterless DSL
Also refered to as G.Lite. See ADSL.

Static IP Address
A static IP is a dotted quad number that is assigned to a computer by and Internet Service Provider (ISP) to be its permanent address on the Internet. Computers use IP addresses to locate and talk to each other on the Internet, much the same way people use phone numbers to locate and talk to one another on the telephone. It would be simple if every computer that connects to the Internet could have its own static IP number, but when the Internet was first conceived, the architects didn?t foresee the need for an unlimited number of IP addresses. Consequently, there are not enough IP numbers to go around. To get around that problem, many Internet service providers limit the number of static IP addresses they allocated, and economize on the remaining number of IP addresses they possess by temporarily assigning an IP address to a requesting DHCP computer to form a pool of IP addresses. The temporary IP address is called a dynamic IP address.

Structured Wiring
A system of low-voltage wires designed to carry electronic signals throughout a home.

Subscriber
The residential or business end-user customer at the receiving end of services from the TELCO or BROADBAND NETWORK OPERATOR.

SWAP (Shared Wireless Access Protocols)
The SWAP specification defines a new common interface that supports wireless voice and data networking in the home (HomeRF).

T-1
A Bell system term for a digital carrier facility used for transmission of data through the telephone hierarchy at a transmission rate of 1.544 Mbps.

TDMA (Time Division Multiple Access)
A technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA divides a radio frequency into time slots and then allocates slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels. TDMA is used by the GSM digital cellular system.

Telco
Telephone company.

Telemetry
Most commonly associated with RG applications that deliver energy utility-based services, the word is derived from ?telemeter,? an electrical apparatus for measuring a quantity (as pressure, speed, or temperature), transmitting the result to a distant station, and there indicating or recording the quantity measured. For purposes of energy utilities, telemetry delivers real-time price and usage information, and enables the service providers to better manage load.

Transaction
An event reflecting the use of an item in an interactive television system. It does not necessarily have to have a price associated with it, nor do funds necessarily change hands. It is always tracked by APPLICATION SERVERS within the television delivery system.

Twisted Pair
A common form of copper cabling used for telephony and data communications. It consists of two copper lines twisted around each other; the twisting protects the communications from electromagnetic frequency and radio frequency interference.

UMTS (Universal Mobile Telecommunications System)
Also called ?third-generation (3G),? broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to and possibly higher than 2 Mbps, offering a consistent set of services to mobile computer and phone users no matter where they are located in the world. Based on the GSM communication standard, UMTS, endorsed by major standards bodies and manufacturers, is the planned standard for mobile users around the world by 2002. Once UMTS is fully implemented, computer and phone users can be constantly attached to the Internet as they travel and, with roaming service, have the same set of capabilities no matter where they travel. Users will have access through a combination of terrestrial wireless and satellite transmissions. Until UMTS is fully implemented, users can have multimode devices that switch to the currently available technology (such as GSM 900 and 1800) where UMTS is not yet available.

Today?s cellular telephone systems are mainly circuit-switched, with connections always dependent on circuit availability. PACKET-SWITCHED connection, using the IP, means that a virtual connection is always available to any other end point in the network. It will also make it possible to provide new services, such as alternative billing methods (pay-per-bit, pay-per-session, flat rate, asymmetric bandwidth, and others). The higher bandwidth of UMTS also promises new services, such as videoconferencing. UMTS promises to realize the Virtual Home Environment (VHE) in which a roaming user can have the same services to which the user is accustomed when at home or in the office through a combination of transparent terrestrial and satellite connections.

Unicast
A content stream directed to a specific SUBSCRIBER (IP network address), and no other. VOD utilizes unicast techniques.

Unified Messaging
Unified messaging (sometimes referred to as the unified messaging system or UMS) is the handling of voice, fax, and regular text messages as objects in a single mailbox that a user can access either with a regular e-mail client or by telephone. PC users can open and play back voice messages, assuming their PC has multimedia capabilities. Fax images can be saved or printed. A user can access the same mailbox by telephone. In this case, ordinary e-mail notes in text are converted into audio files and played back. Unified messaging is particularly convenient for mobile business users because it allows them to reach colleagues and customers through a PC or telephone, whichever happens to be available. Some services offer worldwide telephone access.

UPnP (Universal Plug And Play)
An architecture for pervasive peer-to-peer network connectivity of PCs of all form factors, intelligent appliances, and wireless devices. UPnP is a distributed, open networking architecture that leverages TCP/IP and the Web to define a set of common interfaces that describe devices and services, allow automatic discovery when a device is plugged into a network, and allow other devices and people to use them without complicated setup or configuration.

UTP (Unshielded Twisted Pair)
UTP cabling is used in a variety of networks and does not require the fixed spacing between connections that is necessary with COAXIAL CABLE.

UWB (UltraWideBand)
UWB radio (also known as digital pulse wireless) is a revolutionary wireless technology for transmitting large amounts of digital data over a wide spectrum of frequency bands with very low power. UWB radio not only can carry a huge amount of data over a short distance (up to 230 feet) at very low power (less than 0.5 milliwatts), but has the ability to carry signals through doors and other obstacles that tend to reflect signals at more limited bandwidths and a higher power. UWB radio can be compared with another short-distance wireless technology, Bluetooth, which is a proposed standard for connecting handheld wireless devices with other similar devices and with desktop computers. In the U.S., the Federal Communications Commission (FCC) is considering permitting use of the technology to early applicants. The Federal Aviation Authority (FAA) is concerned about possible interference over aviation channels. The technology?s supporters insist that the power is so low that there is little or no possibility of interference. Time Domain, Radar Inc., and Zircon are three companies that have applied to the FCC for an exemption from spectrum rules so that they can use the new technology.

VDSL (Very High Data Rate Digital Subscriber Line)
A technology that delivers 13 to 52 Mbps downstream and 1.5 to 2.3 Mbps upstream over a single copper twisted-pair. The operating range of VDSL is limited to 1,000 to 4,500 feet (304.8 to 1,372 meters) from the CO. VDSL is championed by several industry organizations, most notably the FS-VDSL. The international standard most closely related to VDSL is the Full Services Access Networks (FSAN) standard, ITU G.983.1.

VHN (VESA Home Networking Committee)
A committee of the Video Electronics Standards Association, the VHN was established in 1995 to develop an open industry architecture standard for digital home networks.

VoATM (Voice Over ATM)
Enables a ROUTER to carry voice traffic (for example, telephone calls and faxes) over an ATM network through a special encapsulation for multiplexed voice.

VOD (Video-On-Demand)
The ability to activate a stored or live motion picture stream, on demand, delivered to a SUBSCRIBER over an operator?s network. Unlike PAY-PER-VIEW, VOD represents a private showing, and may be likened to the rental of a video, but without the inconvenience of driving to the store. VOD is a term used to connote the delivery (unicast) of a movie or video from a centralized video server, to individual SUBSCRIBERs.

The SUBSCRIBER initiates the viewing at any time. Many SUBSCRIBERs can unknowingly be viewing the same movie simultaneously, which forces the operator to plan for peaks and valleys in demand. Different video servers deal with this problem in different ways through scaling, movement of content to the edge of the network, or even caching it to a hard-disk on the SUBSCRIBER?s set-top box.

VoDSL (Voice Over DSL)
Expands on existing DSL service capabilities by providing up to four derived voice channels over the ADSL line and primary POTS line.

VoFR (Voice Over Frame Relay)
Enables a ROUTER to carry voice traffic (for example, telephone calls and faxes) over a Frame Relay network after segmenting and encapsulating it.

VoIP (Voice Over IP)
Voice delivered using the IP. It is a term used in IP TELEPHONY for a set of facilities for managing the delivery of voice information using the IP. In general, this means sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.

VPN (Virtual Private Network)
A network constructed by using public wires to connect nodes. For example, a number of systems enable creation of networks using the Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.

Walled Garden
A Walled Garden is a captive environment designed to keep the SUBSCRIBER within the operator?s own services. The two classic examples of Walled Gardens are cable and satellite television services, and Internet Web portals. With cable and satellite, the SUBSCRIBER receives only what the operator can offer, regardless of the local and network programming available in the SUBSCRIBER's service area. With Web portals, users are admitted into subject areas through menus. Those subject areas are filled with content from business affiliates, which pay the portal operator when an end user clicks to its content. In the interactive TV context, a Walled Garden is a carefully designed and controlled user interface with the above characteristics, designed for rendering within the constraints of the middleware residing within the subscriber?s set-top box.

WAN (Wide-Area Network)
Private network facilities, usually offered by public telephone companies but increasingly available from alternative access providers (sometimes called CAPs), that link business networks.

WAP (Wireless Application Protocol)
WAP is a secure specification that allows users to access information instantly via handheld wireless devices such as mobile phones, pagers, two-way radios, smart phones, and communicators.

WAP supports most wireless networks. These include CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC, and Mobitex. WAP is supported by all operating systems. Ones specifically engineered for handheld devices include PalmOS, EPOC, Windows CE, FLEXOS, OS/9, and JavaOS. WAPs that use displays and access the Internet run what are called microbrowsers with small file sizes that can accommodate the low memory constraints of handheld devices and the low bandwidth constraints of a wireless-handheld network. Although WAP supports HTML and XML, the WML language (an XML application) is specifically devised for small screens and one-hand navigation without a keyboard. WML is scaleable from two-line text displays up through graphic screens found on items such as smart phones and communicators. WAP also supports WMLScript. It is similar to JavaScript, but makes minimal demands on memory and CPU power because it does not contain many of the unnecessary functions found in other scripting languages. Because WAP is fairly new, it is not a formal standard yet. It is still an initiative that was started by Unwired Planet, Motorola, Nokia, and Ericsson.

WECA (Wireless Ethernet Compatibility Alliance)
WECA's mission is to certify interoperability of Wi-Fi? (IEEE 802.11 High Rate) wireless LAN products and to promote Wi-Fi? as the standard for wireless LAN deployments across all market segments.

WML (Wireless Markup Language)
An XML language used to specify content and user interface for WAP devices; the WAP forum provides a DTD for WML. WML is supported by almost every mobile phone browser around the world. WML pages are requested and served in the same way as HDML pages. For Web servers to serve WML pages, they must contain the text/vnd.wap.wml mime type.

X-10
A powerline carrier protocol created by X10 Ltd. in 1978 that carries control signals across standard electrical wire. The X-10 protocol is typically used in simple control scenarios like the remote or automatic turning on/off of lights or appliances.

XDSL
An acronym denoting the use of ?any? DSL, without making reference to specific implementations of DSL, such as ADSL.

XML (Extensible Markup Language)
A specification developed by the W3C. XML is a pared-down version of SGML, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations. Whether XML eventually supplants HTML as the standard Web formatting specification depends a lot on whether it is supported by future Web browsers. Microsoft Internet Explorer version 5 handles XML, but renders it as CSS, and Mozilla (Netscape) is still experimenting with XML support.