Teletex was

ITU-T The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating Standardization, standards fo ...

specification F.200 for a text and document communications service that could be provided over telephone lines. It was rapidly superseded by

e-mail Electronic mail (usually shortened to email; alternatively hyphenated e-mail) is a method of transmitting and receiving Digital media, digital messages using electronics, electronic devices over a computer network. It was conceived in the ...

; however, the name ''Teletex'' lives on in several of the X.500 standard attributes used in

Lightweight Directory Access Protocol The Lightweight Directory Access Protocol (LDAP ) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. Directory serv ...

Overview

Teletex was designed as an upgrade to the conventional telex service. The terminal-to-terminal communication service of telex would be turned into an office-to-office document transmission system by teletex. Teletex envisaged direct communication between

electronic typewriter A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectively ag ...

word processor A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Early word processors were stand-alone devices dedicated to the function, but current word ...

s and

personal computer A personal computer, commonly referred to as PC or computer, is a computer designed for individual use. It is typically used for tasks such as Word processor, word processing, web browser, internet browsing, email, multimedia playback, and PC ...

s. These units had storage for transmitting and receiving messages. The use of such equipment considerably enhanced the

character set Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using computers. The numerical values that make up a c ...

available for document preparation.

Features

Character sets

In addition to the standard character set, a rich set of graphic symbols and a comprehensive set of

control character In computing and telecommunications, a control character or non-printing character (NPC) is a code point in a character encoding, character set that does not represent a written Character (computing), character or symbol. They are used as in-ba ...

s were supported in teletex. The set of control characters helped in preparation and reproduction of documents. In particular, they permitted the positioning of the printing element, specification of page orientation, left and right margins, vertical spacing and the use of underlining. The page control feature allowed standard A4 size papers to be used for receiving messages instead of the

continuous stationery Continuous stationery (UK) or continuous form paper (US) is paper which is designed for use with Dot matrix printing, dot-matrix and line printers with appropriate paper-feed mechanisms. Other names include ''fan-fold paper'', ''sprocket-feed p ...

used in conventional telex systems.

Transmission and reception

A background/foreground operation was envisaged in teletex. Transmission/reception of messages should proceed in the background without affecting the work which the user might be carrying out in the foreground with the equipment. In other words, a user might be preparing a new document, while another document was being transmitted or received. The teletex would also maintain compatibility with the present telex system and inter-operate with it. Telex procedures called for the exchange of header information before the actual document transfer took place. The header information consisted of four parts: * Part 1: Destination ID, * Part 2: Originator ID, * Part 3: Date and time stamp, * Part 4: Document reference. Twenty-four characters were used for source/destination ids, 14 characters for date and time stamp, and 7 characters for document reference (which also specified the number of pages in the document). Destination/source ID consisted of four

fields Fields may refer to: Music *Fields (band), an indie rock band formed in 2006 * Fields (progressive rock band), a progressive rock band formed in 1971 * ''Fields'' (album), an LP by Swedish-based indie rock band Junip (2010) * "Fields", a song by ...

: * Field 1:

Country A country is a distinct part of the world, such as a state, nation, or other political entity. When referring to a specific polity, the term "country" may refer to a sovereign state, state with limited recognition, constituent country, ...

/Network code, * Field 2: National subscriber number, * Field 3: Reserved for future use, * Field 4: Terminal/Owner code. The number of characters allotted to each of the above fields was variable, subject to a maximum for each field, the total being 24 characters.

References

Legacy systems Telegraphy {{Telecomm-stub