Glossary

5ESS

A digital central office manufactured by Lucent Technologies, formerly part of AT&T.

10base-T

An IEEE specification for unshielded twisted pair cabling for Ethernet local area networks which transmit at 10 million bits per second. The distance limitation on 10 base-T networks is 100 meters.

100base-T

An IEEE standard, compatible with 10base-T for transmitting at 100 megabits over twisted pair cabling on local area networks.

ANI (automatic number identification)

The business or residential customer's billing number. Customers such as call centers pay for callers' ANI to be sent to them simultaneously with incoming 800 and 888 calls.

Applet

A small Java program that can be executed on any Java capable browser regardless of PC model. Animation in Internet ads use applets. Document sharing programs work by sending Java applets to the participants in the document sharing session.

ATM (Asynchronous Transfer Mode)

A high-speed switching technique that uses fixed size cells to transmit voice, data and video. A cell is analogous to envelopes that each carry the same number of bits.

Backbone

A segment of a network used to connect smaller segments of networks together. Backbones carry high concentrations of traffic between on and off ramps of networks.

Bandwidth

The measure of the capacity of a communications channel. Analog telephone lines measure capacity in hertz, the difference in the highest and lowest frequency of the channel. Digital channels measure bandwidth in bits per second.

Bit error rate

The percentage of bits received in error in a transmission.

BOC (Bell Operating Company)

One of the 22 local Bell telephone companies owned by AT&T before 1984. Examples of Bell operating companies are Michigan Bell, Illinois Bell and Pac Bell.

Bps (bits per second)

The number of bits sent in a second.

BRI (Basic Rate Interface)

The ISDN (integrated services digital network) interface made up of two B channels at 64 kilobits each and a signaling channel with a speed of 16 kilobits.

Bridge

A device that connects local or remote networks together. Bridges are used to connect small numbers of networks. Bridges do not have routing intelligence. Organizations that wish to connect more than four or five networks use routers.

Broadband

A data transmission scheme where multiple transmissions share a communications path. Cable television uses broadband transmission techniques.

Broadcast

A message from one person or device forwarded to multiple destinations. Voice messaging and e-mail services have broadcast features whereby a user can send the same message to multiple recipients.

CAP (competitive access provider)

Originally provided large- and medium-sized organizations with connections to long distance providers that bypassed local telephone companies. CAPs are now often referred to as competitive local exchange carriers (CLECs). They sell local and long distance telephone and Internet service.

CCIS (common channel interoffice signaling)

A signaling technique used in public networks. Signals such as those for dial tone and ringing are carried on a separate path from the actual telephone call. CCIS allows for telephone company database query used in features such as Caller ID, call forwarding and network-based voice mail. CCIS channels are also used for billing and diagnosing public network services.

CDMA (code division multiple access)

CDMA is one way that carriers transmit digital cellular signals between handheld devices and cellular carriers' networks. CDMA assigns a unique code to every voice and data transmission using a channel of a particular carrier's airwaves. CDMA is a spread spectrum technology.

Central Office

The site with the local telephone company's equipment that routes calls to and from customers. It also connects customers to Internet Service Providers and long distance services.

Centrex (central exchange)

Centrex, like private branch exchanges, routes and switches calls for commercial and non-profit organizations. However, local telephone companies manage Centrex service. The computerized Centrex equipment is most often located at a telephone company's central office rather than at a customer premise.

Channels

A path for analog or digital transmission signals. With services such as ISDN, T-1 and T-3, multiple channels share the same one or two pairs of wires or fiber.

CIC code (carrier identification code)

The four-digit code (previously three digits) assigned to each carrier for billing and call routing purposes. AT&T's CIC code is 0288. If someone at a pay telephone dials 1010288 and then the telephone number they are calling, their call is routed over the AT&T network.

CIR (committed information rate)

A term used in frame relay networks to indicate the speed of the transmission guaranteed between each customer's site and the frame relay network.

Circuit switching

The establishment, by dialing, of a temporary physical circuit (path) between points. The path (circuit) is terminated when either end of the connection sends a disconnect signal by hanging up.

CLEC (competitive local exchange carrier)

A competitor to local telephone companies that has been granted permission by the state regulatory commission to offer local telephone service. CLECs compete with the incumbent telephone company. CLECs are also simply called local telephone companies.

CO (central office)

The location that houses the telephone company switch that routes telephone calls. End offices are central offices that connect end-users to the public network.

Compression

Reducing the size of the data, image, voice or video file sent over a telephone line. This decreases the capacity of the telecommunications line needed to transmit the file.

Concatenation

The linking of channels in optical networks together so that voice or video is transmitted as one stream. This is done to ensure that there are no breaks in the transmission.

Connectionless Service

The Internet protocol is connectionless. Each packet travels through the network separately. If there is congestion, packets are dropped. Packets are re-assembled at their destination.

CPE (customer premise equipment)

Telephone systems, modems and terminals installed at customer sites.

CSU/DSU (channel service unit/data service unit)

A digital interface device that connects customer computers, video equipment, multiplexers and terminals to digital telephone lines.

Dark fiber

Fiber optic cables without any of the electronics, that is, multiplexers and amplifiers. Carriers can quickly lay dark fiber and add SONET, Gigabit Ethernet and wavelength division multiplexers later.

DCE (data circuit-terminating equipment)

A communications device that connects user equipment to telephone lines. Examples are modems for analog lines and CSUs (channel service units) for digital lines.

Dedicated line

A telephone line between two or more sites of a private network. Dedicated lines are always available for the exclusive use of the private network at a fixed monthly fee.

Dense wavelength-division multiplexing (DWDM)

A way of increasing the capacity of fiber optic networks. DWDM carries multiple colors of light, or multiple wavelengths on a single strand of fiber. Also known as WDM or wavelength-division multiplexing. Some people use the term dense wave division multiplexing.

DID (direct inward dialing)

A feature of local telephone service whereby each person in an organization has his or her own ten-digit telephone number. Calls to DID telephone numbers do not have to be answered by on-site operators. They go directly to the person assigned to the ten-digit DID telephone number.

DMS 100

A digital central office switch manufactured by Nortel, formerly Northern Telecom.

DNIS (dialed number identification)

The service used to identify and route toll free and 900 numbers to particular agents or devices within a customer site. For example, if a customer has multiple 800 numbers, the network provider routes each toll free number to a different four digit extension number at the customer's telephone system. The on-site PBX, key system or Centrex system then routes the call to a particular group of agents, voice response system or department.

Domain name

Everything after the @ sign in an e-mail address. It includes the host computer, the organization's name and the type of organization (e.g., com for commercial and edu for educational site). Dot com and .edu are top-level domain names. The domain name can also designate the country such as .bo for Bolivia. A domain name is part of the TCP/IP addressing convention.

DS-0 (digital signal level 0)

The digital signal level 0 is 64 thousand bits per second. It refers to one channel of a T-1, E-1, E-3, T-3, fractional T-1 or fractional T-3 circuit.

DS-1 (digital signal level 1)

The T-1 transmission rate of 1.54 million bits per second. There are 24 channels associated with DS-1 or T-1.

DS-3 (digital signal level 3)

The T-3 transmission rate of 44 million bits per second with 672 channels. (T-3 is equivalent to 28 T-1s.)

DTE (data terminal equipment)

Devices that communicate over telephone lines. Examples are multiplexers, PBXs, key systems and personal computers.

E-1

The European standard for T-1. E-1 has a speed of 2.048 megabits with 30 channels for voice, data or video, plus one channel for signaling and one for diagnostics.

E-3

The European standard for T-3. E-3 has a speed of 34.368 megabits, with 480 channels. It is equivalent to 16 E-1 circuits.

Ethernet

A local area network protocol defined by the IEEE. It defines how data is transmitted on and retrieved from local area computer networks.

FDDI (fiber distributed data interface)

An ANSI-defined protocol whereby computers communicate at 100 million bits per second over fiber-optic cabling. FDDI may be used on backbones that connect local area network segments together. It is not widely used.

Fiber-optic cable

A type of cable made from glass rather than copper. The key advantage of fiber-optic cabling is that it is non-electric. Thus it is immune from electrical interference and interference from other cables within the same conduit. Fiber optic cabling can be used for higher-speed transmissions than twisted pair copper cabling.

Firewall

A firewall is software and hardware that prevents unauthorized access to an organization's network files. The intention is to protect files from computer viruses and electronic snooping.

Fractional T-1

Fractional T-1 lines are cheaper and have a fraction of the 24 channel capacity of T-1 lines. The most common capacities are 2 channels = 128 kilobits, 4 channels = 256 kilobits and 6 channels = 384 kilobits.

Fractional T-3

Fractional T-3 lines have a fraction of the 672 channel capacity of T-3 lines. For example, they might have the capacity of six T-1s or 144 channels. Fractional T-3s are cheaper than a full T-3 line.

Frame relay networks

Public data networks commonly used for local area network to local area network communications. Customers connect to frame relay services over telephone lines from each of their locations to the frame relay network. Frame relay services require less maintenance, hardware and upkeep than traditional private line data communications services for customers with more than about four locations.

FTP (file transfer protocol)

A part of the TCP/IP suite of Internet protocols. It is software that lets users download files from a remote computer to their computer's hard drive.

Gateway

A gateway device allows equipment with different protocols to communicate with each other. For example, gateways are used when incompatible video systems hold a videoconference.

Gigabits

Billions of bits per second. Fiber optic cables carry signals at Gigabit or billions of bits per second. Gbps is short for Gigabits per second.

GPRS (General Packet Radio Services)

A cellular data packet network service. Upgrades to digital cellular networks are required to provision the service. This is an “always on” data service that users do not have to dial into to access.

H.320

The standard for enabling videoconference equipment from multiple vendors to communicate with each other using ISDN service.

H.323

An ITU-based standard for sending voice via the IP, Internet Protocol. H.323 was originally developed for videoconferencing.

H.324

An ITU (International Telecommunications Union) standard for sending video, voice and data between devices over a single analog, dial-up telephone line using a 28,800 bit per second modem. Compression is used on the voice, video and data.

Home page

A home page is the default first page of a World Wide Web site that users see when they visit an organization's Web site. A home page is analogous to the first page and table of contents of a book.

Hub

Each device such as computers and printers on a local area network is wired to the hub, generally located in the wiring closet. Hubs enable local area networks to use twisted pair cabling rather than more expensive, harder to install and move coaxial cabling. Hubs are sometimes referred to as concentrators.

ILEC (incumbent local exchange carrier)

ILECs refer to the Bell and independent telephone companies that sell local telephone service. This term differentiates telephone companies that were the providers of telephone service prior to the Telecommunications Act of 1996 and new competitors such as Allegiance, WorldCom and AT&T. The Telecommunications Act of 1996 decreed that local Bell telephone companies may sell interstate telephone service when they meet FCC guidelines for connecting competitors to their networks.

Independent telephone company

An incumbent local telephone company other than a Regional Bell Operating Company. Examples of independent telephone companies are Alltel Corporation and Cincinnati Bell, Inc.

Internet

The Internet, with a capital I, is composed of multiple worldwide networks tied together by a common protocol, TCP/IP.

Intranet

An intranet is the use of World Wide Web technologies for internal operations. Intranets are used by organizations as a way to make corporate information readily accessible by employees. An example is a corporate telephone directory accessed by a browser.

Inverse Multiplexer

Instead of combining individual channels into one “fat” pipe, which is what a multiplexer does, an inverse multiplexer separates out channels into smaller “chunks.” Inverse multiplexers are used for video conferencing where the 24 channels may be transmitted in groups of 6 channels at a speed of 386 thousand bits per second.

IP (Internet Protocol)

The part of TCP/IP that performs the addressing functions for networks. Each device on an Internet network is assigned a 32-bit IP address. The Internet is running out of addresses, and standards bodies are reviewing ways to upgrade the address schemes so that more addresses will be available.

ISDN (integrated services digital network)

ISDN is a digital network standard that lets users send voice, data and video over one telephone line from a common network interface.

ISP (Internet service provider)

An Internet service provider connects end-users to the Internet via telephone lines. The ISP has banks of modems and devices such as ISDN interfaces for its own customers to dial into which are connected to telephone company central offices. The ISP rents telephone lines to the Internet from its own location. Some Internet service providers such as UUNET also own Internet backbone networks. ISPs supply services such as voice mail, hosting and domain name registration.

IXC (interexchange carrier)

Interexchange carriers are the long distance companies that sell toll free 800, international, data networking and outgoing telephone service on an interstate basis. They now also sell local telecommunications services.

Java

A programming language created by Sun Microsystems. Multiple types of computers can read Java programs. They increase the power of the Internet because programs written in Java can be downloaded temporarily by client computers. They do not take up permanent space on the client hard disc. Interactive games can use Java programs.

Key system

Key systems are on-site telephone systems geared to organizations with under 100 telephones. Like PBXs, they switch calls to and from the public network and within users' premises.

LAN (local area network)

A local area network is located on an individual organization's premise. It enables computer devices such as personal computers, printers, alarm systems and scanners to communicate with each other. Moreover, LANs allow multiple devices to share and have access to expensive peripherals such as printers, fax servers, modem servers and centralized databases.

LATA (local access transport area)

At divestiture in 1984, LATAs were set up as the areas in which Bell telephone companies were allowed to sell local telephone services. LATAs cover metropolitan statistical areas based on population sizes. For example, Massachusetts has two LATAs and Wisconsin has four LATAs, but Wyoming, which has a small population, has one LATA. The rules of divestiture decreed that long distance telephone companies such as AT&T, Sprint and WorldCom were allowed to carry calls between LATAs but that Bell telephone companies such as Illinois Bell could carry calls only within a LATA.

Layer 4

Layer 4 devices can route and prioritize packets based on the source of the packet, the destination port number, the protocol type and the application. For example, layer 4 devices can prioritize voice and video so that networks using the Internet Protocol for voice and data can handle voice without the delays and lost packets associated with lower level protocols.

LDAP (lightweight directory access protocol)

A standard for storing information in a common format. Examples of LDAP directories are the address books in Netscape Communicator 4 and Microsoft Outlook Express browsers. LDAP enables companies to use one central directory to update multiple corporate directories.

Leased line

A leased line is analogous to two tin cans and a string between two or more sites. Organizations that rent leased lines pay a fixed monthly fee for the leased lines that are available exclusively to the organization that leases them. Leased lines can be used to transmit voice, data or video. They are also called private or dedicated lines.

LEC (local exchange carrier)

Any company authorized by the state public utility commission to sell local telephone service.

LMDS (local multipoint distribution service)

A high-speed fixed wireless service used to provision local telephone service without laying fiber to individual customer sites. Some competitive local exchange carriers employ LMDS as a way to provision local telephone, high-speed Internet access and video service.

Local loop

The local loop is the telephone line that runs from the local telephone company to the end user's premise. The local loop can be made up of fiber, copper or wireless media.

MAN (metropolitan area network)

A metropolitan area network is a network that covers a metropolitan area such as a portion of a city. Hospitals, universities, municipalities and large corporations often have telephone lines running between sites within a city or suburban area.

Mbps (million bits per second)

A transmission speed at the rate of millions of bits in one second. Digital telephone lines measure their capacity or bandwidth in bits per second.

Millimeter wireless services

Millimeter wireless services operate at microwave and above very fast frequencies. They include LMDS (local multipoint distribution service) and MMDS (multipoint multichannel distribution service). Millimeter refers to the very short wavelengths of high-frequency services. The wavelength is the distance from the highest or lowest point of one wave to the highest or lowest point of the next wave.

MMDS (multipoint multichannel distribution service)

MMDS is a fixed wireless technology for high-speed data, video and voice. It is a way to provide high-speed Internet access without laying fiber or cable to each customer. It was originally conceived of as a way to supply cable TV services. WorldCom is investing in companies that supply MMDS gear. MMDS uses a lower frequency than LMDS and has less capacity than LMDS. MMDS has a larger range than LMDS; the dishes can be up to 35 miles apart.

Multiplexing (mux)

Multiplexing is a technique whereby multiple devices can share a telephone line. With multiplexing, users do not have to lease individual telephones for each computer that communicates. T-1 multiplexers enable many devices to share one telephone line.

NEBS (Network Equipment Building Standards)

Requirements published in a Bellcore (now Telcordia) technical reference for products placed in a central office environment. Bellcore is the former Bell Telephone central research organization. There are eight standards referring to issues such as environmental, electrical and cabling requirements as well as resistance to natural disasters such as earthquakes.

Network

A network is an arrangement of devices that can communicate with each other. An example of a network is the public switched telephone network over which residential and commercial telephones and modems communicate with each other.

NT1 (network termination type 1)

The NT1 device sits between an ISDN line and an ISDN terminal adapter. The NT1 plugs into the ISDN jack. It provides a point where the network provider can test the ISDN line. The NT1 also converts the ISDN line from the telephone company's two-wire to four-wire cabling. The four wires are the portions of the cabling inside the customer's premise.

Number pooling

Allows local carriers to share a “pool” of telephone numbers within the same exchange. Number pooling is a way to allocate scarce telephone numbers more efficiently. Without pooling, a single local telephone company has rights to the entire 10,000 block of telephone numbers but they may only use a portion of the block.

Packet switching

A network technique that routes data in units called packets. Each packet contains addressing and error checking bits as well as transmitted user data. Packets from a transmission can be routed individually through a network such as an X.25 or frame relay network and be assembled at the end destination.

PBX (private branch exchange)

PBXs are computerized on-site telephone systems located at commercial and non-profit organizations' premises. They route calls both within an organization and from the outside world to people within the organization.

PCMCIA (portable computer memory card industry association)

An industry group that has developed a standard for peripheral cards for portable computers. PCMCIA cards are used for functions such as modems and for additional memory.

Photonics

All of the elements of optical communications. This includes fiber, lasers and optical switches and all elements involved in transmitting light over fiber.

Ping (packet internetwork groper)

A software protocol used to test communications between devices. “To Ping” means to send a packet to another device or host to see if the device sends back a response. The Ping also tests round-trip delay, the time it takes to send a message to another device.

POP (point of presence)

A POP refers to a long distance company's equipment that is connected to the local telephone company's central office. The POP is the point at which telephone and data calls are handed off between local telephone companies and long distance telephone companies.

POTS (plain old telephone service)

Telephone lines connected to most residential and small business users. POTS lines are analog from the end user to the nearest local telephone company equipment. People using POTS service for data communications with modems are limited in the speed at which they can transmit data.

PRI (primary rate interface)

PRI is a form of ISDN (integrated services digital network) with 23 paths for voice, video and data and one channel for signals. Each of the 24 channels transmits at 64 kilobits per second.

QSIG

A standard for networking PBXs from different vendors together over ISDN PRI trunks. The signaling channel of the ISDN circuit carries signals such as those allowing users connected to different PBXs to dial each other using only their three or four digit extension number. Signals can also be used to turn voice mail message lights on and off so different sites can share the same voice mail system.

RBOC (Regional Bell Operating Company)

At divestiture, in 1984, the Justice Department organized the previous 22 Bell telephone companies into seven Regional Bell Operating Companies. Examples of RBOCs are Qwest and BellSouth. Since divestiture, Pacific Telesis and Ameritech merged with SBC, and NYNEX merged with Bell Atlantic. SBC has announced a merger with Ameritech. There are now four RBOCs. Before divestiture, all of the Bell telephone companies were owned by AT&T.

Router

A device with routing intelligence that connects local and remote networks together. Routers are also used in the Internet.

SDH (Synchronous Digital Hierarchy)

A world standard of synchronous optical speeds. The basic SDH speed starts at 155 megabits, also called STM-1 (synchronous transport mode-1) in Europe. SONET (synchronous optical network) is a subset of SDH.

Server

A server is a specialized shared computer on the local area network with corporate files such as electronic mail. It can also be used to handle sharing of printers, fax machines and groups of modems.

SLA (service level agreements)

SLAs are often provided to customers by frame relay, virtual private network and ATM carriers. The SLA defines service parameters such as up-time and response time.

SMS (Short Message Service)

Short, 160 character (including header address information) text messages that can be transmitted between digital cellular telephones.

SMTP (simple mail transfer protocol)

The electronic mail protocol portion of the TCP/IP protocol used on the Internet. Having an electronic mail standard that users adhere to enables people on diverse local area networks to send each other e-mail.

SONET (synchronous optical network)

A standard for multiplexing high-speed digital bits onto fiber optic cabling. SONET converts electronic impulses to light impulses and vice versa. Telephone companies use SONET to transmit data from multiple customers over the same fiber cables.

Streaming video and audio

A means of starting to play a message while the rest of it is being copied. Streaming uses compression to make the voice, video and data smaller so that it can be transmitted in less time. Streaming video and audio are used in broadcasting video and audio over the Internet.

Switched 56

A digital “dial-up” data communications service. It was used more commonly when ISDN was less widely available. If ISDN is not available, switched 56 services can be used for video conferencing.

T.120

The ITU defined standard for document sharing and white boarding. People using T.120 adherent software can participate in document sharing conferences with each other over the Internet. For example, vendors can demonstrate their products to potential customers via computers connected to the Internet at dispersed sites.

T-1

A North American and Japanese standard for communicating at 1.54 million bits per second. A T-1 line has the capacity for 24 voice or data channels.

T-3

A North American standard for communicating at speeds of 44 million bits per second. T-3 lines have 672 channels for voice and/or data. Fiber optic cabling or digital microwave is required for T-3 transmissions.

TA (terminal adapter)

Used with BRI_ISDN service. The terminal adapter allows multiple voice and/or data devices to share a digital ISDN line. The terminal adapter sits between the data communicating device or the telephone and the ISDN line.

TCP (transmission control protocol)

Includes sequence numbers for each packet so that the packets can be reassembled at their destination. The sequence numbers ensure that all of the packets arrive and are assembled in the proper order. If some packets are discarded because of congestion, the network retransmits them. The numbering and tracking of packets make TCP a connection oriented protocol. Router based LAN internetworking uses TCP.

TCP/IP (transmission control protocol/Internet protocol)

The suite of protocols used in the Internet and also by organizations for communications between multiple networks.

TDMA (time division multiple access)

TDMA is one way that carriers transmit digital cellular signals between handheld devices and cellular carriers' networks. It assigns a time slot to every voice or data transmission.

Tier 1 Provider

A loosely defined term for Internet service providers that own Internet backbone fiber optic facilities in addition to ISP services such as hosting and e-mail. Examples include Cable & Wireless, Sprint, WorldCom, UUNET (which is part of MCI WorldCom) and AT&T.

Tunneling

Tunneling is a method of securely transferring data between sites connected by networks such as a virtual private network, the Internet, an intranet or an extranet. Tunneling puts a new header in front of the data so unauthorized users can't read it.

UDP (user data protocol)

Part of the TCP/IP suite of protocols. UDP protocols have less overhead because they do not have bits with packet numbers and acknowledgments. UDP is considered a connectionless protocol because packets arrive at their destination independently from various routes without sequence numbers. There is no assurance that all of the packets for a particular message arrive. The header is smaller with UDP than TCP because UDP headers do not have sequencing and acknowledgment bits. UDP is suited for applications such as database lookups and short messages.

UNE (Unbundled Network Element)

Unbundled Network Elements are parts of the incumbent local telephone company infrastructure that they are required to lease out to other local exchange carriers. Examples of unbundled network elements are the copper lines to customers' premises and ports on central office switches.

URL (Universal Resource Locator)

An address on the World Wide Web. The address is made up of strings of data that identify the server, folder location and other information indicating the location of information on the Internet.

UTP (unshielded twisted pair)

Most inside telephones and computers are connected together via unshielded twisted pair copper cabling. The twists in the copper cables cut down on the electrical interference of signals carried on pairs of wire near each other and near electrical equipment.

VPIM (Voice Profile for Internet Mail)

VPIM is an IP-based digital networking standard for sending voice mail and fax messages as attachments to e-mail messages.

VPNs (virtual private networks)

VPNs provide the functions and features of a private network without the need for dedicated private lines between corporate sites. Each site connects to the network provider's network rather than directly to another corporate location.

WAN (wide area network)

Wide area networks connect computers that are located in different cities, states and countries.

WAP (wireless application protocol)

A protocol that defines how Internet sites can be written to fit on cellular devices' screens and how devices access and view these sites.

WDM (Wavelength division multiplexing)

Also known as dense wavelength division multiplexing; enables multiple colors or frequencies of light to be carried on a single strand of fiber. WDM greatly increases the capacity of network providers' fiber optic networks.

WWW (World Wide Web)

The World Wide Web has multimedia capabilities. It links users from one network to another when they “click” on highlighted text. It was developed in 1989 to make information on the Internet more accessible. A browser is required to navigate and access the World Wide Web.

X.25

An ITU-defined packet switching protocol for communications between end-users and public data networks. X.25 is slower and older than frame relay service.

XML (extensible markup language)

A software language for e-commerce and Web searching. XML is like a data dictionary in that uniform “tags” are attached to elements so those diverse programs can read them. For example, tags can be used to identify elements such as prices, model numbers, product identities or quantities ordered.