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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 Conformance and Error Handling" href="#rfc.section.3">
392      <link rel="Chapter" title="4 Header Field Definition" href="#rfc.section.4">
393      <link rel="Chapter" title="5 Examples" href="#rfc.section.5">
394      <link rel="Chapter" title="6 Internationalization Considerations" href="#rfc.section.6">
395      <link rel="Chapter" title="7 Security Considerations" href="#rfc.section.7">
396      <link rel="Chapter" title="8 IANA Considerations" href="#rfc.section.8">
397      <link rel="Chapter" title="9 Acknowledgements" href="#rfc.section.9">
398      <link rel="Chapter" href="#rfc.section.10" title="10 References">
399      <link rel="Appendix" title="A Changes from the RFC 2616 Definition" href="#rfc.section.A">
400      <link rel="Appendix" title="B Differences compared to RFC 2183" href="#rfc.section.B">
401      <link rel="Appendix" title="C Alternative Approaches to Internationalization" href="#rfc.section.C">
402      <link rel="Appendix" title="D Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.D">
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404      <link rel="schema.dct" href="http://purl.org/dc/terms/">
405      <meta name="dct.creator" content="Reschke, J. F.">
406      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-content-disp-latest">
407      <meta name="dct.issued" scheme="ISO8601" content="2011-02-12">
408      <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.">
409      <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.">
410   </head>
411   <body>
412      <table class="header">
413         <tbody>
414            <tr>
415               <td class="left">HTTPbis Working Group</td>
416               <td class="right">J. Reschke</td>
417            </tr>
418            <tr>
419               <td class="left">Internet-Draft</td>
420               <td class="right">greenbytes</td>
421            </tr>
422            <tr>
423               <td class="left">Updates: <a href="http://tools.ietf.org/html/rfc2616">2616</a> (if approved)
424               </td>
425               <td class="right">February 12, 2011</td>
426            </tr>
427            <tr>
428               <td class="left">Intended status: Standards Track</td>
429               <td class="right"></td>
430            </tr>
431            <tr>
432               <td class="left">Expires: August 16, 2011</td>
433               <td class="right"></td>
434            </tr>
435         </tbody>
436      </table>
437      <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-latest</span></p>
438      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
439      <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.
440         This specification takes over the definition and registration of Content-Disposition, as used in HTTP, and clarifies internationalization
441         aspects.
442      </p>
443      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor before publication)</a></h1>
444      <p>This specification is expected to replace the definition of Content-Disposition in the HTTP/1.1 specification, as currently
445         revised by the IETF HTTPbis working group. See also &lt;<a href="http://trac.tools.ietf.org/wg/httpbis/trac/ticket/123">http://trac.tools.ietf.org/wg/httpbis/trac/ticket/123</a>&gt;.
446      </p> 
447      <p>Discussion of this draft should take place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org). The current issues
448         list is at &lt;<a href="http://trac.tools.ietf.org/wg/httpbis/trac/query?component=content-disp">http://trac.tools.ietf.org/wg/httpbis/trac/query?component=content-disp</a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href="http://tools.ietf.org/wg/httpbis/">http://tools.ietf.org/wg/httpbis/</a>&gt;.
449      </p> 
450      <p>The changes in this draft are summarized in <a href="#changes.since.04" title="Since draft-ietf-httpbis-content-disp-04">Appendix&nbsp;D.9</a>.
451      </p>
452      <h1><a id="rfc.status" href="#rfc.status">Status of This Memo</a></h1>
453      <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
454      <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
455         working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href="http://datatracker.ietf.org/drafts/current/">http://datatracker.ietf.org/drafts/current/</a>.
456      </p>
457      <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
458         documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
459         in progress”.
460      </p>
461      <p>This Internet-Draft will expire on August 16, 2011.</p>
462      <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1>
463      <p>Copyright © 2011 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
464      <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights
465         and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
466         text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
467         BSD License.
468      </p>
469      <hr class="noprint">
470      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
471      <ul class="toc">
472         <li>1.&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a></li>
473         <li>2.&nbsp;&nbsp;&nbsp;<a href="#notational.conventions">Notational Conventions</a></li>
474         <li>3.&nbsp;&nbsp;&nbsp;<a href="#conformance.and.error.handling">Conformance and Error Handling</a></li>
475         <li>4.&nbsp;&nbsp;&nbsp;<a href="#header.field.definition">Header Field Definition</a><ul>
476               <li>4.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.4.1">Grammar</a></li>
477               <li>4.2&nbsp;&nbsp;&nbsp;<a href="#disposition.type">Disposition Type</a></li>
478               <li>4.3&nbsp;&nbsp;&nbsp;<a href="#disposition.parameter.filename">Disposition Parameter: 'Filename'</a></li>
479               <li>4.4&nbsp;&nbsp;&nbsp;<a href="#disposition.parameter.extensions">Disposition Parameter: Extensions</a></li>
480               <li>4.5&nbsp;&nbsp;&nbsp;<a href="#extensibility">Extensibility</a></li>
481            </ul>
482         </li>
483         <li>5.&nbsp;&nbsp;&nbsp;<a href="#examples">Examples</a></li>
484         <li>6.&nbsp;&nbsp;&nbsp;<a href="#i18n">Internationalization Considerations</a></li>
485         <li>7.&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a></li>
486         <li>8.&nbsp;&nbsp;&nbsp;<a href="#iana.considerations">IANA Considerations</a><ul>
487               <li>8.1&nbsp;&nbsp;&nbsp;<a href="#registry">Registry for Disposition Values and Parameter</a></li>
488               <li>8.2&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
489            </ul>
490         </li>
491         <li>9.&nbsp;&nbsp;&nbsp;<a href="#rfc.section.9">Acknowledgements</a></li>
492         <li>10.&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
493               <li>10.1&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
494               <li>10.2&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
495            </ul>
496         </li>
497         <li><a href="#rfc.authors">Author's Address</a></li>
498         <li>A.&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc2616">Changes from the RFC 2616 Definition</a></li>
499         <li>B.&nbsp;&nbsp;&nbsp;<a href="#diffs.compared.to.rfc2183">Differences compared to RFC 2183</a></li>
500         <li>C.&nbsp;&nbsp;&nbsp;<a href="#alternatives">Alternative Approaches to Internationalization</a><ul>
501               <li>C.1&nbsp;&nbsp;&nbsp;<a href="#alternatives.rfc2047">RFC 2047 Encoding</a></li>
502               <li>C.2&nbsp;&nbsp;&nbsp;<a href="#alternatives.percent">Percent Encoding</a></li>
503               <li>C.3&nbsp;&nbsp;&nbsp;<a href="#alternatives.sniff">Encoding Sniffing</a></li>
504               <li>C.4&nbsp;&nbsp;&nbsp;<a href="#alternatives.implementations">Implementations (to be removed by RFC Editor before publication)</a></li>
505            </ul>
506         </li>
507         <li>D.&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
508               <li>D.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.1">Since draft-reschke-rfc2183-in-http-00</a></li>
509               <li>D.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.2">Since draft-reschke-rfc2183-in-http-01</a></li>
510               <li>D.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.3">Since draft-reschke-rfc2183-in-http-02</a></li>
511               <li>D.4&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.4">Since draft-reschke-rfc2183-in-http-03</a></li>
512               <li>D.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></li>
513               <li>D.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></li>
514               <li>D.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></li>
515               <li>D.8&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></li>
516               <li>D.9&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></li>
517            </ul>
518         </li>
519         <li><a href="#rfc.index">Index</a></li>
520      </ul>
521      <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a id="introduction" href="#introduction">Introduction</a></h1>
522      <p id="rfc.section.1.p.1">HTTP/1.1 defines the Content-Disposition response header field in <a href="http://tools.ietf.org/html/rfc2616#section-19.5.1">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="http://tools.ietf.org/html/rfc2616#section-15.5" id="rfc.xref.RFC2616.2">Section 15.5</a>):
523      </p>
524      <blockquote id="rfc.section.1.p.2" cite="http://tools.ietf.org/html/rfc2616#section-15.5">
525         <p>Content-Disposition is not part of the HTTP standard, but since it is widely implemented, we are documenting its use and risks
526            for implementers.
527         </p>
528      </blockquote>
529      <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
530         testing with existing User Agents, it fully defines a profile of the features defined in the Multipurpose Internet Mail Extensions
531         (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.
532      </p>
533      <div class="note" id="rfc.section.1.p.4">
534         <p> <b>Note:</b> this document does not apply to Content-Disposition header fields appearing in message payloads transmitted over HTTP, such
535            as when using the media type "multipart/form-data" (<a href="#RFC2388" id="rfc.xref.RFC2388.1"><cite title="Returning Values from Forms: multipart/form-data">[RFC2388]</cite></a>).
536         </p>
537      </div>
538      <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a id="notational.conventions" href="#notational.conventions">Notational Conventions</a></h1>
539      <p id="rfc.section.2.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
540         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>.
541      </p>
542      <p id="rfc.section.2.p.2">This specification uses the augmented BNF notation defined in <a href="http://tools.ietf.org/html/rfc2616#section-2.1">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 implied linear whitespace (LWS).
543      </p>
544      <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a id="conformance.and.error.handling" href="#conformance.and.error.handling">Conformance and Error Handling</a></h1>
545      <p id="rfc.section.3.p.1">This specification defines conformance criteria for both senders (usually, HTTP origin servers) and recipients (usually, HTTP
546         user agents) of the Content-Location header field. An implementation is considered conformant if it complies with all of the
547         requirements associated with its role.
548      </p>
549      <p id="rfc.section.3.p.2">This specification also defines certain forms of the header field-value to be invalid, using both ABNF and prose requirements,
550         but it does not define special handling these invalid field-values.
551      </p>
552      <p id="rfc.section.3.p.3">Sending implementations <em class="bcp14">MUST NOT</em> generate Content-Location header fields that are invalid.
553      </p>
554      <p id="rfc.section.3.p.4">Consuming implementations <em class="bcp14">MAY</em> take steps to recover a usable field-value from an invalid header field, but <em class="bcp14">SHOULD NOT</em> reject the message outright, unless this is explicitly desirable behaviour (e.g., the implementation is a validator). As such,
555         the default handling of invalid fields is to ignore them.
556      </p>
557      <div id="rfc.iref.h.1"></div>
558      <div id="rfc.iref.c.1"></div>
559      <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a id="header.field.definition" href="#header.field.definition">Header Field Definition</a></h1>
560      <p id="rfc.section.4.p.1">The Content-Disposition response header field is used to convey additional information about how to process the response payload,
561         and also can be used to attach additional metadata, such as the filename to use when saving the response payload locally.
562      </p>
563      <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;Grammar
564      </h2>
565      <div id="rfc.figure.u.1"></div><pre class="inline">  content-disposition = "Content-Disposition" ":"
566                         disposition-type *( ";" disposition-parm )
567
568  disposition-type    = "inline" | "attachment" | disp-ext-type
569                      ; case-insensitive
570  disp-ext-type       = token
571
572  disposition-parm    = filename-parm | disp-ext-parm
573
574  filename-parm       = "filename" "=" value
575                      | "filename*" "=" ext-value
576 
577  disp-ext-parm       = token "=" value
578                      | ext-token "=" ext-value
579  ext-token           = &lt;the characters in token, followed by "*"&gt;
580</pre><div id="rfc.figure.u.2"></div>
581      <p>Defined in <a href="#RFC2616" id="rfc.xref.RFC2616.4"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>:
582      </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="http://tools.ietf.org/html/rfc2616#section-2.2">Section 2.2</a>&gt;
583  quoted-string = &lt;quoted-string, defined in <a href="#RFC2616" id="rfc.xref.RFC2616.6"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="http://tools.ietf.org/html/rfc2616#section-2.2">Section 2.2</a>&gt;
584  value         = &lt;value, defined in <a href="#RFC2616" id="rfc.xref.RFC2616.7"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="http://tools.ietf.org/html/rfc2616#section-3.6">Section 3.6</a>&gt;
585                ; token | quoted-string
586             
587</pre><div id="rfc.figure.u.3"></div>
588      <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>:
589      </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="http://tools.ietf.org/html/rfc5987#section-3.2">Section 3.2</a>&gt;
590</pre><p id="rfc.section.4.1.p.4">Header field values with multiple instances of the same parameter name are invalid.</p>
591      <p id="rfc.section.4.1.p.5">Note that due to the rules for implied linear whitespace (<a href="http://tools.ietf.org/html/rfc2616#section-2.1">Section 2.1</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.8"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>), OPTIONAL whitespace can appear between words (token or quoted-string) and separator characters.
592      </p>
593      <p id="rfc.section.4.1.p.6">Furthermore note that the format used for ext-value allows specifying a natural language; this is of limited use for filenames
594         and is likely to be ignored by recipients.
595      </p>
596      <h2 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a>&nbsp;<a id="disposition.type" href="#disposition.type">Disposition Type</a></h2>
597      <p id="rfc.section.4.2.p.1">If the disposition type matches "attachment" (case-insensitively), this indicates that the user agent should prompt the user
598         to save the response locally, rather than process it normally (as per its media type).
599      </p>
600      <p id="rfc.section.4.2.p.2">On the other hand, if it matches "inline" (case-insensitively), this implies default processing.</p>
601      <p id="rfc.section.4.2.p.3">Unknown or unhandled disposition types <em class="bcp14">SHOULD</em> be handled by recipients 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="http://tools.ietf.org/html/rfc2183#section-2.8">Section 2.8</a>).
602      </p>
603      <h2 id="rfc.section.4.3"><a href="#rfc.section.4.3">4.3</a>&nbsp;<a id="disposition.parameter.filename" href="#disposition.parameter.filename">Disposition Parameter: 'Filename'</a></h2>
604      <p id="rfc.section.4.3.p.1">The parameters "filename" and "filename*", to be matched case-insensitively, provide information on how to construct a filename
605         for storing the message payload.
606      </p>
607      <p id="rfc.section.4.3.p.2">Depending on the disposition type, this information might be used right away (in the "save as..." interaction caused for the
608         "attachment" disposition type), or later on (for instance, when the user decides to save the contents of the current page
609         being displayed).
610      </p>
611      <p id="rfc.section.4.3.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>).
612      </p>
613      <p id="rfc.section.4.3.p.4">Many user agent implementations predating this specification do not understand the "filename*" parameter. Therefore, when
614         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
615         more expressive "filename*" parameter, and the "filename" parameter as fallback for legacy recipients (see <a href="#examples" title="Examples">Section&nbsp;5</a> for an example).
616      </p>
617      <p id="rfc.section.4.3.p.5">It is essential that user agents treat the specified filename as advisory only, thus be very careful in extracting the desired
618         information. In particular:
619      </p>
620      <ul>
621         <li>
622            <p>When the value contains path separator characters ("\" or "/"), recipients <em class="bcp14">SHOULD</em> ignore all but the last path segment. This prevents unintentional overwriting of well-known file system locations (such as
623               "/etc/passwd").
624            </p>
625         </li>
626         <li>
627            <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
628               extension could introduce a privilege escalation when the saved file is later opened (consider ".exe"). Thus, recipients need
629               to ensure that a file extension is used that is safe, optimally matching the media type of the received payload.
630            </p>
631         </li>
632         <li>
633            <p>Recipients are advised to strip or replace character sequences that are known to cause confusion both in user interfaces and
634               in filenames, such as control characters and leading and trailing whitespace.
635            </p>
636         </li>
637         <li>
638            <p>Other aspects recipients need to be aware of are names that have a special meaning in the file system or in shell commands,
639               such as "." and "..", "~", "|", and also device names.
640            </p>
641         </li>
642      </ul>
643      <div class="note" id="rfc.section.4.3.p.6">
644         <p> <b>Note:</b> Many user agents do not properly handle escape characters when using the quoted-string form. Furthermore, some user agents
645            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.
646         </p>
647      </div>
648      <h2 id="rfc.section.4.4"><a href="#rfc.section.4.4">4.4</a>&nbsp;<a id="disposition.parameter.extensions" href="#disposition.parameter.extensions">Disposition Parameter: Extensions</a></h2>
649      <p id="rfc.section.4.4.p.1">To enable future extensions, recipients <em class="bcp14">SHOULD</em> ignore unrecognized parameters (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="http://tools.ietf.org/html/rfc2183#section-2.8">Section 2.8</a>).
650      </p>
651      <h2 id="rfc.section.4.5"><a href="#rfc.section.4.5">4.5</a>&nbsp;<a id="extensibility" href="#extensibility">Extensibility</a></h2>
652      <p id="rfc.section.4.5.p.1">Note that <a href="http://tools.ietf.org/html/rfc2183#section-9">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
653         using Content-Disposition, such as MIME and HTTP. Therefore, not all registered values may make sense in the context of HTTP.
654      </p>
655      <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a id="examples" href="#examples">Examples</a></h1>
656      <div id="rfc.figure.u.4"></div>
657      <p>Direct UA to show "save as" dialog, with a filename of "example.html":</p>  <pre class="text">Content-Disposition: Attachment; filename=example.html
658</pre><div id="rfc.figure.u.5"></div>
659      <p>Direct UA to behave as if the Content-Disposition header field wasn't present, but to remember the filename "an example.html"
660         for a subsequent save operation:
661      </p>  <pre class="text">Content-Disposition: INLINE; FILENAME= "an example.html"
662</pre>  <p>Note: this uses the quoted-string form so that the space character can be included.</p>
663      <div id="rfc.figure.u.6"></div>
664      <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;
665                     filename*= UTF-8''<b>%e2%82%ac</b>%20rates
666</pre>  <p>Here, the 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> is also used to encode the non-ISO-8859-1 character.
667      </p>
668      <div id="rfc.figure.u.7"></div>
669      <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;
670                     filename="EURO rates";
671                     filename*=utf-8''<b>%e2%82%ac</b>%20rates
672</pre>  <p>Note: as of February 2011, those user agents that do not support the RFC 5987 encoding ignore "filename*" when it occurs after
673         "filename". Unfortunately, some user agents that do support RFC 5987 do pick the "filename" rather than the "filename*" parameter
674         when it occurs first; it is expected that this situation is going to improve soon.
675      </p>
676      <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a id="i18n" href="#i18n">Internationalization Considerations</a></h1>
677      <p id="rfc.section.6.p.1">The "filename*" parameter (<a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;4.3</a>), using 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>, allows the server to transmit characters outside the ISO-8859-1 character set, and also to optionally specify the language
678         in use.
679      </p>
680      <p id="rfc.section.6.p.2">Future parameters might also require internationalization, in which case the same encoding can be used.</p>
681      <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a id="security.considerations" href="#security.considerations">Security Considerations</a></h1>
682      <p id="rfc.section.7.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;4.3</a>.
683      </p>
684      <p id="rfc.section.7.p.2">Furthermore, implementers also ought to be aware of the Security Considerations applying to HTTP (see <a href="http://tools.ietf.org/html/rfc2616#section-15">Section 15</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.9"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>), and also the parameter encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.6"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a> (see <a href="http://tools.ietf.org/html/rfc5987#section-5" id="rfc.xref.RFC5987.7">Section 5</a>).
685      </p>
686      <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;<a id="iana.considerations" href="#iana.considerations">IANA Considerations</a></h1>
687      <h2 id="rfc.section.8.1"><a href="#rfc.section.8.1">8.1</a>&nbsp;<a id="registry" href="#registry">Registry for Disposition Values and Parameter</a></h2>
688      <p id="rfc.section.8.1.p.1">This specification does not introduce any changes to the registration procedures for disposition values and parameters that
689         are defined in <a href="http://tools.ietf.org/html/rfc2183#section-9">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>.
690      </p>
691      <h2 id="rfc.section.8.2"><a href="#rfc.section.8.2">8.2</a>&nbsp;<a id="header.field.registration" href="#header.field.registration">Header Field Registration</a></h2>
692      <p id="rfc.section.8.2.p.1">This document updates the definition of the Content-Disposition HTTP header field in the permanent HTTP header field registry
693         (see <a href="#RFC3864" id="rfc.xref.RFC3864.1"><cite title="Registration Procedures for Message Header Fields">[RFC3864]</cite></a>).
694      </p>
695      <p id="rfc.section.8.2.p.2"> </p>
696      <dl>
697         <dt>Header field name:</dt>
698         <dd>Content-Disposition</dd>
699         <dt>Applicable protocol:</dt>
700         <dd>http</dd>
701         <dt>Status:</dt>
702         <dd>standard</dd>
703         <dt>Author/Change controller:</dt>
704         <dd>IETF</dd>
705         <dt>Specification document:</dt>
706         <dd>this specification (<a href="#header.field.definition" id="rfc.xref.header.field.definition.1" title="Header Field Definition">Section&nbsp;4</a>)
707         </dd>
708      </dl>
709      <h1 id="rfc.section.9"><a href="#rfc.section.9">9.</a>&nbsp;Acknowledgements
710      </h1>
711      <p id="rfc.section.9.p.1">Thanks to Adam Barth, Rolf Eike Beer, Bjoern Hoehrmann, Alfred Hoenes, Roar Lauritzsen, Henrik Nordstrom, and Mark Nottingham
712         for their valuable feedback.
713      </p>
714      <h1 id="rfc.references"><a id="rfc.section.10" href="#rfc.section.10">10.</a> References
715      </h1>
716      <h2 id="rfc.references.1"><a href="#rfc.section.10.1" id="rfc.section.10.1">10.1</a> Normative References
717      </h2>
718      <table>       
719         <tr>
720            <td class="reference"><b id="ISO-8859-1">[ISO-8859-1]</b></td>
721            <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>
722         </tr>
723         <tr>
724            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
725            <td class="top"><a href="mailto:sob@harvard.edu" title="Harvard University">Bradner, S.</a>, “<a href="http://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
726            </td>
727         </tr>
728         <tr>
729            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
730            <td class="top"><a href="mailto:fielding@ics.uci.edu" title="University of California, Irvine">Fielding, R.</a>, <a href="mailto:jg@w3.org" title="W3C">Gettys, J.</a>, <a href="mailto:mogul@wrl.dec.com" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="mailto:frystyk@w3.org" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="mailto:masinter@parc.xerox.com" title="Xerox Corporation">Masinter, L.</a>, <a href="mailto:paulle@microsoft.com" title="Microsoft Corporation">Leach, P.</a>, and <a href="mailto:timbl@w3.org" title="W3C">T. Berners-Lee</a>, “<a href="http://tools.ietf.org/html/rfc2616">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
731            </td>
732         </tr>
733         <tr>
734            <td class="reference"><b id="RFC5987">[RFC5987]</b></td>
735            <td class="top"><a href="mailto:julian.reschke@greenbytes.de" title="greenbytes GmbH">Reschke, J.</a>, “<a href="http://tools.ietf.org/html/rfc5987">Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters</a>”, RFC&nbsp;5987, August&nbsp;2010.
736            </td>
737         </tr>
738      </table>
739      <h2 id="rfc.references.2"><a href="#rfc.section.10.2" id="rfc.section.10.2">10.2</a> Informative References
740      </h2>
741      <table>               
742         <tr>
743            <td class="reference"><b id="RFC2046">[RFC2046]</b></td>
744            <td class="top"><a href="mailto:ned@innosoft.com" title="Innosoft International, Inc.">Freed, N.</a> and <a href="mailto:nsb@nsb.fv.com" title="First Virtual Holdings">N. Borenstein</a>, “<a href="http://tools.ietf.org/html/rfc2046">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</a>”, RFC&nbsp;2046, November&nbsp;1996.
745            </td>
746         </tr>
747         <tr>
748            <td class="reference"><b id="RFC2047">[RFC2047]</b></td>
749            <td class="top"><a href="mailto:moore@cs.utk.edu" title="University of Tennessee">Moore, K.</a>, “<a href="http://tools.ietf.org/html/rfc2047">MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text</a>”, RFC&nbsp;2047, November&nbsp;1996.
750            </td>
751         </tr>
752         <tr>
753            <td class="reference"><b id="RFC2183">[RFC2183]</b></td>
754            <td class="top"><a href="mailto:rens@century.com" title="New Century Systems">Troost, R.</a>, <a href="mailto:sdorner@qualcomm.com" title="QUALCOMM Incorporated">Dorner, S.</a>, and <a href="mailto:moore@cs.utk.edu" title="Department of Computer Science">K. Moore</a>, “<a href="http://tools.ietf.org/html/rfc2183">Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field</a>”, RFC&nbsp;2183, August&nbsp;1997.
755            </td>
756         </tr>
757         <tr>
758            <td class="reference"><b id="RFC2231">[RFC2231]</b></td>
759            <td class="top"><a href="mailto:ned.freed@innosoft.com" title="Innosoft International, Inc.">Freed, N.</a> and <a href="mailto:moore@cs.utk.edu" title="University of Tennessee">K. Moore</a>, “<a href="http://tools.ietf.org/html/rfc2231">MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations</a>”, RFC&nbsp;2231, November&nbsp;1997.
760            </td>
761         </tr>
762         <tr>
763            <td class="reference"><b id="RFC2388">[RFC2388]</b></td>
764            <td class="top"><a href="mailto:masinter@parc.xerox.com" title="Xerox Palo Alto Research Center">Masinter, L.</a>, “<a href="http://tools.ietf.org/html/rfc2388">Returning Values from Forms: multipart/form-data</a>”, RFC&nbsp;2388, August&nbsp;1998.
765            </td>
766         </tr>
767         <tr>
768            <td class="reference"><b id="RFC3864">[RFC3864]</b></td>
769            <td class="top"><a href="mailto:GK-IETF@ninebynine.org" title="Nine by Nine">Klyne, G.</a>, <a href="mailto:mnot@pobox.com" title="BEA Systems">Nottingham, M.</a>, and <a href="mailto:JeffMogul@acm.org" title="HP Labs">J. Mogul</a>, “<a href="http://tools.ietf.org/html/rfc3864">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
770            </td>
771         </tr>
772         <tr>
773            <td class="reference"><b id="RFC3986">[RFC3986]</b></td>
774            <td class="top"><a href="mailto:timbl@w3.org" title="World Wide Web Consortium">Berners-Lee, T.</a>, <a href="mailto:fielding@gbiv.com" title="Day Software">Fielding, R.</a>, and <a href="mailto:LMM@acm.org" title="Adobe Systems Incorporated">L. Masinter</a>, “<a href="http://tools.ietf.org/html/rfc3986">Uniform Resource Identifier (URI): Generic Syntax</a>”, STD&nbsp;66, RFC&nbsp;3986, January&nbsp;2005.
775            </td>
776         </tr>
777      </table>
778      <div class="avoidbreak">
779         <h1 id="rfc.authors"><a href="#rfc.authors">Author's Address</a></h1>
780         <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="mailto:julian.reschke@greenbytes.de"><span class="email">julian.reschke@greenbytes.de</span></a></span><span class="vcardline">URI: <a href="http://greenbytes.de/tech/webdav/" class="url">http://greenbytes.de/tech/webdav/</a></span></address>
781      </div>
782      <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>
783      <p id="rfc.section.A.p.1">Compared to <a href="http://tools.ietf.org/html/rfc2616#section-19.5.1">Section 19.5.1</a> of <a href="#RFC2616" id="rfc.xref.RFC2616.10"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, the following normative changes reflecting actual implementations have been made:
784      </p>
785      <ul>
786         <li>According to RFC 2616, the disposition type "attachment" only applies to content of type "application/octet-stream". This
787            restriction has been removed, because user agents in practice do not check the content type, and it also discourages properly
788            declaring the media type.
789         </li>
790         <li>RFC 2616 only allows "quoted-string" for the filename parameter. This would be an exceptional parameter syntax, and also doesn't
791            reflect actual use.
792         </li>
793         <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="http://tools.ietf.org/html/rfc2183#section-2.1">Section 2.1</a>) has been re-added with a suggestion for its processing.
794         </li>
795         <li>This specification requires support for the extended parameter encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.8"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>.
796         </li>
797      </ul>
798      <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a id="diffs.compared.to.rfc2183" href="#diffs.compared.to.rfc2183">Differences compared to RFC 2183</a></h1>
799      <p id="rfc.section.B.p.1"> <a href="http://tools.ietf.org/html/rfc2183#section-2">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". The
800         majority of user agents does not implement these, thus they have been omitted from this specification.
801      </p>
802      <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a id="alternatives" href="#alternatives">Alternative Approaches to Internationalization</a></h1>
803      <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.RFC2616.11"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>, <a href="http://tools.ietf.org/html/rfc2616#section-2.2">Section 2.2</a>). For the "filename" parameter, this of course is an unacceptable restriction.
804      </p>
805      <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
806         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.RFC5987.9"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>).
807      </p>
808      <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
809         to the RFC 5987 encoding used in this specification.
810      </p>
811      <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>
812      <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
813         - see <a href="http://tools.ietf.org/html/rfc2047#section-5">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>:
814      </p>
815      <blockquote id="rfc.section.C.1.p.2" cite="http://tools.ietf.org/html/rfc2047#section-5">
816         <p>An 'encoded-word' MUST NOT appear within a 'quoted-string'.</p> 
817         <p>...</p> 
818         <p>An 'encoded-word' MUST NOT be used in parameter of a MIME Content-Type or Content-Disposition field, or in any structured
819            field body except within a 'comment' or 'phrase'.
820         </p>
821      </blockquote>
822      <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
823         confused by it.
824      </p>
825      <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>
826      <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="http://tools.ietf.org/html/rfc3986#section-2.1">Section 2.1</a>) sequences of characters. The character encoding being used for decoding depends on various factors, including the encoding
827         of the referring page, the user agent's locale, its configuration, and also the actual value of the parameter.
828      </p>
829      <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
830         to the user. For those user agents that do implement this it is difficult to predict what character encoding they actually
831         expect.
832      </p>
833      <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>
834      <p id="rfc.section.C.3.p.1">Some user agents inspect the value (which defaults to ISO-8859-1 for the quoted-string form) and switch to UTF-8 when it seems
835         to be more likely to be the correct interpretation.
836      </p>
837      <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>
838      <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>
839      <p id="rfc.section.C.4.p.1">Unfortunately, as of February 2011, neither the encoding defined in RFCs 2231 and 5987, nor any of the alternate approaches
840         discussed above was implemented interoperably. Thus, this specification recommends the approach defined in RFC 5987, which
841         at least has the advantage of actually being specified properly.
842      </p>
843      <p id="rfc.section.C.4.p.2">The table below shows the implementation support for the various approaches:</p>
844      <div id="rfc.table.u.1">
845         <table class="tt full left" cellpadding="3" cellspacing="0">
846            <thead>
847               <tr>
848                  <th>User Agent</th>
849                  <th>RFC 2231/5987</th>
850                  <th>RFC 2047</th>
851                  <th>Percent Encoding</th>
852                  <th>Encoding Sniffing</th>
853               </tr>
854            </thead>
855            <tbody>
856               <tr>
857                  <td class="left">Chrome</td>
858                  <td class="left">yes</td>
859                  <td class="left">yes</td>
860                  <td class="left">yes</td>
861                  <td class="left">yes</td>
862               </tr>
863               <tr>
864                  <td class="left">Firefox</td>
865                  <td class="left">yes (*)</td>
866                  <td class="left">yes</td>
867                  <td class="left">no</td>
868                  <td class="left">yes</td>
869               </tr>
870               <tr>
871                  <td class="left">Internet Explorer</td>
872                  <td class="left">yes (**)</td>
873                  <td class="left">no</td>
874                  <td class="left">yes</td>
875                  <td class="left">no</td>
876               </tr>
877               <tr>
878                  <td class="left">Konqueror</td>
879                  <td class="left">yes</td>
880                  <td class="left">no</td>
881                  <td class="left">no</td>
882                  <td class="left">no</td>
883               </tr>
884               <tr>
885                  <td class="left">Opera</td>
886                  <td class="left">yes</td>
887                  <td class="left">no</td>
888                  <td class="left">no</td>
889                  <td class="left">no</td>
890               </tr>
891               <tr>
892                  <td class="left">Safari</td>
893                  <td class="left">no</td>
894                  <td class="left">no</td>
895                  <td class="left">no</td>
896                  <td class="left">yes</td>
897               </tr>
898            </tbody>
899         </table>
900      </div>
901      <p id="rfc.section.C.4.p.3">(*) Does not implement the fallback behavior to "filename" described in <a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;4.3</a>.
902      </p>
903      <p id="rfc.section.C.4.p.4">(**) Starting with IE9RC, but only implements UTF-8.</p>
904      <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>
905      <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="http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html">http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html</a>&gt;.
906      </p>
907      <h2 id="rfc.section.D.1"><a href="#rfc.section.D.1">D.1</a>&nbsp;Since draft-reschke-rfc2183-in-http-00
908      </h2>
909      <p id="rfc.section.D.1.p.1">Adjust terminology ("header" -&gt; "header field"). Update rfc2231-in-http reference.</p>
910      <h2 id="rfc.section.D.2"><a href="#rfc.section.D.2">D.2</a>&nbsp;Since draft-reschke-rfc2183-in-http-01
911      </h2>
912      <p id="rfc.section.D.2.p.1">Update rfc2231-in-http reference. Actually define the "filename" parameter. Add internationalization considerations. Add examples
913         using the RFC 5987 encoding. Add overview over other approaches, plus a table reporting implementation status. Add and resolve
914         issue "nodep2183". Add issues "asciivsiso", "deplboth", "quoted", and "registry".
915      </p>
916      <h2 id="rfc.section.D.3"><a href="#rfc.section.D.3">D.3</a>&nbsp;Since draft-reschke-rfc2183-in-http-02
917      </h2>
918      <p id="rfc.section.D.3.p.1">Add and close issue "docfallback". Close issues "asciivsiso", "deplboth", "quoted", and "registry".</p>
919      <h2 id="rfc.section.D.4"><a href="#rfc.section.D.4">D.4</a>&nbsp;Since draft-reschke-rfc2183-in-http-03
920      </h2>
921      <p id="rfc.section.D.4.p.1">Updated to be a Working Draft of the IETF HTTPbis Working Group.</p>
922      <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>
923      <p id="rfc.section.D.5.p.1">Closed issues: </p>
924      <ul>
925         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/242">http://tools.ietf.org/wg/httpbis/trac/ticket/242</a>&gt;: "handling of unknown disposition types"
926         </li>
927      </ul>
928      <p id="rfc.section.D.5.p.2">Slightly updated the notes about the proposed fallback behavior.</p>
929      <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>
930      <p id="rfc.section.D.6.p.1">Various editorial improvements.</p>
931      <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>
932      <p id="rfc.section.D.7.p.1">Closed issues: </p>
933      <ul>
934         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/244">http://tools.ietf.org/wg/httpbis/trac/ticket/244</a>&gt;: "state that repeating parameters are invalid"
935         </li>
936         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/245">http://tools.ietf.org/wg/httpbis/trac/ticket/245</a>&gt;: "warn about %xx in filenames being misinterpreted"
937         </li>
938         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/246">http://tools.ietf.org/wg/httpbis/trac/ticket/246</a>&gt;: "mention control chars when talking about postprecessing the filename parameter"
939         </li>
940      </ul>
941      <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.
942      </p>
943      <h2 id="rfc.section.D.8"><a href="#rfc.section.D.8">D.8</a>&nbsp;<a id="changes.since.03" href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></h2>
944      <p id="rfc.section.D.8.p.1">Closed issues: </p>
945      <ul>
946         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/252">http://tools.ietf.org/wg/httpbis/trac/ticket/252</a>&gt;: "'modification-date' *is* implemented in Konq 4.5"
947         </li>
948         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/253">http://tools.ietf.org/wg/httpbis/trac/ticket/253</a>&gt;: "clarify what LWS means for the Content-Disp grammar"
949         </li>
950         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/258">http://tools.ietf.org/wg/httpbis/trac/ticket/258</a>&gt;: "Avoid passive voice in message requirements"
951         </li>
952         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/263">http://tools.ietf.org/wg/httpbis/trac/ticket/263</a>&gt;: "text about historical percent-decoding unclear"
953         </li>
954         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/264">http://tools.ietf.org/wg/httpbis/trac/ticket/264</a>&gt;: "add explanation of language tagging"
955         </li>
956         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/265">http://tools.ietf.org/wg/httpbis/trac/ticket/265</a>&gt;: "Clarify that C-D spec does not apply to multipart upload"
957         </li>
958      </ul>
959      <h2 id="rfc.section.D.9"><a href="#rfc.section.D.9">D.9</a>&nbsp;<a id="changes.since.04" href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></h2>
960      <p id="rfc.section.D.9.p.1">Updated implementation information (Chrome 9 implements RFC 5987, IE 9 RC implements it for UTF-8 only).</p>
961      <p id="rfc.section.D.9.p.2">Clarify who requirements are on, add a section discussing conformance and handling of invalid field values in general.</p>
962      <p id="rfc.section.D.9.p.3">Closed issues: </p>
963      <ul>
964         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/272">http://tools.ietf.org/wg/httpbis/trac/ticket/272</a>&gt;: "Path Separator Characters"
965         </li>
966      </ul>
967      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
968      <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>
969      </p>
970      <div class="print2col">
971         <ul class="ind">
972            <li><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul>
973                  <li>Content-Disposition header&nbsp;&nbsp;<a href="#rfc.iref.c.1"><b>4</b></a>, <a href="#rfc.xref.header.field.definition.1">8.2</a></li>
974               </ul>
975            </li>
976            <li><a id="rfc.index.H" href="#rfc.index.H"><b>H</b></a><ul>
977                  <li>Headers&nbsp;&nbsp;
978                     <ul>
979                        <li>Content-Disposition&nbsp;&nbsp;<a href="#rfc.iref.h.1"><b>4</b></a>, <a href="#rfc.xref.header.field.definition.1">8.2</a></li>
980                     </ul>
981                  </li>
982               </ul>
983            </li>
984            <li><a id="rfc.index.I" href="#rfc.index.I"><b>I</b></a><ul>
985                  <li><em>ISO-8859-1</em>&nbsp;&nbsp;<a href="#rfc.xref.ISO-8859-1.1">4.3</a>, <a href="#ISO-8859-1"><b>10.1</b></a>, <a href="#rfc.xref.ISO-8859-1.2">C</a></li>
986               </ul>
987            </li>
988            <li><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul>
989                  <li><em>RFC2046</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2046.1">4.3</a>, <a href="#RFC2046"><b>10.2</b></a></li>
990                  <li><em>RFC2047</em>&nbsp;&nbsp;<a href="#RFC2047"><b>10.2</b></a>, <a href="#rfc.xref.RFC2047.1">C.1</a><ul>
991                        <li><em>Section 5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2047.1">C.1</a></li>
992                     </ul>
993                  </li>
994                  <li><em>RFC2119</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2119.1">2</a>, <a href="#RFC2119"><b>10.1</b></a></li>
995                  <li><em>RFC2183</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2183.1">1</a>, <a href="#rfc.xref.RFC2183.2">4.2</a>, <a href="#rfc.xref.RFC2183.3">4.4</a>, <a href="#rfc.xref.RFC2183.4">4.5</a>, <a href="#rfc.xref.RFC2183.5">8.1</a>, <a href="#RFC2183"><b>10.2</b></a>, <a href="#rfc.xref.RFC2183.6">A</a>, <a href="#rfc.xref.RFC2183.7">B</a><ul>
996                        <li><em>Section 2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2183.7">B</a></li>
997                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2183.6">A</a></li>
998                        <li><em>Section 2.8</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2183.2">4.2</a>, <a href="#rfc.xref.RFC2183.3">4.4</a></li>
999                        <li><em>Section 9</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2183.4">4.5</a>, <a href="#rfc.xref.RFC2183.5">8.1</a></li>
1000                     </ul>
1001                  </li>
1002                  <li><em>RFC2231</em>&nbsp;&nbsp;<a href="#RFC2231"><b>10.2</b></a>, <a href="#rfc.xref.RFC2231.1">C</a></li>
1003                  <li><em>RFC2388</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2388.1">1</a>, <a href="#RFC2388"><b>10.2</b></a></li>
1004                  <li><em>RFC2616</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.1">1</a>, <a href="#rfc.xref.RFC2616.2">1</a>, <a href="#rfc.xref.RFC2616.3">2</a>, <a href="#rfc.xref.RFC2616.4">4.1</a>, <a href="#rfc.xref.RFC2616.5">4.1</a>, <a href="#rfc.xref.RFC2616.6">4.1</a>, <a href="#rfc.xref.RFC2616.7">4.1</a>, <a href="#rfc.xref.RFC2616.8">4.1</a>, <a href="#rfc.xref.RFC2616.9">7</a>, <a href="#RFC2616"><b>10.1</b></a>, <a href="#rfc.xref.RFC2616.10">A</a>, <a href="#rfc.xref.RFC2616.11">C</a><ul>
1005                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.3">2</a>, <a href="#rfc.xref.RFC2616.8">4.1</a></li>
1006                        <li><em>Section 2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.5">4.1</a>, <a href="#rfc.xref.RFC2616.6">4.1</a>, <a href="#rfc.xref.RFC2616.11">C</a></li>
1007                        <li><em>Section 3.6</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.7">4.1</a></li>
1008                        <li><em>Section 15.5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.2">1</a></li>
1009                        <li><em>Section 15</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.9">7</a></li>
1010                        <li><em>Section 19.5.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2616.1">1</a>, <a href="#rfc.xref.RFC2616.10">A</a></li>
1011                     </ul>
1012                  </li>
1013                  <li><em>RFC3864</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3864.1">8.2</a>, <a href="#RFC3864"><b>10.2</b></a></li>
1014                  <li><em>RFC3986</em>&nbsp;&nbsp;<a href="#RFC3986"><b>10.2</b></a>, <a href="#rfc.xref.RFC3986.1">C.2</a><ul>
1015                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC3986.1">C.2</a></li>
1016                     </ul>
1017                  </li>
1018                  <li><em>RFC5987</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5987.1">4.1</a>, <a href="#rfc.xref.RFC5987.2">4.1</a>, <a href="#rfc.xref.RFC5987.3">4.3</a>, <a href="#rfc.xref.RFC5987.4">5</a>, <a href="#rfc.xref.RFC5987.5">6</a>, <a href="#rfc.xref.RFC5987.6">7</a>, <a href="#rfc.xref.RFC5987.7">7</a>, <a href="#RFC5987"><b>10.1</b></a>, <a href="#rfc.xref.RFC5987.8">A</a>, <a href="#rfc.xref.RFC5987.9">C</a><ul>
1019                        <li><em>Section 3.2</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5987.2">4.1</a></li>
1020                        <li><em>Section 5</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5987.7">7</a></li>
1021                     </ul>
1022                  </li>
1023               </ul>
1024            </li>
1025         </ul>
1026      </div>
1027   </body>
1028</html>
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