Fax Technology Standards
Glossary of Terms

 

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.

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.

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). Not standardized, but a pre-cursor to work on areas like Internet Printing, which addressed similar document communication issues.   See the Internet Printing section of the PWG web site for details.   

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. Not standardized.  

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. (see Resolution 1)

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.

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

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.

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

Informational RFC - This is a Request for Comments (RFC) document which is for informational use only and is not a standard.  

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.  

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).

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.

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

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).

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).

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 original IETF standards track document which defines six profiles of TIFF image files available for use within Internet Fax.  It has been superseded by RFC 3949.     .

RFC 2305 - This is the original IETF standards track document which defines the simple mode of Internet Fax via email.   It has been superseded by RFC 3965.   

RFC 2306 - This is the informational RFC which defines how the TIFF image file format is most commonly used in computer based fax and voice mail applications.   

RFC 2532 - This is the IETF standards track document which defines the extended mode of Internet Fax via email.

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.

Standards Track - This is the term used by the Internet Engineering Task Force (IETF) for draft documents which are being targeted for Internet standardization and completed RFCs which have become standards.   

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 was responsible for devising U.S. industry standards for technologies related to facsimile and computer based facsimile.   It has now been replaced by TR-30.1.   

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).

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.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).

TR-45 - This is the TIA committee which is responsible for developing standards for the use of digital cellular equipment in North America.

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.434 - (see Binary File Transfer)

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).

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.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.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.  

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