source: draft-ietf-httpbis/06/p5-range.html @ 784

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353</style><link rel="Contents" href="#rfc.toc">
354      <link rel="Author" href="#rfc.authors">
355      <link rel="Copyright" href="#rfc.copyright">
356      <link rel="Index" href="#rfc.index">
357      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
358      <link rel="Chapter" title="2 Range Units" href="#rfc.section.2">
359      <link rel="Chapter" title="3 Status Code Definitions" href="#rfc.section.3">
360      <link rel="Chapter" title="4 Combining Ranges" href="#rfc.section.4">
361      <link rel="Chapter" title="5 Header Field Definitions" href="#rfc.section.5">
362      <link rel="Chapter" title="6 IANA Considerations" href="#rfc.section.6">
363      <link rel="Chapter" title="7 Security Considerations" href="#rfc.section.7">
364      <link rel="Chapter" title="8 Acknowledgments" href="#rfc.section.8">
365      <link rel="Chapter" href="#rfc.section.9" title="9 References">
366      <link rel="Appendix" title="A Internet Media Type multipart/byteranges" href="#rfc.section.A">
367      <link rel="Appendix" title="B Compatibility with Previous Versions" href="#rfc.section.B">
368      <link rel="Appendix" title="C Collected ABNF" href="#rfc.section.C">
369      <link rel="Appendix" title="D Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.D">
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371      <link rel="schema.DC" href="http://purl.org/dc/elements/1.1/">
372      <meta name="DC.Creator" content="Fielding, R.">
373      <meta name="DC.Creator" content="Gettys, J.">
374      <meta name="DC.Creator" content="Mogul, J.">
375      <meta name="DC.Creator" content="Frystyk, H.">
376      <meta name="DC.Creator" content="Masinter, L.">
377      <meta name="DC.Creator" content="Leach, P.">
378      <meta name="DC.Creator" content="Berners-Lee, T.">
379      <meta name="DC.Creator" content="Lafon, Y.">
380      <meta name="DC.Creator" content="Reschke, J. F.">
381      <meta name="DC.Identifier" content="urn:ietf:id:draft-ietf-httpbis-p5-range-06">
382      <meta name="DC.Date.Issued" scheme="ISO8601" content="2009-03">
383      <meta name="DC.Relation.Replaces" content="urn:ietf:rfc:2616">
384      <meta name="DC.Description.Abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 5 of the seven-part specification that defines the protocol referred to as &#34;HTTP/1.1&#34; and, taken together, obsoletes RFC 2616. Part 5 defines range-specific requests and the rules for constructing and combining responses to those requests.">
385   </head>
386   <body>
387      <table summary="header information" class="header" border="0" cellpadding="1" cellspacing="1">
388         <tr>
389            <td class="header left">HTTPbis Working Group</td>
390            <td class="header right">R. Fielding, Editor</td>
391         </tr>
392         <tr>
393            <td class="header left">Internet Draft</td>
394            <td class="header right">Day Software</td>
395         </tr>
396         <tr>
397            <td class="header left">
398               &lt;draft-ietf-httpbis-p5-range-06&gt;
399               
400            </td>
401            <td class="header right">J. Gettys</td>
402         </tr>
403         <tr>
404            <td class="header left">Obsoletes: <a href="http://tools.ietf.org/html/rfc2616">2616</a> (if approved)
405            </td>
406            <td class="header right">One Laptop per Child</td>
407         </tr>
408         <tr>
409            <td class="header left">Intended status: Standards Track</td>
410            <td class="header right">J. Mogul</td>
411         </tr>
412         <tr>
413            <td class="header left">Expires: September 2009</td>
414            <td class="header right">HP</td>
415         </tr>
416         <tr>
417            <td class="header left"></td>
418            <td class="header right">H. Frystyk</td>
419         </tr>
420         <tr>
421            <td class="header left"></td>
422            <td class="header right">Microsoft</td>
423         </tr>
424         <tr>
425            <td class="header left"></td>
426            <td class="header right">L. Masinter</td>
427         </tr>
428         <tr>
429            <td class="header left"></td>
430            <td class="header right">Adobe Systems</td>
431         </tr>
432         <tr>
433            <td class="header left"></td>
434            <td class="header right">P. Leach</td>
435         </tr>
436         <tr>
437            <td class="header left"></td>
438            <td class="header right">Microsoft</td>
439         </tr>
440         <tr>
441            <td class="header left"></td>
442            <td class="header right">T. Berners-Lee</td>
443         </tr>
444         <tr>
445            <td class="header left"></td>
446            <td class="header right">W3C/MIT</td>
447         </tr>
448         <tr>
449            <td class="header left"></td>
450            <td class="header right">Y. Lafon, Editor</td>
451         </tr>
452         <tr>
453            <td class="header left"></td>
454            <td class="header right">W3C</td>
455         </tr>
456         <tr>
457            <td class="header left"></td>
458            <td class="header right">J. F. Reschke, Editor</td>
459         </tr>
460         <tr>
461            <td class="header left"></td>
462            <td class="header right">greenbytes</td>
463         </tr>
464         <tr>
465            <td class="header left"></td>
466            <td class="header right">March 9, 2009</td>
467         </tr>
468      </table>
469      <p class="title">HTTP/1.1, part 5: Range Requests and Partial Responses<br><span class="filename">draft-ietf-httpbis-p5-range-06</span></p>
470      <h1><a id="rfc.status" href="#rfc.status">Status of this Memo</a></h1>
471      <p>This Internet-Draft is submitted to IETF pursuant to, and in full conformance with, the provisions of BCP 78 and BCP 79. This
472         document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
473         10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
474         allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
475         controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
476         works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
477         it into languages other than English.
478      </p>
479      <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note
480         that other groups may also distribute working documents as Internet-Drafts.
481      </p>
482      <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
483         documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
484         in progress”.
485      </p>
486      <p>The list of current Internet-Drafts can be accessed at &lt;<a href="http://www.ietf.org/ietf/1id-abstracts.txt">http://www.ietf.org/ietf/1id-abstracts.txt</a>&gt;.
487      </p>
488      <p>The list of Internet-Draft Shadow Directories can be accessed at &lt;<a href="http://www.ietf.org/shadow.html">http://www.ietf.org/shadow.html</a>&gt;.
489      </p>
490      <p>This Internet-Draft will expire in September 2009.</p>
491      <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1>
492      <p>Copyright © 2009 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
493      <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date
494         of publication of this document (<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>). Please review these documents carefully, as they describe your rights and restrictions with respect to this document.
495      </p>
496      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1> 
497      <p>The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information
498         systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 5 of the
499         seven-part specification that defines the protocol referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616. Part
500         5 defines range-specific requests and the rules for constructing and combining responses to those requests.
501      </p> 
502      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1> 
503      <p>Discussion of this draft should take place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org). The current issues
504         list is at &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/report/11">http://tools.ietf.org/wg/httpbis/trac/report/11</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;.
505      </p> 
506      <p>The changes in this draft are summarized in <a href="#changes.since.05" title="Since draft-ietf-httpbis-p5-range-05">Appendix&nbsp;D.7</a>.
507      </p> 
508      <hr class="noprint">
509      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
510      <ul class="toc">
511         <li class="tocline0">1.&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul class="toc">
512               <li class="tocline1">1.1&nbsp;&nbsp;&nbsp;<a href="#intro.requirements">Requirements</a></li>
513               <li class="tocline1">1.2&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a><ul class="toc">
514                     <li class="tocline1">1.2.1&nbsp;&nbsp;&nbsp;<a href="#core.rules">Core Rules</a></li>
515                     <li class="tocline1">1.2.2&nbsp;&nbsp;&nbsp;<a href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></li>
516                  </ul>
517               </li>
518            </ul>
519         </li>
520         <li class="tocline0">2.&nbsp;&nbsp;&nbsp;<a href="#range.units">Range Units</a></li>
521         <li class="tocline0">3.&nbsp;&nbsp;&nbsp;<a href="#rfc.section.3">Status Code Definitions</a><ul class="toc">
522               <li class="tocline1">3.1&nbsp;&nbsp;&nbsp;<a href="#status.206">206 Partial Content</a></li>
523               <li class="tocline1">3.2&nbsp;&nbsp;&nbsp;<a href="#status.416">416 Requested Range Not Satisfiable</a></li>
524            </ul>
525         </li>
526         <li class="tocline0">4.&nbsp;&nbsp;&nbsp;<a href="#combining.byte.ranges">Combining Ranges</a></li>
527         <li class="tocline0">5.&nbsp;&nbsp;&nbsp;<a href="#header.fields">Header Field Definitions</a><ul class="toc">
528               <li class="tocline1">5.1&nbsp;&nbsp;&nbsp;<a href="#header.accept-ranges">Accept-Ranges</a></li>
529               <li class="tocline1">5.2&nbsp;&nbsp;&nbsp;<a href="#header.content-range">Content-Range</a></li>
530               <li class="tocline1">5.3&nbsp;&nbsp;&nbsp;<a href="#header.if-range">If-Range</a></li>
531               <li class="tocline1">5.4&nbsp;&nbsp;&nbsp;<a href="#header.range">Range</a><ul class="toc">
532                     <li class="tocline1">5.4.1&nbsp;&nbsp;&nbsp;<a href="#byte.ranges">Byte Ranges</a></li>
533                     <li class="tocline1">5.4.2&nbsp;&nbsp;&nbsp;<a href="#range.retrieval.requests">Range Retrieval Requests</a></li>
534                  </ul>
535               </li>
536            </ul>
537         </li>
538         <li class="tocline0">6.&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul class="toc">
539               <li class="tocline1">6.1&nbsp;&nbsp;&nbsp;<a href="#message.header.registration">Message Header Registration</a></li>
540            </ul>
541         </li>
542         <li class="tocline0">7.&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a></li>
543         <li class="tocline0">8.&nbsp;&nbsp;&nbsp;<a href="#ack">Acknowledgments</a></li>
544         <li class="tocline0">9.&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul class="toc">
545               <li class="tocline1">9.1&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
546               <li class="tocline1">9.2&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
547            </ul>
548         </li>
549         <li class="tocline0"><a href="#rfc.authors">Authors' Addresses</a></li>
550         <li class="tocline0">A.&nbsp;&nbsp;&nbsp;<a href="#internet.media.type.multipart.byteranges">Internet Media Type multipart/byteranges</a></li>
551         <li class="tocline0">B.&nbsp;&nbsp;&nbsp;<a href="#compatibility">Compatibility with Previous Versions</a><ul class="toc">
552               <li class="tocline1">B.1&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2068">Changes from RFC 2068</a></li>
553               <li class="tocline1">B.2&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></li>
554            </ul>
555         </li>
556         <li class="tocline0">C.&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
557         <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">
558               <li class="tocline1">D.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.1">Since RFC2616</a></li>
559               <li class="tocline1">D.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.2">Since draft-ietf-httpbis-p5-range-00</a></li>
560               <li class="tocline1">D.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.3">Since draft-ietf-httpbis-p5-range-01</a></li>
561               <li class="tocline1">D.4&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-p5-range-02</a></li>
562               <li class="tocline1">D.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-p5-range-03</a></li>
563               <li class="tocline1">D.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-p5-range-04</a></li>
564               <li class="tocline1">D.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-p5-range-05</a></li>
565            </ul>
566         </li>
567         <li class="tocline0"><a href="#rfc.index">Index</a></li>
568      </ul>
569      <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a id="introduction" href="#introduction">Introduction</a></h1>
570      <p id="rfc.section.1.p.1">HTTP clients often encounter interrupted data transfers as a result of cancelled requests or dropped connections. When a cache
571         has stored a partial representation, it is desirable to request the remainder of that representation in a subsequent request
572         rather than transfer the entire representation. There are also a number of Web applications that benefit from being able to
573         request only a subset of a larger representation, such as a single page of a very large document or only part of an image
574         to be rendered by a device with limited local storage.
575      </p>
576      <p id="rfc.section.1.p.2">This document defines HTTP/1.1 range requests, partial responses, and the multipart/byteranges media type. The protocol for
577         range requests is an <em class="bcp14">OPTIONAL</em> feature of HTTP, designed so resources or recipients that do not implement this feature can respond as if it is a normal GET
578         request without impacting interoperability. Partial responses are indicated by a distinct status code to not be mistaken for
579         full responses by intermediate caches that might not implement the feature.
580      </p>
581      <p id="rfc.section.1.p.3">Although the HTTP range request mechanism is designed to allow for extensible range types, this specification only defines
582         requests for byte ranges.
583      </p>
584      <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a id="intro.requirements" href="#intro.requirements">Requirements</a></h2>
585      <p id="rfc.section.1.1.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
586         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>.
587      </p>
588      <p id="rfc.section.1.1.p.2">An implementation is not compliant if it fails to satisfy one or more of the <em class="bcp14">MUST</em> or <em class="bcp14">REQUIRED</em> level requirements for the protocols it implements. An implementation that satisfies all the <em class="bcp14">MUST</em> or <em class="bcp14">REQUIRED</em> level and all the <em class="bcp14">SHOULD</em> level requirements for its protocols is said to be "unconditionally compliant"; one that satisfies all the <em class="bcp14">MUST</em> level requirements but not all the <em class="bcp14">SHOULD</em> level requirements for its protocols is said to be "conditionally compliant."
589      </p>
590      <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a id="notation" href="#notation">Syntax Notation</a></h2>
591      <p id="rfc.section.1.2.p.1">This specification uses the ABNF syntax defined in <a href="p1-messaging.html#notation" title="Syntax Notation">Section 1.2</a> of <a href="#Part1" id="rfc.xref.Part1.1"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a> (which extends the syntax defined in <a href="#RFC5234" id="rfc.xref.RFC5234.1"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a> with a list rule). <a href="#collected.abnf" title="Collected ABNF">Appendix&nbsp;C</a> shows the collected ABNF, with the list rule expanded.
592      </p>
593      <p id="rfc.section.1.2.p.2">The following core rules are included by reference, as defined in <a href="#RFC5234" id="rfc.xref.RFC5234.2"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a>, <a href="http://tools.ietf.org/html/rfc5234#appendix-B.1">Appendix B.1</a>: ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), HEXDIG
594         (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), VCHAR (any visible USASCII character),
595         and WSP (whitespace).
596      </p>
597      <h3 id="rfc.section.1.2.1"><a href="#rfc.section.1.2.1">1.2.1</a>&nbsp;<a id="core.rules" href="#core.rules">Core Rules</a></h3>
598      <p id="rfc.section.1.2.1.p.1">The core rules below are defined in <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a> of <a href="#Part1" id="rfc.xref.Part1.2"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>:
599      </p>
600      <div id="rfc.figure.u.1"></div><pre class="inline">  <a href="#core.rules" class="smpl">token</a>      = &lt;token, defined in <a href="#Part1" id="rfc.xref.Part1.3"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
601  <a href="#core.rules" class="smpl">OWS</a>        = &lt;OWS, defined in <a href="#Part1" id="rfc.xref.Part1.4"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#basic.rules" title="Basic Rules">Section 1.2.2</a>&gt;
602</pre><h3 id="rfc.section.1.2.2"><a href="#rfc.section.1.2.2">1.2.2</a>&nbsp;<a id="abnf.dependencies" href="#abnf.dependencies">ABNF Rules defined in other Parts of the Specification</a></h3>
603      <p id="rfc.section.1.2.2.p.1">The ABNF rules below are defined in other parts:</p>
604      <div id="rfc.figure.u.2"></div><pre class="inline">  <a href="#abnf.dependencies" class="smpl">HTTP-date</a>  = &lt;HTTP-date, defined in <a href="#Part1" id="rfc.xref.Part1.5"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#full.date" title="Full Date">Section 3.2.1</a>&gt;
605</pre><div id="rfc.figure.u.3"></div><pre class="inline">  <a href="#abnf.dependencies" class="smpl">entity-tag</a> = &lt;entity-tag, defined in <a href="#Part4" id="rfc.xref.Part4.1"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>, <a href="p4-conditional.html#entity.tags" title="Entity Tags">Section 2</a>&gt;
606</pre><h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a id="range.units" href="#range.units">Range Units</a></h1>
607      <p id="rfc.section.2.p.1">HTTP/1.1 allows a client to request that only part (a range of) the response entity be included within the response. HTTP/1.1
608         uses range units in the Range (<a href="#header.range" id="rfc.xref.header.range.1" title="Range">Section&nbsp;5.4</a>) and Content-Range (<a href="#header.content-range" id="rfc.xref.header.content-range.1" title="Content-Range">Section&nbsp;5.2</a>) header fields. An entity can be broken down into subranges according to various structural units.
609      </p>
610      <div id="rfc.figure.u.4"></div><pre class="inline"><span id="rfc.iref.g.1"></span><span id="rfc.iref.g.2"></span><span id="rfc.iref.g.3"></span>  <a href="#range.units" class="smpl">range-unit</a>       = <a href="#range.units" class="smpl">bytes-unit</a> / <a href="#range.units" class="smpl">other-range-unit</a>
611  <a href="#range.units" class="smpl">bytes-unit</a>       = "bytes"
612  <a href="#range.units" class="smpl">other-range-unit</a> = <a href="#core.rules" class="smpl">token</a>
613</pre><p id="rfc.section.2.p.3">HTTP/1.1 has been designed to allow implementations of applications that do not depend on knowledge of ranges. The only range
614         unit defined by HTTP/1.1 is "bytes".
615      </p>
616      <p id="rfc.section.2.p.4">If a range unit is not understood in a request, a server <em class="bcp14">MUST</em> ignore the whole Range header (<a href="#header.range" id="rfc.xref.header.range.2" title="Range">Section&nbsp;5.4</a>). If a range unit is not understood in a response, an intermediary <em class="bcp14">SHOULD</em> pass the response to the client; a client <em class="bcp14">MUST</em> fail.
617      </p>
618      <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;Status Code Definitions
619      </h1>
620      <div id="rfc.iref.3"></div>
621      <div id="rfc.iref.s.1"></div>
622      <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;<a id="status.206" href="#status.206">206 Partial Content</a></h2>
623      <p id="rfc.section.3.1.p.1">The server has fulfilled the partial GET request for the resource. The request <em class="bcp14">MUST</em> have included a Range header field (<a href="#header.range" id="rfc.xref.header.range.3" title="Range">Section&nbsp;5.4</a>) indicating the desired range, and <em class="bcp14">MAY</em> have included an If-Range header field (<a href="#header.if-range" id="rfc.xref.header.if-range.1" title="If-Range">Section&nbsp;5.3</a>) to make the request conditional.
624      </p>
625      <p id="rfc.section.3.1.p.2">The response <em class="bcp14">MUST</em> include the following header fields:
626      </p>
627      <ul>
628         <li>Either a Content-Range header field (<a href="#header.content-range" id="rfc.xref.header.content-range.2" title="Content-Range">Section&nbsp;5.2</a>) indicating the range included with this response, or a multipart/byteranges Content-Type including Content-Range fields
629            for each part. If a Content-Length header field is present in the response, its value <em class="bcp14">MUST</em> match the actual number of OCTETs transmitted in the message-body.
630         </li>
631         <li>Date</li>
632         <li>ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request</li>
633         <li>Expires, Cache-Control, and/or Vary, if the field-value might differ from that sent in any previous response for the same
634            variant
635         </li>
636      </ul>
637      <p id="rfc.section.3.1.p.3">If the 206 response is the result of an If-Range request, the response <em class="bcp14">SHOULD NOT</em> include other entity-headers. Otherwise, the response <em class="bcp14">MUST</em> include all of the entity-headers that would have been returned with a 200 (OK) response to the same request.
638      </p>
639      <p id="rfc.section.3.1.p.4">A cache <em class="bcp14">MUST NOT</em> combine a 206 response with other previously cached content if the ETag or Last-Modified headers do not match exactly, see <a href="#combining.byte.ranges" title="Combining Ranges">Section&nbsp;4</a>.
640      </p>
641      <p id="rfc.section.3.1.p.5">A cache that does not support the Range and Content-Range headers <em class="bcp14">MUST NOT</em> cache 206 (Partial Content) responses. Furthermore, if a response uses a range unit that is not understood by the cache, then
642         it <em class="bcp14">MUST NOT</em> be cached either.
643      </p>
644      <div id="rfc.iref.4"></div>
645      <div id="rfc.iref.s.2"></div>
646      <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a id="status.416" href="#status.416">416 Requested Range Not Satisfiable</a></h2>
647      <p id="rfc.section.3.2.p.1">A server <em class="bcp14">SHOULD</em> return a response with this status code if a request included a Range request-header field (<a href="#header.range" id="rfc.xref.header.range.4" title="Range">Section&nbsp;5.4</a>), and none of the ranges-specifier values in this field overlap the current extent of the selected resource, and the request
648         did not include an If-Range request-header field. (For byte-ranges, this means that the first-byte-pos of all of the byte-range-spec
649         values were greater than the current length of the selected resource.)
650      </p>
651      <p id="rfc.section.3.2.p.2">When this status code is returned for a byte-range request, the response <em class="bcp14">SHOULD</em> include a Content-Range entity-header field specifying the current length of the selected resource (see <a href="#header.content-range" id="rfc.xref.header.content-range.3" title="Content-Range">Section&nbsp;5.2</a>). This response <em class="bcp14">MUST NOT</em> use the multipart/byteranges content-type.
652      </p>
653      <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a id="combining.byte.ranges" href="#combining.byte.ranges">Combining Ranges</a></h1>
654      <p id="rfc.section.4.p.1">A response might transfer only a subrange of an entity-body, either the request included one or more Range specifications,
655         or because a connection was broken prematurely. After several such transfers, a cache might have received several ranges of
656         the same entity-body.
657      </p>
658      <p id="rfc.section.4.p.2">If a cache has a stored non-empty set of subranges for an entity, and an incoming response transfers another subrange, the
659         cache <em class="bcp14">MAY</em> combine the new subrange with the existing set if both the following conditions are met:
660      </p>
661      <ul>
662         <li>Both the incoming response and the cache entry have a cache validator.</li>
663         <li>The two cache validators match using the strong comparison function (see <a href="p4-conditional.html#weak.and.strong.validators" title="Weak and Strong Validators">Section 4</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>).
664         </li>
665      </ul>
666      <p id="rfc.section.4.p.3">If either requirement is not met, the cache <em class="bcp14">MUST</em> use only the most recent partial response (based on the Date values transmitted with every response, and using the incoming
667         response if these values are equal or missing), and <em class="bcp14">MUST</em> discard the other partial information.
668      </p>
669      <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a id="header.fields" href="#header.fields">Header Field Definitions</a></h1>
670      <p id="rfc.section.5.p.1">This section defines the syntax and semantics of HTTP/1.1 header fields related to range requests and partial responses.</p>
671      <p id="rfc.section.5.p.2">For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who
672         receives the entity.
673      </p>
674      <div id="rfc.iref.a.1"></div>
675      <div id="rfc.iref.h.1"></div>
676      <h2 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a>&nbsp;<a id="header.accept-ranges" href="#header.accept-ranges">Accept-Ranges</a></h2>
677      <p id="rfc.section.5.1.p.1">The response-header "Accept-Ranges" field allows the server to indicate its acceptance of range requests for a resource:</p>
678      <div id="rfc.figure.u.5"></div><pre class="inline"><span id="rfc.iref.g.4"></span><span id="rfc.iref.g.5"></span><span id="rfc.iref.g.6"></span>  <a href="#header.accept-ranges" class="smpl">Accept-Ranges</a>     = "Accept-Ranges" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.accept-ranges" class="smpl">Accept-Ranges-v</a>
679  <a href="#header.accept-ranges" class="smpl">Accept-Ranges-v</a>   = <a href="#header.accept-ranges" class="smpl">acceptable-ranges</a>
680  <a href="#header.accept-ranges" class="smpl">acceptable-ranges</a> = 1#<a href="#range.units" class="smpl">range-unit</a> / "none"
681</pre><p id="rfc.section.5.1.p.3">Origin servers that accept byte-range requests <em class="bcp14">MAY</em> send
682      </p>
683      <div id="rfc.figure.u.6"></div><pre class="text">  Accept-Ranges: bytes
684</pre><p id="rfc.section.5.1.p.5">but are not required to do so. Clients <em class="bcp14">MAY</em> generate range requests without having received this header for the resource involved. Range units are defined in <a href="#range.units" title="Range Units">Section&nbsp;2</a>.
685      </p>
686      <p id="rfc.section.5.1.p.6">Servers that do not accept any kind of range request for a resource <em class="bcp14">MAY</em> send
687      </p>
688      <div id="rfc.figure.u.7"></div><pre class="text">  Accept-Ranges: none
689</pre><p id="rfc.section.5.1.p.8">to advise the client not to attempt a range request.</p>
690      <div id="rfc.iref.c.1"></div>
691      <div id="rfc.iref.h.2"></div>
692      <h2 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a>&nbsp;<a id="header.content-range" href="#header.content-range">Content-Range</a></h2>
693      <p id="rfc.section.5.2.p.1">The entity-header "Content-Range" is sent with a partial entity-body to specify where in the full entity-body the partial
694         body should be applied. Range units are defined in <a href="#range.units" title="Range Units">Section&nbsp;2</a>.
695      </p>
696      <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.7"></span><span id="rfc.iref.g.8"></span><span id="rfc.iref.g.9"></span><span id="rfc.iref.g.10"></span><span id="rfc.iref.g.11"></span><span id="rfc.iref.g.12"></span>  <a href="#header.content-range" class="smpl">Content-Range</a> = "Content-Range" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.content-range" class="smpl">Content-Range-v</a>
697  <a href="#header.content-range" class="smpl">Content-Range-v</a> = <a href="#header.content-range" class="smpl">content-range-spec</a>
698 
699  <a href="#header.content-range" class="smpl">content-range-spec</a>      = <a href="#header.content-range" class="smpl">byte-content-range-spec</a>
700                          / <a href="#header.content-range" class="smpl">other-content-range-spec</a>
701  <a href="#header.content-range" class="smpl">byte-content-range-spec</a> = <a href="#range.units" class="smpl">bytes-unit</a> <a href="#notation" class="smpl">SP</a>
702                            <a href="#header.content-range" class="smpl">byte-range-resp-spec</a> "/"
703                            ( <a href="#header.content-range" class="smpl">instance-length</a> / "*" )
704 
705  <a href="#header.content-range" class="smpl">byte-range-resp-spec</a>    = (<a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> "-" <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>)
706                          / "*"
707                         
708  <a href="#header.content-range" class="smpl">instance-length</a>         = 1*<a href="#notation" class="smpl">DIGIT</a>
709 
710  <a href="#header.content-range" class="smpl">other-content-range-spec</a> = <a href="#range.units" class="smpl">other-range-unit</a> <a href="#notation" class="smpl">SP</a>
711                             <a href="#header.content-range" class="smpl">other-range-resp-spec</a>
712  <a href="#header.content-range" class="smpl">other-range-resp-spec</a>    = *<a href="#notation" class="smpl">CHAR</a>
713</pre><p id="rfc.section.5.2.p.3">The header <em class="bcp14">SHOULD</em> indicate the total length of the full entity-body, unless this length is unknown or difficult to determine. The asterisk "*"
714         character means that the instance-length is unknown at the time when the response was generated.
715      </p>
716      <p id="rfc.section.5.2.p.4">Unlike byte-ranges-specifier values (see <a href="#byte.ranges" title="Byte Ranges">Section&nbsp;5.4.1</a>), a byte-range-resp-spec <em class="bcp14">MUST</em> only specify one range, and <em class="bcp14">MUST</em> contain absolute byte positions for both the first and last byte of the range.
717      </p>
718      <p id="rfc.section.5.2.p.5">A byte-content-range-spec with a byte-range-resp-spec whose last-byte-pos value is less than its first-byte-pos value, or
719         whose instance-length value is less than or equal to its last-byte-pos value, is invalid. The recipient of an invalid byte-content-range-spec <em class="bcp14">MUST</em> ignore it and any content transferred along with it.
720      </p>
721      <p id="rfc.section.5.2.p.6">In the case of a byte range request: A server sending a response with status code 416 (Requested range not satisfiable) <em class="bcp14">SHOULD</em> include a Content-Range field with a byte-range-resp-spec of "*". The instance-length specifies the current length of the
722         selected resource as a decimal number. A response with status code 206 (Partial Content) <em class="bcp14">MUST NOT</em> include a Content-Range field with a byte-range-resp-spec of "*".
723      </p>
724      <p id="rfc.section.5.2.p.7">Examples of byte-content-range-spec values, assuming that the entity contains a total of 1234 bytes: </p>
725      <ul>
726         <li>The first 500 bytes:
727            <div id="rfc.figure.u.9"></div><pre class="text">   bytes 0-499/1234
728</pre> </li>
729         <li>The second 500 bytes:
730            <div id="rfc.figure.u.10"></div><pre class="text">   bytes 500-999/1234
731</pre> </li>
732         <li>All except for the first 500 bytes:
733            <div id="rfc.figure.u.11"></div><pre class="text">   bytes 500-1233/1234
734</pre> </li>
735         <li>The last 500 bytes:
736            <div id="rfc.figure.u.12"></div><pre class="text">   bytes 734-1233/1234
737</pre> </li>
738      </ul>
739      <p id="rfc.section.5.2.p.8">When an HTTP message includes the content of a single range (for example, a response to a request for a single range, or to
740         a request for a set of ranges that overlap without any holes), this content is transmitted with a Content-Range header, and
741         a Content-Length header showing the number of bytes actually transferred. For example,
742      </p>
743      <div id="rfc.figure.u.13"></div><pre class="text">  HTTP/1.1 206 Partial Content
744  Date: Wed, 15 Nov 1995 06:25:24 GMT
745  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
746  Content-Range: bytes 21010-47021/47022
747  Content-Length: 26012
748  Content-Type: image/gif
749</pre><p id="rfc.section.5.2.p.10">When an HTTP message includes the content of multiple ranges (for example, a response to a request for multiple non-overlapping
750         ranges), these are transmitted as a multipart message. The multipart media type used for this purpose is "multipart/byteranges"
751         as defined in <a href="#internet.media.type.multipart.byteranges" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>. See <a href="#changes.from.rfc.2068" title="Changes from RFC 2068">Appendix&nbsp;B.1</a> for a compatibility issue.
752      </p>
753      <p id="rfc.section.5.2.p.11">A response to a request for a single range <em class="bcp14">MUST NOT</em> be sent using the multipart/byteranges media type. A response to a request for multiple ranges, whose result is a single range, <em class="bcp14">MAY</em> be sent as a multipart/byteranges media type with one part. A client that cannot decode a multipart/byteranges message <em class="bcp14">MUST NOT</em> ask for multiple ranges in a single request.
754      </p>
755      <p id="rfc.section.5.2.p.12">When a client requests multiple byte-ranges in one request, the server <em class="bcp14">SHOULD</em> return them in the order that they appeared in the request.
756      </p>
757      <p id="rfc.section.5.2.p.13">If the server ignores a byte-range-spec because it is syntactically invalid, the server <em class="bcp14">SHOULD</em> treat the request as if the invalid Range header field did not exist. (Normally, this means return a 200 response containing
758         the full entity).
759      </p>
760      <p id="rfc.section.5.2.p.14">If the server receives a request (other than one including an If-Range request-header field) with an unsatisfiable Range request-header
761         field (that is, all of whose byte-range-spec values have a first-byte-pos value greater than the current length of the selected
762         resource), it <em class="bcp14">SHOULD</em> return a response code of 416 (Requested range not satisfiable) (<a href="#status.416" id="rfc.xref.status.416.1" title="416 Requested Range Not Satisfiable">Section&nbsp;3.2</a>).
763      </p>
764      <dl class="empty">
765         <dd> <b>Note:</b> clients cannot depend on servers to send a 416 (Requested range not satisfiable) response instead of a 200 (OK) response for
766            an unsatisfiable Range request-header, since not all servers implement this request-header.
767         </dd>
768      </dl>
769      <div id="rfc.iref.i.1"></div>
770      <div id="rfc.iref.h.3"></div>
771      <h2 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a>&nbsp;<a id="header.if-range" href="#header.if-range">If-Range</a></h2>
772      <p id="rfc.section.5.3.p.1">If a client has a partial copy of an entity in its cache, and wishes to have an up-to-date copy of the entire entity in its
773         cache, it could use the Range request-header with a conditional GET (using either or both of If-Unmodified-Since and If-Match.)
774         However, if the condition fails because the entity has been modified, the client would then have to make a second request
775         to obtain the entire current entity-body.
776      </p>
777      <p id="rfc.section.5.3.p.2">The request header "If-Range" allows a client to "short-circuit" the second request. Informally, its meaning is `if the entity
778         is unchanged, send me the part(s) that I am missing; otherwise, send me the entire new entity'.
779      </p>
780      <div id="rfc.figure.u.14"></div><pre class="inline"><span id="rfc.iref.g.13"></span><span id="rfc.iref.g.14"></span>  <a href="#header.if-range" class="smpl">If-Range</a>   = "If-Range" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.if-range" class="smpl">If-Range-v</a>
781  <a href="#header.if-range" class="smpl">If-Range-v</a> = <a href="#abnf.dependencies" class="smpl">entity-tag</a> / <a href="#abnf.dependencies" class="smpl">HTTP-date</a>
782</pre><p id="rfc.section.5.3.p.4">If the client has no entity tag for an entity, but does have a Last-Modified date, it <em class="bcp14">MAY</em> use that date in an If-Range header. (The server can distinguish between a valid HTTP-date and any form of entity-tag by examining
783         no more than two characters.) The If-Range header <em class="bcp14">SHOULD</em> only be used together with a Range header, and <em class="bcp14">MUST</em> be ignored if the request does not include a Range header, or if the server does not support the sub-range operation.
784      </p>
785      <p id="rfc.section.5.3.p.5">If the entity tag given in the If-Range header matches the current entity tag for the entity, then the server <em class="bcp14">SHOULD</em> provide the specified sub-range of the entity using a 206 (Partial Content) response. If the entity tag does not match, then
786         the server <em class="bcp14">SHOULD</em> return the entire entity using a 200 (OK) response.
787      </p>
788      <div id="rfc.iref.r.1"></div>
789      <div id="rfc.iref.h.4"></div>
790      <h2 id="rfc.section.5.4"><a href="#rfc.section.5.4">5.4</a>&nbsp;<a id="header.range" href="#header.range">Range</a></h2>
791      <h3 id="rfc.section.5.4.1"><a href="#rfc.section.5.4.1">5.4.1</a>&nbsp;<a id="byte.ranges" href="#byte.ranges">Byte Ranges</a></h3>
792      <p id="rfc.section.5.4.1.p.1">Since all HTTP entities are represented in HTTP messages as sequences of bytes, the concept of a byte range is meaningful
793         for any HTTP entity. (However, not all clients and servers need to support byte-range operations.)
794      </p>
795      <p id="rfc.section.5.4.1.p.2">Byte range specifications in HTTP apply to the sequence of bytes in the entity-body (not necessarily the same as the message-body).</p>
796      <div id="rule.ranges-specifier">
797         <p id="rfc.section.5.4.1.p.3">                  A byte range operation <em class="bcp14">MAY</em> specify a single range of bytes, or a set of ranges within a single entity.
798         </p>
799      </div>
800      <div id="rfc.figure.u.15"></div><pre class="inline"><span id="rfc.iref.g.15"></span><span id="rfc.iref.g.16"></span><span id="rfc.iref.g.17"></span><span id="rfc.iref.g.18"></span><span id="rfc.iref.g.19"></span><span id="rfc.iref.g.20"></span>  <a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> = <a href="#range.units" class="smpl">bytes-unit</a> "=" <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a>
801  <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a>  = 1#( <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> / <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> )
802  <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> = <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> "-" [ <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> ]
803  <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>  = 1*<a href="#notation" class="smpl">DIGIT</a>
804  <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>   = 1*<a href="#notation" class="smpl">DIGIT</a>
805</pre><p id="rfc.section.5.4.1.p.5">The first-byte-pos value in a byte-range-spec gives the byte-offset of the first byte in a range. The last-byte-pos value
806         gives the byte-offset of the last byte in the range; that is, the byte positions specified are inclusive. Byte offsets are
807         decimal and start at zero.
808      </p>
809      <p id="rfc.section.5.4.1.p.6">If the last-byte-pos value is present, it <em class="bcp14">MUST</em> be greater than or equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec is syntactically invalid. The
810         recipient of a byte-range-set that includes one or more syntactically invalid byte-range-spec values <em class="bcp14">MUST</em> ignore the header field that includes that byte-range-set.
811      </p>
812      <p id="rfc.section.5.4.1.p.7">If the last-byte-pos value is absent, or if the value is greater than or equal to the current length of the entity-body, last-byte-pos
813         is taken to be equal to one less than the current length of the entity-body in bytes.
814      </p>
815      <p id="rfc.section.5.4.1.p.8">By its choice of last-byte-pos, a client can limit the number of bytes retrieved without knowing the size of the entity.</p>
816      <div id="rfc.figure.u.16"></div><pre class="inline"><span id="rfc.iref.g.21"></span><span id="rfc.iref.g.22"></span>  <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> = "-" <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>
817  <a href="#rule.ranges-specifier" class="smpl">suffix-length</a> = 1*<a href="#notation" class="smpl">DIGIT</a>
818</pre><p id="rfc.section.5.4.1.p.10">A suffix-byte-range-spec is used to specify the suffix of the entity-body, of a length given by the decimal suffix-length
819         value. (That is, this form specifies the last N bytes of an entity-body.) If the entity is shorter than the specified suffix-length,
820         the entire entity-body is used.
821      </p>
822      <p id="rfc.section.5.4.1.p.11">If a syntactically valid byte-range-set includes at least one byte-range-spec whose first-byte-pos is less than the current
823         length of the entity-body, or at least one suffix-byte-range-spec with a non-zero suffix-length, then the byte-range-set is
824         satisfiable. Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set is unsatisfiable, the server <em class="bcp14">SHOULD</em> return a response with a status of 416 (Requested range not satisfiable). Otherwise, the server <em class="bcp14">SHOULD</em> return a response with a status of 206 (Partial Content) containing the satisfiable ranges of the entity-body.
825      </p>
826      <p id="rfc.section.5.4.1.p.12">Examples of byte-ranges-specifier values (assuming an entity-body of length 10000): </p>
827      <ul>
828         <li>The first 500 bytes (byte offsets 0-499, inclusive): bytes=0-499</li>
829         <li>The second 500 bytes (byte offsets 500-999, inclusive): bytes=500-999</li>
830         <li>The final 500 bytes (byte offsets 9500-9999, inclusive): bytes=-500</li>
831         <li>Or bytes=9500-</li>
832         <li>The first and last bytes only (bytes 0 and 9999): bytes=0-0,-1</li>
833         <li>Several legal but not canonical specifications of the second 500 bytes (byte offsets 500-999, inclusive): <br> bytes=500-600,601-999<br> bytes=500-700,601-999
834         </li>
835      </ul>
836      <h3 id="rfc.section.5.4.2"><a href="#rfc.section.5.4.2">5.4.2</a>&nbsp;<a id="range.retrieval.requests" href="#range.retrieval.requests">Range Retrieval Requests</a></h3>
837      <p id="rfc.section.5.4.2.p.1">HTTP retrieval requests using conditional or unconditional GET methods <em class="bcp14">MAY</em> request one or more sub-ranges of the entity, instead of the entire entity, using the Range request header, which applies
838         to the entity returned as the result of the request:
839      </p>
840      <div id="rfc.figure.u.17"></div><pre class="inline"><span id="rfc.iref.g.23"></span>  <a href="#range.retrieval.requests" class="smpl">Range</a>   = "Range" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#range.retrieval.requests" class="smpl">Range-v</a>
841  <a href="#range.retrieval.requests" class="smpl">Range-v</a> = <a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a>
842          / <a href="#rule.ranges-specifier" class="smpl">other-ranges-specifier</a>
843  <a href="#rule.ranges-specifier" class="smpl">other-ranges-specifier</a> = 1*<a href="#notation" class="smpl">CHAR</a>
844</pre><p id="rfc.section.5.4.2.p.3">A server <em class="bcp14">MAY</em> ignore the Range header. However, HTTP/1.1 origin servers and intermediate caches ought to support byte ranges when possible,
845         since Range supports efficient recovery from partially failed transfers, and supports efficient partial retrieval of large
846         entities.
847      </p>
848      <p id="rfc.section.5.4.2.p.4">If the server supports the Range header and the specified range or ranges are appropriate for the entity: </p>
849      <ul>
850         <li>The presence of a Range header in an unconditional GET modifies what is returned if the GET is otherwise successful. In other
851            words, the response carries a status code of 206 (Partial Content) instead of 200 (OK).
852         </li>
853         <li>The presence of a Range header in a conditional GET (a request using one or both of If-Modified-Since and If-None-Match, or
854            one or both of If-Unmodified-Since and If-Match) modifies what is returned if the GET is otherwise successful and the condition
855            is true. It does not affect the 304 (Not Modified) response returned if the conditional is false.
856         </li>
857      </ul>
858      <p id="rfc.section.5.4.2.p.5">In some cases, it might be more appropriate to use the If-Range header (see <a href="#header.if-range" id="rfc.xref.header.if-range.2" title="If-Range">Section&nbsp;5.3</a>) in addition to the Range header.
859      </p>
860      <p id="rfc.section.5.4.2.p.6">If a proxy that supports ranges receives a Range request, forwards the request to an inbound server, and receives an entire
861         entity in reply, it <em class="bcp14">SHOULD</em> only return the requested range to its client. It <em class="bcp14">SHOULD</em> store the entire received response in its cache if that is consistent with its cache allocation policies.
862      </p>
863      <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a id="IANA.considerations" href="#IANA.considerations">IANA Considerations</a></h1>
864      <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a id="message.header.registration" href="#message.header.registration">Message Header Registration</a></h2>
865      <p id="rfc.section.6.1.p.1">The Message Header Registry located at &lt;<a href="http://www.iana.org/assignments/message-headers/message-header-index.html">http://www.iana.org/assignments/message-headers/message-header-index.html</a>&gt; should be updated with the permanent registrations below (see <a href="#RFC3864" id="rfc.xref.RFC3864.1"><cite title="Registration Procedures for Message Header Fields">[RFC3864]</cite></a>):
866      </p>
867      <div id="rfc.table.1">
868         <div id="iana.header.registration.table"></div>
869         <table summary="" class="tt full" cellpadding="3" cellspacing="0">
870            <thead>
871               <tr>
872                  <th>Header Field Name</th>
873                  <th>Protocol</th>
874                  <th>Status</th>
875                  <th>Reference</th>
876               </tr>
877            </thead>
878            <tbody>
879               <tr>
880                  <td>Accept-Ranges</td>
881                  <td>http</td>
882                  <td>standard</td>
883                  <td> <a href="#header.accept-ranges" id="rfc.xref.header.accept-ranges.1" title="Accept-Ranges">Section&nbsp;5.1</a> 
884                  </td>
885               </tr>
886               <tr>
887                  <td>Content-Range</td>
888                  <td>http</td>
889                  <td>standard</td>
890                  <td> <a href="#header.content-range" id="rfc.xref.header.content-range.4" title="Content-Range">Section&nbsp;5.2</a> 
891                  </td>
892               </tr>
893               <tr>
894                  <td>If-Range</td>
895                  <td>http</td>
896                  <td>standard</td>
897                  <td> <a href="#header.if-range" id="rfc.xref.header.if-range.3" title="If-Range">Section&nbsp;5.3</a> 
898                  </td>
899               </tr>
900               <tr>
901                  <td>Range</td>
902                  <td>http</td>
903                  <td>standard</td>
904                  <td> <a href="#header.range" id="rfc.xref.header.range.5" title="Range">Section&nbsp;5.4</a> 
905                  </td>
906               </tr>
907            </tbody>
908         </table>
909      </div>
910      <p id="rfc.section.6.1.p.2">The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".</p>
911      <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a id="security.considerations" href="#security.considerations">Security Considerations</a></h1>
912      <p id="rfc.section.7.p.1">No additional security considerations have been identified beyond those applicable to HTTP in general <a href="#Part1" id="rfc.xref.Part1.6"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>.
913      </p>
914      <h1 id="rfc.section.8"><a href="#rfc.section.8">8.</a>&nbsp;<a id="ack" href="#ack">Acknowledgments</a></h1>
915      <p id="rfc.section.8.p.1">Most of the specification of ranges is based on work originally done by Ari Luotonen and John Franks, with additional input
916         from Steve Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin Hamilton, Koen Holtman, Shel Kaplan, Paul Leach,
917         Alex Lopez-Ortiz, Larry Masinter, Jeff Mogul, Lou Montulli, David W. Morris, Luigi Rizzo, and Bill Weihl.
918      </p>
919      <h1 id="rfc.references"><a id="rfc.section.9" href="#rfc.section.9">9.</a> References
920      </h1>
921      <h2 id="rfc.references.1"><a href="#rfc.section.9.1" id="rfc.section.9.1">9.1</a> Normative References
922      </h2>
923      <table summary="Normative References">             
924         <tr>
925            <td class="reference"><b id="Part1">[Part1]</b></td>
926            <td class="top"><a title="Day Software">Fielding, R., Ed.</a>, <a title="One Laptop per Child">Gettys, J.</a>, <a title="Hewlett-Packard Company">Mogul, J.</a>, <a title="Microsoft Corporation">Frystyk, H.</a>, <a title="Adobe Systems, Incorporated">Masinter, L.</a>, <a title="Microsoft Corporation">Leach, P.</a>, <a title="World Wide Web Consortium">Berners-Lee, T.</a>, <a title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a title="greenbytes GmbH">J. F. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p1-messaging-06">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-06 (work in progress), March&nbsp;2009.
927            </td>
928         </tr>
929         <tr>
930            <td class="reference"><b id="Part3">[Part3]</b></td>
931            <td class="top"><a title="Day Software">Fielding, R., Ed.</a>, <a title="One Laptop per Child">Gettys, J.</a>, <a title="Hewlett-Packard Company">Mogul, J.</a>, <a title="Microsoft Corporation">Frystyk, H.</a>, <a title="Adobe Systems, Incorporated">Masinter, L.</a>, <a title="Microsoft Corporation">Leach, P.</a>, <a title="World Wide Web Consortium">Berners-Lee, T.</a>, <a title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a title="greenbytes GmbH">J. F. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p3-payload-06">HTTP/1.1, part 3: Message Payload and Content Negotiation</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p3-payload-06 (work in progress), March&nbsp;2009.
932            </td>
933         </tr>
934         <tr>
935            <td class="reference"><b id="Part4">[Part4]</b></td>
936            <td class="top"><a title="Day Software">Fielding, R., Ed.</a>, <a title="One Laptop per Child">Gettys, J.</a>, <a title="Hewlett-Packard Company">Mogul, J.</a>, <a title="Microsoft Corporation">Frystyk, H.</a>, <a title="Adobe Systems, Incorporated">Masinter, L.</a>, <a title="Microsoft Corporation">Leach, P.</a>, <a title="World Wide Web Consortium">Berners-Lee, T.</a>, <a title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a title="greenbytes GmbH">J. F. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-06">HTTP/1.1, part 4: Conditional Requests</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p4-conditional-06 (work in progress), March&nbsp;2009.
937            </td>
938         </tr>
939         <tr>
940            <td class="reference"><b id="Part6">[Part6]</b></td>
941            <td class="top"><a title="Day Software">Fielding, R., Ed.</a>, <a title="One Laptop per Child">Gettys, J.</a>, <a title="Hewlett-Packard Company">Mogul, J.</a>, <a title="Microsoft Corporation">Frystyk, H.</a>, <a title="Adobe Systems, Incorporated">Masinter, L.</a>, <a title="Microsoft Corporation">Leach, P.</a>, <a title="World Wide Web Consortium">Berners-Lee, T.</a>, <a title="World Wide Web Consortium">Lafon, Y., Ed.</a>, and <a title="greenbytes GmbH">J. F. Reschke, Ed.</a>, “<a href="http://tools.ietf.org/html/draft-ietf-httpbis-p6-cache-06">HTTP/1.1, part 6: Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-06 (work in progress), March&nbsp;2009.
942            </td>
943         </tr>
944         <tr>
945            <td class="reference"><b id="RFC2046">[RFC2046]</b></td>
946            <td class="top"><a title="Innosoft International, Inc.">Freed, N.</a> and <a 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.
947            </td>
948         </tr>
949         <tr>
950            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
951            <td class="top"><a 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.
952            </td>
953         </tr>
954         <tr>
955            <td class="reference"><b id="RFC5234">[RFC5234]</b></td>
956            <td class="top"><a title="Brandenburg InternetWorking">Crocker, D., Ed.</a> and <a title="THUS plc.">P. Overell</a>, “<a href="http://tools.ietf.org/html/rfc5234">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
957            </td>
958         </tr>
959      </table>
960      <h2 id="rfc.references.2"><a href="#rfc.section.9.2" id="rfc.section.9.2">9.2</a> Informative References
961      </h2>
962      <table summary="Informative References">     
963         <tr>
964            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
965            <td class="top"><a title="University of California, Irvine">Fielding, R.</a>, <a title="W3C">Gettys, J.</a>, <a title="Compaq Computer Corporation">Mogul, J.</a>, <a title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a title="Xerox Corporation">Masinter, L.</a>, <a title="Microsoft Corporation">Leach, P.</a>, and <a 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.
966            </td>
967         </tr>
968         <tr>
969            <td class="reference"><b id="RFC3864">[RFC3864]</b></td>
970            <td class="top"><a title="Nine by Nine">Klyne, G.</a>, <a title="BEA Systems">Nottingham, M.</a>, and <a 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.
971            </td>
972         </tr>
973         <tr>
974            <td class="reference"><b id="RFC4288">[RFC4288]</b></td>
975            <td class="top"><a title="Sun Microsystems">Freed, N.</a> and <a>J. Klensin</a>, “<a href="http://tools.ietf.org/html/rfc4288">Media Type Specifications and Registration Procedures</a>”, BCP&nbsp;13, RFC&nbsp;4288, December&nbsp;2005.
976            </td>
977         </tr>
978      </table>
979      <h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
980      <address class="vcard"><span class="vcardline"><span class="fn">Roy T. Fielding</span>
981            (editor)
982            <span class="n hidden"><span class="family-name">Fielding</span><span class="given-name">Roy T.</span></span></span><span class="org vcardline">Day Software</span><span class="adr"><span class="street-address vcardline">23 Corporate Plaza DR, Suite 280</span><span class="vcardline"><span class="locality">Newport Beach</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">92660</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline tel">Phone: <a href="tel:+1-949-706-5300"><span class="value">+1-949-706-5300</span></a></span><span class="vcardline tel"><span class="type">Fax</span>: <a href="fax:+1-949-706-5305"><span class="value">+1-949-706-5305</span></a></span><span class="vcardline">EMail: <a><span class="email">fielding@gbiv.com</span></a></span><span class="vcardline">URI: <a href="http://roy.gbiv.com/" class="url">http://roy.gbiv.com/</a></span></address>
983      <address class="vcard"><span class="vcardline"><span class="fn">Jim Gettys</span><span class="n hidden"><span class="family-name">Gettys</span><span class="given-name">Jim</span></span></span><span class="org vcardline">One Laptop per Child</span><span class="adr"><span class="street-address vcardline">21 Oak Knoll Road</span><span class="vcardline"><span class="locality">Carlisle</span>, <span class="region">MA</span>&nbsp;<span class="postal-code">01741</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">EMail: <a><span class="email">jg@laptop.org</span></a></span><span class="vcardline">URI: <a href="http://www.laptop.org/" class="url">http://www.laptop.org/</a></span></address>
984      <address class="vcard"><span class="vcardline"><span class="fn">Jeffrey C. Mogul</span><span class="n hidden"><span class="family-name">Mogul</span><span class="given-name">Jeffrey C.</span></span></span><span class="org vcardline">Hewlett-Packard Company</span><span class="adr"><span class="street-address vcardline">HP Labs, Large Scale Systems Group</span><span class="street-address vcardline">1501 Page Mill Road, MS 1177</span><span class="vcardline"><span class="locality">Palo Alto</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">94304</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">EMail: <a><span class="email">JeffMogul@acm.org</span></a></span></address>
985      <address class="vcard"><span class="vcardline"><span class="fn">Henrik Frystyk Nielsen</span><span class="n hidden"><span class="family-name">Frystyk</span></span></span><span class="org vcardline">Microsoft Corporation</span><span class="adr"><span class="street-address vcardline">1 Microsoft Way</span><span class="vcardline"><span class="locality">Redmond</span>, <span class="region">WA</span>&nbsp;<span class="postal-code">98052</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">EMail: <a><span class="email">henrikn@microsoft.com</span></a></span></address>
986      <address class="vcard"><span class="vcardline"><span class="fn">Larry Masinter</span><span class="n hidden"><span class="family-name">Masinter</span><span class="given-name">Larry</span></span></span><span class="org vcardline">Adobe Systems, Incorporated</span><span class="adr"><span class="street-address vcardline">345 Park Ave</span><span class="vcardline"><span class="locality">San Jose</span>, <span class="region">CA</span>&nbsp;<span class="postal-code">95110</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">EMail: <a><span class="email">LMM@acm.org</span></a></span><span class="vcardline">URI: <a href="http://larry.masinter.net/" class="url">http://larry.masinter.net/</a></span></address>
987      <address class="vcard"><span class="vcardline"><span class="fn">Paul J. Leach</span><span class="n hidden"><span class="family-name">Leach</span><span class="given-name">Paul J.</span></span></span><span class="org vcardline">Microsoft Corporation</span><span class="adr"><span class="street-address vcardline">1 Microsoft Way</span><span class="vcardline"><span class="locality">Redmond</span>, <span class="region">WA</span>&nbsp;<span class="postal-code">98052</span></span></span><span class="vcardline">EMail: <a><span class="email">paulle@microsoft.com</span></a></span></address>
988      <address class="vcard"><span class="vcardline"><span class="fn">Tim Berners-Lee</span><span class="n hidden"><span class="family-name">Berners-Lee</span><span class="given-name">Tim</span></span></span><span class="org vcardline">World Wide Web Consortium</span><span class="adr"><span class="street-address vcardline">MIT Computer Science and Artificial Intelligence Laboratory</span><span class="street-address vcardline">The Stata Center, Building 32</span><span class="street-address vcardline">32 Vassar Street</span><span class="vcardline"><span class="locality">Cambridge</span>, <span class="region">MA</span>&nbsp;<span class="postal-code">02139</span></span><span class="country-name vcardline">USA</span></span><span class="vcardline">EMail: <a><span class="email">timbl@w3.org</span></a></span><span class="vcardline">URI: <a href="http://www.w3.org/People/Berners-Lee/" class="url">http://www.w3.org/People/Berners-Lee/</a></span></address>
989      <address class="vcard"><span class="vcardline"><span class="fn">Yves Lafon</span>
990            (editor)
991            <span class="n hidden"><span class="family-name">Lafon</span><span class="given-name">Yves</span></span></span><span class="org vcardline">World Wide Web Consortium</span><span class="adr"><span class="street-address vcardline">W3C / ERCIM</span><span class="street-address vcardline">2004, rte des Lucioles</span><span class="vcardline"><span class="locality">Sophia-Antipolis</span>, <span class="region">AM</span>&nbsp;<span class="postal-code">06902</span></span><span class="country-name vcardline">France</span></span><span class="vcardline">EMail: <a><span class="email">ylafon@w3.org</span></a></span><span class="vcardline">URI: <a href="http://www.raubacapeu.net/people/yves/" class="url">http://www.raubacapeu.net/people/yves/</a></span></address>
992      <address class="vcard"><span class="vcardline"><span class="fn">Julian F. Reschke</span>
993            (editor)
994            <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 tel">Phone: <a href="tel:+492512807760"><span class="value">+49 251 2807760</span></a></span><span class="vcardline tel"><span class="type">Fax</span>: <a href="fax:+492512807761"><span class="value">+49 251 2807761</span></a></span><span class="vcardline">EMail: <a><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>
995      <div id="rfc.iref.m.1"></div>
996      <div id="rfc.iref.m.2"></div>
997      <h1 id="rfc.section.A"><a href="#rfc.section.A">A.</a>&nbsp;<a id="internet.media.type.multipart.byteranges" href="#internet.media.type.multipart.byteranges">Internet Media Type multipart/byteranges</a></h1>
998      <p id="rfc.section.A.p.1">When an HTTP 206 (Partial Content) response message includes the content of multiple ranges (a response to a request for multiple
999         non-overlapping ranges), these are transmitted as a multipart message-body (<a href="#RFC2046" id="rfc.xref.RFC2046.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a>, <a href="http://tools.ietf.org/html/rfc2046#section-5.1">Section 5.1</a>). The media type for this purpose is called "multipart/byteranges". The following is to be registered with IANA <a href="#RFC4288" id="rfc.xref.RFC4288.1"><cite title="Media Type Specifications and Registration Procedures">[RFC4288]</cite></a>.
1000      </p>
1001      <p id="rfc.section.A.p.2">The multipart/byteranges media type includes one or more parts, each with its own Content-Type and Content-Range fields. The
1002         required boundary parameter specifies the boundary string used to separate each body-part.
1003      </p>
1004      <p id="rfc.section.A.p.3"> </p>
1005      <dl>
1006         <dt>Type name:</dt>
1007         <dd>multipart</dd>
1008         <dt>Subtype name:</dt>
1009         <dd>byteranges</dd>
1010         <dt>Required parameters:</dt>
1011         <dd>boundary</dd>
1012         <dt>Optional parameters:</dt>
1013         <dd>none</dd>
1014         <dt>Encoding considerations:</dt>
1015         <dd>only "7bit", "8bit", or "binary" are permitted</dd>
1016         <dt>Security considerations:</dt>
1017         <dd>none</dd>
1018         <dt>Interoperability considerations:</dt>
1019         <dd>none</dd>
1020         <dt>Published specification:</dt>
1021         <dd>This specification (see <a href="#internet.media.type.multipart.byteranges" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>).
1022         </dd>
1023         <dt>Applications that use this media type:</dt>
1024         <dt>Additional information:</dt>
1025         <dd> 
1026            <dl>
1027               <dt>Magic number(s):</dt>
1028               <dd>none</dd>
1029               <dt>File extension(s):</dt>
1030               <dd>none</dd>
1031               <dt>Macintosh file type code(s):</dt>
1032               <dd>none</dd>
1033            </dl> 
1034         </dd>
1035         <dt>Person and email address to contact for further information:</dt>
1036         <dd>See Authors Section.</dd>
1037         <dt>Intended usage:</dt>
1038         <dd>COMMON</dd>
1039         <dt>Restrictions on usage:</dt>
1040         <dd>none</dd>
1041         <dt>Author/Change controller:</dt>
1042         <dd>IESG</dd>
1043      </dl>
1044      <div id="rfc.figure.u.18"></div>
1045      <p>For example:</p><pre class="text">  HTTP/1.1 206 Partial Content
1046  Date: Wed, 15 Nov 1995 06:25:24 GMT
1047  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
1048  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1049 
1050  --THIS_STRING_SEPARATES
1051  Content-type: application/pdf
1052  Content-range: bytes 500-999/8000
1053 
1054  ...the first range...
1055  --THIS_STRING_SEPARATES
1056  Content-type: application/pdf
1057  Content-range: bytes 7000-7999/8000
1058 
1059  ...the second range
1060  --THIS_STRING_SEPARATES--
1061</pre><p id="rfc.section.A.p.5">Notes: </p>
1062      <ol>
1063         <li>Additional CRLFs may precede the first boundary string in the entity.</li>
1064         <li>Although <a href="#RFC2046" id="rfc.xref.RFC2046.2"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a> permits the boundary string to be quoted, some existing implementations handle a quoted boundary string incorrectly.
1065         </li>
1066         <li>A number of browsers and servers were coded to an early draft of the byteranges specification to use a media type of multipart/x-byteranges<span id="rfc.iref.m.3"></span><span id="rfc.iref.m.4"></span>, which is almost, but not quite compatible with the version documented in HTTP/1.1.
1067         </li>
1068      </ol>
1069      <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a id="compatibility" href="#compatibility">Compatibility with Previous Versions</a></h1>
1070      <h2 id="rfc.section.B.1"><a href="#rfc.section.B.1">B.1</a>&nbsp;<a id="changes.from.rfc.2068" href="#changes.from.rfc.2068">Changes from RFC 2068</a></h2>
1071      <p id="rfc.section.B.1.p.1">Transfer-coding and message lengths all interact in ways that required fixing exactly when chunked encoding is used (to allow
1072         for transfer encoding that may not be self delimiting); it was important to straighten out exactly how message lengths are
1073         computed. (<a href="#header.content-range" id="rfc.xref.header.content-range.5" title="Content-Range">Section&nbsp;5.2</a>, see also <a href="#Part1" id="rfc.xref.Part1.7"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="#Part3" id="rfc.xref.Part3.1"><cite title="HTTP/1.1, part 3: Message Payload and Content Negotiation">[Part3]</cite></a> and <a href="#Part6" id="rfc.xref.Part6.1"><cite title="HTTP/1.1, part 6: Caching">[Part6]</cite></a>)
1074      </p>
1075      <p id="rfc.section.B.1.p.2">There are situations where a server (especially a proxy) does not know the full length of a response but is capable of serving
1076         a byterange request. We therefore need a mechanism to allow byteranges with a content-range not indicating the full length
1077         of the message. (<a href="#header.content-range" id="rfc.xref.header.content-range.6" title="Content-Range">Section&nbsp;5.2</a>)
1078      </p>
1079      <p id="rfc.section.B.1.p.3">Range request responses would become very verbose if all meta-data were always returned; by allowing the server to only send
1080         needed headers in a 206 response, this problem can be avoided. (Section <a href="#status.206" id="rfc.xref.status.206.1" title="206 Partial Content">3.1</a> and <a href="#header.if-range" id="rfc.xref.header.if-range.4" title="If-Range">5.3</a>)
1081      </p>
1082      <p id="rfc.section.B.1.p.4">Fix problem with unsatisfiable range requests; there are two cases: syntactic problems, and range doesn't exist in the document.
1083         The 416 status code was needed to resolve this ambiguity needed to indicate an error for a byte range request that falls outside
1084         of the actual contents of a document. (Section <a href="#status.416" id="rfc.xref.status.416.2" title="416 Requested Range Not Satisfiable">3.2</a>, <a href="#header.content-range" id="rfc.xref.header.content-range.7" title="Content-Range">5.2</a>)
1085      </p>
1086      <h2 id="rfc.section.B.2"><a href="#rfc.section.B.2">B.2</a>&nbsp;<a id="changes.from.rfc.2616" href="#changes.from.rfc.2616">Changes from RFC 2616</a></h2>
1087      <p id="rfc.section.B.2.p.1">Clarify that it is not ok to use a weak cache validator in a 206 response. (<a href="#status.206" id="rfc.xref.status.206.2" title="206 Partial Content">Section&nbsp;3.1</a>)
1088      </p>
1089      <p id="rfc.section.B.2.p.2">Clarify that multipart/byteranges can consist of a single part. (<a href="#internet.media.type.multipart.byteranges" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>)
1090      </p>
1091      <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a id="collected.abnf" href="#collected.abnf">Collected ABNF</a></h1>
1092      <div id="rfc.figure.u.19"></div> <pre class="inline"><a href="#header.accept-ranges" class="smpl">Accept-Ranges</a> = "Accept-Ranges:" OWS Accept-Ranges-v
1093<a href="#header.accept-ranges" class="smpl">Accept-Ranges-v</a> = acceptable-ranges
1094
1095<a href="#header.content-range" class="smpl">Content-Range</a> = "Content-Range:" OWS Content-Range-v
1096<a href="#header.content-range" class="smpl">Content-Range-v</a> = content-range-spec
1097
1098<a href="#abnf.dependencies" class="smpl">HTTP-date</a> = &lt;HTTP-date, defined in [Part1], Section 3.2.1&gt;
1099
1100<a href="#header.if-range" class="smpl">If-Range</a> = "If-Range:" OWS If-Range-v
1101<a href="#header.if-range" class="smpl">If-Range-v</a> = entity-tag / HTTP-date
1102
1103<a href="#core.rules" class="smpl">OWS</a> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
1104
1105<a href="#range.retrieval.requests" class="smpl">Range</a> = "Range:" OWS Range-v
1106<a href="#range.retrieval.requests" class="smpl">Range-v</a> = byte-ranges-specifier / other-ranges-specifier
1107
1108<a href="#header.accept-ranges" class="smpl">acceptable-ranges</a> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
1109 range-unit ] ) ) / "none"
1110
1111<a href="#header.content-range" class="smpl">byte-content-range-spec</a> = bytes-unit SP byte-range-resp-spec "/" (
1112 instance-length / "*" )
1113<a href="#header.content-range" class="smpl">byte-range-resp-spec</a> = ( first-byte-pos "-" last-byte-pos ) / "*"
1114<a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> = ( *( "," OWS ) byte-range-spec ) / (
1115 suffix-byte-range-spec *( OWS "," [ ( OWS byte-range-spec ) /
1116 suffix-byte-range-spec ] ) )
1117<a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> = first-byte-pos "-" [ last-byte-pos ]
1118<a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> = bytes-unit "=" byte-range-set
1119<a href="#range.units" class="smpl">bytes-unit</a> = "bytes"
1120
1121<a href="#header.content-range" class="smpl">content-range-spec</a> = byte-content-range-spec /
1122 other-content-range-spec
1123
1124<a href="#abnf.dependencies" class="smpl">entity-tag</a> = &lt;entity-tag, defined in [Part4], Section 2&gt;
1125
1126<a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> = 1*DIGIT
1127
1128<a href="#header.content-range" class="smpl">instance-length</a> = 1*DIGIT
1129
1130<a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> = 1*DIGIT
1131
1132<a href="#header.content-range" class="smpl">other-content-range-spec</a> = other-range-unit SP other-range-resp-spec
1133<a href="#header.content-range" class="smpl">other-range-resp-spec</a> = *CHAR
1134<a href="#range.units" class="smpl">other-range-unit</a> = token
1135<a href="#rule.ranges-specifier" class="smpl">other-ranges-specifier</a> = 1*CHAR
1136
1137<a href="#range.units" class="smpl">range-unit</a> = bytes-unit / other-range-unit
1138
1139<a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> = "-" suffix-length
1140<a href="#rule.ranges-specifier" class="smpl">suffix-length</a> = 1*DIGIT
1141
1142<a href="#core.rules" class="smpl">token</a> = &lt;token, defined in [Part1], Section 1.2.2&gt;
1143
1144
1145</pre> <div id="rfc.figure.u.20"></div>
1146      <p>ABNF diagnostics:</p><pre class="inline">; Accept-Ranges defined but not used
1147; Content-Range defined but not used
1148; If-Range defined but not used
1149; Range defined but not used
1150</pre><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>
1151      <h2 id="rfc.section.D.1"><a href="#rfc.section.D.1">D.1</a>&nbsp;Since RFC2616
1152      </h2>
1153      <p id="rfc.section.D.1.p.1">Extracted relevant partitions from <a href="#RFC2616" id="rfc.xref.RFC2616.1"><cite title="Hypertext Transfer Protocol -- HTTP/1.1">[RFC2616]</cite></a>.
1154      </p>
1155      <h2 id="rfc.section.D.2"><a href="#rfc.section.D.2">D.2</a>&nbsp;Since draft-ietf-httpbis-p5-range-00
1156      </h2>
1157      <p id="rfc.section.D.2.p.1">Closed issues: </p>
1158      <ul>
1159         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/18">http://tools.ietf.org/wg/httpbis/trac/ticket/18</a>&gt;: "Cache validators in 206 responses" (&lt;<a href="http://purl.org/NET/http-errata#ifrange206">http://purl.org/NET/http-errata#ifrange206</a>&gt;)
1160         </li>
1161         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/35">http://tools.ietf.org/wg/httpbis/trac/ticket/35</a>&gt;: "Normative and Informative references"
1162         </li>
1163         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/86">http://tools.ietf.org/wg/httpbis/trac/ticket/86</a>&gt;: "Normative up-to-date references"
1164         </li>
1165      </ul>
1166      <h2 id="rfc.section.D.3"><a href="#rfc.section.D.3">D.3</a>&nbsp;Since draft-ietf-httpbis-p5-range-01
1167      </h2>
1168      <p id="rfc.section.D.3.p.1">Closed issues: </p>
1169      <ul>
1170         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/55">http://tools.ietf.org/wg/httpbis/trac/ticket/55</a>&gt;: "Updating to RFC4288"
1171         </li>
1172      </ul>
1173      <p id="rfc.section.D.3.p.2">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
1174      </p>
1175      <ul>
1176         <li>Add explicit references to BNF syntax and rules imported from other parts of the specification.</li>
1177      </ul>
1178      <h2 id="rfc.section.D.4"><a href="#rfc.section.D.4">D.4</a>&nbsp;<a id="changes.since.02" href="#changes.since.02">Since draft-ietf-httpbis-p5-range-02</a></h2>
1179      <p id="rfc.section.D.4.p.1">Ongoing work on IANA Message Header Registration (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/40">http://tools.ietf.org/wg/httpbis/trac/ticket/40</a>&gt;):
1180      </p>
1181      <ul>
1182         <li>Reference RFC 3984, and update header registrations for headers defined in this document.</li>
1183      </ul>
1184      <h2 id="rfc.section.D.5"><a href="#rfc.section.D.5">D.5</a>&nbsp;<a id="changes.since.03" href="#changes.since.03">Since draft-ietf-httpbis-p5-range-03</a></h2>
1185      <h2 id="rfc.section.D.6"><a href="#rfc.section.D.6">D.6</a>&nbsp;<a id="changes.since.04" href="#changes.since.04">Since draft-ietf-httpbis-p5-range-04</a></h2>
1186      <p id="rfc.section.D.6.p.1">Closed issues: </p>
1187      <ul>
1188         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/133">http://tools.ietf.org/wg/httpbis/trac/ticket/133</a>&gt;: "multipart/byteranges minimum number of parts"
1189         </li>
1190      </ul>
1191      <p id="rfc.section.D.6.p.2">Ongoing work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
1192      </p>
1193      <ul>
1194         <li>Use "/" instead of "|" for alternatives.</li>
1195         <li>Introduce new ABNF rules for "bad" whitespace ("BWS"), optional whitespace ("OWS") and required whitespace ("RWS").</li>
1196         <li>Rewrite ABNFs to spell out whitespace rules, factor out header value format definitions.</li>
1197      </ul>
1198      <h2 id="rfc.section.D.7"><a href="#rfc.section.D.7">D.7</a>&nbsp;<a id="changes.since.05" href="#changes.since.05">Since draft-ietf-httpbis-p5-range-05</a></h2>
1199      <p id="rfc.section.D.7.p.1">Closed issues: </p>
1200      <ul>
1201         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/142">http://tools.ietf.org/wg/httpbis/trac/ticket/142</a>&gt;: "State base for *-byte-pos and suffix-length"
1202         </li>
1203      </ul>
1204      <p id="rfc.section.D.7.p.2">Ongoing work on Custom Ranges (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/85">http://tools.ietf.org/wg/httpbis/trac/ticket/85</a>&gt;):
1205      </p>
1206      <ul>
1207         <li>Remove bias in favor of byte ranges; allow custom ranges in ABNF.</li>
1208      </ul>
1209      <p id="rfc.section.D.7.p.3">Final work on ABNF conversion (&lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/36">http://tools.ietf.org/wg/httpbis/trac/ticket/36</a>&gt;):
1210      </p>
1211      <ul>
1212         <li>Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.</li>
1213      </ul>
1214      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
1215      <p class="noprint"><a href="#rfc.index.2">2</a> <a href="#rfc.index.4">4</a> <a href="#rfc.index.A">A</a> <a href="#rfc.index.C">C</a> <a href="#rfc.index.G">G</a> <a href="#rfc.index.H">H</a> <a href="#rfc.index.I">I</a> <a href="#rfc.index.M">M</a> <a href="#rfc.index.P">P</a> <a href="#rfc.index.R">R</a> <a href="#rfc.index.S">S</a> 
1216      </p>
1217      <div class="print2col">
1218         <ul class="ind">
1219            <li class="indline0"><a id="rfc.index.2" href="#rfc.index.2"><b>2</b></a><ul class="ind">
1220                  <li class="indline1">206 Partial Content (status code)&nbsp;&nbsp;<a class="iref" href="#rfc.iref.3"><b>3.1</b></a>, <a class="iref" href="#rfc.xref.status.206.1">B.1</a>, <a class="iref" href="#rfc.xref.status.206.2">B.2</a></li>
1221               </ul>
1222            </li>
1223            <li class="indline0"><a id="rfc.index.4" href="#rfc.index.4"><b>4</b></a><ul class="ind">
1224                  <li class="indline1">416 Requested Range Not Satisfiable (status code)&nbsp;&nbsp;<a class="iref" href="#rfc.iref.4"><b>3.2</b></a>, <a class="iref" href="#rfc.xref.status.416.1">5.2</a>, <a class="iref" href="#rfc.xref.status.416.2">B.1</a></li>
1225               </ul>
1226            </li>
1227            <li class="indline0"><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul class="ind">
1228                  <li class="indline1">Accept-Ranges header&nbsp;&nbsp;<a class="iref" href="#rfc.iref.a.1"><b>5.1</b></a>, <a class="iref" href="#rfc.xref.header.accept-ranges.1">6.1</a></li>
1229               </ul>
1230            </li>
1231            <li class="indline0"><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul class="ind">
1232                  <li class="indline1">Content-Range header&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.content-range.1">2</a>, <a class="iref" href="#rfc.xref.header.content-range.2">3.1</a>, <a class="iref" href="#rfc.xref.header.content-range.3">3.2</a>, <a class="iref" href="#rfc.iref.c.1"><b>5.2</b></a>, <a class="iref" href="#rfc.xref.header.content-range.4">6.1</a>, <a class="iref" href="#rfc.xref.header.content-range.5">B.1</a>, <a class="iref" href="#rfc.xref.header.content-range.6">B.1</a>, <a class="iref" href="#rfc.xref.header.content-range.7">B.1</a></li>
1233               </ul>
1234            </li>
1235            <li class="indline0"><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul class="ind">
1236                  <li class="indline1"><tt>Grammar</tt>&nbsp;&nbsp;
1237                     <ul class="ind">
1238                        <li class="indline1"><tt>Accept-Ranges</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.4"><b>5.1</b></a></li>
1239                        <li class="indline1"><tt>Accept-Ranges-v</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.5"><b>5.1</b></a></li>
1240                        <li class="indline1"><tt>acceptable-ranges</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.6"><b>5.1</b></a></li>
1241                        <li class="indline1"><tt>byte-content-range-spec</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.10"><b>5.2</b></a></li>
1242                        <li class="indline1"><tt>byte-range-resp-spec</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.11"><b>5.2</b></a></li>
1243                        <li class="indline1"><tt>byte-range-set</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.17"><b>5.4.1</b></a></li>
1244                        <li class="indline1"><tt>byte-range-spec</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.18"><b>5.4.1</b></a></li>
1245                        <li class="indline1"><tt>byte-ranges-specifier</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.16"><b>5.4.1</b></a></li>
1246                        <li class="indline1"><tt>bytes-unit</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.2"><b>2</b></a></li>
1247                        <li class="indline1"><tt>Content-Range</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.7"><b>5.2</b></a></li>
1248                        <li class="indline1"><tt>content-range-spec</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.9"><b>5.2</b></a></li>
1249                        <li class="indline1"><tt>Content-Range-v</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.8"><b>5.2</b></a></li>
1250                        <li class="indline1"><tt>first-byte-pos</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.19"><b>5.4.1</b></a></li>
1251                        <li class="indline1"><tt>If-Range</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.13"><b>5.3</b></a></li>
1252                        <li class="indline1"><tt>If-Range-v</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.14"><b>5.3</b></a></li>
1253                        <li class="indline1"><tt>instance-length</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.12"><b>5.2</b></a></li>
1254                        <li class="indline1"><tt>last-byte-pos</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.20"><b>5.4.1</b></a></li>
1255                        <li class="indline1"><tt>other-range-unit</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.3"><b>2</b></a></li>
1256                        <li class="indline1"><tt>Range</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.23"><b>5.4.2</b></a></li>
1257                        <li class="indline1"><tt>range-unit</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.1"><b>2</b></a></li>
1258                        <li class="indline1"><tt>ranges-specifier</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.15"><b>5.4.1</b></a></li>
1259                        <li class="indline1"><tt>suffix-byte-range-spec</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.21"><b>5.4.1</b></a></li>
1260                        <li class="indline1"><tt>suffix-length</tt>&nbsp;&nbsp;<a class="iref" href="#rfc.iref.g.22"><b>5.4.1</b></a></li>
1261                     </ul>
1262                  </li>
1263               </ul>
1264            </li>
1265            <li class="indline0"><a id="rfc.index.H" href="#rfc.index.H"><b>H</b></a><ul class="ind">
1266                  <li class="indline1">Headers&nbsp;&nbsp;
1267                     <ul class="ind">
1268                        <li class="indline1">Accept-Ranges&nbsp;&nbsp;<a class="iref" href="#rfc.iref.h.1"><b>5.1</b></a>, <a class="iref" href="#rfc.xref.header.accept-ranges.1">6.1</a></li>
1269                        <li class="indline1">Content-Range&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.content-range.1">2</a>, <a class="iref" href="#rfc.xref.header.content-range.2">3.1</a>, <a class="iref" href="#rfc.xref.header.content-range.3">3.2</a>, <a class="iref" href="#rfc.iref.h.2"><b>5.2</b></a>, <a class="iref" href="#rfc.xref.header.content-range.4">6.1</a>, <a class="iref" href="#rfc.xref.header.content-range.5">B.1</a>, <a class="iref" href="#rfc.xref.header.content-range.6">B.1</a>, <a class="iref" href="#rfc.xref.header.content-range.7">B.1</a></li>
1270                        <li class="indline1">If-Range&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.if-range.1">3.1</a>, <a class="iref" href="#rfc.iref.h.3"><b>5.3</b></a>, <a class="iref" href="#rfc.xref.header.if-range.2">5.4.2</a>, <a class="iref" href="#rfc.xref.header.if-range.3">6.1</a>, <a class="iref" href="#rfc.xref.header.if-range.4">B.1</a></li>
1271                        <li class="indline1">Range&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.range.1">2</a>, <a class="iref" href="#rfc.xref.header.range.2">2</a>, <a class="iref" href="#rfc.xref.header.range.3">3.1</a>, <a class="iref" href="#rfc.xref.header.range.4">3.2</a>, <a class="iref" href="#rfc.iref.h.4"><b>5.4</b></a>, <a class="iref" href="#rfc.xref.header.range.5">6.1</a></li>
1272                     </ul>
1273                  </li>
1274               </ul>
1275            </li>
1276            <li class="indline0"><a id="rfc.index.I" href="#rfc.index.I"><b>I</b></a><ul class="ind">
1277                  <li class="indline1">If-Range header&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.if-range.1">3.1</a>, <a class="iref" href="#rfc.iref.i.1"><b>5.3</b></a>, <a class="iref" href="#rfc.xref.header.if-range.2">5.4.2</a>, <a class="iref" href="#rfc.xref.header.if-range.3">6.1</a>, <a class="iref" href="#rfc.xref.header.if-range.4">B.1</a></li>
1278               </ul>
1279            </li>
1280            <li class="indline0"><a id="rfc.index.M" href="#rfc.index.M"><b>M</b></a><ul class="ind">
1281                  <li class="indline1">Media Type&nbsp;&nbsp;
1282                     <ul class="ind">
1283                        <li class="indline1">multipart/byteranges&nbsp;&nbsp;<a class="iref" href="#rfc.iref.m.1"><b>A</b></a></li>
1284                        <li class="indline1">multipart/x-byteranges&nbsp;&nbsp;<a class="iref" href="#rfc.iref.m.4">A</a></li>
1285                     </ul>
1286                  </li>
1287                  <li class="indline1">multipart/byteranges Media Type&nbsp;&nbsp;<a class="iref" href="#rfc.iref.m.2"><b>A</b></a></li>
1288                  <li class="indline1">multipart/x-byteranges Media Type&nbsp;&nbsp;<a class="iref" href="#rfc.iref.m.3">A</a></li>
1289               </ul>
1290            </li>
1291            <li class="indline0"><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul class="ind">
1292                  <li class="indline1"><em>Part1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part1.1">1.2</a>, <a class="iref" href="#rfc.xref.Part1.2">1.2.1</a>, <a class="iref" href="#rfc.xref.Part1.3">1.2.1</a>, <a class="iref" href="#rfc.xref.Part1.4">1.2.1</a>, <a class="iref" href="#rfc.xref.Part1.5">1.2.2</a>, <a class="iref" href="#rfc.xref.Part1.6">7</a>, <a class="iref" href="#Part1"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.Part1.7">B.1</a><ul class="ind">
1293                        <li class="indline1"><em>Section 1.2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part1.1">1.2</a></li>
1294                        <li class="indline1"><em>Section 1.2.2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part1.2">1.2.1</a>, <a class="iref" href="#rfc.xref.Part1.3">1.2.1</a>, <a class="iref" href="#rfc.xref.Part1.4">1.2.1</a></li>
1295                        <li class="indline1"><em>Section 3.2.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part1.5">1.2.2</a></li>
1296                     </ul>
1297                  </li>
1298                  <li class="indline1"><em>Part3</em>&nbsp;&nbsp;<a class="iref" href="#Part3"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.Part3.1">B.1</a></li>
1299                  <li class="indline1"><em>Part4</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part4.1">1.2.2</a>, <a class="iref" href="#rfc.xref.Part4.2">4</a>, <a class="iref" href="#Part4"><b>9.1</b></a><ul class="ind">
1300                        <li class="indline1"><em>Section 2</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part4.1">1.2.2</a></li>
1301                        <li class="indline1"><em>Section 4</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.Part4.2">4</a></li>
1302                     </ul>
1303                  </li>
1304                  <li class="indline1"><em>Part6</em>&nbsp;&nbsp;<a class="iref" href="#Part6"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.Part6.1">B.1</a></li>
1305               </ul>
1306            </li>
1307            <li class="indline0"><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul class="ind">
1308                  <li class="indline1">Range header&nbsp;&nbsp;<a class="iref" href="#rfc.xref.header.range.1">2</a>, <a class="iref" href="#rfc.xref.header.range.2">2</a>, <a class="iref" href="#rfc.xref.header.range.3">3.1</a>, <a class="iref" href="#rfc.xref.header.range.4">3.2</a>, <a class="iref" href="#rfc.iref.r.1"><b>5.4</b></a>, <a class="iref" href="#rfc.xref.header.range.5">6.1</a></li>
1309                  <li class="indline1"><em>RFC2046</em>&nbsp;&nbsp;<a class="iref" href="#RFC2046"><b>9.1</b></a>, <a class="iref" href="#rfc.xref.RFC2046.1">A</a>, <a class="iref" href="#rfc.xref.RFC2046.2">A</a><ul class="ind">
1310                        <li class="indline1"><em>Section 5.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2046.1">A</a></li>
1311                     </ul>
1312                  </li>
1313                  <li class="indline1"><em>RFC2119</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC2119.1">1.1</a>, <a class="iref" href="#RFC2119"><b>9.1</b></a></li>
1314                  <li class="indline1"><em>RFC2616</em>&nbsp;&nbsp;<a class="iref" href="#RFC2616"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC2616.1">D.1</a></li>
1315                  <li class="indline1"><em>RFC3864</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC3864.1">6.1</a>, <a class="iref" href="#RFC3864"><b>9.2</b></a></li>
1316                  <li class="indline1"><em>RFC4288</em>&nbsp;&nbsp;<a class="iref" href="#RFC4288"><b>9.2</b></a>, <a class="iref" href="#rfc.xref.RFC4288.1">A</a></li>
1317                  <li class="indline1"><em>RFC5234</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC5234.1">1.2</a>, <a class="iref" href="#rfc.xref.RFC5234.2">1.2</a>, <a class="iref" href="#RFC5234"><b>9.1</b></a><ul class="ind">
1318                        <li class="indline1"><em>Appendix B.1</em>&nbsp;&nbsp;<a class="iref" href="#rfc.xref.RFC5234.2">1.2</a></li>
1319                     </ul>
1320                  </li>
1321               </ul>
1322            </li>
1323            <li class="indline0"><a id="rfc.index.S" href="#rfc.index.S"><b>S</b></a><ul class="ind">
1324                  <li class="indline1">Status Codes&nbsp;&nbsp;
1325                     <ul class="ind">
1326                        <li class="indline1">206 Partial Content&nbsp;&nbsp;<a class="iref" href="#rfc.iref.s.1"><b>3.1</b></a>, <a class="iref" href="#rfc.xref.status.206.1">B.1</a>, <a class="iref" href="#rfc.xref.status.206.2">B.2</a></li>
1327                        <li class="indline1">416 Requested Range Not Satisfiable&nbsp;&nbsp;<a class="iref" href="#rfc.iref.s.2"><b>3.2</b></a>, <a class="iref" href="#rfc.xref.status.416.1">5.2</a>, <a class="iref" href="#rfc.xref.status.416.2">B.1</a></li>
1328                     </ul>
1329                  </li>
1330               </ul>
1331            </li>
1332         </ul>
1333      </div>
1334   </body>
1335</html>
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