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*/ This version: http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/ Latest version: http://www.w3.org/TR/ttaf1-req/ Previous version: http://www.w3.org/TR/2003/WD-tt-af-1-0-req-20030915/ Editor: Glenn Adams, Extensible Formatting Systems, Inc. <[email protected]> Copyright W3C ® MIT ERCIM Keio liability trademark document use This document specifies usage scenarios and requirements for a timed text authoring format. A timed text authoring format is a content type that represents timed text media for the purpose of interchange among authoring systems. Timed text is textual information that is intrinsically or extrinsically associated with timing information. This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index This Working Group Note is the third publication of the Timed Text (TT) Authoring Format 1.0 Use Cases and Requirements, and represents an editorial revision from the previous version in order to transition from Working Draft to Working Group Note. This document has been produced by the Timed Text Working Group Synchronized Multimedia Activity Comments on this document should be sent to the email list [email protected] list archives [email protected] subscribe Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress. As of this publication, the Working Group does not expect this document to become a W3C Recommendation, and therefore it has no associated W3C Patent Policy This document was produced by a group operating under the 24 January 2002 CPP W3C Patent Policy Transition Procedure public list of any patent disclosures Essential Claim(s) section 6 of the W3C Patent Policy 1 Introduction Motivation System Model Definitions Acronyms Terminology Notations Use Case Scenarios Requirements General Content Styling Timing Animation Metadata A References Other References Acknowledgments This document specifies usage scenarios and requirements for a timed text authoring format. A timed text authoring format is a content type that represents timed text media for the purpose of interchange among authoring systems. Timed text is textual information that is intrinsically or extrinsically associated with timing information. Note: This document incorporates requirements regarding stylistic and timing functionality that range from simple to relatively complex. It is expected that the use of this functionality will be partitioned into one or more profiles represented by document types of increasing complexity. It is not expected that every authoring system or ultimate consumer of timed text content will support all of this functionality. A principal motivation for the development of a common authoring format for timed text is the lack of a standard content format that supports the representation and interchange of textual information which is synchronized with other media elements or which serves as a synchronization master itself. Popular proprietary multimedia systems and their corresponding player components have defined distinct timed text formats for each proprietary use. As a consequence there is no common authoring format that serves as a portable interchange format between such systems. A goal of the present work is to define such a portable interchange format to ease the burden of authoring tool developers and users as well as enhance portability of timed text content. A side effect of the development and deployment of a common timed text authoring format is that it simplifies the creation and distribution of synchronized text for use with a multitude of devices, such as multimedia players, caption, subtitle, and teletext encoders and decoders, character generators, LED displays, and other text display devices. The uses cases and requirements specified in this document are based upon a system model, depicted in Figure 1 – System Model Figure 1 – System Model Note: In the figure depicted above, the acronym DFXP Note: This system model does not preclude the timed text authoring format from being used as a distribution format in its own right. TT Timed Text TT AS Timed Text Authoring System TT AF Timed Text Authoring Format TT WG Timed Text Working Group Timed Text Textual information that is intrinsically or extrinsically associated with timing information. Timed Text Authoring Format A content type that represents timed text media for the purpose of interchange among authoring systems. Timed Text Authoring System A content authoring system capable of importing and exporting timed text authoring format content. The following notations are employed in this document: SXXX XXX RXXX XXX RX9X X9X NXXX XXX A caption service provider needs a common content authoring format by means of which a textual expression of audio information may be associated with such audio information in a time synchronized manner. Note: In the context of captioning an aggregate audio/video service, both audio and caption information are typically synchronized to the video track as the timebase master. A subtitle service provider needs a common content authoring format by means of which a textual expression of the original or a translation of the original natural language (speech) audio information may be associated with such audio information in a time synchronized manner. Note: In the context of subtitling an aggregate audio/video service, both audio and subtitle information are typically synchronized to the video track as the timebase master. Note: The distinction between captioning subtitling In the absence of captioning information, subtitling information may also be used by deaf and hard of hearing users, provided that it is available in the original natural language. Note: Some user communities use the term subtitling A description service provider needs a common content authoring format in which a textual description of video information or a textual expression of an audio description of video information may be associated with such video information in a time synchronized manner. Note: When a description is rendered by an audio track, such a description is commonly referred to as an Audio Description Note: In the use of aural forms of visual description, it may be the case that the duration of an aural form of a description exceeds the duration of the visual information being described. In a presentation device, this necessitates manual or automatic pausing of the video track in order to fully render the aural form of description. It is likely that similar modes of presentation will be required for timed text representations of video descriptions. Note: This use case scenario is not intended to serve as a general form of metadata A generic timed text service provider needs a common content authoring format in which textual information can be presented in a time synchronized manner. Note: In the context of using a generic timed text service, timed text information serves as the timebase master, with which other possible timed media may be associated. Note: Examples of the use of generic timed text include (but are not limited to): marquee signs, timed text oriented presentations, scrolling text presentation, etc. The TT AF specification(s) shall be authored using XML and XSL Stylesheets based on [XML Spec] The TT AF specification(s) shall be defined in a modular manner that logically separates significant areas of functionality to as great extent as is practical. The TT AF specification(s) shall be organized in such a manner as to separate the following aspects: TT Framework TT Core Vocabulary TT Core Document Types TT Extension Vocabulary(ies) TT Extension Document Type(s) The TT AF specification(s) shall be defined in such a manner that core functionality is logically separated from peripheral functionality. The TT AF specification(s) shall be defined in such a manner that core functionality can evolve over time, e.g., by the specification of multiple levels (or versions) of core functionality. The TT AF specification(s) shall be defined in such a manner that core functionality be specified soley by the TT WG or, in the event that the TT WG is terminated, its successors within the W3C. Note: It is assumed that one or more appropriate namespace mechanisms will be used to segregate core functionality defined or adopted in the TT AF from peripheral functionality defined or adopted by clients of the TT AF. The TT AF specification(s) shall be defined in such a manner that for every item in the TT AF core vocabulary, there shall be at least one TT AF core document type that makes use of that item, i.e., there exists a surjection from the set of TT AF core document types to the set of TT AF vocabulary items referenced by those document types. Note: The TT AF specification(s) may define standardized peripheral vocabulary that is not referenced by any TT AF core document type. The TT AF specification(s) shall be defined in such a manner that peripheral functionality can evolve over time, e.g., by the future specification of one or more peripheral functionality modules. The TT AF specification(s) shall be defined in such a manner that peripheral functionality need not be specified by the TT WG or the W3C, but may be specified by other W3C WGs as well as non-W3C clients of the TT AF. The TT AF shall be capable of being transformed, without undue complexity, into one or more legacy timed text content formats, e.g., [3GPP] [QText] [RealText] [SAMI] Note: The above list of potential target timed text content formats is strictly informative, and is not intended to be exhuastive. The TT AF shall be capable of being transformed into an idealized streamable representation format. Note: It is not required that an idealized streamable representation format be defined by the TT AF specification(s); however, the definition of such a format may be the subject of future activities by the TT WG. Note: It is intended that existing closed captioning and subtitle streaming formats used by analog and digital television services as well as timed text used in the context of streaming audio and motion video formats be potentially targeted by one or more transformations of the TT AF. These formats include [EIA-608B] [EIA-708B] [EN 300 706] [EN 300 743] The TT AF shall include the following accessibility related features: Support for a mechanism to explicitly associate Equivalent Alternatives [WAI XML AG] Support for Content Rendering Adaption [WAI SMIL AG] Conditional Content Use of a default text vocabulary that satisfies guideline 2 of [WAI XML AG] Ability to extend or replace the default text vocabulary with other XML dialects to represent the textual information of the TT presentation. See also Intrinsic and Extrinsic Text Content Support for explicit definition of a Navigational Structure [WAI SMIL AG] The TT AF specification(s) shall be defined in such a manner as to require a TT AS to adhere to all applicable aspects of [ATAG 1.0] The TT AF shall be capable of being created and modified using a plain text editor, e.g., emacs, vi, etc. The TT AF shall be capable of representing content of different natural languages, where the content of distinct languages may be segregated into separate document instances or may be integrated into a single document instance. The TT AF shall be capable of representing content of at least those specific natural languages that may be represented with [Unicode 3.2] The TT AF shall be capable of associating natural language binding information with plain text information at the granularity of a single coded character. The TT AF shall be capable of representing every coded character available in [Unicode 3.2] [ASCII (ANSI X3.4)] Note: This requirement facilitates the entry and editing of characters in a TT AF document instance that would otherwise not be permitted due to lack of an appropriate character input method or lack of support for a non-ASCII character encoding system. It is assumed that every TT AS will provide a means to enter and edit TT AF document instances represented in the ASCII character set. The TT AF shall be capable of expressing text content intrinsically within a TT AF document instance, extrinsically by referencing from a TT AF document instance to text content in one or more external resources, or in any combination of these two modes. The TT AF shall be capable of associating structural markup with intrinsic and extrinsic text content, where such markup may denote either or both semantic (functional) and presentational (formal) properties of the content. Note: In this context, presentational The TT AF shall be capable of expressing conditional content, where each alternative content choice is governed by one or more test expressions such that exactly one or zero content choice is selected when evaluating each choice in a predefined order. The TT AF shall be capable of expressing authorial intention to flow (layout) text content in an idealized, but unspecified user agent. Note: In this context, the concept of flow Note: It is not required that an idealized user agent or behavior of such a user agent be defined by the TT AF specification(s); however, the definition of such a user agent or user agent behavior may be the subject of future activities by the TT WG. The TT AF shall be capable of expressing the following vocabulary as pertains to logical flowed text content: body division paragraph phrase Note: A generic role paragraph division Note: One possible mapping for this vocabulary is to xhtml:body xhtml:div xhtml:p xhtml:span [XHTML 1.0] The TT AF shall be capable of expressing the following vocabulary as pertains to presentational flowed text content: block block container character flow forced line break inline inline container region viewport Note: The items enumerated above are drawn in part from similarly named items defined by [XSL 1.0] Formatting Objects Note: The forced line break character The use of this item in combination with a wrap option nowrap Note: The viewport region [XSL 1.0] fo:simple-page-master fo:region-* The TT AF shall be defined in such a manner that a default relationship between logical and presentational flowed text vocabulary may be assumed as follows: body ⇔ flow division (display: block) ⇔ block container paragraph ⇔ block division (display: inline) ⇔ inline container phrase ⇔ inline Note: Parsed character data ( #PCDATA character The TT AF shall be defined in such a manner that use of logical flowed text vocabulary is separated from use of presentational flowed text vocabulary. Note: It is not required that the TT AF specification(s) define a document type that supports the simultaneous use of both logical and presentational flowed text vocabulary. The TT AF shall be capable of expressing authorial intention to render non-flowed text content in an idealized, but unspecified user agent. Note: In this context, the concept of non-flowed text Note: It is not required that an idealized user agent or behavior of such a user agent be defined by the TT AF specification(s); however, the definition of such a user agent or user agent behavior may be the subject of future activities by the TT WG. The TT AF shall be capable of expressing the following vocabulary as pertains to non-flowed text content: area glyph glyph sequence Note: The glyph and glyph sequence vocabulary items are intended to make direct reference to specific glyphs in specific fonts, having already been transformed from the character domain to the glyph domain. References to glyphs would typically take the form of a glyph identifier or a glyph code. For further information on character to the glyph mapping process, see [CharMod] Units of Visual Rendering The TT AF shall be capable of expressing authorial intention to create a hybrid of flowed and non-flowed text content; however, such an expression may require that these two types of content be segregated at a specific level of granularity. The TT AF shall be capable of expressing simple hyperlinks, where the ending (destination) resource is either the starting (source) resource or an external resource. The TT AF shall be capable of expressing block and inline, embedded graphics of both bitmap and vector or outline formats. If block or inline graphics are used for the purpose of expressing pre-rasterized text in a bitmap format, then the original text that produced such a pre-rasterized form shall also be required to be present in TT AF content. The TT AF shall be capable of expressing block and inline, non-embedded graphics of both bitmap and vector or outline formats, where a graphic is represented by an external resource. If block or inline graphics are used for the purpose of expressing pre-rasterized text in a bitmap format, then the original text that produced such a pre-rasterized form shall also be required to be present in TT AF content. The TT AF shall be capable of expressing embedded fonts of both bitmap and outline formats. The TT AF shall be capable of expressing non-embedded fonts of both bitmap and outline formats, where a font is represented by an external resource. The TT AF shall be capable of associating text content with descriptive information from an appropriate domain of discourse. Note: See [TEI] Base Tag Set for Drama Transcription of Speech The TT AF shall be capable of expressing embedded audio that is intended to be played or rendered in sequence or in parallel with associated text content. Note: The use of embedded audio is intended to support aural cues that may accompany text. The TT AF shall be capable of expressing non-embedded audio that is intended to be played or rendered in sequence or in parallel with associated text content, where the audio content is represented by an external resource. Note: The use of non-embedded audio is intended to support aural cues that may accompany text. The TT AF shall support the use of both [XML 1.0] [XML 1.1] Note: See [XML InfoSet] XML information set The TT AF shall require or recommend adherence to the practices recommended by [Unicode in XML] The TT AF shall support the use of [XLink] The TT AF specification(s) shall be defined in such a manner that the normative validity of markup content be specified in terms of either or both [RELAX NG] [XML Schema Part 1] [XML Schema Part 2] The TT AF shall be capable of inline styling, where inline styling means the inclusion of stylistic presentation information in a TT AF document instance. The TT AF shall be capable of specifying inline styling by means of (1) distinct attributes, (2) a generic attribute, e.g., style The TT AF shall be capable of out-of-line styling, where out-of-line styling means the association of stylistic presentation information with TT AF content via some mechanism external to a TT AF document instance. The TT AF shall be capable of specifying out-of-line styling by means of one or more external stylesheets. The TT AF shall be capable of associating priorities with stylistic presentation information in order to permit the resolution of multiple style specifications that apply to the same content. The TT AF shall be capable of associating the following aural style parameters with timed text content: azimuth cue before, during, after elevation pause before, after pitch pitch range richness speaking mode speech rate stress voice family volume Note: For further information on these style parameters, see [XSL 1.0] Common Aural Properties [CSS Level 2] Note: For further information on the speaking mode speak speak-numeral speak-punctuation [XSL 1.0] The TT AF shall be capable of associating the following visual style parameters with timed text content: absolute position background color baseline alignment point baseline alignment baseline dominance baseline shift bidirectional treatment block progression dimension block scroll amount border before, after, start, end break before, after clear color color profile name display none, block, inline display alignment float font family font size font style font weight height indent start, end inline progression dimension inline scroll amount intrusion-displace line feed treatment line height line stacking strategy line wrapping option opacity origin (top, left) overflow padding before, after, start, end reference orientation relative position space before, after, start, end text alignment text altitude (ascent) text decoration text depth (descent) text indent (first line) text shadow visibility white space collapse white space treatment width writing mode z-index Note: For further information on these style parameters, see [XSL 1.0] Formatting Properties [CSS Level 2] Note: The style parameters break before break after [XSL 1.0] Keeps and Breaks Properties auto line inherit line Unlike XSL, these parameters apply only to inline vocabulary, and not block vocabulary. Note: A style parameter The TT AF may be capable of associating the following visual style parameters that pertain to temporal filling (flowing) of timed text content: temporal fill mode temporal fill direction temporal block clear mode temporal fill interval temporal inter-fill interval Note: These parameters are intended to permit the expression of authorial intent with respect to the temporal filling (stacking) of glyph areas within a line area and line areas within a block area. The temporal fill mode temporal fill direction temporal block clear mode temporal fill interval temporal inter-fill interval The TT AF shall be defined in such a manner that if a stylistic presentation parameter may be specified as a style property, then that parameter shall also be specifiable as a style attribute, and vice-versa. Note: In this context, a style attribute property The TT AF shall be defined in such a manner that if there is a conflict when adopting the name or value semantics of a style parameter specification, then the following order shall hold for resolving such a conflict: XSL FO SVG SMIL CSS Level 2 CSS Level 3 The TT AF shall be defined in such a manner that to the extent that stylistic oriented markup element types are defined or adopted, then such element types shall be defined as shorthand equivalents of non-stylistic oriented element types in combination with specific style parameters. The TT AF shall be capable of inline timing, where inline timing means the inclusion of temporal presentation markup in a TT AF document instance. The TT AF shall be capable of out-of-line timing, where out-of-line timing means the association of temporal presentation information with TT AF content via some mechanism external to a TT AF document instance. The TT AF shall be capable of expressing the following synchronization parameters in terms of any legal combination that expresses a possibly repeated or restarted, single, simple interval: begin dur end endsync fill fillDefault repeatCount repeatDur restart restartDefault Note: For further information on these synchronization parameters, see [SMIL 2.0] The SMIL 2.0 Timing and Synchronization Module Note: It is not required that the TT AF support the specification of multiple simple intervals, i.e., multiple start, duration, or begin values. The TT AF shall be capable of expressing the following synchronization parameter value space semantics: Offset Values Event Values Access Key Values Media Marker Values Wallclock Values Note: It is not required that the TT AF support the specification of negative offset values. The TT AF shall be capable of expressing sequential, parallel, and exclusive time containment semantics of consituent timed text content. Note: For further information on these time containment semantics, see [SMIL 2.0] The SMIL 2.0 Timing and Syncrhonization Module The TT AF shall be capable of expressing animation according to the following modes: continuous – linear continuous – non-linear discrete Note: By animation The TT AF shall be capable of expressing animated scrolling of content, both in block and inline progression directions, with independent expression of scroll in, scroll out, and scroll repetition. The TT AF shall be capable of expressing animated highlighting of content, with granularity at the level of individual characters or glyphs. The TT AF shall be capable of expressing animated fade transitions of content, with granularity at the level of individual regions or areas. Note: See Presentational Flowed Text Vocabulary Non-Flowed Text Vocabulary region area The TT AF shall be capable of animating the following aural style parameters: azimuth elevation speaking mode speech rate volume The TT AF shall be capable of animating the following visual style parameters: background color block scroll amount border color color display inline scroll amount opacity origin visibility Note: It is possible to express fade-in and fade-out transitions by means of animating the opacity Note: Animation of the display The TT AF is not required to support the animation of content. Note: By animation of content The TT AF shall be capable of associating arbitrary metadata, expressed as metadata items Note: It is not required that metadata be able to be associated with an element's attributes or with any other child of an element other than a child that is characterized as an element itself. The TT AF shall be capable of expressing the following constituents of individual metadata items: name value type value The TT AF shall give preference to the representation of metadata item values as element content as opposed to attribute content. Note: By element content attribute content The TT AF shall be capable of expressing metadata items whose names, value types, and semantics are defined externally to the TT AF specification(s). The TT AF specification(s) shall be defined in such a manner as to permit and potentially require the ability to validate metadata. The TT AF specification(s) shall be defined in such a manner as to give preference to those metadata items defined by [DCMES 1.1] American National Standards Institute. ANSI X3.4: Coded character set – 7-bit American national code for information interchange Jutta Treviranus, Charles McCathieNevile, Ian Jacobs, Jan Richards, Eds., Authoring Tool Accessibility Guidelines 1.0 http://www.w3.org/TR/ATAG10/ Dublin Core Metadata Initiative, Dublin Core Metadata Element Set, Version 1.1: Reference Description http://dublincore.org/documents/dces/ James Clark and Makato Murata, Eds., RELAX NG Specification http://www.relaxng.org/spec-20011203.html The Unicode Consortium, The Unicode Standard, Version 3.2.0 The Unicode Standard, Version 3.0 Unicode Standard Annex #27: Unicode 3.1 http://www.unicode.org/reports/tr27 Unicode Standard Annex #28: Unicode 3.2 http://www.unicode.org/reports/tr28 Martin J. Dürst and Asums Freytag, Unicode in XML and other Markup Languages http://www.w3.org/TR/unicode-xml/ Marja-Riitta Koivunen, Accessibility Features of SMIL http://www.w3.org/TR/SMIL-access/ Daniel Dardailler, Sean B. Palmer, Charles McCathieNevile, Eds., XML Accessibility Guidelines http://www.w3.org/TR/xag.html Steve DeRose, Eve Maler, David Orchard, Eds., XML Linking Language (XLink) Version 1.0 http://www.w3.org/TR/xlink/ Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, Eds., Extensible Markup Language (XML) 1.0 (Second Edition) http://www.w3.org/TR/REC-xml John Cowan, Extensible Markup Language (XML) 1.1 http://www.w3.org/TR/2002/CR-xml11-20021015/ John Cowan and Richard Tobin, XML Information Set http://www.w3.org/TR/xml-infoset/ Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn, Eds., XML Schema Part 1: Structures http://www.w3.org/TR/xmlschema-1/ Paul Biron and Ashok Malhotra, XML Schema Part 2: Datatypes http://www.w3.org/TR/xmlschema-2/ Norman Walsh, The XML Spec Schema and Stylesheets http://www.w3.org/2002/xmlspec/ 3rd Generation Partnership Project, Technical Specification Group Services and System Aspects; Transparent End-To-End Packet-Switched Streaming Service (PSS); Protocols and Codecs http://www.3gpp.org/ftp/Specs/html-info/26234.htm Martin J. Dürst et al., Eds., Character Model for the World Wide Web 1.0: Fundamentals http://www.w3.org/TR/charmod/ Bert Bos, Håkon Wium Lie, Chris Lilley, Ian Jacobs, Eds., Cascading Style Sheets, Level 2 http://www.w3.org/TR/REC-CSS2/ Dublin Core Metadata Initiative, DCMI Metadata Terms http://dublincore.org/documents/2003/03/04/dcmi-terms/ Electronics Industry Alliance (EIA), Line 21 Data Services http://www.ce.org/ Electronics Industry Alliance (EIA), Digital Television (DTV) Closed Captioning http://www.ce.org/ European Telecommunications Standards Institute, Enhanced Teletext Specification http://webapp.etsi.org/action%5COP/OP20030411/en_300706v010201o.pdf European Telecommunications Standards Institute, Digital Video Broadcasting (DVB); Subtitling Systems http://webapp.etsi.org/action%5COP/OP20021004/en_300743v010201o.pdf Apple Computers, Inc., QuickTime Text http://www.apple.com/quicktime/tutorials/texttracks.html RealNetworks, Inc., RealText Markup http://www.realnetworks.com/resources/howto/realtext/index.html Microsoft Corporation, SAMI – Synchronized Accessible Media Interchange for Windows Media Player http://www.msdn.microsoft.com/library/default.asp?url=/library/en-us/dnacc/html/atg_samiarticle.asp Jeff Ayars, Dick Bulterman, et al., Eds., Synchronized Multimedia Integration Language (SMIL 2.0) http://www.w3.org/TR/smil20/ C. M. Sperberg-McQueen and Lou Burnard, Eds., TEI P4: Guidelines for Electronic Text Encoding and Interchange http://www.tei-c.org/Guidelines2/index.html Steven Pemberton, et al., Eds., XHTML™ 1.0 Extensible Hypertext Markup Language (Second Edition) http://www.w3.org/TR/xhtml1/ Sharon Adler, Anders Berglund, et al., Eds., Extensible Stylesheet Language, Version 1.0 http://www.w3.org/TR/xsl/ The editor acknowledges the members of the Timed Text Working Group, the members of other W3C Working Groups, and industry experts in other forums who have contributed directly or indirectly to the process or content of creating this document. The current and former members of the Timed Text Working Group are: Glenn Adams, Extensible Formatting Systems, Inc. (chair); Kees Blom, CWI; Brad Botkin, WGBH; Dick Bulterman, CWI; Michael Dolan, Invited Expert; Gerry Fields, WGBH; Geoff Freed, WGBH; Markus Gylling, DAISY Consortium; Markku Hakkinen, Japanese Society for Rehabilitation of Persons with Disabilities; Sean Hayes, Microsoft; Erik Hodge, RealNetworks; Masahiko Kaneko, Microsoft; George Kerscher, DAISY Consortium; David Kirby, BBC; Thierry Michel, W3C (team contact); Patrick Schmitz, Invited Expert; and, Dave Singer, Apple Computer. The Timed Text Working Group has benefited in its work from the participation and contributions of a number of people not currently members of the Working Group, including in particular those named below. Affiliations given are those current at the time of their work with the WG. John Birch, Screen Subtitling Systems; Bert Bos, W3C (chair, CSS WG); Martin Dürst, W3C (leader, I18N Activity); Al Gilman (chair, WAI Protocol and Formats WG); Philipp Hoschka, W3C (leader, Interaction Domain); Chris Lilley, W3C (chair, SVG WG).