Teletex was

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...

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 It was rapidly superseded by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 (email or e-mail) is a method of exchanging messages ("mail") between people using electronic devices. Email was thus conceived as the electronic ( digital) version of, or counterpart to, mail, at a time when "mail" mean ...

but the name ''Teletex'' lives on in several of the

X.500 X.500 is a series of computer networking standards covering electronic directory services. The X.500 series was developed by the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T). ITU-T was formerly kno ...

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 typewriters,

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. Word processor (electronic device), Early word processors were stand-alone devices ded ...

s and

personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...

s. These units had storage for transmitting and receiving messages. The use of such equipment considerably enhanced the character set 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 telecommunication, a control character or non-printing character (NPC) is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the ...

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 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: * Field 1:

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/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