1、BRITISH STANDARDBS EN 62298-4:2005TeleWeb application Part 4: Hyperteletext profileThe European Standard EN 62298-4:2005 has the status of a British StandardICS 33.160.25; 35.240.99g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g3
2、6g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 62298-4:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2006 BSI 2006ISBN 0 580 48296 0National forewordThis British Standard is the official En
3、glish language version of EN 62298-4:2005. It is identical with IEC 62298-4:2005.The UK participation in its preparation was entrusted to Technical Committee EPL/100, Audio, video and multimedia systems, which has the responsibility to: aid enquirers to understand the text; present to the responsibl
4、e international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.A list of organizations represented on this committee can be obtained on request to i
5、ts secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic
6、Catalogue or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis docume
7、nt comprises a front cover, an inside front cover, the EN title page, pages 2 to 37 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARD EN 62298-4 NORME EUROPENNE E
8、UROPISCHE NORM December 2005 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2005 CENELEC - All rights of exploitation in any fo
9、rm and by any means reserved worldwide for CENELEC members. Ref. No. EN 62298-4:2005 E ICS 33.160.25; 35.240.99 English version TeleWeb application Part 4: Hyperteletext profile (IEC 62298-4:2005) Application TeleWeb Partie 4: Profil hypertltexte (CEI 62298-4:2005) TeleWeb-Anwendung Teil 4: Hypertel
10、etext-Profil (IEC 62298-4:2005) This European Standard was approved by CENELEC on 2005-11-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to
11、-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in two official versions (English, German). A version in any other language made by translation under the re
12、sponsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, H
13、ungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Foreword The text of document 100/1000/FDIS, future edition 1 of IEC 62298-4, prepared by IEC TC 100, Audio, video and mult
14、imedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62298-4 on 2005-11-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement
15、 (dop) 2006-08-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2008-11-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62298-4:2005 was approved by CENELEC as a European Standard without any modi
16、fication. _ EN 62298-4:2005 2 3 EN 62298-4:2005 CONTENTS INTRODUCTION.4 1 Scope 5 2 Normative references .5 3 Terms, definitions and abbreviations .6 3.1 Terms and definitions 6 3.2 Abbreviations 6 4 Mandatory Superteletext profile features .7 4.1 Font issues7 4.2 Dithering .7 4.3 TeleWeb EPG7 4.4 C
17、ross-linking between services7 4.5 Memory requirements 7 5 General display-related extensions .8 5.1 Downloadable fonts .8 5.2 Support for non-Latin alphabets .8 5.3 Page size and page scrolling .8 6 Hypertext extensions 8 6.1 HTML frames.9 6.2 Forms15 6.3 Internationalization 24 6.4 tag 25 6.5 tag
18、.26 7 User profiles.28 8 ISP interface 28 8.1 The ISP special function 28 8.2 Network congestion control30 9 Device ID (OPTIONAL) .32 10 Cross-linking and context-switching 32 10.1 Additional URI schemes.32 11 Audio clips (OPTIONAL) .32 12 Style sheets .33 13 Scripting.33 13.1 ECMAScript.33 13.2 tag
19、 .34 13.3 Events.34 13.4 Document object model (DOM) 34 14 Additional content types34 14.1 Graphic files34 14.2 Text files .34 Annex A (informative) Security considerations.35 Annex ZA (normative) Normative references to international publications with their corresponding European publications36 EN
20、62298-4:2005 4 INTRODUCTION The aim of TeleWeb is to deliver World Wide Web-style content to the living room TV to give the viewer an enhanced television experience. A TeleWeb service broadcasts data files containing text and high-definition graphics to suitable decoders. The data transmitted can be
21、 closely linked to events within the accompanying TV programmes, or can be more general in nature to emulate a traditional, but higher definition, super teletext service. Different profiles are defined. It is the intention that TV-based decoders can be implemented in a cost-effective manner without
22、recourse to the technology normally associated with personal computers. In part, this is achieved by limiting the number of different types of multimedia data that can be used within a service. By careful design of the user interface, decoder manufacturers will be able to offer easy-to-use equipment
23、 for accessing TeleWeb services without requiring the consumer to be computer-literate. In addition, they will be able to customize their products to differentiate them from those of their competitors. This document specifies the TeleWeb Hyperteletext profile and focuses on the presentation layer es
24、pecially the implementation of TeleWeb HTML and scripting. It further defines the graphical requirements like fonts and the content formats used. 5 EN 62298-4:2005 TELEWEB APPLICATION Part 4: Hyperteletext profile 1 Scope This part of IEC 62298 specifies the TeleWeb Hyperteletext profile that allows
25、 Web-style text and graphics to be displayed on suitable decoders. A TeleWeb service comprises multimedia data files whose format and attributes are defined by this specification. This standard is backwards compatible with IEC 62298-3 and extends it with features like scripting and style-sheets. The
26、 graphical capability is extended with features like frames and forms. For information regarding general information and the transport layer, refer to IEC 62298-1 and IEC 62298-2. 2 Normative references The following referenced documents are indispensable for the application of this document. For da
27、ted references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 62298-1: TeleWeb application Part 1: General description IEC 62298-2: TeleWeb application Part 2: Delivery methods IEC 62298-3: TeleWeb applic
28、ation Part 3: Superteletext profile ISO/IEC 11172-3:1993, Information technology Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s Part 3: Audio ISO/IEC 14496-3:2001, Information technology Coding of audio-visual objects Part 3: Audio ISO 8601:2004, D
29、ata elements and interchange formats Information interchange Representation of dates and times ETSI EN 300 468, Digital Video Broadcasting (DVB) Specification for Service Information (SI) in DVB systems W3C Recommendation, Cascading Style Sheets, level 1 (CSS1) W3C Recommendation, HyperText Markup L
30、anguage, version 4.0 SMPTE 363M:2002, Television Declarative Data Essence Content Level 1 SMPTE 366M:2002, Television Document Object Model Level 0 (DOM-0) and Related Object Environment IETF RFC 2046, Multipurpose Internet Mail Extensions (MIME) Part Two: Media types PFR v1.2, Bitstream Inc. Coding
31、 of Outline Fonts PFR Specification, version 1.2 EN 62298-4:2005 6 3 Terms, definitions and abbreviations 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 button part of the user interface that enables the viewer to select a page or trigge
32、r an event, etc. It may not necessarily exist as a physical button on a remote control handset 3.1.2 CDATA character data in an HTML document. Character entities and HTML mark-up is not recognized 3.1.3 conditional access (CA) mechanism by which user access to service components can be restricted 3.
33、1.4 PCDATA parsed character data in an HTML document. Character entities (numeric and named entities) as well as HTML mark-up is recognized in the data 3.2 Abbreviations CATV Cable TV CRC Cyclic Redundancy Check DECT Digital European Cordless Telecommunications DTD Document Type Definition DVB Digit
34、al Video Broadcasting GIF Graphics Interchange Format GSM Global System for Mobile Communication HTML Hyper Text Mark-up Language HTTP Hypertext Transfer Protocol HTTPS Hypertext Transfer Protocol Security IDL Interface Definition Language ISDN Integrated Services Digital Network LMDS Local Multipoi
35、nt Distribution Service MJD Modified Julian Date PSTN Plain Old Telephone System RFC Internet Request for Comment SMATV Satellite Master Antenna Television URI Uniform Resource Identifier URL Uniform Resource Locator UTC Universal Time Coordinated WWW World Wide Web 7 EN 62298-4:2005 4 Mandatory Sup
36、erteletext profile features This clause identifies the features listed as optional in IEC 62298-3, which are made mandatory for receivers conforming to this specification. All other optional features of IEC 62298-3 remain optional in this profile. 4.1 Font issues Support of “bold“, “italics“ and “bo
37、ld italics“ is mandatory for all Latin fonts whether fixed or proportional, resident or downloaded. 4.2 Dithering If the content is authored without reference to the TeleWeb default colour palette defined in IEC 62298-3, and a decoder is unable to reproduce a colour faithfully, the decoder shall emp
38、loy a dithering algorithm and shall not use colour-matching techniques. NOTE Examples of such algorithms are ordered dithering or error-diffusion algorithms (for example, Floyd-Steinberg). 4.3 TeleWeb EPG A TeleWeb EPG as described in IEC 62298-3, Clause 5, is mandatory in the decoder. 4.4 Cross-lin
39、king between services Cross-linking refers to the ability to navigate between different TeleWeb services or to Teletext services. A decoder shall support cross-linking between any TeleWeb services through absolute TeleWeb URLs defined in IEC 62298-3. It is up to the device to decide if user activati
40、on of a cross-link will result in a channel switch. It is good practice to inform the user of the consequences of a possible re-tuning. The usefulness of cross-linking is ultimately a question of resources in the device. A larger memory capacity and an extra tuner will significantly enhance the cros
41、s-linking capability of the device and therefore the user experience. In a DVB-compliant device cross-linking is more useful than in an analogue device, since cross-linking within the same multiplex does not result in re-tuning. The same holds for cross-linking between short and full TeleWeb service
42、s of the same channel. Code of Practice: if the service is not available in the memory, the decoder can try to retrieve the content through the return channel. 4.5 Memory requirements The broadcast size for a full service according to this profile shall not exceed 9,8 Mbytes, including up to 4,9 Mby
43、tes of Superteletext profile data. The broadcast size for a short service according to this profile shall not exceed 0,2 Mbytes, including up to 0,1 Mbytes of Superteletext profile data. The maximum transmission cycle time for the short service shall remain at 60 s. EN 62298-4:2005 8 A device accord
44、ing to this profile shall support at least one full TeleWeb service and one short TeleWeb service providing storage for the specified broadcast sizes (9,8 + 0,2 Mbytes). If a full service and/or a short service exceed the indicated cache sizes, the behaviour of the decoder is not covered by this spe
45、cification. A device according to this profile must provide some persistent storage to store at least the following parameters: user group Id, decoder configuration data, user profiles, ISP information. Decoder configuration data might include channel presets, preferred TeleWeb provider, etc. NOTE T
46、he term broadcast size refers to the data transmitted and may include compressed data. 5 General display-related extensions 5.1 Downloadable fonts In order to support fonts other than the resident one(s) and character sets other than Latin-1, this profile shall support downloadable fonts. Downloadab
47、le fonts can also be used to gain access to true bold or italic styles. The requirements are as follows. Fonts shall be bitmap fonts. Unicode character encoding shall be used. Replacing a built-in font with a downloaded font shall be supported. Font data shall not be encrypted. Font data may be comp
48、ressed through methods allowed by this profile. Only the used characters shall be downloaded (provided by the service provider). Supplementing a built-in or downloaded font shall be supported. Downloadable fonts shall use the file format specified in PFR V1.2. 5.2 Support for non-Latin alphabets HTM
49、L documents can specify the character set to use for rendering them, by using the META tag. See 6.3.1. This data shall be copied to the http header. 5.3 Page size and page scrolling Horizontal scrolling shall not be supported. Vertical scrolling must be limited to 1 440 pixels vertically (3 480). The choice to limit vertical scrolling to three pages greatly simplifies its implementation. The implementation details of vertical scrolling is at the discretion of the decode
