Network Working Group M. Froumentin
Request for Comments: 4267 W3C
Category: Informational November 2005
The W3C Speech Interface Framework Media Types:
application/voicexml+xml, application/ssml+xml, application/srgs,
application/srgs+xml, application/ccxml+xml, and application/pls+xml
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document defines the media types for the languages of the W3C
Speech Interface Framework, as designed by the Voice Browser Working
Group in the following specifications: the Voice Extensible Markup
Language (VoiceXML), the Speech Synthesis Markup Language (SSML), the
Speech Recognition Grammar Specification (SRGS), the Call Control XML
(CCXML), and the Pronunciation Lexicon Specification (PLS).
Table of Contents
1. Introduction ....................................................2
2. Registration of application/voicexml+xml, application/ssml+xml,
application/srgs+xml, application/ccxml+xml, and
application/pls+xml .............................................3
2.1. Encoding Considerations ....................................3
2.2. Interoperability Considerations ............................3
2.3. Published Specifications ...................................3
2.4. Applications that Use These Media Types ....................4
2.5. Security Considerations ....................................4
2.6. Additional Information .....................................4
2.6.1. Magic Numbers .......................................4
2.6.2. File Extensions .....................................4
2.6.3. Fragment Identifiers ................................5
2.6.4. Macintosh File Type Code ............................5
2.6.5. Person and Email Address to Contact for
Further Information .................................5
2.6.6. Intended Usage ......................................5
2.6.7. Change Controller ...................................5
Froumentin Informational [Page 1]
RFC 4267 W3C Speech Interface Media Types November 2005 3. Registration of application/srgs ................................5 3.1. Encoding Considerations ....................................5 3.2. Interoperability Considerations ............................5 3.3. Published Specifications ...................................5 3.4. Applications That Use This Media Type ......................6 3.5. Security Considerations ....................................6 3.6. Additional Information .....................................6 3.6.1. Magic Numbers .......................................6 3.6.2. File Extensions .....................................6 3.6.3. Macintosh File Type Code ............................6 3.6.4. Person and Email Address to Contact for Further Information .................................7 3.6.5. Intended Usage ......................................7 3.6.6. Change Controller ...................................7 4. IANA Considerations .............................................7 5. Normative References ............................................7 1. Introduction This specification defines the media types of the Voice Extensible Markup Language (VoiceXML), the Speech Synthesis Markup Language (SSML), the Speech Recognition Grammar Specification (SRGS), the Call Control XML (CCXML), and the Pronunciation Lexicon Specification (PLS), the specifications of the W3C Speech Interface Framework. VoiceXML ([VoiceXML2.0]) is an Extensible Markup Language (XML) designed for creating audio dialogs that feature synthesized speech, digitized audio, recognition of spoken and DTMF key input, recording of spoken input, telephony, and mixed initiative conversations. The associated media type defined in this document is "application/voicexml+xml". The Speech Synthesis Markup Language specification (SSML) defines an XML-based markup language for assisting the generation of synthetic speech in Web and other applications. The essential role of SSML is to provide authors of synthesizable content a standard way to control aspects of speech such as pronunciation, volume, pitch, and rate, across different synthesis-capable platforms. The associated media type defined in this document is "application/ssml+xml". The Speech Recognition Grammar Specification (SRGS) defines syntax for representing grammars for use in speech recognition so that developers can specify the words and patterns of words to be listened for by a speech recognizer. The syntax of the grammar format exists in two forms, an Augmented BNF (ABNF) Form and an XML Form. The respective media types defined in this document are "application/srgs" and "application/srgs+xml". Froumentin Informational [Page 2]
RFC 4267 W3C Speech Interface Media Types November 2005 The Call Control EXtensible Markup Language (CCXML) is an XML designed to provide telephony call control support for dialog systems, such as VoiceXML. The associated media type defined in this document is "application/ccxml+xml". The Pronunciation Lexicon Specification (PLS) defines an XML syntax for specifying pronunciation lexicons to be used by speech recognition and speech synthesis engines in voice browser applications. The associated media type defined in this document is "application/pls+xml". 2. Registration of application/voicexml+xml, application/ssml+xml, application/srgs+xml, application/ccxml+xml, and application/pls+xml MIME media type name: application MIME subtype names: voicexml+xml, ssml+xml, srgs+xml, ccxml+xml, pls+xml Required parameters: none Optional parameters: "charset": This parameter has identical semantics to the charset parameter of the "application/xml" media type as specified in RFC 3023 [RFC3023]. 2.1. Encoding Considerations Identical to those of "application/xml" as described in RFC 3023 [RFC3023], section 3.2. 2.2. Interoperability Considerations There are no known interoperability issues. 2.3. Published Specifications Voice Extensible Markup Language 2.0 [VoiceXML2.0] Voice Extensible Markup Language 2.1 [VoiceXML2.1] Speech Synthesis Markup Language (SSML) Version 1.0 [SSML] Speech Recognition Grammar Specification Version 1.0 [SRGS] Voice Browser Call Control: CCXML Version 1.0 [CCXML] Froumentin Informational [Page 3]
RFC 4267 W3C Speech Interface Media Types November 2005 Pronunciation Lexicon Specification (PLS) Version 1.0 [PLS] 2.4. Applications that Use These Media Types Various W3C Speech Interface Framework implementations use these media types. 2.5. Security Considerations Several instructions in the cited specifications may cause arbitrary Uniform Resource Identifiers (URIs) to be dereferenced. In this case, the security issues of [RFC3986], section 7, should be considered. In addition, because of the extensibility features of those specifications, it is possible that the registered media types may describe content that has security implications beyond those described here. However, if the processor follows only the normative semantics of the specifications, this content will be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. And in that case, they would fall outside the domain of this registration document. 2.6. Additional Information 2.6.1. Magic Numbers Although no byte sequences can be counted on to always be present, XML MIME entities in ASCII-compatible charsets (including UTF-8) often begin with hexadecimal 3C 3F 78 6D 6C ("<?xml"), and those in UTF-16 often begin with hexadecimal FE FF 00 3C 00 3F 00 78 00 6D 00 6C or FF FE 3C 00 3F 00 78 00 6D 00 6C 00 (the Byte Order Mark (BOM) followed by "<?xml"). For more information, see Appendix F of [XML]. 2.6.2. File Extensions VoiceXML files: .vxml SSML files: .ssml SRGS files (XML syntax): .grxml CCXML files: .ccxml PLS files: .pls Froumentin Informational [Page 4]
RFC 4267 W3C Speech Interface Media Types November 2005 2.6.3. Fragment Identifiers Identical to that of "application/xml" as described in RFC 3023 [RFC3023], section 5. 2.6.4. Macintosh File Type Code "TEXT" 2.6.5. Person and Email Address to Contact for Further Information World Wide Web Consortium <web-human@w3.org> 2.6.6. Intended Usage COMMON 2.6.7. Change Controller The Speech Interface Framework specifications set is a work product of the World Wide Web Consortium's Voice Browser Working Group. The W3C has change control over these specifications. 3. Registration of application/srgs MIME media type name: application MIME subtype names: srgs Required parameters: none Optional parameters: none 3.1. Encoding Considerations The ABNF Form of SRGS follows the character encoding handling defined for XML: an ABNF grammar processor must accept both the UTF-8 and UTF-16 encodings of ISO/IEC 10646 and may support other character encodings. 3.2. Interoperability Considerations There are no known interoperability issues. 3.3. Published Specifications Speech Recognition Grammar Specification Version 1.0 [SRGS] Froumentin Informational [Page 5]
RFC 4267 W3C Speech Interface Media Types November 2005 3.4. Applications That Use This Media Type Various SRGS implementations use this media type. 3.5. Security Considerations Several instructions in SRGS may cause arbitrary URIs to be dereferenced. In this case, the security issues of [RFC3986], section 7, should be considered. In addition, because of the extensibility features of SRGS, it is possible that the registered media types may describe content that has security implications beyond those described here. However, if the processor follows only the normative semantics of the specifications, this content will be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. In that case, they would fall outside the domain of this registration document. 3.6. Additional Information 3.6.1. Magic Numbers The ABNF self-identifying header must be present in any legal stand- alone ABNF Form grammar document. The first character of an ABNF document must be the "#" symbol (x23) unless preceded by an optional XML 1.0 byte order mark. The ABNF byte order mark follows the XML definition and requirements. For example, documents encoded in UTF- 16 must begin with the byte order mark. The optional byte order mark and required "#" symbol must be followed immediately by the exact string "ABNF" (x41 x42 x4d x46) or the appropriate equivalent for the document's encoding (e.g., for UTF-16 little-endian: x23 x00 x41 x00 x42 x00 x4d x00 x46 x00). If the byte order mark is absent on a grammar encoded in UTF-16, then the grammar processor should perform auto-detection of character encoding in a manner analogous to auto- detection of character encoding in XML. Next follows a single-space character (x20) and the required version number, which is "1.0" for this specification (x31 x2e x30). 3.6.2. File Extensions .gram 3.6.3. Macintosh File Type Code "TEXT" Froumentin Informational [Page 6]
RFC 4267 W3C Speech Interface Media Types November 2005 3.6.4. Person and Email Address to Contact for Further Information World Wide Web Consortium <web-human@w3.org> 3.6.5. Intended Usage COMMON 3.6.6. Change Controller The SRGS specification is a work product of the World Wide Web Consortium's Voice Browser Working Group. The W3C has change control over the SRGS specification. 4. IANA Considerations This document registers six new MIME media types, according to the registrations in Section 2 and Section 3. 5. Normative References [CCXML] Auburn, RJ., Ed., "Voice Browser Call Control: CCXML Version 1.0, W3C Working Draft", January 2005, <http://www.w3.org/TR/2005/WD-ccxml-20050111/>. [PLS] Baggia, P., Ed., "Pronunciation Lexicon Specification (PLS) Version 1.0, W3C Working Draft", February 2005, <http://w3.org/TR/2005/WD-pronunciation-lexicon- 20050214/>. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [SRGS] Hunt, A., Ed. and S. McGlashan, Ed., "Speech Recognition Grammar Specification Version 1.0, W3C Recommendation", March 2004, <http://www.w3.org/TR/2004/REC-speech-grammar- 20040316/>. [SSML] Burnett, D., Ed., Walker, M., Ed., and A. Hunt, Ed., "Speech Synthesis Markup Language (SSML) Version 1.0, W3C Recommendation", September 2004, <http://www.w3.org/TR/2004/REC-speech-synthesis- 20040907/>. Froumentin Informational [Page 7]
RFC 4267 W3C Speech Interface Media Types November 2005 [VoiceXML2.0] McGlashan, S., Ed., "Voice Extensible Markup Language (VoiceXML) Version 2.0, W3C Recommendation", March 2004, <http://www.w3.org/TR/2004/REC-voicexml20- 20040316/>. [VoiceXML2.1] Oshry, M., Ed., "Voice Extensible Markup Language (VoiceXML) Version 2.1, W3C Working Draft", July 2004, <http://www.w3.org/TR/2004/WD-voicexml21-20040728/>. [XML] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, "Extensible Markup Language (XML) 1.0 (Third Edition)", February 2004, <http://www.w3.org/TR/2004/REC-xml-20040204/>. Author's Address Max Froumentin World Wide Web Consortium EMail: mf@w3.org Froumentin Informational [Page 8]
RFC 4267 W3C Speech Interface Media Types November 2005 Full Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Froumentin Informational [Page 9]
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