W3C Architecture Domain

"Television and the Web" Interest Group Charter

This charter is written in accordance with section 3.2.2 of the W3C Process.

Table of Contents

Mission Statement

W3C held a Workshop on "Television and the Web" (TVWeb) in June 1998. At this workshop, it became evident that different standardization bodies and vendors will make a significant effort over the next year to integrate Web and television technologies. This enables applications such as browsing the Web using a television set, or using Web content formats to annotate a television broadcast, making the television more interactive.

Historically, television standards tend to differ between regions of the world, and are issued by regional standardization bodies. Thus, a television receiver purchased in one part of the world is not necessarily usable in another part of the world. This is in stark contrast with the technology used by the Word Wide Web. Any Web user can read all Web pages, no matter where in the world they are stored, because the Web uses the same technology all over the world. The integration of TV and the Web should not lead to a fragmentation of the Web, even though such fragmentation is typical in the television world.

The World Wide Web Consortium is an international organisation, with branches in America, Asia and Europe. It is therefore well-positioned to avoid the regional solutions typical of TV standards when it comes to integrating the Web and television.

The participants at the "TVWeb" workshop expressed interest in W3C taking a more active role in the ongoing efforts of TV/Web integration, particularly since these efforts concern subsetting or extending some of the core W3C technologies (HTML, CSS, XML, ...).

This Interest Group has three missions:

  1. It serves as a pool of experts on TV/Web integration, some of which will participate in the W3C working groups relevant to TV/Web integration.
  2. It serves as a coordination body with the TV-specific regional standardization groups working on TV/Web integration.
  3. It will prepare and review documents related to TV/Web integration.
    These documents should be produced quickly (typically within two months). Their purpose is mainly to point out specific requirements in the area of TV/Web integration, and to give rough ideas on how these requirements can be resolved.
    It is not the main purpose of this Interest Group (or any W3C Interest Group, for that matter) to produce specifications. Production of specifications and W3C recommendations is reserved to W3C working groups (see definition of interest group in W3C process).

Scope and Deliverables

The W3C process defines the general scope of an interest group as follows:

"An Interest Group brings together people who wish to evaluate potential Web technologies and policies. An Interest Group does not have the goals of a Working Group -- development of specifications or code. Instead, it serves as a forum to explore cooperation and exchange ideas.

It is quite possible that an Interest Group's studies will lead to the creation of a Working Group, but this may not be known in advance nor is it guaranteed."

The following list of topics and deliverables is based on discussions at the W3C workshop on "Television and the Web". Additional topics may be added during the lifetime of the Interest Group, if there is enough interest.

Deliverables that are documents must fulfil the following conditions:

Coordination with TV standardization bodies

A first important mission of the TVWeb IG is to coordinate with efforts in other TV standardization groups, avoiding duplication of effort and fragmentation of the Web by incompatible standards.

Deliverable:  List of contact persons to other standardization bodies

To fulfill its goal as a forum for coordination and exchange between TV standardization bodies and W3C, the TV IG should produce and maintain a list of contact persons to relevant organisations, e.g. the ones listed in the section "external groups". A contact person will inform the IG (or the IG chair, if confidentiality requires this) of relevant event in the group she is responsible for, such as the publication of a new Web-related specification, a Web-related meeting etc. The contact person will also inform the external group about relevant W3C events, if W3C's confidentiality requirements allow this.

TV-specific use of HTML and CSS

In the television community, there is a desire to adapt certain W3C specifications before using them in TVWeb applications. This means that only a limited set of features of these specifications may be supported, or that new, TV-specific features are added to these specifications. This requires that some members of the Interest Group represent TV-specific interests in the HTML- and CSS working groups.

Deliverable 1: Document on TV-specific requirements to HTML

These additions may take the form of a specialised tagset within the framework set by the W3C working group on HTML.


  1. Minimal Membership Commitment: Two authors for the document must sign up.
  2. Minimal Membership Commitment: At least one member employee must sign up as representative to the HTML WG.

Deliverable 2:  Document on   TV-specific requirements on CSS


  1. Minimal Membership Commitment: Two authors for the document must sign up.
  2. Minimal Membership Commitment: At least one member employee must sign up as representative to the CSS WG.

"tv" URL-scheme

A new URL scheme is needed to address content that is broadcast in a TV channel.

Deliverable: Document on "tv" URL-scheme

This requires to study and, potentially, harmonize existing proposals for tv-related URLs, such as the following:

The review must take the results URL registration Working Group in the IETF of the into account. The idea is to review the existing approaches within the W3C TV IG, after which they will be proposed to the IETF, in order to become standards-tracks RFCs, similar to other URL schemes (mailto:, ...).


  1. For the W3C TV IG to take on this issue, the organisations or authors currently of tv-related URL specifications must make at least a request that they should be reviewed by the W3C, and preferably submit them as documents.
  2. Minimal Membership Commitment: Two authors for the document must sign up.

Optional Work Items

The following work items have been suggested at the W3C workshop on "Television and the Web". It depends on whether there is sufficient interest and commitment within the group to pursue them:

Authoring guidelines
These authoring guidelines should describe in layman-terms how to use HTML and CSS so that you can do "author-once - display anywhere", instead of having to redevelop every site several times for different display environments.
Default style sheet for TV
A television set has different display characteristics than an PC. Consequently, the default presentation rules for HTML on PCs cannot be transformed without modification into the TV world. But TVs can also benefit from the existence of a well-defined default style sheet. This requires analysing existing products, and distilling common rules used in these products for displaying HTML on a TV screen. The result should be a document produced by the TV IG, documenting existing practice and recommending (but not necessarily standardizing) empirical default settings to implementors of new products. A first draft of a default style sheet is already available.
Metadata description/transport
There is an opportunity to harmonize work in the television community on MPEG-7 with W3C's RDF work. This required submitting RDF to a call for proposals by RDF.
Interaction mechanisms for continuous media
This concerns issues such as starting/stopping/fast forwarding an video/audio stream, but also "interesting linking behavior". The TV IG should come up with an initial draft that is then passed to a Working Group in the DOM activity.
Device profiles
To avoid that the set-top box tries to display content with features that it does not support, a mechanism for describing device profiles is needed. This should be coordinated with the techniques used by the Mobile IG , and take into account the results of the IETF Working Group on Content Negotiation
Guidelines for re-processing color palettes
Guidelines on how to translate between different color palettes of different devices will help content authors to know what color transformations will take place.
Transition effects in CSS
CSS appears to be the right vehicle to express an enumerated set of transition effects, as it is concerned with presentation. Another possibility is expressing transition effects in SMIL, since this language takes into account temporal aspects. The TV IG should come up with a document listing a set of "standard" transition effects, and communicate it to the CSS working group and the former SMIL working group.
Accurate layout control/Accurate Timing Control
Accurate layout and timing control are important issues when integrating Web content with television content. The interest group should clarify in how far the existing mechanisms in the W3C recommendations CSS and SMIL are insufficient to achieve these goals. If missing functionality is identified, it should be integrated into future versions of these W3C recommendations.
API to VCR controls (and other devices)
A Web page can provide functionality to control devices such as a VCR used to register a television program. This requires a standardized API.
Flexible temporal synchronization using CSS
Expressing temporal synchronization in CSS allows reuse of certain kinds of Web content. This effort should be aligned with the SMIL approach to synchronization. Properties should be added to CSS that allow expressing temporal aspects of presenting information. These properties should be aligned with the SMIL attributes and time model.
Unidirectional HTTP
Unidirectional HTTP as proposed by the Advanced Television Enhancement Forum (ATVEF) mainly defines a subset of headers used in http responses that should be transmitted together with the web-content in the television signal.


This Interest Group is scheduled for one year, from end of September 1998 to end of September 1999.

Success Criteria

The Interest Group has fulfilled its mission if it succeeds in unifying the efforts of different TV standardization bodies for Web integration, and in avoiding a fragmentation of the Web.

Release Policy

By defaults, all documents developed by the IG are public.

Documents have a date at which they will be declared stable. Any remaining issues at this date will be described in the document, and not delay of making the document stable.

Documents that are prepared as deliverables of the Interest Group will be published on the W3C site.

Documents that do not fulfill the criterion above (e.g. longer documents describing specific technical solutions brought up by one member of the IG) have to be submitted to W3C before they can be published on the W3C site.


Milestones are only set for the first months of this Interest Group. Additional milestones may be added when the group decides to take on additional work items.

20 August, 1998:
Interest Group Proposal/Call for Participation
17 September, 1998:
Deadline to submit AC Votes on Proposal
6 October, 1998:
Director's Decision
Start work on tv-URL scheme
Start work on document on TV-specific requirements to HTML
Start work on document on TV-specific requirements to CSS
13 October, 1998
Appoint representative(s) of TV IG to HTML WG
Appoint representative(s) of TV IG to CSS WG
Publish first list of contact persons to external groups
10 November, 1998
First stable document of TV-specific requirements to CSS
First stable document of TV-specific requirements to HTML
30 November, 1998
Submit stable document on tv-URL scheme to IETF (for December IETF meeting (Dec 7 - 11))
Pre-register RDF in MPEG-7 "Call for Proposals" (deadline: 1 December)
15 January
Submit RDF as response to MPEG-7 "Call for Proposals" (deadline: 1 February)
30 September, 1999:
Interest Group Completion


To facilitate cooperation with the TV community, this charter and the archives of the Group's mailing list (www-tv@w3.org) will be open to the public.

Relationship with other W3C Activities

The TVWeb IG will have to into account technologies developed by other groups within W3C, and to advise them about the requirements of television. As of today, the following ongoing W3C activities are concerned:

Coordination with External Groups

The following is a list of groups that are known or presumed to be working on or interested in integration of Television and Web technology, with pointers to the respective projects.

Communication Mechanisms

The participants of the "Television and the Web" IG communicate via a public, archived mailing list, www-tv@w3.org (archive).


W3C Members

Official membership in the IG is open to all employees of W3C member organizations. There are no minimum requirements, neither in terms of expertise, not in terms of time dedicated to the group. If the IG decides to prepare a document, the editor(s) will be asked to commit to a certain percentage of their time.

Non W3C Members

Employees of organisations that are currently not W3C members can participate in the discussions on the IG's mailing list www-tv@w3.org (archive).

W3C Team

The TVWeb IG will be chaired by a W3C Team member (Philipp Hoschka). He will also be W3C staff contact. Resources of additional W3C team members will be required for some of the deliverables  (review of "tv" URL schemes, TV-specific subsets of HTML and CSS, Authoring guidelines etc.), should the conditions for starting these deliverables be met .

Philipp Hoschka (ph@w3.org)