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6      <title>Use of the Content-Disposition&nbsp;Header&nbsp;Field
7         in the Hypertext&nbsp;Transfer&nbsp;Protocol&nbsp;(HTTP)
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385</style><link rel="Contents" href="#rfc.toc">
386      <link rel="Author" href="#rfc.authors">
387      <link rel="Copyright" href="#rfc.copyrightnotice">
388      <link rel="Index" href="#rfc.index">
389      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
390      <link rel="Chapter" title="2 Notational Conventions" href="#rfc.section.2">
391      <link rel="Chapter" title="3 Header Field Definition" href="#rfc.section.3">
392      <link rel="Chapter" title="4 Examples" href="#rfc.section.4">
393      <link rel="Chapter" title="5 Internationalization Considerations" href="#rfc.section.5">
394      <link rel="Chapter" title="6 Security Considerations" href="#rfc.section.6">
395      <link rel="Chapter" title="7 IANA Considerations" href="#rfc.section.7">
396      <link rel="Chapter" title="8 Acknowledgements" href="#rfc.section.8">
397      <link rel="Chapter" href="#rfc.section.9" title="9 References">
398      <link rel="Appendix" title="A Changes from the RFC 2616 Definition" href="#rfc.section.A">
399      <link rel="Appendix" title="B Differences compared to RFC 2183" href="#rfc.section.B">
400      <link rel="Appendix" title="C Alternative Approaches to Internationalization" href="#rfc.section.C">
401      <link rel="Appendix" title="D Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.D">
402      <meta name="generator" content=", Revision 1.524, 2010-09-14 12:37:11, XSLT vendor: SAXON 8.9 from Saxonica">
403      <link rel="schema.dct" href="">
404      <meta name="dct.creator" content="Reschke, J. F.">
405      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-content-disp-03">
406      <meta name="dct.issued" scheme="ISO8601" content="2010-10-25">
407      <meta name="dct.abstract" content="HTTP/1.1 defines the Content-Disposition response header field, but points out that it is not part of the HTTP/1.1 Standard. This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization aspects.">
408      <meta name="description" content="HTTP/1.1 defines the Content-Disposition response header field, but points out that it is not part of the HTTP/1.1 Standard. This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization aspects.">
409   </head>
410   <body>
411      <table class="header">
412         <tbody>
413            <tr>
414               <td class="left">HTTPbis Working Group</td>
415               <td class="right">J. Reschke</td>
416            </tr>
417            <tr>
418               <td class="left">Internet-Draft</td>
419               <td class="right">greenbytes</td>
420            </tr>
421            <tr>
422               <td class="left">Updates: <a href="">2616</a> (if approved)
423               </td>
424               <td class="right">October 25, 2010</td>
425            </tr>
426            <tr>
427               <td class="left">Intended status: Standards Track</td>
428               <td class="right"></td>
429            </tr>
430            <tr>
431               <td class="left">Expires: April 28, 2011</td>
432               <td class="right"></td>
433            </tr>
434         </tbody>
435      </table>
436      <p class="title">Use of the Content-Disposition&nbsp;Header&nbsp;Field in the Hypertext&nbsp;Transfer&nbsp;Protocol&nbsp;(HTTP)<br><span class="filename">draft-ietf-httpbis-content-disp-03</span></p>
437      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
438      <p>HTTP/1.1 defines the Content-Disposition response header field, but points out that it is not part of the HTTP/1.1 Standard.
439         This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization
440         aspects.
441      </p>
442      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor before publication)</a></h1>
443      <p>This specification is expected to replace the definition of Content-Disposition in the HTTP/1.1 specification, as currently
444         revised by the IETF HTTPbis working group. See also &lt;<a href=""></a>&gt;.
445      </p> 
446      <p>Discussion of this draft should take place on the HTTPBIS working group mailing list ( The current issues
447         list is at &lt;<a href=""></a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href=""></a>&gt;.
448      </p> 
449      <p>The changes in this draft are summarized in <a href="#changes.since.02" title="Since draft-ietf-httpbis-content-disp-02">Appendix&nbsp;D.7</a>.
450      </p>
451      <h1><a id="rfc.status" href="#rfc.status">Status of This Memo</a></h1>
452      <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
453      <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
454         working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href=""></a>.
455      </p>
456      <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
457         documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
458         in progress”.
459      </p>
460      <p>This Internet-Draft will expire on April 28, 2011.</p>
461      <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1>
462      <p>Copyright © 2010 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
463      <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (<a href=""></a>) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights
464         and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
465         text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
466         BSD License.
467      </p>
468      <hr class="noprint">
469      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
470      <ul class="toc">
471         <li class="tocline0">1.&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a></li>
472         <li class="tocline0">2.&nbsp;&nbsp;&nbsp;<a href="#rfc.section.2">Notational Conventions</a></li>
473         <li class="tocline0">3.&nbsp;&nbsp;&nbsp;<a href="#header.field.definition">Header Field Definition</a><ul class="toc">
474               <li class="tocline1">3.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.3.1">Grammar</a></li>
475               <li class="tocline1">3.2&nbsp;&nbsp;&nbsp;<a href="#disposition.type">Disposition Type</a></li>
476               <li class="tocline1">3.3&nbsp;&nbsp;&nbsp;<a href="#disposition.parameter.filename">Disposition Parameter: 'Filename'</a></li>
477               <li class="tocline1">3.4&nbsp;&nbsp;&nbsp;<a href="#disposition.parameter.extensions">Disposition Parameter: Extensions</a></li>
478               <li class="tocline1">3.5&nbsp;&nbsp;&nbsp;<a href="#extensibility">Extensibility</a></li>
479            </ul>
480         </li>
481         <li class="tocline0">4.&nbsp;&nbsp;&nbsp;<a href="#examples">Examples</a></li>
482         <li class="tocline0">5.&nbsp;&nbsp;&nbsp;<a href="#i18n">Internationalization Considerations</a></li>
483         <li class="tocline0">6.&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a></li>
484         <li class="tocline0">7.&nbsp;&nbsp;&nbsp;<a href="#iana.considerations">IANA Considerations</a><ul class="toc">
485               <li class="tocline1">7.1&nbsp;&nbsp;&nbsp;<a href="#registry">Registry for Disposition Values and Parameter</a></li>
486               <li class="tocline1">7.2&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
487            </ul>
488         </li>
489         <li class="tocline0">8.&nbsp;&nbsp;&nbsp;<a href="#rfc.section.8">Acknowledgements</a></li>
490         <li class="tocline0">9.&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul class="toc">
491               <li class="tocline1">9.1&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
492               <li class="tocline1">9.2&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
493            </ul>
494         </li>
495         <li class="tocline0"><a href="#rfc.authors">Author's Address</a></li>
496         <li class="tocline0">A.&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc2616">Changes from the RFC 2616 Definition</a></li>
497         <li class="tocline0">B.&nbsp;&nbsp;&nbsp;<a href="">Differences compared to RFC 2183</a></li>
498         <li class="tocline0">C.&nbsp;&nbsp;&nbsp;<a href="#alternatives">Alternative Approaches to Internationalization</a><ul class="toc">
499               <li class="tocline1">C.1&nbsp;&nbsp;&nbsp;<a href="#alternatives.rfc2047">RFC 2047 Encoding</a></li>
500               <li class="tocline1">C.2&nbsp;&nbsp;&nbsp;<a href="#alternatives.percent">Percent Encoding</a></li>
501               <li class="tocline1">C.3&nbsp;&nbsp;&nbsp;<a href="#alternatives.sniff">Encoding Sniffing</a></li>
502               <li class="tocline1">C.4&nbsp;&nbsp;&nbsp;<a href="#alternatives.implementations">Implementations (to be removed by RFC Editor before publication)</a></li>
503            </ul>
504         </li>
505         <li class="tocline0">D.&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul class="toc">
506               <li class="tocline1">D.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.1">Since draft-reschke-rfc2183-in-http-00</a></li>
507               <li class="tocline1">D.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.2">Since draft-reschke-rfc2183-in-http-01</a></li>
508               <li class="tocline1">D.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.3">Since draft-reschke-rfc2183-in-http-02</a></li>
509               <li class="tocline1">D.4&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.4">Since draft-reschke-rfc2183-in-http-03</a></li>
510               <li class="tocline1">D.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></li>
511               <li class="tocline1">D.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></li>
512               <li class="tocline1">D.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></li>
513            </ul>
514         </li>
515         <li class="tocline0"><a href="#rfc.index">Index</a></li>
516      </ul>
517      <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a id="introduction" href="#introduction">Introduction</a></h1>
518      <p id="rfc.section.1.p.1">HTTP/1.1 defines the Content-Disposition response header field in <a href="">Section 19.5.1</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, but points out that it is not part of the HTTP/1.1 Standard (<a href="" id="rfc.xref.RFC2616.2">Section 15.5</a>):
519      </p>
520      <blockquote id="rfc.section.1.p.2" cite="">
521         <p>Content-Disposition is not part of the HTTP standard, but since it is widely implemented, we are documenting its use and risks
522            for implementers.
523         </p>
524      </blockquote>
525      <p id="rfc.section.1.p.3">This specification takes over the definition and registration of Content-Disposition, as used in HTTP. Based on interoperability
526         testing with existing User Agents, it fully defines a profile of the features defined in the Multipurpose Internet Mail Extensions
527         (MIME) variant (<a href="#RFC2183" id="rfc.xref.RFC2183.1"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a>) of the header field, and also clarifies internationalization aspects.
528      </p>
529      <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;Notational Conventions
530      </h1>
531      <p id="rfc.section.2.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
532         in this document are to be interpreted as described in <a href="#RFC2119" id="rfc.xref.RFC2119.1"><cite title="Key words for use in RFCs to Indicate Requirement Levels">[RFC2119]</cite></a>.
533      </p>
534      <p id="rfc.section.2.p.2">This specification uses the augmented BNF notation defined in <a href="">Section 2.1</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.3"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, including its rules for linear whitespace (LWS).
535      </p>
536      <div id="rfc.iref.h.1"></div>
537      <div id="rfc.iref.c.1"></div>
538      <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a id="header.field.definition" href="#header.field.definition">Header Field Definition</a></h1>
539      <p id="rfc.section.3.p.1">The Content-Disposition response header field is used to convey additional information about how to process the response payload,
540         and also can be used to attach additional metadata, such as the filename to use when saving the response payload locally.
541      </p>
542      <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;Grammar
543      </h2>
544      <div id="rfc.figure.u.1"></div><pre class="inline">  content-disposition = "Content-Disposition" ":"
545                         disposition-type *( ";" disposition-parm )
547  disposition-type    = "inline" | "attachment" | disp-ext-type
548                      ; case-insensitive
549  disp-ext-type       = token
551  disposition-parm    = filename-parm | disp-ext-parm
553  filename-parm       = "filename" "=" value
554                      | "filename*" "=" ext-value
556  disp-ext-parm       = token "=" value
557                      | ext-token "=" ext-value
558  ext-token           = &lt;the characters in token, followed by "*"&gt;
559</pre><div id="rfc.figure.u.2"></div>
560      <p>Defined in <a href="#RFC2616" id="rfc.xref.RFC2616.4"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>:
561      </p>  <pre class="inline">  token       = &lt;token, defined in <a href="#RFC2616" id="rfc.xref.RFC2616.5"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="">Section 2.2</a>&gt;
562  value       = &lt;value, defined in <a href="#RFC2616" id="rfc.xref.RFC2616.6"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="">Section 3.6</a>&gt;
563</pre><div id="rfc.figure.u.3"></div>
564      <p>Defined in <a href="#RFC5987" id="rfc.xref.RFC5987.1"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>:
565      </p>  <pre class="inline">  ext-value   = &lt;ext-value, defined in <a href="#RFC5987" id="rfc.xref.RFC5987.2"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>, <a href="">Section 3.2</a>&gt;
566</pre><p id="rfc.section.3.1.p.4">Parameter names <em class="bcp14">MUST NOT</em> be repeated; a header field value with multiple instances of the same parameter <em class="bcp14">SHOULD</em> be treated as invalid.
567      </p>
568      <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a id="disposition.type" href="#disposition.type">Disposition Type</a></h2>
569      <p id="rfc.section.3.2.p.1">If the disposition type matches "attachment" (case-insensitively), this indicates that the user agent should prompt the user
570         to save the response locally, rather than process it normally (as per its media type).
571      </p>
572      <p id="rfc.section.3.2.p.2">On the other hand, if it matches "inline" (case-insensitively), this implies default processing.</p>
573      <p id="rfc.section.3.2.p.3">Unknown or unhandled disposition types <em class="bcp14">SHOULD</em> be handled the same way as "attachment" (see also <a href="#RFC2183" id="rfc.xref.RFC2183.2"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a>, <a href="">Section 2.8</a>).
574      </p>
575      <h2 id="rfc.section.3.3"><a href="#rfc.section.3.3">3.3</a>&nbsp;<a id="disposition.parameter.filename" href="#disposition.parameter.filename">Disposition Parameter: 'Filename'</a></h2>
576      <p id="rfc.section.3.3.p.1">The parameters "filename" and "filename*", to be matched case-insensitively, provide information on how to construct a filename
577         for storing the message payload.
578      </p>
579      <p id="rfc.section.3.3.p.2">Depending on the disposition type, this information might be used right away (in the "save as..." interaction caused for the
580         "attachment" disposition type), or later on (for instance, when the user decides to save the contents of the current page
581         being displayed).
582      </p>
583      <p id="rfc.section.3.3.p.3">The parameters "filename" and "filename*" differ only in that "filename*" uses the encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.3"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>, allowing the use of characters not present in the ISO-8859-1 character set (<a href="#ISO-8859-1" id="rfc.xref.ISO-8859-1.1"><cite title="Information technology -- 8-bit single-byte coded graphic character sets -- Part 1: Latin alphabet No. 1">[ISO-8859-1]</cite></a>).
584      </p>
585      <p id="rfc.section.3.3.p.4">Many user agent implementations predating this specification do not understand the "filename*" parameter. Therefore, when
586         both "filename" and "filename*" are present in a single header field value, recipients <em class="bcp14">SHOULD</em> pick "filename*" and ignore "filename". This way, senders can avoid special-casing specific user agents by sending both the
587         more expressive "filename*" parameter, and the "filename" parameter as fallback for legacy recipients (see <a href="#examples" title="Examples">Section&nbsp;4</a> for an example).
588      </p>
589      <p id="rfc.section.3.3.p.5">It is essential that user agents treat the specified filename as advisory only, thus be very careful in extracting the desired
590         information. In particular:
591      </p>
592      <ul>
593         <li>
594            <p>When the value contains path separator characters, all but the last segment <em class="bcp14">SHOULD</em> be ignored. This prevents unintentional overwriting of well-known file system location (such as "/etc/passwd").
595            </p>
596         </li>
597         <li>
598            <p>Many platforms do not use Internet Media Types (<a href="#RFC2046" id="rfc.xref.RFC2046.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a>) to hold type information in the file system, but rely on filename extensions instead. Trusting the server-provided file
599               extension could introduce a privilege escalation when the saved file is later opened (consider ".exe"). Thus, recipients need
600               to ensure that a file extension is used that is safe, optimally matching the media type of the received payload.
601            </p>
602         </li>
603         <li>
604            <p>Recipients are advised to strip or replace character sequences that are known to cause confusion both in user interfaces and
605               in filenames, such as control characters and leading and trailing whitespace.
606            </p>
607         </li>
608         <li>
609            <p>Other aspects recipients need to be aware of are names that have a special meaning in the file system or in shell commands,
610               such as "." and "..", "~", "|", and also device names.
611            </p>
612         </li>
613      </ul>
614      <div class="note" id="rfc.section.3.3.p.6">
615         <p> <b>Note:</b> Many user agents do not properly handle escape characters when using the quoted-string form. Furthermore, some user agents
616            erroneously try to perform unescaping of "percent" escapes (see <a href="#alternatives.percent" title="Percent Encoding">Appendix&nbsp;C.2</a>), and thus might misinterpret filenames containing the percent character followed by two hex digits.
617         </p>
618      </div>
619      <h2 id="rfc.section.3.4"><a href="#rfc.section.3.4">3.4</a>&nbsp;<a id="disposition.parameter.extensions" href="#disposition.parameter.extensions">Disposition Parameter: Extensions</a></h2>
620      <p id="rfc.section.3.4.p.1">To enable future extensions, unknown parameters <em class="bcp14">SHOULD</em> be ignored (see also <a href="#RFC2183" id="rfc.xref.RFC2183.3"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a>, <a href="">Section 2.8</a>).
621      </p>
622      <h2 id="rfc.section.3.5"><a href="#rfc.section.3.5">3.5</a>&nbsp;<a id="extensibility" href="#extensibility">Extensibility</a></h2>
623      <p id="rfc.section.3.5.p.1">Note that <a href="">Section 9</a> of <a href="#RFC2183" id="rfc.xref.RFC2183.4"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a> defines IANA registries both for disposition types and disposition parameters. This registry is shared by different protocols
624         using Content-Disposition, such as MIME and HTTP. Therefore, not all registered values may make sense in the context of HTTP.
625      </p>
626      <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a id="examples" href="#examples">Examples</a></h1>
627      <div id="rfc.figure.u.4"></div>
628      <p>Direct UA to show "save as" dialog, with a filename of "example.html":</p>  <pre class="text">Content-Disposition: Attachment; filename=example.html
629</pre><div id="rfc.figure.u.5"></div>
630      <p>Direct UA to behave as if the Content-Disposition header field wasn't present, but to remember the filename "example.html"
631         for a subsequent save operation:
632      </p>  <pre class="text">Content-Disposition: INLINE; FILENAME= "example.html"
633</pre><div id="rfc.figure.u.6"></div>
634      <p>Direct UA to show "save as" dialog, with a filename of "an example":</p>  <pre class="text">Content-Disposition: Attachment; Filename*=UTF-8'<b>en</b>'an<b>%20</b>example
635</pre>  <p>Note that this example uses the extended encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.4"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a> to specify that the natural language of the filename is English, and also to encode the space character which is not allowed
636         in the token production.
637      </p>
638      <div id="rfc.figure.u.7"></div>
639      <p>Direct UA to show "save as" dialog, with a filename containing the Unicode character U+20AC (EURO SIGN):</p>  <pre class="text">Content-Disposition: attachment;
640                     filename*= UTF-8''<b>%e2%82%ac</b>%20rates
641</pre>  <p>Here, the encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.5"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a> is also used to encode the non-ISO-8859-1 character.
642      </p>
643      <div id="rfc.figure.u.8"></div>
644      <p>Same as above, but adding the "filename" parameter for compatibility with user agents not implementing RFC 5987:</p>  <pre class="text">Content-Disposition: attachment;
645                     filename="EURO rates";
646                     filename*=utf-8''<b>%e2%82%ac</b>%20rates
647</pre>  <p>Note: as of October 2010, those user agents that do not support the RFC 5987 encoding ignore "filename*" when it occurs after
648         "filename". Unfortunately, some user agents that do support RFC 5987 do pick the "filename" rather than the "filename*" parameter
649         when it occurs first; it is expected that this situation is going to improve soon.
650      </p>
651      <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a id="i18n" href="#i18n">Internationalization Considerations</a></h1>
652      <p id="rfc.section.5.p.1">The "filename*" parameter (<a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;3.3</a>), using the encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.6"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>, allows the server to transmit characters outside the ISO-8859-1 character set, and also to optionally specify the language
653         in use.
654      </p>
655      <p id="rfc.section.5.p.2">Future parameters might also require internationalization, in which case the same encoding can be used.</p>
656      <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a id="security.considerations" href="#security.considerations">Security Considerations</a></h1>
657      <p id="rfc.section.6.p.1">Using server-supplied information for constructing local filenames introduces many risks. These are summarized in <a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;3.3</a>.
658      </p>
659      <p id="rfc.section.6.p.2">Furthermore, implementers also ought to be aware of the Security Considerations applying to HTTP (see <a href="">Section 15</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.7"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>), and also the parameter encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.7"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a> (see <a href="" id="rfc.xref.RFC5987.8">Section 5</a>).
660      </p>
661      <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a id="iana.considerations" href="#iana.considerations">IANA Considerations</a></h1>
662      <h2 id="rfc.section.7.1"><a href="#rfc.section.7.1">7.1</a>&nbsp;<a id="registry" href="#registry">Registry for Disposition Values and Parameter</a></h2>
663      <p id="rfc.section.7.1.p.1">This specification does not introduce any changes to the registration procedures for disposition values and parameters that
664         are defined in <a href="">Section 9</a> of <a href="#RFC2183" id="rfc.xref.RFC2183.5"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a>.
665      </p>
666      <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a>&nbsp;<a id="header.field.registration" href="#header.field.registration">Header Field Registration</a></h2>
667      <p id="rfc.section.7.2.p.1">This document updates the definition of the Content-Disposition HTTP header field in the permanent HTTP header field registry
668         (see <a href="#RFC3864" id="rfc.xref.RFC3864.1"><cite title="Registration Procedures for Message Header Fields">[RFC3864]</cite></a>).
669      </p>
670      <p id="rfc.section.7.2.p.2"> </p>
671      <dl>
672         <dt>Header field name:</dt>
673         <dd>Content-Disposition</dd>
674         <dt>Applicable protocol:</dt>
675         <dd>http</dd>
676         <dt>Status:</dt>
677         <dd>standard</dd>
678         <dt>Author/Change controller:</dt>
679         <dd>IETF</dd>
680         <dt>Specification document:</dt>
681         <dd>this specification (<a href="#header.field.definition" id="rfc.xref.header.field.definition.1" title="Header Field Definition">Section&nbsp;3</a>)
682         </dd>
683      </dl>
684      <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;Acknowledgements
685      </h1>
686      <p id="rfc.section.8.p.1">Thanks to Adam Barth, Rolf Eike Beer, Bjoern Hoehrmann, Alfred Hoenes, Roar Lauritzsen, Henrik Nordstrom, and Mark Nottingham
687         for their valuable feedback.
688      </p>
689      <h1 id="rfc.references"><a id="rfc.section.9" href="#rfc.section.9">9.</a> References
690      </h1>
691      <h2 id="rfc.references.1"><a href="#rfc.section.9.1" id="rfc.section.9.1">9.1</a> Normative References
692      </h2>
693      <table>       
694         <tr>
695            <td class="reference"><b id="ISO-8859-1">[ISO-8859-1]</b></td>
696            <td class="top">International Organization for Standardization, “Information technology -- 8-bit single-byte coded graphic character sets -- Part 1: Latin alphabet No. 1”, ISO/IEC&nbsp;8859-1:1998, 1998.</td>
697         </tr>
698         <tr>
699            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
700            <td class="top"><a href="" title="Harvard University">Bradner, S.</a>, “<a href="">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
701            </td>
702         </tr>
703         <tr>
704            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
705            <td class="top"><a href="" title="University of California, Irvine">Fielding, R.</a>, <a href="" title="W3C">Gettys, J.</a>, <a href="" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="" title="Xerox Corporation">Masinter, L.</a>, <a href="" title="Microsoft Corporation">Leach, P.</a>, and <a href="" title="W3C">T. Berners-Lee</a>, “<a href="">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
706            </td>
707         </tr>
708         <tr>
709            <td class="reference"><b id="RFC5987">[RFC5987]</b></td>
710            <td class="top"><a href="" title="greenbytes GmbH">Reschke, J.</a>, “<a href="">Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters</a>”, RFC&nbsp;5987, August&nbsp;2010.
711            </td>
712         </tr>
713      </table>
714      <h2 id="rfc.references.2"><a href="#rfc.section.9.2" id="rfc.section.9.2">9.2</a> Informative References
715      </h2>
716      <table>             
717         <tr>
718            <td class="reference"><b id="RFC2046">[RFC2046]</b></td>
719            <td class="top"><a href="" title="Innosoft International, Inc.">Freed, N.</a> and <a href="" title="First Virtual Holdings">N. Borenstein</a>, “<a href="">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</a>”, RFC&nbsp;2046, November&nbsp;1996.
720            </td>
721         </tr>
722         <tr>
723            <td class="reference"><b id="RFC2047">[RFC2047]</b></td>
724            <td class="top"><a href="" title="University of Tennessee">Moore, K.</a>, “<a href="">MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text</a>”, RFC&nbsp;2047, November&nbsp;1996.
725            </td>
726         </tr>
727         <tr>
728            <td class="reference"><b id="RFC2183">[RFC2183]</b></td>
729            <td class="top"><a href="" title="New Century Systems">Troost, R.</a>, <a href="" title="QUALCOMM Incorporated">Dorner, S.</a>, and <a href="" title="Department of Computer Science">K. Moore</a>, “<a href="">Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field</a>”, RFC&nbsp;2183, August&nbsp;1997.
730            </td>
731         </tr>
732         <tr>
733            <td class="reference"><b id="RFC2231">[RFC2231]</b></td>
734            <td class="top"><a href="" title="Innosoft International, Inc.">Freed, N.</a> and <a href="" title="University of Tennessee">K. Moore</a>, “<a href="">MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations</a>”, RFC&nbsp;2231, November&nbsp;1997.
735            </td>
736         </tr>
737         <tr>
738            <td class="reference"><b id="RFC3629">[RFC3629]</b></td>
739            <td class="top"><a href="" title="Alis Technologies">Yergeau, F.</a>, “<a href="">UTF-8, a transformation format of ISO 10646</a>”, STD&nbsp;63, RFC&nbsp;3629, November&nbsp;2003.
740            </td>
741         </tr>
742         <tr>
743            <td class="reference"><b id="RFC3864">[RFC3864]</b></td>
744            <td class="top"><a href="" title="Nine by Nine">Klyne, G.</a>, <a href="" title="BEA Systems">Nottingham, M.</a>, and <a href="" title="HP Labs">J. Mogul</a>, “<a href="">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
745            </td>
746         </tr>
747         <tr>
748            <td class="reference"><b id="RFC3986">[RFC3986]</b></td>
749            <td class="top"><a href="" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="" title="Day Software">Fielding, R.</a>, and <a href="" title="Adobe Systems Incorporated">L. Masinter</a>, “<a href="">Uniform Resource Identifier (URI): Generic Syntax</a>”, STD&nbsp;66, RFC&nbsp;3986, January&nbsp;2005.
750            </td>
751         </tr>
752      </table>
753      <div class="avoidbreak">
754         <h1 id="rfc.authors"><a href="#rfc.authors">Author's Address</a></h1>
755         <address class="vcard"><span class="vcardline"><span class="fn">Julian F. Reschke</span><span class="n hidden"><span class="family-name">Reschke</span><span class="given-name">Julian F.</span></span></span><span class="org vcardline">greenbytes GmbH</span><span class="adr"><span class="street-address vcardline">Hafenweg 16</span><span class="vcardline"><span class="locality">Muenster</span>, <span class="region">NW</span>&nbsp;<span class="postal-code">48155</span></span><span class="country-name vcardline">Germany</span></span><span class="vcardline">Email: <a href=""><span class="email"></span></a></span><span class="vcardline">URI: <a href="" class="url"></a></span></address>
756      </div>
757      <h1 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a id="changes.from.rfc2616" href="#changes.from.rfc2616">Changes from the RFC 2616 Definition</a></h1>
758      <p id="rfc.section.A.p.1">Compared to <a href="">Section 19.5.1</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.8"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, the following normative changes reflecting actual implementations have been made:
759      </p>
760      <ul>
761         <li>According to RFC 2616, the disposition type "attachment" only applies to content of type "application/octet-stream". This
762            restriction has been removed, because user agents in practice do not check the content type, and it also discourages properly
763            declaring the media type.
764         </li>
765         <li>RFC 2616 only allows "quoted-string" for the filename parameter. This would be an exceptional parameter syntax, and also doesn't
766            reflect actual use.
767         </li>
768         <li>The definition for the disposition type "inline" (<a href="#RFC2183" id="rfc.xref.RFC2183.6"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a>, <a href="">Section 2.1</a>) has been re-added with a suggestion for its processing.
769         </li>
770         <li>This specification requires support for the extended parameter encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.9"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>.
771         </li>
772      </ul>
773      <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a id="" href="">Differences compared to RFC 2183</a></h1>
774      <p id="rfc.section.B.p.1"> <a href="">Section 2</a> of <a href="#RFC2183" id="rfc.xref.RFC2183.7"><cite title="Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field">[RFC2183]</cite></a> defines several additional disposition parameters: "creation-date", "modification-date", "quoted-date-time", and "size". These
775         do not appear to be implemented by any user agent, thus have been omitted from this specification.
776      </p>
777      <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a id="alternatives" href="#alternatives">Alternative Approaches to Internationalization</a></h1>
778      <p id="rfc.section.C.p.1">By default, HTTP header field parameters cannot carry characters outside the ISO-8859-1 (<a href="#ISO-8859-1" id="rfc.xref.ISO-8859-1.2"><cite title="Information technology -- 8-bit single-byte coded graphic character sets -- Part 1: Latin alphabet No. 1">[ISO-8859-1]</cite></a>) character encoding (see <a href="#RFC2616" id="rfc.xref.RFC2616.9"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="">Section 2.2</a>). For the "filename" parameter, this of course is an unacceptable restriction.
779      </p>
780      <p id="rfc.section.C.p.2">Unfortunately, user agent implementers have not managed to come up with an interoperable approach, although the IETF Standards
781         Track specifies exactly one solution (<a href="#RFC2231" id="rfc.xref.RFC2231.1"><cite title="MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations">[RFC2231]</cite></a>, clarified and profiled for HTTP in <a href="#RFC5987" id="rfc.xref.RFC5987.10"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>).
782      </p>
783      <p id="rfc.section.C.p.3">For completeness, the sections below describe the various approaches that have been tried, and explains how they are inferior
784         to the RFC 5987 encoding used in this specification.
785      </p>
786      <h2 id="rfc.section.C.1"><a href="#rfc.section.C.1">C.1</a>&nbsp;<a id="alternatives.rfc2047" href="#alternatives.rfc2047">RFC 2047 Encoding</a></h2>
787      <p id="rfc.section.C.1.p.1">RFC 2047 defines an encoding mechanism for header fields, but this encoding is not supposed to be used for header field parameters
788         - see <a href="">Section 5</a> of <a href="#RFC2047" id="rfc.xref.RFC2047.1"><cite title="MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text">[RFC2047]</cite></a>:
789      </p>
790      <blockquote id="rfc.section.C.1.p.2" cite="">
791         <p>An 'encoded-word' MUST NOT appear within a 'quoted-string'.</p> 
792         <p>...</p> 
793         <p>An 'encoded-word' MUST NOT be used in parameter of a MIME Content-Type or Content-Disposition field, or in any structured
794            field body except within a 'comment' or 'phrase'.
795         </p>
796      </blockquote>
797      <p id="rfc.section.C.1.p.3">In practice, some user agents implement the encoding, some do not (exposing the encoded string to the user), and some get
798         confused by it.
799      </p>
800      <h2 id="rfc.section.C.2"><a href="#rfc.section.C.2">C.2</a>&nbsp;<a id="alternatives.percent" href="#alternatives.percent">Percent Encoding</a></h2>
801      <p id="rfc.section.C.2.p.1">Some user agents accept percent encoded (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="">Section 2.1</a>) sequences of characters encoded using the UTF-8 (<a href="#RFC3629" id="rfc.xref.RFC3629.1"><cite title="UTF-8, a transformation format of ISO 10646">[RFC3629]</cite></a>) character encoding.
802      </p>
803      <p id="rfc.section.C.2.p.2">In practice, this is hard to use because those user agents that do not support it will display the escaped character sequence
804         to the user.
805      </p>
806      <p id="rfc.section.C.2.p.3">Furthermore, the first user agent to implement this did choose the encoding based on local settings; thus making it very hard
807         to use in multi-lingual environments.
808      </p>
809      <h2 id="rfc.section.C.3"><a href="#rfc.section.C.3">C.3</a>&nbsp;<a id="alternatives.sniff" href="#alternatives.sniff">Encoding Sniffing</a></h2>
810      <p id="rfc.section.C.3.p.1">Some user agents inspect the value (which defaults to ISO-8859-1) and switch to UTF-8 when it seems to be more likely to be
811         the correct interpretation.
812      </p>
813      <p id="rfc.section.C.3.p.2">As with the approaches above, this is not interoperable and furthermore risks misinterpreting the actual value.</p>
814      <h2 id="rfc.section.C.4"><a href="#rfc.section.C.4">C.4</a>&nbsp;<a id="alternatives.implementations" href="#alternatives.implementations">Implementations (to be removed by RFC Editor before publication)</a></h2>
815      <p id="rfc.section.C.4.p.1">Unfortunately, as of October 2010, neither the encoding defined in RFCs 2231 and 5987, nor any of the alternate approaches
816         discussed above was implemented interoperably. Thus, this specification recommends the approach defined in RFC 5987, which
817         at least has the advantage of actually being specified properly.
818      </p>
819      <p id="rfc.section.C.4.p.2">The table below shows the implementation support for the various approaches:</p>
820      <div id="rfc.table.u.1">
821         <table class="tt full left" cellpadding="3" cellspacing="0">
822            <thead>
823               <tr>
824                  <th>User Agent</th>
825                  <th>RFC 2231/5987</th>
826                  <th>RFC 2047</th>
827                  <th>Percent Encoding</th>
828                  <th>Encoding Sniffing</th>
829               </tr>
830            </thead>
831            <tbody>
832               <tr>
833                  <td class="left">Chrome</td>
834                  <td class="left">no</td>
835                  <td class="left">yes</td>
836                  <td class="left">yes</td>
837                  <td class="left">yes</td>
838               </tr>
839               <tr>
840                  <td class="left">Firefox</td>
841                  <td class="left">yes (*)</td>
842                  <td class="left">yes</td>
843                  <td class="left">no</td>
844                  <td class="left">yes</td>
845               </tr>
846               <tr>
847                  <td class="left">Internet Explorer</td>
848                  <td class="left">no</td>
849                  <td class="left">no</td>
850                  <td class="left">yes</td>
851                  <td class="left">no</td>
852               </tr>
853               <tr>
854                  <td class="left">Konqueror</td>
855                  <td class="left">yes</td>
856                  <td class="left">no</td>
857                  <td class="left">no</td>
858                  <td class="left">no</td>
859               </tr>
860               <tr>
861                  <td class="left">Opera</td>
862                  <td class="left">yes</td>
863                  <td class="left">no</td>
864                  <td class="left">no</td>
865                  <td class="left">no</td>
866               </tr>
867               <tr>
868                  <td class="left">Safari</td>
869                  <td class="left">no</td>
870                  <td class="left">no</td>
871                  <td class="left">no</td>
872                  <td class="left">yes</td>
873               </tr>
874            </tbody>
875         </table>
876         <p>(*) Does not implement the fallback behavior to "filename" described in <a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;3.3</a>.
877         </p>
878      </div>
879      <h1 id="rfc.section.D"><a href="#rfc.section.D">D.</a>&nbsp;<a id="change.log" href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
880      <p id="rfc.section.D.p.1">Note: the issues names in the change log entries for draft-reschke-rfc2183-in-http refer to &lt;<a href=""></a>&gt;.
881      </p>
882      <h2 id="rfc.section.D.1"><a href="#rfc.section.D.1">D.1</a>&nbsp;Since draft-reschke-rfc2183-in-http-00
883      </h2>
884      <p id="rfc.section.D.1.p.1">Adjust terminology ("header" -&gt; "header field"). Update rfc2231-in-http reference.</p>
885      <h2 id="rfc.section.D.2"><a href="#rfc.section.D.2">D.2</a>&nbsp;Since draft-reschke-rfc2183-in-http-01
886      </h2>
887      <p id="rfc.section.D.2.p.1">Update rfc2231-in-http reference. Actually define the "filename" parameter. Add internationalization considerations. Add examples
888         using the RFC 5987 encoding. Add overview over other approaches, plus a table reporting implementation status. Add and resolve
889         issue "nodep2183". Add issues "asciivsiso", "deplboth", "quoted", and "registry".
890      </p>
891      <h2 id="rfc.section.D.3"><a href="#rfc.section.D.3">D.3</a>&nbsp;Since draft-reschke-rfc2183-in-http-02
892      </h2>
893      <p id="rfc.section.D.3.p.1">Add and close issue "docfallback". Close issues "asciivsiso", "deplboth", "quoted", and "registry".</p>
894      <h2 id="rfc.section.D.4"><a href="#rfc.section.D.4">D.4</a>&nbsp;Since draft-reschke-rfc2183-in-http-03
895      </h2>
896      <p id="rfc.section.D.4.p.1">Updated to be a Working Draft of the IETF HTTPbis Working Group.</p>
897      <h2 id="rfc.section.D.5"><a href="#rfc.section.D.5">D.5</a>&nbsp;<a id="changes.since.00" href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></h2>
898      <p id="rfc.section.D.5.p.1">Closed issues: </p>
899      <ul>
900         <li> &lt;<a href=""></a>&gt;: "handling of unknown disposition types"
901         </li>
902      </ul>
903      <p id="rfc.section.D.5.p.2">Slightly updated the notes about the proposed fallback behavior.</p>
904      <h2 id="rfc.section.D.6"><a href="#rfc.section.D.6">D.6</a>&nbsp;<a id="changes.since.01" href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></h2>
905      <p id="rfc.section.D.6.p.1">Various editorial improvements.</p>
906      <h2 id="rfc.section.D.7"><a href="#rfc.section.D.7">D.7</a>&nbsp;<a id="changes.since.02" href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></h2>
907      <p id="rfc.section.D.7.p.1">Closed issues: </p>
908      <ul>
909         <li> &lt;<a href=""></a>&gt;: "state that repeating parameters are invalid"
910         </li>
911         <li> &lt;<a href=""></a>&gt;: "warn about %xx in filenames being misinterpreted"
912         </li>
913         <li> &lt;<a href=""></a>&gt;: "mention control chars when talking about postprecessing the filename parameter"
914         </li>
915      </ul>
916      <p id="rfc.section.D.7.p.2">Update <a href="#alternatives.implementations" title="Implementations (to be removed by RFC Editor before publication)">Appendix&nbsp;C.4</a>; Opera 10.63 RC implements the recommended fallback behavior.
917      </p>
918      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
919      <p class="noprint"><a href="#rfc.index.C">C</a> <a href="#rfc.index.H">H</a> <a href="#rfc.index.I">I</a> <a href="#rfc.index.R">R</a>
920      </p>
921      <div class="print2col">
922         <ul class="ind">
923            <li class="indline0"><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul class="ind">
924                  <li class="indline1">Content-Disposition header&nbsp;&nbsp;<a class="iref" href="#rfc.iref.c.1"><b>3</b></a>, <a class="iref" href="#rfc.xref.header.field.definition.1">7.2</a></li>
925               </ul>
926            </li>
927            <li class="indline0"><a id="rfc.index.H" href="#rfc.index.H"><b>H</b></a><ul class="ind">
928                  <li class="indline1">Headers&nbsp;&nbsp;
929                     <ul class="ind">
930                        <li class="indline1">Content-Disposition&nbsp;&nbsp;<a class="iref" href="#rfc.iref.h.1"><b>3</b></a>, <a class="iref" href="#rfc.xref.header.field.definition.1">7.2</a></li>
931                     </ul>
932                  </li>
933               </ul>
934            </li>
935            <li class="indline0"><a id="rfc.index.I" href="#rfc.index.I"><b>I</b></a><ul class="ind">
936                  <li class="indline1"><em>ISO-8859-1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.ISO-8859-1.1">3.3</a>, <a class="iref" href="#ISO-8859-1"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.ISO-8859-1.2">C</a></li>
937               </ul>
938            </li>
939            <li class="indline0"><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul class="ind">
940                  <li class="indline1"><em>RFC2046</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2046.1">3.3</a>, <a class="iref" href="#RFC2046"><b>9.2</b></a></li>
941                  <li class="indline1"><em>RFC2047</em>&nbsp;&nbsp;<a class="iref" href="#RFC2047"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC2047.1">C.1</a><ul class="ind">
942                        <li class="indline1"><em>Section 5</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2047.1">C.1</a></li>
943                     </ul>
944                  </li>
945                  <li class="indline1"><em>RFC2119</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2119.1">2</a>, <a class="iref" href="#RFC2119"><b>9.1</b></a></li>
946                  <li class="indline1"><em>RFC2183</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2183.1">1</a>, <a class="iref" href="#rfc.xref.RFC2183.2">3.2</a>, <a class="iref" href="#rfc.xref.RFC2183.3">3.4</a>, <a class="iref" href="#rfc.xref.RFC2183.4">3.5</a>, <a class="iref" href="#rfc.xref.RFC2183.5">7.1</a>, <a class="iref" href="#RFC2183"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC2183.6">A</a>, <a class="iref" href="#rfc.xref.RFC2183.7">B</a><ul class="ind">
947                        <li class="indline1"><em>Section 2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2183.7">B</a></li>
948                        <li class="indline1"><em>Section 2.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2183.6">A</a></li>
949                        <li class="indline1"><em>Section 2.8</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2183.2">3.2</a>, <a class="iref" href="#rfc.xref.RFC2183.3">3.4</a></li>
950                        <li class="indline1"><em>Section 9</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2183.4">3.5</a>, <a class="iref" href="#rfc.xref.RFC2183.5">7.1</a></li>
951                     </ul>
952                  </li>
953                  <li class="indline1"><em>RFC2231</em>&nbsp;&nbsp;<a class="iref" href="#RFC2231"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC2231.1">C</a></li>
954                  <li class="indline1"><em>RFC2616</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.1">1</a>, <a class="iref" href="#rfc.xref.RFC2616.2">1</a>, <a class="iref" href="#rfc.xref.RFC2616.3">2</a>, <a class="iref" href="#rfc.xref.RFC2616.4">3.1</a>, <a class="iref" href="#rfc.xref.RFC2616.5">3.1</a>, <a class="iref" href="#rfc.xref.RFC2616.6">3.1</a>, <a class="iref" href="#rfc.xref.RFC2616.7">6</a>, <a class="iref" href="#RFC2616"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.RFC2616.8">A</a>, <a class="iref" href="#rfc.xref.RFC2616.9">C</a><ul class="ind">
955                        <li class="indline1"><em>Section 2.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.3">2</a></li>
956                        <li class="indline1"><em>Section 2.2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.5">3.1</a>, <a class="iref" href="#rfc.xref.RFC2616.9">C</a></li>
957                        <li class="indline1"><em>Section 3.6</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.6">3.1</a></li>
958                        <li class="indline1"><em>Section 15.5</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.2">1</a></li>
959                        <li class="indline1"><em>Section 15</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.7">6</a></li>
960                        <li class="indline1"><em>Section 19.5.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2616.1">1</a>, <a class="iref" href="#rfc.xref.RFC2616.8">A</a></li>
961                     </ul>
962                  </li>
963                  <li class="indline1"><em>RFC3629</em>&nbsp;&nbsp;<a class="iref" href="#RFC3629"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC3629.1">C.2</a></li>
964                  <li class="indline1"><em>RFC3864</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC3864.1">7.2</a>, <a class="iref" href="#RFC3864"><b>9.2</b></a></li>
965                  <li class="indline1"><em>RFC3986</em>&nbsp;&nbsp;<a class="iref" href="#RFC3986"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC3986.1">C.2</a><ul class="ind">
966                        <li class="indline1"><em>Section 2.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC3986.1">C.2</a></li>
967                     </ul>
968                  </li>
969                  <li class="indline1"><em>RFC5987</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC5987.1">3.1</a>, <a class="iref" href="#rfc.xref.RFC5987.2">3.1</a>, <a class="iref" href="#rfc.xref.RFC5987.3">3.3</a>, <a class="iref" href="#rfc.xref.RFC5987.4">4</a>, <a class="iref" href="#rfc.xref.RFC5987.5">4</a>, <a class="iref" href="#rfc.xref.RFC5987.6">5</a>, <a class="iref" href="#rfc.xref.RFC5987.7">6</a>, <a class="iref" href="#rfc.xref.RFC5987.8">6</a>, <a class="iref" href="#RFC5987"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.RFC5987.9">A</a>, <a class="iref" href="#rfc.xref.RFC5987.10">C</a><ul class="ind">
970                        <li class="indline1"><em>Section 3.2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC5987.2">3.1</a></li>
971                        <li class="indline1"><em>Section 5</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC5987.8">6</a></li>
972                     </ul>
973                  </li>
974               </ul>
975            </li>
976         </ul>
977      </div>
978   </body>
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