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TrustFax > Fax Glossary

Fax Glossary

Alphanumeric

A term used to describe a character set containing letters and digits.

Application Program Interface (API)

This term describes an organized method for arranging communications between multiple computer programs or between multiple modules of a single program. Usually an API is either based on a standard file exchange method or a collection (library) of different functions.

Auto fax/Tel switch

Automatically determines whether incoming calls are voice calls or fax calls and routes them accordingly. Some switches incorporate an answering machine feature.

Automatic document feeder

A device that feeds documents into a facsimile machine without operator assistance.

Binary File Transfer (BFT)

This is an approved standard format for transferring binary files via facsimile and other telecommunications services. The ITU-T document which describes this standard is T.434 and the US version is TIA/EIA-614.

bps

Bits per second. Used to designate the speed at which data flows over transmission lines. For example, 9,600 bps would indicate that 9,600 bits of information are being transmitted per second.

Broadcast

The transmission of one set of documents to two or more receivers.

CCITT

This is the abbreviation for the International Telephone and Telegraph Consultative Committee, which is the international standards body which has created standards (also called recommendations) for data communications systems and equipment. This term has been phased out in favor of ITU-T. (See ITU).

CIELAB

This is a convention for specifying colors via a "color space" which is independent of the type of device or media on which a color image or document is reproduced.

Class 1

The Class 1 digital interface is for fax devices which only do fax data transfer, where the T.4/T.6 data compression and T.30 session management are handled by software on a controlling computer. This was originally published as EIA/TIA-578 and since updated as TIA/EIA-578-A. The ITU version is T.31.

Class 2

The Class 2 digital interface is a proposed standard for controlling fax devices which can handle T.30 session management, where the T.4/T.6 data compression is handled by software on a controlling computer. This has been published as TIA/EIA-592. Amendments have been published as IS-134. The ITU version is T.32.

Class 3

Class 3 is a type of digital interface and related command set which will apply to a class of fax devices which provide both T.30 session management and T.4/T.6 presentation management (e.g. text to fax and other format conversions). This functionality may be incorporated in a future MFPI proposed standard. (see MFPI)

Class X

The Class X digital interface has been proposed to control fax devices which will act as data pumps. Computer resident software will manage T.30 fax session management and T.4/T.6 data compression. Batching of commands will be permitted to relieve critical timing problems.

Compatibility

Indicates the ITU-T communication mode supported by the machine. There are four standard modes: Group 1 (G1) mode, which is also referred to as 6-minute FM mode, was used on the first generation of analog machines; Group 2 (G2) mode, which is faster and more automated than Group 1 machines, was used on the second-generation analog machines; Group 3 (G3) mode, which supports bit-per-second rates up to 14.4 Kbps, is the first mode to utilize digital technology. Many Group 3 machines are also compatible with the older Group 2 and Group 1 machines. G3 is the most common mode presently in use. Group 4 (G4) mode is the latest standard. It is designed for high-speed communication (up to 64,000 bps) and must be used on private or special digital (as opposed to analog) telephone lines.

DCE

This is Data Circuit-terminating Equipment, which is any device which connects a computer or terminal (DTE) to a data communications network. In the case of fax, this could be a fax modem or other fax device.

Determination

This is the first step of the Resolution 1 process used for approving ITU-T recommendations. A draft recommendation may be "determined" at a Study Group or Working Party meeting once the content is considered to be technically stable.

Digital

Transmission of data in the form of on/off electrical impulses representing digits, as opposed to the continuously varying signal of analog transmission.

Dpi

Dots per inch. A measure of resolution in input devices such as scanners, display devices such as monitors, and output devices such as fax machines and laser printers.

DSVD

This term is an abbreviation for Digital Simultaneous Voice and Data. This is a method by which a user can simultaneously make a voice phone call and send data to the same recipient. The voice is compressed and the data is transmitted using the remaining bandwidth of the analog voice channel. There is a series of pending ITU-T recommendations for this method.

DTE

This is Data Terminal Equipment which is any terminal or computer which can provide commands to operate a data communications device (DCE). For fax, this device can be a computer of any size.

Energy-saver mode

The condition that exists when the machine is not sending, receiving or printing, and has previously reached operating conditions but is consuming less power than when the machine is in stand-by mode.

ETSI

This is the European Telecommunications Standards Institute which is a group of manufacturers that produces telecommunications standards for use in European countries.

fax (facsimile)

short for facsimile

fax forwarding

A user can program a fax machine to automatically transmit received documents to a specified destination.

fax machine

This is generally a single purpose device that can send and receive facsimiles. The machine is normally able to scan in a document and transmit it over a phone line to another fax machine. Also, it can receive faxes from other machines and print them out.

Grayscale/Halftones

This indicates the reproduction of shades of gray. This feature is used when transmitting photographs or material with halftones. Today's facsimile machines generally offer between a 16- and 64-level halftone capability.

Group 3 Facsimile

This is a standard for facsimile communications over analog telephone lines originally approved by the CCITT in its T.4 and T.30 recommendations in 1980. This standard is supported by almost all of the current install base of fax machines and fax devices and is continuing to be updated.

Group 4 Facsimile

This is a standard for facsimile communications over digital telephone networks which was originally approved in 1984 and updated in 1988. This standard has been adapted more in Europe and Japan than in the United States and is predominately used for fixed point to point high volume communications.

Group dialing

The ability to store multiple numbers under one key for broadcasting or polling.

Halftones

Also known as "grayscale." Refers to reproduction of shades of gray.

Handshake

An exchange of electronic signals preceding a communication between two facsimile machines to determine the proper connection for transmission.

IETF

This is the Internet Engineering Task Force. It is a group which develops standards (called RFC's) for use on networks such as the Internet which use the TCP/IP and other IP network protocols. (see RFC).

ISDN

This is the Integrated Services Digital Network which is an industry standard public digital telephone network. This network is gradually being implemented in the United States and in other countries worldwide as an advanced alternative to the current analog telephone network or PSTN (see PSTN).

ISO

This is the International Standard Organization which is a group which is responsible for the development of many international computer standards.

ITU

This is the International Telecommunications Union, which has been the parent body of the CCITT. As of 1993, all the former CCITT telecommunications standards activities will be handled by the ITU Telecommunications Standardization Sector (ITU-T).

JBIG

This is the Joint Binary Image Group which is a group of experts from the CCITT and ISO who have developed the bi-level image standard ITU-T T.82. There is also a new pending JBIG-2 compression method.

JPEG

This is the Joint Photographic Experts Group which is a group of experts from the ITU-T and ISO who have developed as advanced data compression standard for compressing images (color or B/W) or still frame video. The resulting standard is ITU-T T.81. There is also a new pending JPEG 2000 compression method.

Keypad dialing

Also known as "on-hook dialing." Allows the user to dial directly through the keypad without having to pick up the telephone handset.

Memory transmission

The storage of documents in memory for transmitting when the phone line is free or at a time predetermined by the user.

MFPI

This is the Multi-Functional Peripheral Interface, which is an interim standard under TR-29.2 project PN-1906 for a new class of hybrid devices which may have fax, print, scan and copy capabilities, as well as local storage. This work is approved as interim standard IS-650.

MIME

MIME is short for Multipurpose Internet Mail Extensions and has been standardized by the Internet Engineering Task Force (IETF) as document RFC 2045-2049 (replacing RFC 1521 - see RFC).

Modem data speed

This refers to the top speed in bits per second (bps) at which the facsimile machine transmits code.

One-touch dialing

The ability to dial programmed numbers using one keystroke instead of using a conventional keypad.

On-hook dialing

The ability to dial numbers using the keypad on the fax unit without lifting the handset.

Paper capacity

Indicates the maximum number of sheets held by the unit's standard cassettes, trays or drawers.

Paper source

Indicates the number of cassettes, trays or drawers the machine is equipped with in its standard configuration and the size of the cassettes, trays or drawers (ltr=letter, lgl=legal, ldg=ledger and adj=adjustable); if the machine does not use cut-sheet paper, the type of paper used (thermal roll) is indicated.

PC interface

Indicates type of interface offered, either serial or parallel, and whether it's available as an option. When connected, a PC interface enables the fax unit to allow scanning, printing and PC-based faxing.

Polling

A feature that permits a facsimile machine to call another machine and request it to transmit documents.

Print speed

The speed, expressed in pages per minute or seconds per page, at which a facsimile machine prints pages.

Programmable Communication Interfaces (PCIs)

This is the term used by the ITU-T for a family of programmable interfaces (see the definition for API above) between different layers of application and communications programs. For example, T.611 Appli/Com is an example of a PCI at the application program level and there are other versions of PCIs for lower level communications functions which establish telephone network connections.

PSTN

This is the Public Switched Telephone Network (PSTN) which supports analog voice and fax calls. It is also sometimes called the General Switched Telephone Network (GSTN).

Question

This is the term used by ITU-T for active projects within a Study Group.

Recommendation

This is the term used by ITU-T to describe international standards approved by its members (e.g. the ITU-T T.30 recommendation).

Resolution 1

This is a method for rapidly approving an ITU-T recommendation which is supported by a consensus of ITU-T members. Using this approach, a standard can be approved and published in about a year. The steps are: (1) Determination (see Determination) (2) Approval via letter ballot among member countries (70 % constitutes approval) and (3) Decision by unanimous consent at the next Study Group meeting.

Resolution

In facsimile, the resolution is expressed in the number of lines per inch scanned and recorded.

RFC

This is short for Request For Comment. It is the term used by the Internet Engineering Task Force (IETF) for Internet standards documents and other published information.

RFC 2301

This is the IETF standards track document which defines six profiles of TIFF image files available for use within Internet Fax

RFC 2305

This is the IETF standards track document which defines the simple mode of Internet Fax via email.

RFC 2532

This is the IETF standards track document which defines the extended mode of Internet Fax via email.

RS-232C interface

Usually available as an option, this feature allows the fax to communicate with a computer.

Standards Track

This is the term used by the Internet Engineering Task Force (IETF) for draft documents which are being targeted for Internet standardization.

T.30

This is the portion of the ITU-T Group 3 facsimile standard which specifies the protocol through which fax devices can exchange information about their supported characteristics and manage the fax session.

T.37

This is the ITU-T recommendation which defines a store and forward method for Internet Fax.

T.38

This is the ITU-T recommendation which defines a real time method for fax over IP networks.

T.4

This is the portion of the ITU-T Group 3 facsimile standard which specifies how image data is to be formatted for facsimile transmission and reception.

T.434

(see Binary File Transfer)

T.6

This is an ITU-T recommendation which describes a two dimensional compression method which is more efficient than T.4, using a coding technique known as Modified Modified Read (MMR).

T.611

This is the ITU-T recommendation describing a generalized software interface which permits application programs to request ITU-T telecommunications services which include Group 3 fax, Group 4 fax, electronic mail, file transfer, telex and teletex. (see PCI).

TIA

This is the Telecommunications Industry Association which is a trade association that sponsors the accredited engineering standards committees for data communications technology in the United States. These engineering committees also formulate the positions taken by the United States in the ITU-T international standards body.

TR-29

This is the identifier for the Facsimile Systems and Equipment Engineering Committee sponsored by the Telecommunications Industry Association (TIA). This committee is responsible for devising U.S. industry standards for technologies related to facsimile and computer based facsimile.

TR-29.1

This is the subcommittee of TR-29 which develops Facsimile and File Transfer Protocols for the US (now merged into the TR-29 parent committee as of 1999).

TR-29.2

This is a subcommittee of TR-29 which specializes in the development of standards in the area of programmable facsimile interfaces, notably for controlling the interaction between computers and fax devices (now merged into the TR-29 parent committee as of 1999).

TR-45

This is the TIA committee which is responsible for developing standards for the use of digital cellular equipment in North America.

Transmission speed

The speed provided is the amount of time it takes to transmit one page of the ITU-T Test Chart #1 to a remote machine made by the same manufacturer and model.

V.34

This is the ITU-T recommendation describing an advanced modulation method which can be used to transmit data at rates of up to 33.6 kilobits per seconds over analog telephone lines (the PSTN).

V.8

This is the ITU-T recommendation describing a pre-session negotiations method which is used between two modems to select the type of session which is desired and negotiate various related session attributes.

V.90

This is the ITU-T recommendation describing an advanced modulation method which can be used to transmit data downstream at rates of up to 56 kilobits per second and upstream at rates of 33.6 kilobits per seconds over analog telephone lines (the PSTN). It features use of an analog and digital modem pair.