Internet-Draft October 2006 Lemonade Internet Draft: CONVERT S. H. Maes Document: draft-ietf-lemonade-convert-05 R. Cromwell (Editors) Expires: April 2007 October 2006 CONVERT Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 30, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract CONVERT defines IMAP extensions allowing clients to request adaptation and/or transcoding of attachments. Clients can specify the conversion details or allow servers to decide based on knowledge of client capabilities, on user or administrator preferences or its settings. Conventions used in this document Maes Expires April 2007 [Page 1] Internet-Draft October 2006 In examples, "C:" and "S:" indicate lines sent by the client and server respectively. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. When describing the general syntax, some definitions are omitted as they are defined in [RFC3501]. Table of Contents Status of this Memo ....................................... 1 Copyright Notice........................................... 1 Abstract................................................... 1 Conventions used in this document.......................... 1 Table of Contents.......................................... 2 1. Introduction............................................ 3 2. Relation with other E-mail specifications............... 3 3. Scope of Conversions.................................... 4 4. Discovery with the CAPABILITY and GETMETADATA Commands.. 4 4.1. CAPABILITY......................................... 4 4.2. GETMETADATA ....................................... 4 5. CONVERT BODY and BINARY data item extension............. 5 6. CONVERT transcoding parameters.......................... 7 6.1. Mandatory Transcoding support...................... 7 6.1.1. Additional features for mobile usage.......... 8 7. FETCH response extensions............................... 8 8. Status responses, Response code extensions.............. 8 9. Formal Syntax........................................... 9 10. IANA Considerations.................................... 11 11. IANA Entry and Attribute registrations ................ 11 11.1. IANA Entry "/convert"............................. 11 11.2. IANA Attribute "types"............................ 12 11.3. IANA Attribute "params"........................... 12 Security Considerations.................................... 12 Normative References....................................... 13 Informative References..................................... 14 Version History............................................ 14 Acknowledgments............................................ 15 Maes Expires April 2007 [Page 2] Internet-Draft October 2006 Authors' Addresses........................................ 15 Intellectual Property Statement........................... 16 Disclaimer of Validity.................................... 16 Copyright Statement .......................................16 1. Introduction CONVERT is based on IMAPv4 Rev1 [RFC3501]. It defines additional enhancements for optimization in a mobile setting: extensions to the IMAPv4Rev1 protocol [RFC3501] that allows adaptation and transcoding of body parts as needed by the client. Conversion (adaptation, transcoding) may be requested by the client and performed by the server on a best effort basis or decided by the server based on its knowledge of the client capabilities, user or administrator preferences or its settings. These are important features required in particular to support mobile email use cases [MEMAIL], [OMA-ME-RD]. A server that supports CONVERT can convert leaf body parts to other formats to be viewed on a mobile device. The client can explicitly request a particular conversion. The server complies on a best effort basis. When not possible, the server determines based on its own strategy (e.g. based on knowledge of the client as discussed hereafter) how to convert. If the server knows the characteristics of the device or can determine them (out of scope of CONVERT), the attachments can also be optimized for the capabilities of the devices (e.g. form factor of pictures). This is a recommended server behavior. 2. Relation with other E-mail specifications The Lemonade Profile [LEMONADEPROFILE] specifies the Lemonade Pull Model that governs the exchanges among mail servers or between desktop mail client and mail servers. Lemonade investigates adding mobile optimizations for the next version of the profile. CONVERT should be seen as a way to address the issues of mobile optimization and an input to the Lemonade Profile work. It addresses the topic of attachment conversions identified by the Lemonade work as critical for mobile email. CONVERT does not address conversion and streaming of media as also identified of interest by Lemonade. CONVERT depends on the METADATA extension [ANNOTATEMORE] to support discovery of supported conversion formats. In addition, to use Maes Expires April 2007 [Page 3] Internet-Draft October 2006 CONVERT, the server MUST support the IMAP Binary specification [RFC3516]. 3. Scope of Conversions Conversions only affect what is sent to the client; the original data in the message store MUST NOT be altered. This document does not specify how the server performs conversions. (The requirement that original data be unaltered allows such data to remain accessible by other clients, permits replies or forwards of the documents, and preserves BODYSTRUCTURE and related information.) 4. Discovery with the CAPABILITY and GETMETADATA Commands 4.1. CAPABILITY A server that supports CONVERT MUST return "CONVERT", "METADATA", and "BINARY" and in the CAPABILITY response. Example: A server that implements CONVERT C: a001 CAPABILITY S: * CAPABILITY IMAP4rev1 AUTH=LOGIN IDLE CONVERT BINARY METADATA S: a001 OK CAPABILITY completed 4.2. GETMETADATA To determine which conversions are supported, server annotations are used. For each source mime-type that the client is interested in, it SHOULD determine which target conversions are supported. For any proposed conversion, the client SHOULD discover a list of optional parameters that the conversion will accept. MIME type/subtype are mapped to a hierarchy under the root "/convert". For each mime type under "/convert", a value for "types.shared" SHOULD exist which is a semicolon separated list of output formats. Example: Discover all image conversions C: a GETMETADATA /convert/image/* types.shared S: * METADATA /convert/image/jpeg (types.shared "image/jpeg;image/png;image/gif;image/wbmp") S: a OK GETMETADATA complete The above example shows that the server supports one kind of input image transcoding, from image/jpeg to four different outputs: JPEG, PNG, GIF, and WBMP. Maes Expires April 2007 [Page 4] Internet-Draft October 2006 For a given conversion, optional transcoding parameters MAY be present. These are mapped into a value "params.shared" under "/convert/sourcetype/destinationtype". Example: Discover optional parameters for image/jpeg -> image/gif. C: a GETMETADATA /convert/image/jpeg/image/gif "params.shared" S: * METADATA /convert/image/jpeg/image/gif ("params.shared" "width;height;depth;interlaced") S: a OK GETMETADATA complete The above example shows that to convert from image/jpeg to image/gif, the transcoding supports the following types of option parameters: width, height, depth, and interlaced. A client MAY use these values to check whether or not a desired conversion is possible, or it may present the parameters as a GUI preferences pane for the user to customize. A baseline set of register transcoding parameter names should be standardized (see [OMA-STI]) in the future, and it is beyond the scope of this spec to allow the client to discover the underlying legal values that these parameters may take. 5. CONVERT BODY and BINARY data item extension CONVERT is a FETCH extension used to transcode the media type of a leaf MIME part into another media type, and/or the same media type, with different encoding parameters. It adds new options to the section-spec part of the BODY data item, a new FETCH response data item BODYPARTSTRUCTURE, and new response codes. It is also expected to work with IMAP BINARY data item extension, whose grammar is modified as well. The response to a CONVERT request always includes a BODYPARTSTRUCTURE. CONVERT's syntax is modeled after the HEADER.FIELDS syntax in RFC3501, and is generally structured as: BODY[section-part.CONVERT[.STRICT] ("media type/subtype" (parameters))] BODY.PEEK[section-part.CONVERT[.STRICT] ("media type/subtype" (parameters))] BINARY[section-part.CONVERT[.STRICT] ("media type/subtype" (parameters))] Maes Expires April 2007 [Page 5] Internet-Draft October 2006 BINARY.PEEK[section-part.CONVERT[.STRICT] ("media type/subtype" (parameters))] BINARY.SIZE[section-part.CONVERT[.STRICT] ("media type/subtype" (parameters))] Example: The client fetches body part section 3 in the message with the message sequence number of 2 and asks to have that attachment converted to pdf format. C: a001 FETCH 2 BODY[3.CONVERT ("APPLICATION/PDF")] S: * 2 FETCH (BODYPARTSTRUCTURE[3] ("APPLICATION" "PDF" () NIL NIL "Base64" 2135 NIL NIL NIL) BODY[3] {2135} ) S: a001 OK FETCH COMPLETED Example: The client requests for conversion of a text/html section as text/plain and asks for a charset of us-ascii. The server cannot respect the charset request because there are non-us-ascii characters in the html code. Thus, in the untagged response, the server returns the charset of UTF-8 and utilizes a content transfer encoding capable of representing the full 8-bit range, along with the converted text. C: a001 FETCH 2 BODY[3.CONVERT ("text/plain" ("charset" "us- ascii"))] S: * 2 FETCH (BODYPARTSTRUCTURE[3] ("TEXT" "PLAIN" ("charset" "utf-8") NIL NIL "Base64" 2135 181 NIL NIL NIL) BODY[3] {2135} the document in text/plain format with utf-8 character set ) S: a001 OK FETCH COMPLETED Example: The client requests for conversion of a text/html section as text/plain, but only wants 1000 bytes, starting from byte 2001. C: a001 FETCH 2 BODY[3.CONVERT ("TEXT/PLAIN" ("CHARSET" "us- ascii"))]<2001.1000> S: * 2 FETCH (BODYPARTSTRUCTURE[3] ("TEXT" "PLAIN" ("charset" "us- ascii") NIL NIL "7bit" 2135 181 NIL NIL NIL) BODY[3]<2001> {135} bytes 2001 - 2135 of the document in text/plain format ) S: a001 OK FETCH COMPLETED The server is not required to respect a particular transcoding request or its request parameters unless the STRICT qualifier is used, although it MAY try to make a best effort to fulfill that request if it is omitted. Indeed, the server may know a priori information about the client obtained through a different mechanism Maes Expires April 2007 [Page 6] Internet-Draft October 2006 outside the scope of CONVERT (e.g. dynamically through device description mechanisms or when the device was associated to the account). These preferences may be used to predefine what conversions are possible. Ideally the client should request the same conversions. In addition, this information may also allow attachment adaptation (e.g. picture form factor) instead of solely format conversion. 6. CONVERT transcoding parameters IMAP servers which support CONVERT MAY support additional transcoding parameters for each media type. All such servers MUST minally support recognition of charset for text/* mime types, although they may decline to honor some requests. For media types other than text, it is beyond the scope of this document to define conversion parameters. In general however, CONVERT compliant servers MAY choose to support additional parameters, and if so, they SHOULD follow the OMA STI 1.0 spec [OMA-STI] adopting the same parameter names as defined in section 5.2.4 and above for the most popular image/*, video/*, and audio/* codecs As an example, in section 5.2.6.2 of [OMA-STI], the parameters "width" and "height" are defined. The following example illustrates how these OMA STI parameters are used with CONVERT. C: a001 UID FETCH 100 BINARY[2.CONVERT ("IMAGE" "JPG" ("WIDTH" "128" "HEIGHT" "96"))] S: * 2 FETCH (UID 100 BODYPARTSTRUCTURE[2] ("IMAGE" "JPG" () NIL NIL "8bit" 4182 NIL NIL NIL) BINARY[2] ~{4182} ) S: a001 OK UID FETCH COMPLETED 6.1. Mandatory Transcoding support A server implementing CONVERT MUST support character set conversions for the text/plain mime type, and MUST support character set conversions from iso-8859-* to utf-8. A client requesting the server annotation "/convert/text/plain" MUST return "text/plain" as an allowed destination conversion. And a request for annotation "/convert/text/plain/text/plain" must return "charset" as a supported transcoding parameter. Servers SHOULD offer additional character encoding conversions where they make sense as libraries of conversion facilities are generally available on many platforms. Maes Expires April 2007 [Page 7] Internet-Draft October 2006 If for some reason, the server cannot carry about the trancoding while preserving all the characters, the server should add an INFORMATIONLOSS response code to the response, unless STRICT is request, in which case it may return a BADPARAMETERS response code. 6.1.1. Additional features for mobile usage Based on the expected usage of convert in mobile environments: - Servers SHOULD support conversion of HTML and XHTML documents to text/plain in ways that preserve at the minimum the document structure and tables. - Server SHOULD support image conversions among the types image/gif, image/jpeg and image/png for at least the parameters: o Size limit (i.e. reduce quality), o width, o height, o resize directive (crop, stretch, aspect ratio) depth may also be of interest. Audio conversion is of significant interest but the relevant formats depend significantly on the usage context. Support of other formats like proprietary document formats and video can also be described as MIME types with STI parameters. Their support depends on the usage context. 7. FETCH response extensions The BODYPARTSTRUCTURE data item is introduced when using the CONVERT extension. It follows the exact syntax specified in the [RFC3501] BODYSTRUCTURE data item, but contains information for only the converted part. All information contained in BODYPARTSTRUCTURE pertains to the state of the part after it is converted, such as the converted mime-type, sub-type, size, or charset. The client must respect the return values and not assume the conversion request succeeds exactly as requested unless the STRICT qualifier is used. 8. Status responses, Response code extensions Some transcodings may require parameters. If a transcoding request is sent for a format which requires parameters, the server can reply with a NO response. Likewise, malformed mime types may also generate NO responses. If the server is unable to perform the requested conversion because a resource is unavailable (e.g. internal error, transcoding service down) then a NO response should be returned. Maes Expires April 2007 [Page 8] Internet-Draft October 2006 If a request is denied because of an operational error, such as lack of disk space, or because the requested conversion for some reason cannot be performed, and there is no fallback for this particular device (such as the case where a proprietary document format has no existing transcoding implementation, and the server recognizes that the client has no default viewer for it), the server MUST return a NO response. Otherwise, the server should return an OK response. The client in general can tell from the BODYPARTSTRUCTURE response whether or not its request was honored exactly, but may not know the reasons why. The following extension response codes are provided for OK and NO responses to disambiguate those situations, or warn about possible important data loss. INFORMATIONLOSS the conversion was satisfied for conversion request, but it may have resulted in the loss of important data (primarily of use for loss of text data, since rich media is often compressed with loss) BADPARAMETERS "(" convert-params ")" the listed parameters were not understood, or could not be honored for the reasons noted in section- text. In particular, a CONVERT.STRICT request may be fail because the server has no way to honor it. SERVEROVERRIDE the server override the request because it determined it could substitute a better one based on preferences, device capability knowledge, or server policy. If CONVERT.STRICT is used, the server MUST NOT return SERVEROVERRIDE. It must either honor the request, or fail. 9. Formal Syntax The following syntax specification uses the augmented Backus-Naur Form (ABNF) notation as used in [ABNF], and incorporates by reference the Core Rules defined in that document. This syntax augments the grammar specified in [RFC3501] and [RFC3516]. In the ABNF section-msgtext grammar in section 9 of [RFC3501], Section-msgtext is hereby amended to read: section-msgtext =/ "CONVERT" SP convert-params convert-params = "(" (media-basic / default-conversion) [SP "(" transcoding-params ")"] ")" Maes Expires April 2007 [Page 9] Internet-Draft October 2006 transcoding-params = transcoding-param-name SP transcoding-param- value *(SP transcoding-param-name SP transcoding-param-value) transcoding-param-name = astring transcoding-param-value = astring default-conversion = "NIL" In the ABNF syntax "section-binary" of [RFC3516], is amended to: section-binary = "[" [section-part [".CONVERT"[.STRICT] SP convert-params] "]" In the ABNF syntax "msg-att-static" of [RFC3501], is amended to: msg-att-static =/ "BODYPARTSTRUCTURE" "(" body-type-1part ")" In the ABNF syntax "resp-text-code" of [RFC3501], is amended to: Resp-text-code =/ "INFORMATIONLOSS" / "SERVEROVERRIDE" / "BADPARAMETERS" SP "(" bad-param-list ")" bad-param-list = transcoding-params In addition, the following ABNF describes the syntax of the GETMETADATA entries in Section 4.2 convert-entry-req = available-conversions / available- transcoding-parameters available-conversions = "/convert/" from-mime-type from-mime-type = "*" /(astring ["/" (astring / "*")] ; i.e. "*" or "type/*" or "type/subtype" from-concrete-mime-type = astring "/" astring ; i.e. "type/subtype" to-mime-type = astring "/" astring available-transcoding-parameters = "/convert/" from-concrete- mime-type "/" to-mime-type ;i.e. /convert/fromtype/fromsubtype/totype/tosubtype Maes Expires April 2007 [Page 10] Internet-Draft October 2006 Finally, two standard annotation attributes are defined. Under available-conversions entry, there will be an attribute named "types.shared" with the following ABNF: types-shared-value = from-concrete-mime-type(";" from-concrete- mime-type)* And under an available-transcoding-parameters entry, there will be an attribute named "params.shared" with the following ABNF: params-shared-value = transcoding-param-name (";" transcoding- param-name)* 10. IANA Considerations IMAP4 capabilities are registered by publishing a standards track or IESG approved experimental RFC. The registry is currently located at . This document defines the CONVERT IMAP capability. This extension shall be submitted to the IANA IMAP Capability registry. 11. IANA Entry and Attribute registrations The following sections specify IANA registrations for entries and attributes used in this document. 11.1. IANA Entry "/convert" To: iana@iana.org Subject: IMAP METADATA Registration Please register the following IMAP METADATA item: [x] Entry [ ] Attribute [ ] Mailbox [x] Server Name: /convert Description: Defined in IMAP CONVERT extension document. Content-type: text/plain; charset=utf-8 Contact person: Stephane Maes email: stephane.maes@oracle.com Maes Expires April 2007 [Page 11] Internet-Draft October 2006 11.2. IANA Attribute "types" To: iana@iana.org Subject: IMAP METADATA Registration Please register the following IMAP METADATA item: [ ] Entry [x] Attribute [ ] Mailbox [x] Server Name: types Description: Defined in IMAP CONVERT extension document. Content-type: - Contact person: Stephane Maes email: stephane.maes@oracle.com 11.3. IANA Attribute "params" To: iana@iana.org Subject: IMAP METADATA Registration Please register the following IMAP METADATA item: [ ] Entry [x] Attribute [ ] Mailbox [x] Server Name: params Description: Defined in IMAP CONVERT extension document. Content-type: - Contact person: Stephane Maes email: stephane.maes@oracle.com Security Considerations Maes Expires April 2007 [Page 12] Internet-Draft October 2006 It is to be noted that some conversions may present security threats (e.g. converting a document to a damaging executable, exploiting a buffer overflow in a media codec/parser, or a denial of service attack against a client or server such as requesting an image be scaled to extremely large dimensions). Clients should be careful when requesting conversions or processing transformed attachments. Servers should avoid dangerous conversions if possible. It may of interest to consider, when possible, server-side verification of the converted attachments before providing to the client. On bandwidth limited mobile networks where users pay per data volumes, spam may become an important issue. It can be mitigated with appropriate filters and server-side spam prevention tools. These are of course outside the scope of CONVERT. It is also recommended that clients be explicitly registered with the server through separate channels / application. Exchanges should then be paired. Deployments that utilize object level encryption may present security challenges to be carefully considered, such as if a conversion is requested for S/MIME encrypted data. This is currently considered as taking place outside the scope of CONVERT. Deployments in which the actual transcoding is done outside the IMAP server in a separate server are recommended to keep the servers in the same trusted domain (e.g. subnet) Normative References [ANNOTATEMORE] Daboo, C., "IMAP ANNOTATEMORE Extension" , draft-daboo-imap-annotatemore-09, 2006. [ABNF] D. Crocker, et al. "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. http://www.ietf.org/rfc/rfc2234 [RFC2119] Brader, S. "Keywords for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. http://www.ietf.org/rfc/rfc2119 [RFC3501] Crispin, M. "IMAP4, Internet Message Access Protocol Version 4 rev1", RFC 3501, March 2003. http://www.ietf.org/rfc/rfc3501 [RFC3516] Nerenberg, L. "IMAP4 Binary Content Extension", RFC 3516, April 2003. http://www.ietf.org/rfc/rfc3516.txt Maes Expires April 2007 [Page 13] Internet-Draft October 2006 Informative References [LEMONADEPROFILE] Maes, S.H. and Melnikov A., "Lemonade Profile", draft-ietf-lemonade-profile-XX.txt, (work in progress). [MEMAIL] Maes, S.H., "Lemonade and Mobile e-mail", draft-maes- lemonade-mobile-email-xx.txt, (work in progress). [OMA-ME-RD] Open Mobile Alliance Mobile Email Requirement Document, (Work in progress). http://www.openmobilealliance.org/ [OMA-STI] Open Mobile Alliance, Standard Transcoding Interface Specification, version 1.0, [Work in progress] (http://member.openmobilealliance.org/ftp/Public_documents/BAC/STI /Permanent_documents/OMA-STI-V1_0-20050209-D.zip). [P-IMAP] Maes, S.H., Lima R., Kuang, C., Cromwell, R., Ha, V. and Chiu, E., Day, J., Ahad R., Jeong W-H., Rosell G., Sini, J., Sohn S-M., Xiaohui F. and Lijun Z., "Push Extensions to the IMAP Protocol (P-IMAP)", draft-maes-lemonade-p-imap-xx.txt, (work in progress). Version History Release 05 - Client not mandated to support BINARY - Misc syntax and spelling fixes - New abstract contributed by Randall Gellens Release 04 - Remove compression and encryption - Update to use latest METADATA draft - Add IANA registrations Release 03 - Add mandatory character set conversions. - Add object level compression - Add object level encryption Release 02 Fixed a normative example to be informative. Added formal syntax for BODYPARTSTUCTURE, response text codes, and formal structure of composite GETANNOTATE values. Release 01 Maes Expires April 2007 [Page 14] Internet-Draft October 2006 Corrected some grammatical mistakes. Clarified meaning of GETTANNOTATION response properties. Changed CONVERT grammar to merge media type and subtype into a single parameter instead of two parameters. Clarified that BODYSTRUCTURERESPONSE is always returned for CONVERT requests. Moved transcoding parameter discussion to main body from appendix. Release 00 Initial release published in October 2005 based on draft-maes- lemonade-lconvert-00 and the comments received at the London face to face meeting end of September 2005. Acknowledgments The authors want to specifically acknowledge the excellent criticism and comments received from Randall Gellens Qualcomm, and Alexey Melnikov Isode which improved the quality of the CONVERT specification considerably. The authors also want to thank all who have contributed key insight and extensively reviewed and discussed the concepts of CONVERT and its early introduction P-IMAP [P-IMAP]. In particular, this includes the authors of the LCONVERT draft: Rafiul Ahad Oracle Corporation, Eugene Chiu Oracle Corporation, Ray Cromwell Oracle Corporation, Jia-der Day Oracle Corporation, Vi Ha Oracle Corporation, Wook- Hyun Jeong Samsung Electronics Co. LTF, Chang Kuang Oracle Corporation, Rodrigo Lima Oracle Corporation, Stephane H. Maes Oracle Corporation, Gustaf Rosell - Sony Ericsson, Jean Sini Symbol Technologies, Sung-Mu Son LG Electronics, Fan Xiaohui - CHINA MOBILE COMMUNICATIONS CORPORATION (CMCC), Zhao Lijun - CHINA MOBILE COMMUNICATIONS CORPORATION (CMCC). Authors' Addresses Stephane H. Maes Oracle Corporation 500 Oracle Parkway M/S 4op634 Redwood Shores, CA 94065 USA Phone: +1-650-607-6296 Email: stephane.maes@oracle.com Ray Cromwell Oracle Corporation 500 Oracle Parkway Maes Expires April 2007 [Page 15] Internet-Draft October 2006 Redwood Shores, CA 94065 USA Intellectual Property Statement 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. Disclaimer of Validity 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. Copyright Statement Copyright (C) The Internet Society (2006). 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. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Maes Expires April 2007 [Page 16]