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'''Content Duration MIME Header Definition'''
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- Network Working Group
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-Request for Comments: [DEL(rfc3803)[2424]] [INS(rfc3803)[3803]]
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-[INS(rfc3803)[Obsoletes: 2424]]
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-Category: Standards Track
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- G. Vaudreuil
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- Lucent Technologies
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- G. Parsons
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- [DEL(rfc3803)[Northern Telecom]]
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- [INS(rfc3803)[Nortel Networks]]
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- [DEL(rfc3803)[September 1998]]
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- [INS(rfc3803)[June 2004]]
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* Status of this Memo
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This document specifies an Internet standards track protocol for the
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Internet community, and requests discussion and suggestions for
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improvements. Please refer to the current edition of the "Internet
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Official Protocol Standards" (STD 1) for the standardization state
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and status of this protocol. Distribution of this memo is unlimited.
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* Copyright Notice
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> Copyright (C) The Internet Society [DEL(rfc3803)[(1998)]] [INS(rfc3803)[(2004)]]. [DEL(rfc3803)[All Rights Reserved.]]
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* [DEL(rfc3803)[Overview]] [INS(rfc3803)[Abstract]]
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> This document describes the MIME header Content-Duration that is
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intended for use with any [DEL(rfc3803)[timed]] [INS(rfc3803)[time varying]] media content (typically audio/* or video/*).
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*1. [DEL(rfc3803)[Abstract]] [INS(rfc3803)[Introduction]]
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> This document describes the MIME header Content-Duration that is
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intended for use with any time varying media content (typically
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audio/* or video/*). The length of time is represented in seconds
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without any units indication. [DEL(rfc3803)[This document obsoletes RFC 2424.]]
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[INS(rfc3803)[
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> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [REQ].
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]INS]
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* 2. Content-Duration Header Field
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> Time varying media contents, for example, a spoken voice message or a
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video clip, have an inherent time duration. Many audio and video
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encodings may include their duration as header information or may
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allow accurate calculation based on the byte length of the data.
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However, it may be useful to present the time duration of the content
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in a MIME header to allow its simple determination without dealing
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with the actual content.
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時変化媒体内容、例えば話し声メッセージやビデオは元から時間を持っています。
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多くの音声や動画の符号化はこの時間情報を頭部情報として含めていたり、
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データのバイト長に基づいて正確に計算できたりします。
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しかし、実際の内容を処理せずに MIME
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頭で簡単に内容の時間を決定できれば便利です。
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[DEL(rfc3803)[
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> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in [REQ].
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]DEL]
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**2.1[INS(rfc3803)[.]] Syntax
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> The Content-Duration field's value is a single number specifying the
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time duration in seconds of the content. Formally:
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[CODE(MIME)[Content-Duration]] 欄の値は数値1つで、
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内容の時間を秒数で指定します。
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> duration := "Content-Duration" ":" 1*10DIGIT
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> Note that practically (though highly unlikely in MIME media), the
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upper bound on the numerical value of the time duration is (2^^31 -1)
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or 2147483647.
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実際上は (MIME 媒体ではありそうにありませんが) 時間の数値の上限は
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[CODE(math)[2[SUP[31]] − 1]] (2147483647) であることに注意して下さい。
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*2.2[INS(rfc3803)[.]] Semantics
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> This field represents the time duration of the associated time
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varying media content. The time duration is noted in seconds with no
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units tag. The time value should be exact, however the exact value of
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the time duration cannot be known without opening the content and
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playing it. If an exact value must be known, then the latter method
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should be used. This mechanism simply allows placing a sender
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determined time duration value in the header for easy access.
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この欄は時変化媒体内容に関する時間を表します。
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時間は単位指定なしで秒単位で記述します。
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時間値は、正確には内容を開いて演奏するまでわからないかもしれませんが、
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正確であるべきです。
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正確な値が分からないと行けない時には、実際に開いて確かめてみるべきです。
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この方法簡単に時間値を決定できるように送信者が値を置けるようにするだけのものです。
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> Though there are several ways to present this duration to the
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recipient (e.g.[INS(rfc3803)[,]] with the inbox headers, when audio attachment
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opened), the actual use of this field on reception is a local
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implementation issue.
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この時間を受信者に示す方法は色々あります
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(例えば添付音声を開いた時に受信箱の頭部に提示) が、
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受信者側でのこの欄の実際の用法は各実装の問題です。
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*2.3[INS(rfc3803)[.]] Example
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> In this example the content duration represents 33 seconds:
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> Content-Duration: 33
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この例では内容の時間は33秒です。
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* 3. VPIM Usage
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> The Content-Duration header field for the audio/32KADPCM sub-type is
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a useful component of the VPIM specification [VPIM2]. All VPIM
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Messages MUST contain this sub-type to carry the audio of a voice
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message. It may be useful in some instances (e.g.[INS(rfc3803)[,]] viewing on a
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simple MIME or non-MIME desktop) to have the time duration of the
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voice message available without having to open the audio content.
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[CODE(MIME)[[[audio/32kadpcm]]]] 亜型に対する
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[CODE(MIME)[[[Content-Duration]]]] 頭欄は [[VPIM]]
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仕様の便利な部品です。すべての VPIM
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部品は動画メッセージの音声を伝達するためにこの亜型を含めなければ'''なりません'''。
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場合によっては音声内容を開かなくても同がメッセージの時間が分かると
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(例えば単純 MIME 机上や非 MIME 机上で見るのに) 便利です。
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* 4. Security Considerations
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> This definition introduces the option of explicitly identifying the
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time duration of an audio/* or video/* content outside of the binary
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data that forms the content. In some environments (though likely not
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the majority), the identification of the actual time duration in a
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header field may be a security issue and as a result should not be
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noted. Reliance on the time indicated in this header field cannot be
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trusted for the purposes of determining the exact size of the data.
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The exact length of the data must be determined by examining the data
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itself.
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この定義は [CODE(MIME)[[[audio/[VAR[*]]]]]] や
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[CODE(MIME)[[[video/[VAR[*]]]]]] の内容の時間を、
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その内容を形成するバイナリ・データの外部で明示的に識別するという選択肢を導入します。
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環境によっては (大部分ではないにしろ) 頭欄で実際の時間を識別すると安全上問題となり、
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結果として示すべきではないとなるかもしれません。
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この頭欄で示す次官はデータの実際の大きさを決定する目的では信頼できません。
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データの実際の長さはデータ自体を検査して決定しなければなりません。
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*5. References
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**5.1. Normative References
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[INS(rfc3803)[
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>
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[MIME2] Gellens, R., "The Text/Plain Format Parameter", RFC 2646,
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August 1999.
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[VPIM2R2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet
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Mail - version 2 (VPIMv2)", RFC 3801, June 2004.
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[REQ] Bradner, S., "Key words for use in RFCs to Indicate
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Requirement Levels", BCP 14, RFC 2119, March 1997.
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]INS]
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**5.2. Informative References
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[INS(rfc3803)[
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>
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[DUR] Parsons, G. and G. Vaudreuil, "Content Duration MIME Header
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Definition", RFC 2424, September 1998.
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[VPIM2] Vaudreuil, G. and G. Parsons, "Voice Profile for Internet
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Mail - version 2", RFC 2421, September 1998.
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]INS]
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*6. Changes from RFC 2424
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[INS(rfc3803)[
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> Only editorial and boilerplate changes from RFC 2424 have been made
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to this document.
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]INS]
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*[DEL(rfc3803)[5.]] [INS(rfc3803)[7.]] Authors' Addresses
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[INS(rfc3803)[
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>
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Gregory M. Vaudreuil
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Lucent Technologies
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7291 Williamson Rd
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Dallas, TX 75214
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United States
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EMail: gregv@ieee.org
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]DEL]
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>
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Glenn W. Parsons
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[DEL(rfc3803)[Northern Telecom]]
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[INS(rfc3803)[Nortel Networks]]
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P.O. Box 3511, Station C
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Ottawa, ON K1Y 4H7
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Canada
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Phone: +1-613-763-7582
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Fax: [DEL(rfc3803)[+1-613-763-4461]] [INS(rfc3803)[+1-613-763-2697]]
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EMail: [DEL(rfc3803)[Glenn.Parsons@Nortel.ca]] [INS(rfc3803)[gparsons@nortelnetworks.com]]
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[DEL(rfc3803)[
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>
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Gregory M. Vaudreuil
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Lucent Technologies
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17080 Dallas Parkway
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Dallas, TX 75248-1905
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United States
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Phone/Fax: +1-972-733-2722
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EMail: GregV@Lucent.Com
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]DEL]
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*6. References
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[DEL(rfc3803)[
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>
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[MIME2] Freed, N., and N. Borenstein, "Multipurpose Internet Mail
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Extensions (MIME) Part Two: Media Types", RFC 2046, November
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1996.
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[VPIM2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet
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Mail - version 2", RFC 2421, September 1998.
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[REQ] Bradner, S., "Key words for use in RFCs to Indicate Requirement
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Levels", BCP 14, RFC 2119, March 1997.
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]DEL]
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*7. Full Copyright Statement
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[DEL(rfc3803)[
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> Copyright (C) The Internet Society (1998). All Rights Reserved.
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This document and translations of it may be copied and furnished to
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others, and derivative works that comment on or otherwise explain it
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or assist in its implementation may be prepared, copied, published
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and distributed, in whole or in part, without restriction of any
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kind, provided that the above copyright notice and this paragraph are
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included on all such copies and derivative works. However, this
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document itself may not be modified in any way, such as by removing
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the copyright notice or references to the Internet Society or other
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Internet organizations, except as needed for the purpose of
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developing Internet standards in which case the procedures for
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copyrights defined in the Internet Standards process must be
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followed, or as required to translate it into languages other than
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English.
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The limited permissions granted above are perpetual and will not be
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revoked by the Internet Society or its successors or assigns.
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This document and the information contained herein is provided on an
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"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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]DEL]
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*8. Full Copyright Statement
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[INS(rfc3803)[
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Copyright (C) The Internet Society (2004). This document is subject
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to the rights, licenses and restrictions contained in BCP 78, and
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except as set forth therein, the authors retain all their rights.
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This document and the information contained herein are provided on an
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"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
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ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
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INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
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INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
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WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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]INS]
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*Intellectual Property
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[INS(rfc3803)[
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The IETF takes no position regarding the validity or scope of any
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Intellectual Property Rights or other rights that might be claimed to
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pertain to the implementation or use of the technology described in
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this document or the extent to which any license under such rights
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might or might not be available; nor does it represent that it has
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made any independent effort to identify any such rights. Information
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on the procedures with respect to rights in RFC documents can be
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found in BCP 78 and BCP 79.
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Copies of IPR disclosures made to the IETF Secretariat and any
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assurances of licenses to be made available, or the result of an
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attempt made to obtain a general license or permission for the use of
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such proprietary rights by implementers or users of this
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specification can be obtained from the IETF on-line IPR repository at
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http://www.ietf.org/ipr.
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The IETF invites any interested party to bring to its attention any
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copyrights, patents or patent applications, or other proprietary
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rights that may cover technology that may be required to implement
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this standard. Please address the information to the IETF at ietf-
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ipr@ietf.org.
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]INS]
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*Acknowledgement
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[INS(rfc3803)[
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> Funding for the RFC Editor function is currently provided by the
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Internet Society.
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]INS]
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*memo |
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