SIST ETS 300 706 E1:2003

• Abstract:

  Enhanced Teletext specification.

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.050.30 - Equipment for telex, teletext, telefax
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 706 ed.1 (1997-05) - Enhanced Teletext specification

SIST ETS 300 706 E1:2003 is the Slovenian publication of ETS 300 706 Edition 1 from ETSI and the EBU. It specifies Enhanced Teletext for broadcast television systems, including how teletext data is carried, coded, displayed and linked into pages, magazines and services. Engineers, quality managers and buyers use it when they need compatible teletext transmission or decoding across Levels 1, 1.5, 2.5 and 3.5.

What does SIST ETS 300 706 E1:2003 specify?

SIST ETS 300 706 E1:2003 specifies the application of CCIR Teletext System B to CCIR 625 line 50-field television systems B, D, G, H, I, K and L. The document is aimed at broadcast media, especially cable, terrestrial and satellite transmission, where teletext pages must fit into the television signal timing and remain compatible with existing receivers.

The standard covers how teletext data is organized into packets, pages, magazines and services. It also defines presentation levels, character sets, enhancement data, navigation aids and decoder behaviour so that newer services can be added without making older equipment unusable.

The main structure is:

• Clauses 1 to 3: scope, normative references, definitions, symbols and abbreviations
• Clauses 4 to 9: data lines, signalling, packet identification, data organization, coding and packet formats
• Clauses 10 to 15: presentation, navigation, display, objects, DRCS and character sets
• Annexes A to D: normative encoding, transmission, decoding and default-operation rules
• Annexes E to Q: informative guidance, transmission and decoding aspects, navigation methods, related applications and bibliography

Annex	What it covers
A	Encoding rules
B	Transmission rules
C	Decoding rules
D	Default operation of decoders
E	Encoding aspects
F	Transmission aspects
G	Decoding aspects
H	Code of Practice for navigation via FLOF
I	Navigation via Table Of Pages (TOP)
J	Magazine Inventory Pages (MIP)
K	VCR programming and control via Teletext
L	Teletext data for Automatic Channel Installation
M	Data transmission via Teletext
N	Data broadcasting services, including EPG
O	Relationship to earlier specifications
P	Non-Teletext signals in the VBI
Q	Bibliography

What are the key requirements of SIST ETS 300 706 E1:2003?

SIST ETS 300 706 E1:2003 defines the transport and coding rules that make teletext pages readable by compliant decoders. The most important requirements are the packet format, error protection, presentation levels, enhancement data and the rules for how services are transmitted and decoded in practice.

Packet structure and signalling

Clause 6 defines how a teletext packet is identified on a television line: it starts with a clock run-in, then a framing code, then the packet address. Clause 7 says a packet contains 360 bits arranged as 45 bytes, and packets may be page headers, directly displayable packets or non-displayable packets.

In practice, this means equipment must lock onto the timing pattern, identify the packet type and then place the data into the right page or service location. Clause 5 defines binary NRZ signalling, the data signal levels and the bit rate, so transmitter and receiver designs must match the specified teletext waveform.

Error protection and byte coding

Clause 8 defines the coding methods used in teletext data bytes: odd parity, Hamming 8/4, Hamming 24/18 and plain 8-bit data. These methods are used to protect basic data, address information and enhancement data.

In practice, this is what allows a decoder to detect or correct errors caused by the broadcast channel. Clause 8 makes a clear distinction between simple parity checks for display data and Hamming protection for addressing and enhancement information.

Page organization and packet use

Clause 7 explains how packets combine into pages, magazines and services. Pages are normally repeated in sequence, while some packets have stand-alone functions and some service-related packets are not tied to a specific page or magazine.

Clause 9 then assigns functions to packet types. It covers directly displayable packets such as X/0 to X/25, page enhancement packets such as X/26 and X/28, magazine-related enhancement packets M/29, page-linking packets X/27, and broadcast service packets 8/30.

For a user of the standard, this means the page layout, enhancement features and linkage data are not ad hoc - they follow fixed packet roles that decoder firmware can interpret consistently.

Presentation levels and display features

Clause 12 defines four Presentation Levels:

• Level 1
• Level 1.5
• Level 2.5
• Level 3.5

Level 1 is the basic teletext page with 24 rows and 40 columns, spacing attributes and a fixed colour palette. Level 1.5 extends the character repertoire. Levels 2.5 and 3.5 add more languages, re-definable colours, non-spacing attributes, simple re-definable characters and side panels, with Level 3.5 extending the complexity of re-definable characters and adding font-style and proportional spacing features.

In practice, this is the compatibility framework for service design. A broadcaster can add richer presentation while keeping a basic page readable on older decoders.

Enhancement data, objects and DRCS

Clause 10 defines the system components used for presentation, including page-specific, magazine-specific and public enhancement data. Clause 13 defines Objects as reusable enhancement blocks, with three types:

• Active Objects
• Adaptive Objects
• Passive Objects

Clause 14 defines Dynamically Re-definable Characters (DRCS), including downloading pages, character modes and flashing DRCS. This is the part of the standard that supports logos, icons, special symbols and custom glyphs.

In practice, a service designer uses these clauses when a page needs graphics or characters that go beyond the basic teletext character set. A decoder manufacturer uses them to know how objects are invoked, how their priority works and how DRCS data is stored and displayed.

Character sets and navigation

Clause 15 defines the Latin, Cyrillic, Greek, Arabic and Hebrew character sets and the rules for designation of default and modified sets. This matters when the same service has to display different writing systems or national option subsets.

Clause 11 and Annexes H and I define navigation via Full Level One Facilities (FLOF) and Table Of Pages (TOP), and Clause 11.3 defines Magazine Inventory Pages (MIP). These features help viewers move through a teletext service faster, and they give decoder designers a structured way to present page indexes and links.

What terms does SIST ETS 300 706 E1:2003 define?

SIST ETS 300 706 E1:2003 defines several terms that are central to teletext implementation.

• Teletext packet - A sequence of bits sent on one television line, containing synchronization, address and information data.
• Page address - The combination of page number and sub-code used to identify a teletext page.
• Magazine - A set of one or more teletext pages normally transmitted in sequence.
• Page Format - CA - A data-broadcasting method defined in ETS 300 708 where data is carried within teletext pages and may use conditional access and scrambling.
• Page Format - Clear - A data-broadcasting method defined in ETS 300 708 where data is carried within teletext pages without conditional access and scrambling.
• Dynamically Re-definable Character Set (DRCS) - A set of characters downloaded as bit patterns so that new symbols can be displayed.
• Full Level One Facilities (FLOF) - A navigation method that uses linked page addresses and colour-key prompts to help viewers choose pages.
• Table Of Pages (TOP) - A navigation structure that groups pages by themes and supports direct access and user guidance.

Who uses SIST ETS 300 706 E1:2003?

SIST ETS 300 706 E1:2003 is used by broadcast engineers, teletext service editors, receiver and decoder manufacturers, and conformance test teams. It is also relevant to cable, terrestrial and satellite operators that carry teletext in the VBI or in full-field transmissions.

In practice, the standard is used for:

• designing teletext encoders and decoders
• creating page layouts, links and navigation aids
• defining DRCS and object pages
• allocating pages for programme listings, warnings and service data
• supporting VCR programming, automatic channel installation and EPG transport
• checking interoperability between broadcaster workflows and receiver behaviour

Which standards are used with SIST ETS 300 706 E1:2003?

SIST ETS 300 706 E1:2003 cites several normative references that support specific parts of the system.

• ETS 300 231 - provides Programme Delivery Control (PDC) for television systems
• ETS 300 708 - provides the data-transmission framework within Teletext, including Page Format - CA and Page Format - Clear
• ETS 300 707 - defines the Electronic Programme Guide (EPG) protocol using teletext data packets
• ISO 6937/2 - provides the Latin coded character set used for text communication
• ETR 287 - gives the Code of Practice for Enhanced Teletext
• TR 101 231 - provides country and network identification codes for Teletext-based systems
• prTR 101 233 - gives guidance for allocating services in the Vertical Blanking Interval (VBI)

What does the SIST ETS 300 706 E1:2003 document contain?

SIST ETS 300 706 E1:2003 contains the packet formats, coding rules, display rules and transmission rules needed to implement Enhanced Teletext. It includes figures for usable TV lines, packet identification, object structure, DRCS downloading, presentation levels and navigation tables.

The document also contains tables for colour maps, DRCS modes, page-function coding and character-set designation. Those tables are used when designing or testing decoder behaviour, because they define which bytes mean what and how the decoder should present them.

Annexes A to D give the rules for encoding, transmission, decoding and default operation. Annexes E to G add implementation guidance, while Annexes H and I explain FLOF and TOP navigation in practical service terms. Annexes J to N cover MIP, VCR control, automatic channel installation, data transmission and data broadcasting, including EPG-related use.

SLOVENSKI STANDARD
01-december-2003
Specifikacija za izboljšani Teletext
Enhanced Teletext specification
Ta slovenski standard je istoveten z: ETS 300 706 Edition 1
ICS:
33.050.30 Oprema za teleks, teletekst, Equipment for telex, teletext,
telefaks telefax
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 706
TELECOMMUNICATION May 1997
STANDARD
Source: EBU/CENELEC/ETSI JTC Reference: DE/JTC-TTEXT-EACEM
ICS: 33.020
Key words: Broadcasting, data, transmission, Teletext, TV
Union Européenne de Radio-Télévision
European Broadcasting Union
Enhanced Teletext specification
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [e-mail]
Tel.: [phone] - Fax: [phone]
Copyright Notification:
No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997.
© European Broadcasting Union 1997.
All rights reserved.
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ETS 300 706: May 1997
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 706: May 1997
Contents
Foreword .9
1 Scope .11
2 Normative references.12
3 Definitions, symbols and abbreviations.12
3.1 Definitions .12
3.2 Symbols .13
3.3 Abbreviations .13
4 TV lines usable as data lines.14
4.1 When multiplexed with a composite video signal .14
4.2 When not multiplexed with a composite video signal .14
5 Signalling characteristics.15
5.1 Signalling method .15
5.2 Data Signal Levels .15
5.3 Bit Rate .15
5.4 Spectrum of data pulses.15
6 Teletext packet identification.15
6.1 Clock run-in.15
6.2 Framing code.16
6.3 Timing reference.16
7 Organization of Teletext data elements .17
7.1 Elements of a Teletext packet .17
7.1.1 Synchronization sequence .17
7.1.2 Packet address.17
7.1.3 Data bytes .17
7.1.4 Packet types.17
7.2 Elements of a page.18
7.2.1 Definition of a page .18
7.2.2 Page header packet .19
7.2.3 The body of a page .19
7.3 Elements of a magazine .19
7.4 Elements of the service .20
8 Byte coding and error protection .21
8.1 Odd parity .21
8.2 Hamming 8/4 .21
8.3 Hamming 24/18 .22
9 Coding of data packets .23
9.1 Overview of packet types.23
9.2 Reserved bits.26
9.3 Directly displayable data packets.26
9.3.1 Page header.26
9.3.1.1 Page number .27
9.3.1.2 Page sub-code.27
9.3.1.3 Control bits.27
9.3.1.4 Data bytes.28
9.3.2 Packets X/1 to X/25.29
9.4 Page enhancement data packets .29
9.4.1 Packet X/26.30

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9.4.2 Packet X/28/0 Format 1. 30
9.4.2.1 Page Function and Page Coding . 30
9.4.2.2 Coding for basic Level 1 Teletext pages. 31
9.4.2.3 Coding for data broadcasting pages . 34
9.4.2.4 Coding for other types of page. 34
9.4.3 Packet X/28/0 - Format 2. 34
9.4.4 Packet X/28/1 . 35
9.4.5 Packet X/28/2 . 36
9.4.6 Packet X/28/3 . 36
9.4.7 Packet X/28/4 . 37
9.5 Magazine-Related Page Enhancement Data Packets . 38
9.5.1 Packet M/29/0. 38
9.5.2 Packet M/29/1. 39
9.5.3 Packet M/29/4. 40
9.6 Packets for Page Linking . 41
9.6.1 Packets X/27/0 to X/27/3 for Editorial Linking . 41
9.6.2 Packets X/27/4 and X/27/5 - Format 1 - for compositional linking in
presentation enhancement applications . 43
9.6.3 Packets X/27/4 to X/27/7 - Format 2 - for compositional linking in data
broadcasting applications . 46
9.7 General Coding of packets 30 and 31. 47
9.8 Broadcast Service Data Packets. 48
9.8.1 Packet 8/30 Format 1 . 48
9.8.2 Packet 8/30 Format 2 . 50
10 System Components for Presentation. 51
10.1 Basic Teletext - Presentation Levels 1 and 1.5. 51
10.2 Enhanced Teletext - Presentation Levels 2.5 and 3.5 . 52
10.3 Page Specific Enhancement Data . 52
10.3.1 Enhancements via X/26/0 - 15. 53
10.3.2 Enhancements via X/28/0 Format 1 . 53
10.3.3 Enhancements via X/28/1. 53
10.3.4 Enhancements via X/28/4. 53
10.4 Magazine Specific Enhancement Data . 53
10.5 Public Enhancement Data. 54
10.5.1 Object Definition Pages . 54
10.5.1.1 Page Format . 54
10.5.1.2 Pointer Table. 54
10.5.1.3 Object Definition Area . 55
10.5.1.4 Page Number Identification. 56
10.5.2 DRCS Downloading Pages. 56
10.5.2.1 Page Format . 56
10.5.2.2 Page Number Identification. 56
10.6 Magazine Organization Table . 56
10.6.1 Page Format. 56
10.6.2 Object Page Association. 58
10.6.3 DRCS Page Association. 58
10.6.4 Object Links. 58
10.6.4.1 Default Objection Invocation . 59
10.6.5 DRCS Links . 60
10.6.6 Number of Enhancement Pages . 61
10.7 Links between Enhanced System Components. 62
10.7.1 Linking to Object and DRCS Pages via the MOT. 62
10.7.2 Linking to Object and DRCS Pages via Packets X/27/4 and X/27/5 . 63
11 System Components for Navigation . 64
11.1 Navigation via FLOF. 64
11.1.1 Principles . 64
11.1.2 Additional components . 64
11.2 Navigation via TOP . 65
11.2.1 Principles . 65
11.2.2 Additional components . 66
11.3 Magazine Inventory Page. 67

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11.3.1 Principles.67
11.3.2 Format of the Magazine Inventory Page .67
11.3.3 Page Function Coding.68
11.3.4 Sub-page range.71
12 Presentation Levels.71
12.1 Display Components.72
12.2 Spacing attributes .76
12.3 Non-spacing attributes and additional characters.80
12.3.1 Use of Packets X/26.80
12.3.2 Active Position.82
12.3.3 Row Address triplets .82
12.3.4 Column Address triplets .89
12.4 Colour Map .96
12.5 Side Panels.96
12.5.1 Panel position.97
12.5.2 Panel size.97
12.5.3 Data transmission and addressing.97
12.5.4 Display rules.98
13 Objects .98
13.1 Object definitions .98
13.2 Display priority order .99
13.3 Active Objects.99
13.4 Adaptive Objects.99
13.5 Passive Objects .100
13.6 Object invocation .100
13.7 Screen position of Object elements.101
13.8 Default Objects .101
13.9 Object example.102
14 Dynamically Re-definable Characters .103
14.1 Downloading pages .103
14.2 DRCS Character Modes .104
14.2.1 Mode 0 - 12x10x1.104
14.2.2 Mode 1 - 12x10x2.104
14.2.3 Mode 2 - 12x10x4.104
14.2.4 Mode 3 - 6x5x4.105
14.3 Flashing DRCS .105
14.3.1 Mode 0 .105
14.3.2 Modes 1, 2 and 3.105
14.4 DRCS availability .105
14.4.1 Level 2.5.105
14.4.2 Level 3.5.106
15 Character sets and their designation.108
15.1 Overview of designation requirements .108
15.2 Designation of default G0 and G2 sets and national option sub-sets.108
15.3 Second G0 Set Designation and National Option Set Selection.110
15.4 Modified G0 and G2 Character Set Designation .112
15.5 Spacing attributes .113
15.6 Alphanumeric Character Sets.113
15.6.1 Latin G0 Set .114
15.6.2 Latin National Option Sub-Sets .115
15.6.3 Latin G2 Set .116
15.6.4 Cyrillic G0 Set - Option 1 - Serbian/Croatian.117
15.6.5 Cyrillic G0 Set - Option 2 - Russian/Bulgarian.118
15.6.6 Cyrillic G0 Set - Option 3 - Ukrainian .119
15.6.7 Cyrillic G2 Set.120
15.6.8 Greek G0 Set .121
15.6.9 Greek G2 Set .122
15.6.10 Arabic G0 Set .123
15.6.11 Arabic G2 Set .124

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15.6.12 Hebrew G0 Set . 125
15.7 Graphics Character Sets. 126
15.7.1 G1 Block Mosaics Set. 126
15.7.2 G3 Smooth Mosaics and Line Drawing Set. 127
Annex A (normative): Encoding Rules. 128
A.1 Page numbering . 128
A.2 Use of control bits C4 (Erase Page) and C8 (Update Indicator). 129
A.3 Backwards compatibility in X/26 addressing. 129
A.4 Addressing order for enhancement triplets. 129
A.5 Rules for row and screen colours . 130
A.6 Object definition pages . 130
A.7 Rules for the overlapping and interleaving of objects. 130
A.7.1 Overlapping rules . 130
A.7.2 Interleaving rules. 131
A.8 Number of objects per page . 131
A.9 Coding of packets 8/30, Formats 1 and 2. 132
Annex B (normative): Transmission Rules . 133
B.1 Transmission of basic Teletext pages with a page erasure interval. 133
B.2 Transmission order of packets with Y = 26, 27 and 28 . 133
B.3 Serial mode transmission . 133
B.4 Parallel mode transmission . 134
B.5 Transmission of packets 8/30. 134
B.6 Rules for the transmission of presentation enhancement data . 134
B.7 Transmission sequence of enhancement data for page updates. 135
B.8 Rules for the transmission of Magazine Inventory Pages (MIP). 135
Annex C (normative): Decoding Rules. 136
C.1 Relationship between the display planes. 136
C.2 Rules for determining priorities of spacing and non-spacing attributes. 136
C.3 Rules applying to the size attributes . 137
C.4 Interpretation of character set and DRCS table changes at enhanced levels. 138
Annex D (normative): Default operation of decoders. 139
D.1 Page level . 139
D.1.1 Missing packets X/1 to X/25. 139
D.1.2 No packets X/26. 139
D.1.3 Packets X/26 with non-sequential designation codes . 139
D.1.4 No packet X/27/4. 139

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D.1.5 No packet X/28/0 Format 1.140
D.1.6 No packet X/28/1 .140
D.1.7 No packet X/28/3 .140
D.1.8 No packet X/28/4 .140
D.2 Magazine level.140
D.2.1 No packet M/29/0.140
D.2.2 No packet M/29/1.141
D.2.3 No packet M/29/4.141
D.3 Service level .141
Annex E (informative): Encoding aspects .142
E.1 Page numbers for object definition and DRCS data pages.142
E.2 Page Time-Code .142
E.3 Use of packets X/26 in Level 1.5 transmissions .142
E.4 Preferred use of packets X/27/4 and X/27/5 .142
E.5 Character set designation .142
E.6 Use of DRCS characters within objects .143
E.7 Objects in row 24.143
E.8 Limits for global enhancement data .143
E.9 Selection of national option sub-sets.143
E.10 Characters including diacritical marks.143
E.11 Invocation of default objects.144
Annex F (informative): Transmission aspects.145
F.1 Cycle Times.145
F.1.1 Serial transmissions.145
F.1.2 Parallel transmissions.145
F.1.3 Complex systems .145
F.2 Interrupted pages .145
F.3 Packets M/29.145
F.4 Allocation of Teletext packets to VBI lines .145
F.5 Use of lines 22 and 335.145
F.6 Teletext transmissions outside of the VBI.145
Annex G (informative): Decoding aspects.147
G.1 Mixed mode operation of decoders.147
G.2 Character displays.147
G.3 Behaviour of display attributes .147
G.3.1 Start Box and End Box.147
G.3.2 Separated Mosaic Graphics .147

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ETS 300 706: May 1997
G.3.3 Hold Mosaics, Release Mosaics and Separated Mosaic Graphics. 147
G.4 Minimum decoder configurations. 148
Annex H (informative): Code of Practice for navigation via FLOF. 149
H.1 Objectives. 149
H.2 Packets with Y = 27 for automatic page acquisition . 149
H.2.1 Coloured keys - prompt mode. 149
H.2.2 Link address number 4. 149
H.2.3 Link address number 5. 149
H.2.4 Link Control Byte . 149
H.2.5 Basic page check word . 149
H.3 Packets with Y = 24 . 150
H.4 Fall-back conditions. 150
H.4.1 No packet 8/30 . 150
H.4.2 No packet with Y = 27 and no packet with Y = 24. 150
H.4.3 Packet with Y = 27 but no packet with Y = 24 . 150
H.4.4 Packet with Y = 24 included, other than for prompts in conformity with this Code of
Practice . 150
Annex I (informative): Navigation via Table Of Pages (TOP) . 151
I.1 Objectives. 151
I.2 Main principles. 151
I.2.1 User-controlled selection of pages. 151
I.2.2 Direct page access. 152
I.2.3 Additional features. 152
Annex J (informative): Magazine Inventory Pages (MIP). 153
Annex K (informative): VCR programming and control via Teletext. 155
Annex L (informative): Use of Teletext Data for Automatic Channel Installation . 156
Annex M (informative): Data transmission via Teletext. 157
Annex N (informative): Data broadcasting services . 158
N.1 Electronic Programme Guide (EPG) . 158
Annex O (informative): Relationship to earlier specifications. 159
Annex P (informative): Non-Teletext signals in the VBI. 160
Annex Q (informative): Bibliography . 161
History. 162

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ETS 300 706: May 1997
Foreword
This European Telecommunication Standard (ETS) has been produced by the Joint Technical Committee
(JTC) of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique
(CENELEC) and the European Telecommunications Standards Institute (ETSI).
NOTE: The EBU/ETSI JTC was established in 1990 to co-ordinate the drafting of ETSs in the
specific field of broadcasting and related fields. Since 1995 the JTC became a tripartite
body by including in the Memorandum of Understanding also CENELEC, which is
responsible for the standardization of radio and television receivers.
The EBU is a professional association of broadcasting organizations whose work
includes the co-ordination of its Members' activities in the technical, legal, programme-
making and programme-exchange domains. The EBU has Active Members in about
60 countries in the European Broadcasting Area; its headquarters is in Geneva *.
* European Broadcasting Union
Case Postale 67
CH-1218 GRAND SACONNEX (Geneva)
Switzerland
Tel: [phone]
Fax: [phone]
Transposition dates
Date of adoption: 7 March 1997
Date of latest announcement of this ETS (doa): 31 August 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 28 February 1998
Date of withdrawal of any conflicting National Standard (dow): 28 February 1998

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ETS 300 706: May 1997
1 Scope
This European Telecommunication Standard (ETS) defines the application of CCIR Teletext System B to
CCIR 625 Line 50 field Television Systems B, D, G, H, I, K and L. The System is optimised for broadcast
media using cable, terrestrial and satellite transmission and the associated service and product
environment. Reliable reception of data is ensured, since there is a good match between the service area
defined for vision and sound reception and that provided for Teletext data broadcasting.
The data is organized in a manner optimum for broadcast media by using the rigid timing framework of the
television signal. When multiplexed with a video waveform, this permits a fixed relationship to be provided
between the data bytes on a television signal data line and locations in the decoder memory. Using this
relationship, error identification and correction are available, matched to the statistical occurrence of bit
errors. Critical control data and addressing information are protected by Hamming coding. Basic data is
protected by using parity checks.
Teletext data packets are normally grouped together to form "pages" of information, although some have
a "stand-alone" function. The range of presentation and application features are arranged to be downward
compatible. This permits initial services to be defined and existing services to be upgraded, without
rendering obsolete equipment already in the field.
Four presentation Levels are defined:
Level 1: - Alphamosaic characters
- spacing attributes
- fixed colour palette
- 24 rows of 40 columns
Level 1.5: - Extends the character repertoire
Level 2.5: - Extends the language repertoire
- increases the colour palette with re-definable colours
- introduces non-spacing attributes
- allows a number of simple re-definable characters
- provides side panels for additional text or graphics
Level 3.5: - Extends the number of re-definable characters and their complexity
- introduces different font styles and proportional spacing
Levels 2.5 and 3.5 are intended to replace Levels 2 and 3 respectively as defined in earlier specifications.
The new Levels offer more display features and can be transmitted more efficiently. Level 1.5 has evolved
in the field due to the language requirements in certain countries and is documented here for the first time.
The facility to invoke the presentation of characters of any writing system or language, or a mixture of
such systems is included. This ETS includes the coding for Arabic, Cyrillic, Greek, Hebrew and Latin
alphabets. Where appropriate the character repertoires and coding structures of the ISO are used.
In addition to the basic text and graphics display presentation, a wide range of other applications can be
supported. Protocols for user-friendly navigation techniques also exist. These topics are covered in the
reference documents and the other documents listed in annex Q.

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ETS 300 706: May 1997
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ETS 300 231: "Television Systems; Specification of the domestic video
Programme Delivery Control system (PDC)".
[2] ETS 300 708: "Data transmission within Teletext".
[3] ETS 300 707: "Electronic Programme Guide (EPG); Protocol for a TV-Guide
using electronic data transmission".
[4] ISO 6937/2 (1983) + Addendum 1 (1989): "Information processing - Coded
character sets for text communication - Part 2: Latin alphabet and non-alphabet
graphic characters".
[5] ETR 287: "Code of Practice for Enhanced Teletext".
[6] TR 101 231: "Register of Country and Network Identification codes for Teletext
based systems".
[7] prTR 101 233: "Television systems; Code of Practice for allocation of services in
the Vertical Blanking Interval (VBI)."
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of this ETS, the following definitions apply:
Active position: The active position is defined by row and column co-ordinates and is a reference to a
screen location within the normal page area. It is used to position enhancement data when overwriting a
basic Level 1 Teletext page.
Bit numbering within bytes: The bits of Teletext data bytes are numbered 1 to 8 (LSB to MSB).
Designation code: A data byte used as a packet address extender. It is used to differentiate between
instances of the packet X/Y/n. The designation code is the byte after the magazine and packet address
and is 8/4 Hamming coded.
Magazine number 8: A packet with a magazine value of 0 is referred to as belonging to magazine 8.
Packet: A sequence of data bits transmitted as a single entity on one TV line. The packet includes
elements to establish synchronization within a decoder plus address and information data bits.
Page address: A page address is shown as page number plus sub-code - M Pt Pu: S4 S3 S2 S1
Page Format - CA: A method of data broadcasting defined in ETS 300 708 [2] clause 5 where the data is
transmitted within Teletext pages. Conditional access and scrambling techniques may be used at the
transport layer.
Page Format - Clear: A method of data broadcasting defined in ETS 300 708 [2] clause 4 where the data
is transmitted within Teletext pages but without the possibility of applying conditional access and
scrambling techniques at the transport layer.

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ETS 300 706: May 1997
Page number: A page number is shown as M Pt Pu, where
M = magazine (range 1 - 8)
Pt = page number tens (range 0 - F)
Pu = page number units (range 0 - F)
Prefix: The sequence of clock run-in, framing code and packet address bytes at the start of every Teletext
packet.
Sub-code: A page sub-code is shown as S4 S3 S2 S1, where
S1 = LSB digit (range 0 - F)
S2 = LSB+1 digit (range 0 - 7)
S3 = LSB+2 digit (range 0 - F)
S4 = MSB digit (range 0 - 3)
Time filling headers: Page header
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