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441       content: "HTTP/1.1 Range Requests";
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465</style><link rel="Contents" href="#rfc.toc">
466      <link rel="Author" href="#rfc.authors">
467      <link rel="Copyright" href="#rfc.copyrightnotice">
468      <link rel="Index" href="#rfc.index">
469      <link rel="Chapter" title="1 Introduction" href="#rfc.section.1">
470      <link rel="Chapter" title="2 Range Units" href="#rfc.section.2">
471      <link rel="Chapter" title="3 Range Requests" href="#rfc.section.3">
472      <link rel="Chapter" title="4 Responses to a Range Request" href="#rfc.section.4">
473      <link rel="Chapter" title="5 IANA Considerations" href="#rfc.section.5">
474      <link rel="Chapter" title="6 Security Considerations" href="#rfc.section.6">
475      <link rel="Chapter" title="7 Acknowledgments" href="#rfc.section.7">
476      <link rel="Chapter" href="#rfc.section.8" title="8 References">
477      <link rel="Appendix" title="A Internet Media Type multipart/byteranges" href="#rfc.section.A">
478      <link rel="Appendix" title="B Changes from RFC 2616" href="#rfc.section.B">
479      <link rel="Appendix" title="C Imported ABNF" href="#rfc.section.C">
480      <link rel="Appendix" title="D Collected ABNF" href="#rfc.section.D">
481      <link rel="Appendix" title="E Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.E">
482      <link href="p4-conditional.html" rel="prev">
483      <link href="p6-cache.html" rel="next">
484      <meta name="generator" content=", Revision 1.603, 2013/09/18 20:22:25, XSLT vendor: SAXON 8.9 from Saxonica">
485      <link rel="schema.dct" href="">
486      <meta name="dct.creator" content="Fielding, R.">
487      <meta name="dct.creator" content="Lafon, Y.">
488      <meta name="dct.creator" content="Reschke, J. F.">
489      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p5-range-24">
490      <meta name="dct.issued" scheme="ISO8601" content="2013-09-25">
491      <meta name="dct.replaces" content="urn:ietf:rfc:2616">
492      <meta name="dct.abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypertext information systems. This document defines range requests and the rules for constructing and combining responses to those requests.">
493      <meta name="description" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypertext information systems. This document defines range requests and the rules for constructing and combining responses to those requests.">
494   </head>
495   <body onload="init();">
496      <table class="header">
497         <tbody>
498            <tr>
499               <td class="left">HTTPbis Working Group</td>
500               <td class="right">R. Fielding, Editor</td>
501            </tr>
502            <tr>
503               <td class="left">Internet-Draft</td>
504               <td class="right">Adobe</td>
505            </tr>
506            <tr>
507               <td class="left">Obsoletes: <a href="">2616</a> (if approved)
508               </td>
509               <td class="right">Y. Lafon, Editor</td>
510            </tr>
511            <tr>
512               <td class="left">Intended status: Standards Track</td>
513               <td class="right">W3C</td>
514            </tr>
515            <tr>
516               <td class="left">Expires: March 29, 2014</td>
517               <td class="right">J. Reschke, Editor</td>
518            </tr>
519            <tr>
520               <td class="left"></td>
521               <td class="right">greenbytes</td>
522            </tr>
523            <tr>
524               <td class="left"></td>
525               <td class="right">September 25, 2013</td>
526            </tr>
527         </tbody>
528      </table>
529      <p class="title">Hypertext Transfer Protocol (HTTP/1.1): Range Requests<br><span class="filename">draft-ietf-httpbis-p5-range-24</span></p>
530      <h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
531      <p>The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypertext information
532         systems. This document defines range requests and the rules for constructing and combining responses to those requests.
533      </p>
534      <h1 id="rfc.note.1"><a href="#rfc.note.1">Editorial Note (To be removed by RFC Editor)</a></h1>
535      <p>Discussion of this draft takes place on the HTTPBIS working group mailing list (, which is archived at &lt;<a href=""></a>&gt;.
536      </p>
537      <p>The current issues list is at &lt;<a href=""></a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href=""></a>&gt;.
538      </p>
539      <p>The changes in this draft are summarized in <a href="#changes.since.23" title="Since draft-ietf-httpbis-p5-range-23">Appendix&nbsp;E.5</a>.
540      </p>
541      <div id="rfc.status">
542         <h1><a href="#rfc.status">Status of This Memo</a></h1>
543         <p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
544         <p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute
545            working documents as Internet-Drafts. The list of current Internet-Drafts is at <a href=""></a>.
546         </p>
547         <p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other
548            documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work
549            in progress”.
550         </p>
551         <p>This Internet-Draft will expire on March 29, 2014.</p>
552      </div>
553      <div id="rfc.copyrightnotice">
554         <h1><a href="#rfc.copyrightnotice">Copyright Notice</a></h1>
555         <p>Copyright © 2013 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
556         <p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (<a href=""></a>) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights
557            and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License
558            text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified
559            BSD License.
560         </p>
561         <p>This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November
562            10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to
563            allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s)
564            controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative
565            works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate
566            it into languages other than English.
567         </p>
568      </div>
569      <hr class="noprint">
570      <h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
571      <ul class="toc">
572         <li><a href="#rfc.section.1">1.</a>&nbsp;&nbsp;&nbsp;<a href="#introduction">Introduction</a><ul>
573               <li><a href="#rfc.section.1.1">1.1</a>&nbsp;&nbsp;&nbsp;<a href="#conformance">Conformance and Error Handling</a></li>
574               <li><a href="#rfc.section.1.2">1.2</a>&nbsp;&nbsp;&nbsp;<a href="#notation">Syntax Notation</a></li>
575            </ul>
576         </li>
577         <li><a href="#rfc.section.2">2.</a>&nbsp;&nbsp;&nbsp;<a href="#range.units">Range Units</a><ul>
578               <li><a href="#rfc.section.2.1">2.1</a>&nbsp;&nbsp;&nbsp;<a href="#byte.ranges">Byte Ranges</a></li>
579               <li><a href="#rfc.section.2.2">2.2</a>&nbsp;&nbsp;&nbsp;<a href="#range.units.other">Other Range Units</a></li>
580               <li><a href="#rfc.section.2.3">2.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.accept-ranges">Accept-Ranges</a></li>
581            </ul>
582         </li>
583         <li><a href="#rfc.section.3">3.</a>&nbsp;&nbsp;&nbsp;<a href="#range.requests">Range Requests</a><ul>
584               <li><a href="#rfc.section.3.1">3.1</a>&nbsp;&nbsp;&nbsp;<a href="#header.range">Range</a></li>
585               <li><a href="#rfc.section.3.2">3.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.if-range">If-Range</a></li>
586            </ul>
587         </li>
588         <li><a href="#rfc.section.4">4.</a>&nbsp;&nbsp;&nbsp;<a href="#range.response">Responses to a Range Request</a><ul>
589               <li><a href="#rfc.section.4.1">4.1</a>&nbsp;&nbsp;&nbsp;<a href="#status.206">206 Partial Content</a></li>
590               <li><a href="#rfc.section.4.2">4.2</a>&nbsp;&nbsp;&nbsp;<a href="#header.content-range">Content-Range</a></li>
591               <li><a href="#rfc.section.4.3">4.3</a>&nbsp;&nbsp;&nbsp;<a href="#combining.byte.ranges">Combining Ranges</a></li>
592               <li><a href="#rfc.section.4.4">4.4</a>&nbsp;&nbsp;&nbsp;<a href="#status.416">416 Range Not Satisfiable</a></li>
593            </ul>
594         </li>
595         <li><a href="#rfc.section.5">5.</a>&nbsp;&nbsp;&nbsp;<a href="#IANA.considerations">IANA Considerations</a><ul>
596               <li><a href="#rfc.section.5.1">5.1</a>&nbsp;&nbsp;&nbsp;<a href="#range.unit.registry">Range Unit Registry</a><ul>
597                     <li><a href="#rfc.section.5.1.1">5.1.1</a>&nbsp;&nbsp;&nbsp;<a href="#range.unit.registry.procedure">Procedure</a></li>
598                     <li><a href="#rfc.section.5.1.2">5.1.2</a>&nbsp;&nbsp;&nbsp;<a href="#range.unit.registration">Registrations</a></li>
599                  </ul>
600               </li>
601               <li><a href="#rfc.section.5.2">5.2</a>&nbsp;&nbsp;&nbsp;<a href="#status.code.registration">Status Code Registration</a></li>
602               <li><a href="#rfc.section.5.3">5.3</a>&nbsp;&nbsp;&nbsp;<a href="#header.field.registration">Header Field Registration</a></li>
603            </ul>
604         </li>
605         <li><a href="#rfc.section.6">6.</a>&nbsp;&nbsp;&nbsp;<a href="#security.considerations">Security Considerations</a><ul>
606               <li><a href="#rfc.section.6.1">6.1</a>&nbsp;&nbsp;&nbsp;<a href="#overlapping.ranges">Denial of Service Attacks using Range</a></li>
607            </ul>
608         </li>
609         <li><a href="#rfc.section.7">7.</a>&nbsp;&nbsp;&nbsp;<a href="#acks">Acknowledgments</a></li>
610         <li><a href="#rfc.section.8">8.</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references">References</a><ul>
611               <li><a href="#rfc.section.8.1">8.1</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.1">Normative References</a></li>
612               <li><a href="#rfc.section.8.2">8.2</a>&nbsp;&nbsp;&nbsp;<a href="#rfc.references.2">Informative References</a></li>
613            </ul>
614         </li>
615         <li><a href="#rfc.authors">Authors' Addresses</a></li>
616         <li><a href="#rfc.section.A">A.</a>&nbsp;&nbsp;&nbsp;<a href="">Internet Media Type multipart/byteranges</a></li>
617         <li><a href="#rfc.section.B">B.</a>&nbsp;&nbsp;&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></li>
618         <li><a href="#rfc.section.C">C.</a>&nbsp;&nbsp;&nbsp;<a href="#imported.abnf">Imported ABNF</a></li>
619         <li><a href="#rfc.section.D">D.</a>&nbsp;&nbsp;&nbsp;<a href="#collected.abnf">Collected ABNF</a></li>
620         <li><a href="#rfc.section.E">E.</a>&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
621               <li><a href="#rfc.section.E.1">E.1</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.19">Since draft-ietf-httpbis-p5-range-19</a></li>
622               <li><a href="#rfc.section.E.2">E.2</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.20">Since draft-ietf-httpbis-p5-range-20</a></li>
623               <li><a href="#rfc.section.E.3">E.3</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.21">Since draft-ietf-httpbis-p5-range-21</a></li>
624               <li><a href="#rfc.section.E.4">E.4</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.22">Since draft-ietf-httpbis-p5-range-22</a></li>
625               <li><a href="#rfc.section.E.5">E.5</a>&nbsp;&nbsp;&nbsp;<a href="#changes.since.23">Since draft-ietf-httpbis-p5-range-23</a></li>
626            </ul>
627         </li>
628         <li><a href="#rfc.index">Index</a></li>
629      </ul>
630      <div id="introduction">
631         <h1 id="rfc.section.1" class="np"><a href="#rfc.section.1">1.</a>&nbsp;<a href="#introduction">Introduction</a></h1>
632         <p id="rfc.section.1.p.1">Hypertext Transfer Protocol (HTTP) clients often encounter interrupted data transfers as a result of canceled requests or
633            dropped connections. When a client has stored a partial representation, it is desirable to request the remainder of that representation
634            in a subsequent request rather than transfer the entire representation. Likewise, devices with limited local storage might
635            benefit from being able to request only a subset of a larger representation, such as a single page of a very large document,
636            or the dimensions of an embedded image.
637         </p>
638         <p id="rfc.section.1.p.2">This document defines HTTP/1.1 range requests, partial responses, and the multipart/byteranges media type. Range requests
639            are an <em class="bcp14">OPTIONAL</em> feature of HTTP, designed so that recipients not implementing this feature (or not supporting it for the target resource)
640            can respond as if it is a normal GET request without impacting interoperability. Partial responses are indicated by a distinct
641            status code to not be mistaken for full responses by caches that might not implement the feature.
642         </p>
643         <p id="rfc.section.1.p.3">Although the range request mechanism is designed to allow for extensible range types, this specification only defines requests
644            for byte ranges.
645         </p>
646         <div id="conformance">
647            <h2 id="rfc.section.1.1"><a href="#rfc.section.1.1">1.1</a>&nbsp;<a href="#conformance">Conformance and Error Handling</a></h2>
648            <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"
649               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>.
650            </p>
651            <p id="rfc.section.1.1.p.2">Conformance criteria and considerations regarding error handling are defined in <a href="p1-messaging.html#conformance" title="Conformance and Error Handling">Section 2.5</a> of <a href="#Part1" id="rfc.xref.Part1.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>.
652            </p>
653         </div>
654         <div id="notation">
655            <h2 id="rfc.section.1.2"><a href="#rfc.section.1.2">1.2</a>&nbsp;<a href="#notation">Syntax Notation</a></h2>
656            <p id="rfc.section.1.2.p.1">This specification uses the Augmented Backus-Naur Form (ABNF) notation of <a href="#RFC5234" id="rfc.xref.RFC5234.1"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a> with the list rule extension defined in <a href="p1-messaging.html#abnf.extension" title="ABNF list extension: #rule">Section 7</a> of <a href="#Part1" id="rfc.xref.Part1.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>. <a href="#imported.abnf" title="Imported ABNF">Appendix&nbsp;C</a> describes rules imported from other documents. <a href="#collected.abnf" title="Collected ABNF">Appendix&nbsp;D</a> shows the collected ABNF with the list rule expanded.
657            </p>
658         </div>
659      </div>
660      <div id="range.units">
661         <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a href="#range.units">Range Units</a></h1>
662         <p id="rfc.section.2.p.1">A representation can be partitioned into subranges according to various structural units, depending on the structure inherent
663            in the representation's media type. This "<dfn>range unit</dfn>" is used in the <a href="#header.accept-ranges" class="smpl">Accept-Ranges</a> (<a href="#header.accept-ranges" id="rfc.xref.header.accept-ranges.1" title="Accept-Ranges">Section&nbsp;2.3</a>) response header field to advertise support for range requests, the <a href="#header.range" class="smpl">Range</a> (<a href="#header.range" id="rfc.xref.header.range.1" title="Range">Section&nbsp;3.1</a>) request header field to delineate the parts of a representation that are requested, and the <a href="#header.content-range" class="smpl">Content-Range</a> (<a href="#header.content-range" id="rfc.xref.header.content-range.1" title="Content-Range">Section&nbsp;4.2</a>) payload header field to describe which part of a representation is being transferred.
664         </p>
665         <div id="rfc.figure.u.1"></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="#byte.ranges" class="smpl">bytes-unit</a> / <a href="#range.units.other" class="smpl">other-range-unit</a>
666</pre><div id="byte.ranges">
667            <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a href="#byte.ranges">Byte Ranges</a></h2>
668            <p id="rfc.section.2.1.p.1">Since representation data is transferred in payloads as a sequence of octets, a byte range is a meaningful substructure for
669               any representation transferable over HTTP (<a href="p2-semantics.html#representations" title="Representations">Section 3</a> of <a href="#Part2" id="rfc.xref.Part2.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). We define the "bytes" range unit for expressing subranges of the data's octet sequence.
670            </p>
671            <div id="rfc.figure.u.2"></div><pre class="inline"><span id="rfc.iref.g.4"></span>  <a href="#byte.ranges" class="smpl">bytes-unit</a>       = "bytes"
672</pre><div id="rule.ranges-specifier">
673               <p id="rfc.section.2.1.p.3">        A byte range request can specify a single range of bytes, or a set of ranges within a single representation.</p>
674            </div>
675            <div id="rfc.figure.u.3"></div><pre class="inline"><span id="rfc.iref.g.5"></span><span id="rfc.iref.g.6"></span><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>  <a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> = <a href="#byte.ranges" class="smpl">bytes-unit</a> "=" <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a>
676  <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> )
677  <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> ]
678  <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>  = 1*<a href="#imported.abnf" class="smpl">DIGIT</a>
679  <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>   = 1*<a href="#imported.abnf" class="smpl">DIGIT</a>
680</pre><p id="rfc.section.2.1.p.5">The <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> value in a <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> gives the byte-offset of the first byte in a range. The <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> value gives the byte-offset of the last byte in the range; that is, the byte positions specified are inclusive. Byte offsets
681               start at zero.
682            </p>
683            <p id="rfc.section.2.1.p.6">Examples of <a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> values:
684            </p>
685            <ul>
686               <li>The first 500 bytes (byte offsets 0-499, inclusive):
687                  <div id="rfc.figure.u.4"></div><pre class="text">  bytes=0-499
688</pre> </li>
689               <li>The second 500 bytes (byte offsets 500-999, inclusive):
690                  <div id="rfc.figure.u.5"></div><pre class="text">  bytes=500-999
691</pre> </li>
692            </ul>
693            <p id="rfc.section.2.1.p.7">A <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> is invalid if the <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> value is present and less than the <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>.
694            </p>
695            <p id="rfc.section.2.1.p.8">A client can limit the number of bytes requested without knowing the size of the selected representation. If the <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> value is absent, or if the value is greater than or equal to the current length of the representation data, the byte range
696               is interpreted as the remainder of the representation (i.e., the server replaces the value of <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> with a value that is one less than the current length of the selected representation).
697            </p>
698            <p id="rfc.section.2.1.p.9">A client can request the last N bytes of the selected representation using a <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a>.
699            </p>
700            <div id="rfc.figure.u.6"></div><pre class="inline"><span id="rfc.iref.g.11"></span><span id="rfc.iref.g.12"></span>  <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> = "-" <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>
701  <a href="#rule.ranges-specifier" class="smpl">suffix-length</a> = 1*<a href="#imported.abnf" class="smpl">DIGIT</a>
702</pre><p id="rfc.section.2.1.p.11">If the selected representation is shorter than the specified <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, the entire representation is used.
703            </p>
704            <p id="rfc.section.2.1.p.12">Additional examples, assuming a representation of length 10000: </p>
705            <ul>
706               <li>The final 500 bytes (byte offsets 9500-9999, inclusive):
707                  <div id="rfc.figure.u.7"></div><pre class="text">  bytes=-500
708</pre> Or: <div id="rfc.figure.u.8"></div><pre class="text">  bytes=9500-
709</pre> </li>
710               <li>The first and last bytes only (bytes 0 and 9999):
711                  <div id="rfc.figure.u.9"></div><pre class="text">  bytes=0-0,-1
712</pre> </li>
713               <li>Other valid (but not canonical) specifications of the second 500 bytes (byte offsets 500-999, inclusive):
714                  <div id="rfc.figure.u.10"></div><pre class="text">  bytes=500-600,601-999
715  bytes=500-700,601-999
716</pre> </li>
717            </ul>
718            <p id="rfc.section.2.1.p.13">If a valid <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> includes at least one <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> with a <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> that is less than the current length of the representation, or at least one <a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> with a non-zero <a href="#rule.ranges-specifier" class="smpl">suffix-length</a>, then the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is satisfiable. Otherwise, the <a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> is unsatisfiable.
719            </p>
720            <p id="rfc.section.2.1.p.14">In the byte range syntax, <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a>, <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>, and <a href="#rule.ranges-specifier" class="smpl">suffix-length</a> are expressed as decimal number of octets. Since there is no predefined limit to the length of a payload, recipients ought
721               to anticipate potentially large decimal numerals and prevent parsing errors due to integer conversion overflows.
722            </p>
723         </div>
724         <div id="range.units.other">
725            <h2 id="rfc.section.2.2"><a href="#rfc.section.2.2">2.2</a>&nbsp;<a href="#range.units.other">Other Range Units</a></h2>
726            <p id="rfc.section.2.2.p.1">Range units are intended to be extensible. New range units ought to be registered with IANA, as defined in <a href="#range.unit.registry" title="Range Unit Registry">Section&nbsp;5.1</a>.
727            </p>
728            <div id="rfc.figure.u.11"></div><pre class="inline"><span id="rfc.iref.g.13"></span>  <a href="#range.units.other" class="smpl">other-range-unit</a> = <a href="#imported.abnf" class="smpl">token</a>
730         <div id="header.accept-ranges">
731            <div id="rfc.iref.a.1"></div>
732            <h2 id="rfc.section.2.3"><a href="#rfc.section.2.3">2.3</a>&nbsp;<a href="#header.accept-ranges">Accept-Ranges</a></h2>
733            <p id="rfc.section.2.3.p.1">The "Accept-Ranges" header field allows a server to indicate that it supports range requests for the target resource.</p>
734            <div id="rfc.figure.u.12"></div><pre class="inline"><span id="rfc.iref.g.14"></span><span id="rfc.iref.g.15"></span>  <a href="#header.accept-ranges" class="smpl">Accept-Ranges</a>     = <a href="#header.accept-ranges" class="smpl">acceptable-ranges</a>
735  <a href="#header.accept-ranges" class="smpl">acceptable-ranges</a> = 1#<a href="#range.units" class="smpl">range-unit</a> / "none"
736</pre><p id="rfc.section.2.3.p.3">An origin server that supports byte-range requests for a given target resource <em class="bcp14">MAY</em> send
737            </p>
738            <div id="rfc.figure.u.13"></div><pre class="text">  Accept-Ranges: bytes
739</pre><p id="rfc.section.2.3.p.5">to indicate what range units are supported. A client <em class="bcp14">MAY</em> generate range requests without having received this header field for the resource involved. Range units are defined in <a href="#range.units" title="Range Units">Section&nbsp;2</a>.
740            </p>
741            <p id="rfc.section.2.3.p.6">A server that does not support any kind of range request for the target resource resource <em class="bcp14">MAY</em> send
742            </p>
743            <div id="rfc.figure.u.14"></div><pre class="text">  Accept-Ranges: none
744</pre><p id="rfc.section.2.3.p.8">to advise the client not to attempt a range request.</p>
745         </div>
746      </div>
747      <div id="range.requests">
748         <h1 id="rfc.section.3"><a href="#rfc.section.3">3.</a>&nbsp;<a href="#range.requests">Range Requests</a></h1>
749         <div id="header.range">
750            <div id="rfc.iref.r.1"></div>
751            <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a>&nbsp;<a href="#header.range">Range</a></h2>
752            <p id="rfc.section.3.1.p.1">The "Range" header field on a GET request modifies the method semantics to request transfer of only one or more subranges
753               of the selected representation data, rather than the entire selected representation data.
754            </p>
755            <div id="rfc.figure.u.15"></div><pre class="inline"><span id="rfc.iref.g.16"></span>  <a href="#header.range" class="smpl">Range</a> = <a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> / <a href="#header.range" class="smpl">other-ranges-specifier</a>
756  <a href="#header.range" class="smpl">other-ranges-specifier</a> = <a href="#range.units.other" class="smpl">other-range-unit</a> "=" <a href="#header.range" class="smpl">other-range-set</a>
757  <a href="#header.range" class="smpl">other-range-set</a> = 1*<a href="#imported.abnf" class="smpl">CHAR</a>
758</pre><p id="rfc.section.3.1.p.3">A server <em class="bcp14">MAY</em> ignore the Range header field. However, origin servers and intermediate caches ought to support byte ranges when possible,
759               since Range supports efficient recovery from partially failed transfers and partial retrieval of large representations. A
760               server <em class="bcp14">MUST</em> ignore a Range header field received with a request method other than GET.
761            </p>
762            <p id="rfc.section.3.1.p.4">An origin server <em class="bcp14">MUST</em> ignore a Range header field that contains a range unit it does not understand. A proxy <em class="bcp14">MAY</em> discard a Range header field that contains a range unit it does not understand.
763            </p>
764            <p id="rfc.section.3.1.p.5">A server that supports range requests <em class="bcp14">MAY</em> ignore or reject a <a href="#header.range" class="smpl">Range</a> header field that consists of more than two overlapping ranges, or a set of many small ranges that are not listed in ascending
765               order, since both are indications of either a broken client or a deliberate denial of service attack (<a href="#overlapping.ranges" title="Denial of Service Attacks using Range">Section&nbsp;6.1</a>). A client <em class="bcp14">SHOULD NOT</em> request multiple ranges that are inherently less efficient to process and transfer than a single range that encompasses the
766               same data.
767            </p>
768            <p id="rfc.section.3.1.p.6">A client that is requesting multiple ranges <em class="bcp14">SHOULD</em> list those ranges in ascending order (the order in which they would typically be received in a complete representation) unless
769               there is a specific need to request a later part earlier. For example, a user agent processing a large representation with
770               an internal catalog of parts might need to request later parts first, particularly if the representation consists of pages
771               stored in reverse order and the user agent wishes to transfer one page at a time.
772            </p>
773            <p id="rfc.section.3.1.p.7">The Range header field is evaluated after evaluating the precondition header fields defined in <a href="#Part4" id="rfc.xref.Part4.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>, and only if the result in absence of the Range header field would be a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response. In other words, Range is ignored when a conditional GET would result in a <a href="p4-conditional.html#status.304" class="smpl">304 (Not Modified)</a> response.
774            </p>
775            <p id="rfc.section.3.1.p.8">The If-Range header field (<a href="#header.if-range" id="rfc.xref.header.if-range.1" title="If-Range">Section&nbsp;3.2</a>) can be used as a precondition to applying the Range header field.
776            </p>
777            <p id="rfc.section.3.1.p.9">If all of the preconditions are true, the server supports the Range header field for the target resource, and the specified
778               range(s) are valid and satisfiable (as defined in <a href="#byte.ranges" title="Byte Ranges">Section&nbsp;2.1</a>), the server <em class="bcp14">SHOULD</em> send a <a href="#status.206" class="smpl">206 (Partial Content)</a> response with a payload containing one or more partial representations that correspond to the satisfiable ranges requested,
779               as defined in <a href="#range.response" title="Responses to a Range Request">Section&nbsp;4</a>.
780            </p>
781            <p id="rfc.section.3.1.p.10">If all of the preconditions are true, the server supports the Range header field for the target resource, and the specified
782               range(s) are invalid or unsatisfiable, the server <em class="bcp14">SHOULD</em> send a <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> response.
783            </p>
784         </div>
785         <div id="header.if-range">
786            <div id="rfc.iref.i.1"></div>
787            <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a>&nbsp;<a href="#header.if-range">If-Range</a></h2>
788            <p id="rfc.section.3.2.p.1">If a client has a partial copy of a representation and wishes to have an up-to-date copy of the entire representation, it
789               could use the <a href="#header.range" class="smpl">Range</a> header field with a conditional GET (using either or both of <a href="p4-conditional.html#header.if-unmodified-since" class="smpl">If-Unmodified-Since</a> and <a href="p4-conditional.html#header.if-match" class="smpl">If-Match</a>.) However, if the precondition fails because the representation has been modified, the client would then have to make a second
790               request to obtain the entire current representation.
791            </p>
792            <p id="rfc.section.3.2.p.2">The "If-Range" header field allows a client to "short-circuit" the second request. Informally, its meaning is: if the representation
793               is unchanged, send me the part(s) that I am requesting in Range; otherwise, send me the entire representation.
794            </p>
795            <div id="rfc.figure.u.16"></div><pre class="inline"><span id="rfc.iref.g.17"></span>  <a href="#header.if-range" class="smpl">If-Range</a> = <a href="#imported.abnf" class="smpl">entity-tag</a> / <a href="#imported.abnf" class="smpl">HTTP-date</a>
796</pre><p id="rfc.section.3.2.p.4">A client <em class="bcp14">MUST NOT</em> generate an If-Range header field in a request that does not contain a <a href="#header.range" class="smpl">Range</a> header field. A server <em class="bcp14">MUST</em> ignore an If-Range header field received in a request that does not contain a <a href="#header.range" class="smpl">Range</a> header field. An origin server <em class="bcp14">MUST</em> ignore an If-Range header field received in a request for a target resource that does not support Range requests.
797            </p>
798            <p id="rfc.section.3.2.p.5">A client <em class="bcp14">MUST NOT</em> generate an If-Range header field containing an entity-tag that is marked as weak. A client <em class="bcp14">MUST NOT</em> generate an If-Range header field containing an <a href="#imported.abnf" class="smpl">HTTP-date</a> unless the client has no entity-tag for the corresponding representation and the date is a strong validator in the sense defined
799               by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>.
800            </p>
801            <p id="rfc.section.3.2.p.6">A server that evaluates an If-Range precondition <em class="bcp14">MUST</em> use the strong comparison function when comparing entity-tags (<a href="p4-conditional.html#entity.tag.comparison" title="Comparison">Section 2.3.2</a> of <a href="#Part4" id="rfc.xref.Part4.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>) and <em class="bcp14">MUST</em> evaluate the condition as false if an <a href="#imported.abnf" class="smpl">HTTP-date</a> validator is provided that is not a strong validator in the sense defined by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>. (A server can distinguish between a valid <a href="#imported.abnf" class="smpl">HTTP-date</a> and any form of entity-tag by examining the first two characters.)
802            </p>
803            <p id="rfc.section.3.2.p.7">If the validator given in the If-Range header field matches the current validator for the selected representation of the target
804               resource, then the server <em class="bcp14">SHOULD</em> process the <a href="#header.range" class="smpl">Range</a> header field as requested. If the validator does not match, the server <em class="bcp14">MUST</em> ignore the <a href="#header.range" class="smpl">Range</a> header field.
805            </p>
806         </div>
807      </div>
808      <div id="range.response">
809         <h1 id="rfc.section.4"><a href="#rfc.section.4">4.</a>&nbsp;<a href="#range.response">Responses to a Range Request</a></h1>
810         <div id="status.206">
811            <div id="rfc.iref.20"></div>
812            <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a>&nbsp;<a href="#status.206">206 Partial Content</a></h2>
813            <p id="rfc.section.4.1.p.1">The <dfn>206 (Partial Content)</dfn> status code indicates that the server is successfully fulfilling a range request for the target resource by transferring one
814               or more parts of the selected representation that correspond to the satisfiable ranges found in the request's <a href="#header.range" class="smpl">Range</a> header field (<a href="#header.range" id="rfc.xref.header.range.2" title="Range">Section&nbsp;3.1</a>).
815            </p>
816            <p id="rfc.section.4.1.p.2">If a single part is being transferred, the server generating the 206 response <em class="bcp14">MUST</em> generate a <a href="#header.content-range" class="smpl">Content-Range</a> header field, describing what range of the selected representation is enclosed, and a payload consisting of the range. For
817               example:
818            </p>
819            <div id="rfc.figure.u.17"></div><pre class="text">HTTP/1.1 206 Partial Content
820Date: Wed, 15 Nov 1995 06:25:24 GMT
821Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
822Content-Range: bytes 21010-47021/47022
823Content-Length: 26012
824Content-Type: image/gif
826... 26012 bytes of partial image data ...
827</pre><p id="rfc.section.4.1.p.4">If multiple parts are being transferred, the server generating the 206 response <em class="bcp14">MUST</em> generate a "multipart/byteranges" payload, as defined in <a href="" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>, and a <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> header field containing the multipart/byteranges media type and its required boundary parameter. To avoid confusion with single
828               part responses, a server <em class="bcp14">MUST NOT</em> generate a <a href="#header.content-range" class="smpl">Content-Range</a> header field in the HTTP header section of a multiple part response (this field will be sent in each part instead).
829            </p>
830            <p id="rfc.section.4.1.p.5">Within the header area of each body part in the multipart payload, the server <em class="bcp14">MUST</em> generate a <a href="#header.content-range" class="smpl">Content-Range</a> header field corresponding to the range being enclosed in that body part. If the selected representation would have had a <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> header field in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response, the server <em class="bcp14">SHOULD</em> generate that same <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> field in the header area of each body part. For example:
831            </p>
832            <div id="rfc.figure.u.18"></div><pre class="text">HTTP/1.1 206 Partial Content
833Date: Wed, 15 Nov 1995 06:25:24 GMT
834Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
835Content-Length: 1741
836Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
839Content-Type: application/pdf
840Content-Range: bytes 500-999/8000
842...the first range...
844Content-Type: application/pdf
845Content-Range: bytes 7000-7999/8000
847...the second range
849</pre><p id="rfc.section.4.1.p.7">When multiple ranges are requested, a server <em class="bcp14">MAY</em> coalesce any of the ranges that overlap or that are separated by a gap that is smaller than the overhead of sending multiple
850               parts, regardless of the order in which the corresponding byte-range-spec appeared in the received <a href="#header.range" class="smpl">Range</a> header field. Since the typical overhead between parts of a multipart/byteranges payload is around 80 bytes, depending on
851               the selected representation's media type and the chosen boundary parameter length, it can be less efficient to transfer many
852               small disjoint parts than it is to transfer the entire selected representation.
853            </p>
854            <p id="rfc.section.4.1.p.8">A server <em class="bcp14">MUST NOT</em> generate a multipart response to a request for a single range, since a client that does not request multiple parts might not
855               support multipart responses. However, a server <em class="bcp14">MAY</em> generate a multipart/byteranges payload with only a single body part if multiple ranges were requested and only one range
856               was found to be satisfiable or only one range remained after coalescing. A client that cannot process a multipart/byteranges
857               response <em class="bcp14">MUST NOT</em> generate a request that asks for multiple ranges.
858            </p>
859            <p id="rfc.section.4.1.p.9">When a multipart response payload is generated, the server <em class="bcp14">SHOULD</em> send the parts in the same order that the corresponding byte-range-spec appeared in the received <a href="#header.range" class="smpl">Range</a> header field, excluding those ranges that were deemed unsatisfiable or that were coalesced into other ranges. A client that
860               receives a multipart response <em class="bcp14">MUST</em> inspect the <a href="#header.content-range" class="smpl">Content-Range</a> header field present in each body part in order to determine which range is contained in that body part; a client cannot rely
861               on receiving the same ranges that it requested, nor the same order that it requested.
862            </p>
863            <p id="rfc.section.4.1.p.10">When a 206 response is generated, the server <em class="bcp14">MUST</em> generate the following header fields, in addition to those required above, if the field would have been sent in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response to the same request: <a href="" class="smpl">Date</a>, <a href="p6-cache.html#header.cache-control" class="smpl">Cache-Control</a>, <a href="p4-conditional.html#header.etag" class="smpl">ETag</a>, <a href="p6-cache.html#header.expires" class="smpl">Expires</a>, <a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a>, and <a href="p2-semantics.html#header.vary" class="smpl">Vary</a>.
864            </p>
865            <p id="rfc.section.4.1.p.11">If a 206 is generated in response to a request with an <a href="#header.if-range" class="smpl">If-Range</a> header field, the sender <em class="bcp14">SHOULD NOT</em> generate other representation header fields beyond those required above, because the client is understood to already have
866               a prior response containing those header fields. Otherwise, the sender <em class="bcp14">MUST</em> generate all of the representation header fields that would have been sent in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response to the same request.
867            </p>
868            <p id="rfc.section.4.1.p.12">A 206 response is cacheable unless otherwise indicated by explicit cache controls (see <a href="p6-cache.html#heuristic.freshness" title="Calculating Heuristic Freshness">Section 4.2.2</a> of <a href="#Part6" id="rfc.xref.Part6.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>).
869            </p>
870         </div>
871         <div id="header.content-range">
872            <div id="rfc.iref.c.1"></div>
873            <h2 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a>&nbsp;<a href="#header.content-range">Content-Range</a></h2>
874            <p id="rfc.section.4.2.p.1">The "Content-Range" header field is sent in a single part <a href="#status.206" class="smpl">206 (Partial Content)</a> response to indicate the partial range of the selected representation enclosed as the message payload, sent in each part of
875               a multipart 206 response to indicate the range enclosed within each body part, and sent in <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> responses to provide information about the selected representation.
876            </p>
877            <div id="rfc.figure.u.19"></div><pre class="inline"><span id="rfc.iref.g.18"></span><span id="rfc.iref.g.19"></span><span id="rfc.iref.g.20"></span><span id="rfc.iref.g.21"></span><span id="rfc.iref.g.22"></span><span id="rfc.iref.g.23"></span><span id="rfc.iref.g.24"></span><span id="rfc.iref.g.25"></span>  <a href="#header.content-range" class="smpl">Content-Range</a>       = <a href="#header.content-range" class="smpl">byte-content-range</a>
878                      / <a href="#header.content-range" class="smpl">other-content-range</a>
880  <a href="#header.content-range" class="smpl">byte-content-range</a>  = <a href="#byte.ranges" class="smpl">bytes-unit</a> <a href="#imported.abnf" class="smpl">SP</a>
881                        ( <a href="#header.content-range" class="smpl">byte-range-resp</a> / <a href="#header.content-range" class="smpl">unsatisfied-range</a> )
883  <a href="#header.content-range" class="smpl">byte-range-resp</a>     = <a href="#header.content-range" class="smpl">byte-range</a> "/" ( <a href="#header.content-range" class="smpl">complete-length</a> / "*" )
884  <a href="#header.content-range" class="smpl">byte-range</a>          = <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> "-" <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a>
885  <a href="#header.content-range" class="smpl">unsatisfied-range</a>   = "*/" <a href="#header.content-range" class="smpl">complete-length</a>
887  <a href="#header.content-range" class="smpl">complete-length</a>     = 1*<a href="#imported.abnf" class="smpl">DIGIT</a>
889  <a href="#header.content-range" class="smpl">other-content-range</a> = <a href="#range.units.other" class="smpl">other-range-unit</a> <a href="#imported.abnf" class="smpl">SP</a> <a href="#header.content-range" class="smpl">other-range-resp</a>
890  <a href="#header.content-range" class="smpl">other-range-resp</a>    = *<a href="#imported.abnf" class="smpl">CHAR</a>
891</pre><p id="rfc.section.4.2.p.3">If a <a href="#status.206" class="smpl">206 (Partial Content)</a> response contains a <a href="#header.content-range" class="smpl">Content-Range</a> header field with a <a href="#range.units" class="smpl">range unit</a> (<a href="#range.units" title="Range Units">Section&nbsp;2</a>) that the recipient does not understand, the recipient <em class="bcp14">MUST NOT</em> attempt to recombine it with a stored representation. A proxy that receives such a message <em class="bcp14">SHOULD</em> forward it downstream.
892            </p>
893            <p id="rfc.section.4.2.p.4">For byte ranges, a sender <em class="bcp14">SHOULD</em> indicate the complete length of the representation from which the range has been extracted, unless the complete length is
894               unknown or difficult to determine. An asterisk character ("*") in place of the complete-length indicates that the representation
895               length was unknown when the header field was generated.
896            </p>
897            <p id="rfc.section.4.2.p.5">The following example illustrates when the complete length of the selected representation is known by the sender to be 1234
898               bytes:
899            </p>
900            <div id="rfc.figure.u.20"></div><pre class="text">  Content-Range: bytes 42-1233/1234
901</pre><p id="rfc.section.4.2.p.7">and this second example illustrates when the complete length is unknown:</p>
902            <div id="rfc.figure.u.21"></div><pre class="text">  Content-Range: bytes 42-1233/*
903</pre><p id="rfc.section.4.2.p.9">A Content-Range field value is invalid if it contains a <a href="#header.content-range" class="smpl">byte-range-resp</a> that has a <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> value less than its <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> value, or a <a href="#header.content-range" class="smpl">complete-length</a> value less than or equal to its <a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> value. The recipient of an invalid <a href="#header.content-range" class="smpl">Content-Range</a> <em class="bcp14">MUST NOT</em> attempt to recombine the received content with a stored representation.
904            </p>
905            <p id="rfc.section.4.2.p.10">A server generating a <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> response to a byte range request <em class="bcp14">SHOULD</em> send a Content-Range header field with an <a href="#header.content-range" class="smpl">unsatisfied-range</a> value, as in the following example:
906            </p>
907            <div id="rfc.figure.u.22"></div><pre class="text">  Content-Range: bytes */1234
908</pre><p id="rfc.section.4.2.p.12">The complete-length in a 416 response indicates the current length of the selected representation.</p>
909            <p id="rfc.section.4.2.p.13">The "Content-Range" header field has no meaning for status codes that do not explicitly describe its semantic. For this specification,
910               only the <a href="#status.206" class="smpl">206 (Partial Content)</a> and <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> status codes describe a meaning for Content-Range.
911            </p>
912            <p id="rfc.section.4.2.p.14">The following are examples of Content-Range values in which the selected representation contains a total of 1234 bytes: </p>
913            <ul>
914               <li>The first 500 bytes:
915                  <div id="rfc.figure.u.23"></div><pre class="text">  Content-Range: bytes 0-499/1234
916</pre> </li>
917               <li>The second 500 bytes:
918                  <div id="rfc.figure.u.24"></div><pre class="text">  Content-Range: bytes 500-999/1234
919</pre> </li>
920               <li>All except for the first 500 bytes:
921                  <div id="rfc.figure.u.25"></div><pre class="text">  Content-Range: bytes 500-1233/1234
922</pre> </li>
923               <li>The last 500 bytes:
924                  <div id="rfc.figure.u.26"></div><pre class="text">  Content-Range: bytes 734-1233/1234
925</pre> </li>
926            </ul>
927         </div>
928         <div id="combining.byte.ranges">
929            <h2 id="rfc.section.4.3"><a href="#rfc.section.4.3">4.3</a>&nbsp;<a href="#combining.byte.ranges">Combining Ranges</a></h2>
930            <p id="rfc.section.4.3.p.1">A response might transfer only a subrange of a representation if the connection closed prematurely or if the request used
931               one or more Range specifications. After several such transfers, a client might have received several ranges of the same representation.
932               These ranges can only be safely combined if they all have in common the same strong validator (<a href="p4-conditional.html#weak.and.strong.validators" title="Weak versus Strong">Section 2.1</a> of <a href="#Part4" id="rfc.xref.Part4.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>).
933            </p>
934            <p id="rfc.section.4.3.p.2">A client that has received multiple partial responses to GET requests on a target resource <em class="bcp14">MAY</em> combine those responses into a larger continuous range if they share the same strong validator.
935            </p>
936            <p id="rfc.section.4.3.p.3">If the most recent response is an incomplete <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response, then the header fields of that response are used for any combined response and replace those of the matching stored
937               responses.
938            </p>
939            <p id="rfc.section.4.3.p.4">If the most recent response is a <a href="#status.206" class="smpl">206 (Partial Content)</a> response and at least one of the matching stored responses is a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a>, then the combined response header fields consist of the most recent 200 response's header fields. If all of the matching
940               stored responses are 206 responses, then the stored response with the most recent header fields is used as the source of header
941               fields for the combined response, except that the client <em class="bcp14">MUST</em> use other header fields provided in the new response, aside from <a href="#header.content-range" class="smpl">Content-Range</a>, to replace all instances of the corresponding header fields in the stored response.
942            </p>
943            <p id="rfc.section.4.3.p.5">The combined response message body consists of the union of partial content ranges in the new response and each of the selected
944               responses. If the union consists of the entire range of the representation, then the client <em class="bcp14">MUST</em> process the combined response as if it were a complete <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response, including a <a href="p1-messaging.html#header.content-length" class="smpl">Content-Length</a> header field that reflects the complete length. Otherwise, the client <em class="bcp14">MUST</em> process the set of continuous ranges as one of the following: an incomplete <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response if the combined response is a prefix of the representation, a single <a href="#status.206" class="smpl">206 (Partial Content)</a> response containing a multipart/byteranges body, or multiple <a href="#status.206" class="smpl">206 (Partial Content)</a> responses, each with one continuous range that is indicated by a <a href="#header.content-range" class="smpl">Content-Range</a> header field.
945            </p>
946         </div>
947         <div id="status.416">
948            <div id="rfc.iref.29"></div>
949            <h2 id="rfc.section.4.4"><a href="#rfc.section.4.4">4.4</a>&nbsp;<a href="#status.416">416 Range Not Satisfiable</a></h2>
950            <p id="rfc.section.4.4.p.1">The <dfn>416 (Range Not Satisfiable)</dfn> status code indicates that none of the ranges in the request's <a href="#header.range" class="smpl">Range</a> header field (<a href="#header.range" id="rfc.xref.header.range.3" title="Range">Section&nbsp;3.1</a>) overlap the current extent of the selected resource or that the set of ranges requested has been rejected due to invalid
951               ranges or an excessive request of small or overlapping ranges.
952            </p>
953            <p id="rfc.section.4.4.p.2">For byte ranges, failing to overlap the current extent means that the <a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> of all of the <a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> values were greater than the current length of the selected representation. When this status code is generated in response
954               to a byte range request, the sender <em class="bcp14">SHOULD</em> generate a <a href="#header.content-range" class="smpl">Content-Range</a> header field specifying the current length of the selected representation (<a href="#header.content-range" id="rfc.xref.header.content-range.2" title="Content-Range">Section&nbsp;4.2</a>).
955            </p>
956            <div id="rfc.figure.u.27"></div>
957            <p>For example:</p><pre class="text">HTTP/1.1 416 Range Not Satisfiable
958Date: Fri, 20 Jan 2012 15:41:54 GMT
959Content-Range: bytes */47022
960</pre><div class="note" id="rfc.section.4.4.p.4">
961               <p><b>Note:</b> Because servers are free to ignore <a href="#header.range" class="smpl">Range</a>, many implementations will simply respond with the entire selected representation in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response. That is partly because most clients are prepared to receive a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> to complete the task (albeit less efficiently) and partly because clients might not stop making an invalid partial request
962                  until they have received a complete representation. Thus, clients cannot depend on receiving a <a href="#status.416" class="smpl">416 (Range Not Satisfiable)</a> response even when it is most appropriate.
963               </p>
964            </div>
965         </div>
966      </div>
967      <div id="IANA.considerations">
968         <h1 id="rfc.section.5"><a href="#rfc.section.5">5.</a>&nbsp;<a href="#IANA.considerations">IANA Considerations</a></h1>
969         <div id="range.unit.registry">
970            <h2 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a>&nbsp;<a href="#range.unit.registry">Range Unit Registry</a></h2>
971            <p id="rfc.section.5.1.p.1">The HTTP Range Unit Registry defines the name space for the range unit names and refers to their corresponding specifications.
972               The registry will be created and maintained at &lt;<a href=""></a>&gt;.
973            </p>
974            <div id="range.unit.registry.procedure">
975               <h3 id="rfc.section.5.1.1"><a href="#rfc.section.5.1.1">5.1.1</a>&nbsp;<a href="#range.unit.registry.procedure">Procedure</a></h3>
976               <p id="rfc.section.5.1.1.p.1">Registration of an HTTP Range Unit <em class="bcp14">MUST</em> include the following fields:
977               </p>
978               <ul>
979                  <li>Name</li>
980                  <li>Description</li>
981                  <li>Pointer to specification text</li>
982               </ul>
983               <p id="rfc.section.5.1.1.p.2">Values to be added to this name space require IETF Review (see <a href="#RFC5226" id="rfc.xref.RFC5226.1"><cite title="Guidelines for Writing an IANA Considerations Section in RFCs">[RFC5226]</cite></a>, <a href="">Section 4.1</a>).
984               </p>
985            </div>
986            <div id="range.unit.registration">
987               <h3 id="rfc.section.5.1.2"><a href="#rfc.section.5.1.2">5.1.2</a>&nbsp;<a href="#range.unit.registration">Registrations</a></h3>
988               <p id="rfc.section.5.1.2.p.1">The initial HTTP Range Unit Registry shall contain the registrations below:</p>
989               <div id="rfc.table.1">
990                  <div id="iana.range.units.table"></div>
991                  <table class="tt full left" cellpadding="3" cellspacing="0">
992                     <thead>
993                        <tr>
994                           <th>Range Unit Name</th>
995                           <th>Description</th>
996                           <th>Reference</th>
997                        </tr>
998                     </thead>
999                     <tbody>
1000                        <tr>
1001                           <td class="left">bytes</td>
1002                           <td class="left">a range of octets</td>
1003                           <td class="left"><a href="#byte.ranges" title="Byte Ranges">Section&nbsp;2.1</a></td>
1004                        </tr>
1005                        <tr>
1006                           <td class="left">none</td>
1007                           <td class="left">reserved as keyword, indicating no ranges are supported</td>
1008                           <td class="left"><a href="#header.accept-ranges" id="rfc.xref.header.accept-ranges.2" title="Accept-Ranges">Section&nbsp;2.3</a></td>
1009                        </tr>
1010                     </tbody>
1011                  </table>
1012               </div>
1013               <p id="rfc.section.5.1.2.p.2">The change controller is: "IETF ( - Internet Engineering Task Force".</p>
1014            </div>
1015         </div>
1016         <div id="status.code.registration">
1017            <h2 id="rfc.section.5.2"><a href="#rfc.section.5.2">5.2</a>&nbsp;<a href="#status.code.registration">Status Code Registration</a></h2>
1018            <p id="rfc.section.5.2.p.1">The HTTP Status Code Registry located at &lt;<a href=""></a>&gt; shall be updated with the registrations below:
1019            </p>
1020            <div id="rfc.table.2">
1021               <div id="iana.status.code.registration.table"></div>
1022               <table class="tt full left" cellpadding="3" cellspacing="0">
1023                  <thead>
1024                     <tr>
1025                        <th>Value</th>
1026                        <th>Description</th>
1027                        <th>Reference</th>
1028                     </tr>
1029                  </thead>
1030                  <tbody>
1031                     <tr>
1032                        <td class="left">206</td>
1033                        <td class="left">Partial Content</td>
1034                        <td class="left"><a href="#status.206" id="rfc.xref.status.206.1" title="206 Partial Content">Section&nbsp;4.1</a>
1035                        </td>
1036                     </tr>
1037                     <tr>
1038                        <td class="left">416</td>
1039                        <td class="left">Range Not Satisfiable</td>
1040                        <td class="left"><a href="#status.416" id="rfc.xref.status.416.1" title="416 Range Not Satisfiable">Section&nbsp;4.4</a>
1041                        </td>
1042                     </tr>
1043                  </tbody>
1044               </table>
1045            </div>
1046         </div>
1047         <div id="header.field.registration">
1048            <h2 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a>&nbsp;<a href="#header.field.registration">Header Field Registration</a></h2>
1049            <p id="rfc.section.5.3.p.1">HTTP header fields are registered within the Message Header Field Registry maintained at &lt;<a href=""></a>&gt;.
1050            </p>
1051            <p id="rfc.section.5.3.p.2">This document defines the following HTTP header fields, so their associated registry entries shall be updated according to
1052               the permanent registrations below (see <a href="#BCP90" id="rfc.xref.BCP90.1"><cite title="Registration Procedures for Message Header Fields">[BCP90]</cite></a>):
1053            </p>
1054            <div id="rfc.table.3">
1055               <div id="iana.header.registration.table"></div>
1056               <table class="tt full left" cellpadding="3" cellspacing="0">
1057                  <thead>
1058                     <tr>
1059                        <th>Header Field Name</th>
1060                        <th>Protocol</th>
1061                        <th>Status</th>
1062                        <th>Reference</th>
1063                     </tr>
1064                  </thead>
1065                  <tbody>
1066                     <tr>
1067                        <td class="left">Accept-Ranges</td>
1068                        <td class="left">http</td>
1069                        <td class="left">standard</td>
1070                        <td class="left"><a href="#header.accept-ranges" id="rfc.xref.header.accept-ranges.3" title="Accept-Ranges">Section&nbsp;2.3</a>
1071                        </td>
1072                     </tr>
1073                     <tr>
1074                        <td class="left">Content-Range</td>
1075                        <td class="left">http</td>
1076                        <td class="left">standard</td>
1077                        <td class="left"><a href="#header.content-range" id="rfc.xref.header.content-range.3" title="Content-Range">Section&nbsp;4.2</a>
1078                        </td>
1079                     </tr>
1080                     <tr>
1081                        <td class="left">If-Range</td>
1082                        <td class="left">http</td>
1083                        <td class="left">standard</td>
1084                        <td class="left"><a href="#header.if-range" id="rfc.xref.header.if-range.2" title="If-Range">Section&nbsp;3.2</a>
1085                        </td>
1086                     </tr>
1087                     <tr>
1088                        <td class="left">Range</td>
1089                        <td class="left">http</td>
1090                        <td class="left">standard</td>
1091                        <td class="left"><a href="#header.range" id="rfc.xref.header.range.4" title="Range">Section&nbsp;3.1</a>
1092                        </td>
1093                     </tr>
1094                  </tbody>
1095               </table>
1096            </div>
1097            <p id="rfc.section.5.3.p.3">The change controller is: "IETF ( - Internet Engineering Task Force".</p>
1098         </div>
1099      </div>
1100      <div id="security.considerations">
1101         <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a href="#security.considerations">Security Considerations</a></h1>
1102         <p id="rfc.section.6.p.1">This section is meant to inform developers, information providers, and users of known security concerns specific to the HTTP/1.1
1103            range request mechanisms. More general security considerations are addressed in HTTP messaging <a href="#Part1" id="rfc.xref.Part1.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a> and semantics <a href="#Part2" id="rfc.xref.Part2.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>.
1104         </p>
1105         <div id="overlapping.ranges">
1106            <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a>&nbsp;<a href="#overlapping.ranges">Denial of Service Attacks using Range</a></h2>
1107            <p id="rfc.section.6.1.p.1">Unconstrained multiple range requests are susceptible to denial of service attacks because the effort required to request
1108               many overlapping ranges of the same data is tiny compared to the time, memory, and bandwidth consumed by attempting to serve
1109               the requested data in many parts. Servers ought to ignore, coalesce, or reject egregious range requests, such as requests
1110               for more than two overlapping ranges or for many small ranges in a single set, particularly when the ranges are requested
1111               out of order for no apparent reason. Multipart range requests are not designed to support random access.
1112            </p>
1113         </div>
1114      </div>
1115      <div id="acks">
1116         <h1 id="rfc.section.7"><a href="#rfc.section.7">7.</a>&nbsp;<a href="#acks">Acknowledgments</a></h1>
1117         <p id="rfc.section.7.p.1">See <a href="p1-messaging.html#acks" title="Acknowledgments">Section 10</a> of <a href="#Part1" id="rfc.xref.Part1.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>.
1118         </p>
1119      </div>
1120      <h1 id="rfc.references"><a id="rfc.section.8" href="#rfc.section.8">8.</a> References
1121      </h1>
1122      <h2 id="rfc.references.1"><a href="#rfc.section.8.1" id="rfc.section.8.1">8.1</a> Normative References
1123      </h2>
1124      <table>
1125         <tr>
1126            <td class="reference"><b id="Part1">[Part1]</b></td>
1127            <td class="top"><a href="" title="Adobe Systems Incorporated">Fielding, R., Ed.</a> and <a href="" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="">Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p1-messaging-24 (work in progress), September&nbsp;2013.
1128            </td>
1129         </tr>
1130         <tr>
1131            <td class="reference"><b id="Part2">[Part2]</b></td>
1132            <td class="top"><a href="" title="Adobe Systems Incorporated">Fielding, R., Ed.</a> and <a href="" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="">Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p2-semantics-24 (work in progress), September&nbsp;2013.
1133            </td>
1134         </tr>
1135         <tr>
1136            <td class="reference"><b id="Part4">[Part4]</b></td>
1137            <td class="top"><a href="" title="Adobe Systems Incorporated">Fielding, R., Ed.</a> and <a href="" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="">Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p4-conditional-24 (work in progress), September&nbsp;2013.
1138            </td>
1139         </tr>
1140         <tr>
1141            <td class="reference"><b id="Part6">[Part6]</b></td>
1142            <td class="top"><a href="" title="Adobe Systems Incorporated">Fielding, R., Ed.</a>, <a href="" title="Akamai">Nottingham, M., Ed.</a>, and <a href="" title="greenbytes GmbH">J. Reschke, Ed.</a>, “<a href="">Hypertext Transfer Protocol (HTTP/1.1): Caching</a>”, Internet-Draft&nbsp;draft-ietf-httpbis-p6-cache-24 (work in progress), September&nbsp;2013.
1143            </td>
1144         </tr>
1145         <tr>
1146            <td class="reference"><b id="RFC2046">[RFC2046]</b></td>
1147            <td class="top"><a href="" title="Innosoft International, Inc.">Freed, N.</a> and <a href="" title="First Virtual Holdings">N. Borenstein</a>, “<a href="">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</a>”, RFC&nbsp;2046, November&nbsp;1996.
1148            </td>
1149         </tr>
1150         <tr>
1151            <td class="reference"><b id="RFC2119">[RFC2119]</b></td>
1152            <td class="top"><a href="" title="Harvard University">Bradner, S.</a>, “<a href="">Key words for use in RFCs to Indicate Requirement Levels</a>”, BCP&nbsp;14, RFC&nbsp;2119, March&nbsp;1997.
1153            </td>
1154         </tr>
1155         <tr>
1156            <td class="reference"><b id="RFC5234">[RFC5234]</b></td>
1157            <td class="top"><a href="" title="Brandenburg InternetWorking">Crocker, D., Ed.</a> and <a href="" title="THUS plc.">P. Overell</a>, “<a href="">Augmented BNF for Syntax Specifications: ABNF</a>”, STD&nbsp;68, RFC&nbsp;5234, January&nbsp;2008.
1158            </td>
1159         </tr>
1160      </table>
1161      <h2 id="rfc.references.2"><a href="#rfc.section.8.2" id="rfc.section.8.2">8.2</a> Informative References
1162      </h2>
1163      <table>
1164         <tr>
1165            <td class="reference"><b id="BCP13">[BCP13]</b></td>
1166            <td class="top"><a href="" title="Oracle">Freed, N.</a>, <a href="">Klensin, J.</a>, and <a href="" title="AT&amp;T Laboratories">T. Hansen</a>, “<a href="">Media Type Specifications and Registration Procedures</a>”, BCP&nbsp;13, RFC&nbsp;6838, January&nbsp;2013.
1167            </td>
1168         </tr>
1169         <tr>
1170            <td class="reference"><b id="BCP90">[BCP90]</b></td>
1171            <td class="top"><a href="" title="Nine by Nine">Klyne, G.</a>, <a href="" title="BEA Systems">Nottingham, M.</a>, and <a href="" title="HP Labs">J. Mogul</a>, “<a href="">Registration Procedures for Message Header Fields</a>”, BCP&nbsp;90, RFC&nbsp;3864, September&nbsp;2004.
1172            </td>
1173         </tr>
1174         <tr>
1175            <td class="reference"><b id="RFC2616">[RFC2616]</b></td>
1176            <td class="top"><a href="" title="University of California, Irvine">Fielding, R.</a>, <a href="" title="W3C">Gettys, J.</a>, <a href="" title="Compaq Computer Corporation">Mogul, J.</a>, <a href="" title="MIT Laboratory for Computer Science">Frystyk, H.</a>, <a href="" title="Xerox Corporation">Masinter, L.</a>, <a href="" title="Microsoft Corporation">Leach, P.</a>, and <a href="" title="W3C">T. Berners-Lee</a>, “<a href="">Hypertext Transfer Protocol -- HTTP/1.1</a>”, RFC&nbsp;2616, June&nbsp;1999.
1177            </td>
1178         </tr>
1179         <tr>
1180            <td class="reference"><b id="RFC5226">[RFC5226]</b></td>
1181            <td class="top"><a href="" title="IBM">Narten, T.</a> and <a href="" title="Google">H. Alvestrand</a>, “<a href="">Guidelines for Writing an IANA Considerations Section in RFCs</a>”, BCP&nbsp;26, RFC&nbsp;5226, May&nbsp;2008.
1182            </td>
1183         </tr>
1184      </table>
1185      <div class="avoidbreak">
1186         <h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
1187         <p><b>Roy T. Fielding</b>
1188            (editor)
1189            <br>Adobe Systems Incorporated<br>345 Park Ave<br>San Jose, CA&nbsp;95110<br>USA<br>Email: <a href=""></a><br>URI: <a href=""></a></p>
1190         <p><b>Yves Lafon</b>
1191            (editor)
1192            <br>World Wide Web Consortium<br>W3C / ERCIM<br>2004, rte des Lucioles<br>Sophia-Antipolis, AM&nbsp;06902<br>France<br>Email: <a href=""></a><br>URI: <a href=""></a></p>
1193         <p><b>Julian F. Reschke</b>
1194            (editor)
1195            <br>greenbytes GmbH<br>Hafenweg 16<br>Muenster, NW&nbsp;48155<br>Germany<br>Email: <a href=""></a><br>URI: <a href=""></a></p>
1196      </div>
1197      <div id="">
1198         <div id="rfc.iref.m.1"></div>
1199         <div id="rfc.iref.m.2"></div>
1200         <h1 id="rfc.section.A" class="np"><a href="#rfc.section.A">A.</a>&nbsp;<a href="">Internet Media Type multipart/byteranges</a></h1>
1201         <p id="rfc.section.A.p.1">When a <a href="#status.206" class="smpl">206 (Partial Content)</a> response message includes the content of multiple ranges, they are transmitted as body parts in 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="">Section 5.1</a>) with the media type of "multipart/byteranges". The following definition is to be registered with IANA <a href="#BCP13" id="rfc.xref.BCP13.1"><cite title="Media Type Specifications and Registration Procedures">[BCP13]</cite></a>.
1202         </p>
1203         <p id="rfc.section.A.p.2">The multipart/byteranges media type includes one or more body parts, each with its own <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> and <a href="#header.content-range" class="smpl">Content-Range</a> fields. The required boundary parameter specifies the boundary string used to separate each body part.
1204         </p>
1205         <p id="rfc.section.A.p.3"></p>
1206         <dl>
1207            <dt>Type name:</dt>
1208            <dd>multipart</dd>
1209            <dt>Subtype name:</dt>
1210            <dd>byteranges</dd>
1211            <dt>Required parameters:</dt>
1212            <dd>boundary</dd>
1213            <dt>Optional parameters:</dt>
1214            <dd>none</dd>
1215            <dt>Encoding considerations:</dt>
1216            <dd>only "7bit", "8bit", or "binary" are permitted</dd>
1217            <dt>Security considerations:</dt>
1218            <dd>none</dd>
1219            <dt>Interoperability considerations:</dt>
1220            <dd>none</dd>
1221            <dt>Published specification:</dt>
1222            <dd>This specification (see <a href="" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>).
1223            </dd>
1224            <dt>Applications that use this media type:</dt>
1225            <dd>HTTP components supporting multiple ranges in a single request.</dd>
1226            <dt>Additional information:</dt>
1227            <dd>
1228               <dl>
1229                  <dt>Magic number(s):</dt>
1230                  <dd>none</dd>
1231                  <dt>File extension(s):</dt>
1232                  <dd>none</dd>
1233                  <dt>Macintosh file type code(s):</dt>
1234                  <dd>none</dd>
1235               </dl>
1236            </dd>
1237            <dt>Person and email address to contact for further information:</dt>
1238            <dd>See Authors Section.</dd>
1239            <dt>Intended usage:</dt>
1240            <dd>COMMON</dd>
1241            <dt>Restrictions on usage:</dt>
1242            <dd>none</dd>
1243            <dt>Author:</dt>
1244            <dd>See Authors Section.</dd>
1245            <dt>Change controller:</dt>
1246            <dd>IESG</dd>
1247         </dl>
1248         <p id="rfc.section.A.p.4">Implementation Notes: </p>
1249         <ol>
1250            <li>Additional CRLFs might precede the first boundary string in the body.</li>
1251            <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.
1252            </li>
1253            <li>A number of clients and servers were coded to an early draft of the byteranges specification that used 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 this type.
1254            </li>
1255         </ol>
1256         <p id="rfc.section.A.p.5">Despite the name, the "multipart/byteranges" media type is not limited to byte ranges. The following example uses an "exampleunit"
1257            range unit:
1258         </p>
1259         <div id="rfc.figure.u.28"></div><pre class="text">HTTP/1.1 206 Partial Content
1260Date: Tue, 14 Nov 1995 06:25:24 GMT
1261Last-Modified: Tue, 14 July 04:58:08 GMT
1262Content-Length: 2331785
1263Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1266Content-Type: video/example
1267Content-Range: exampleunit 1.2-4.3/25
1269...the first range...
1271Content-Type: video/example
1272Content-Range: exampleunit 11.2-14.3/25
1274...the second range
1277      <div id="changes.from.rfc.2616">
1278         <h1 id="rfc.section.B"><a href="#rfc.section.B">B.</a>&nbsp;<a href="#changes.from.rfc.2616">Changes from RFC 2616</a></h1>
1279         <p id="rfc.section.B.p.1">Servers are given more leeway in how they respond to a range request, in order to mitigate abuse by malicious (or just greedy)
1280            clients. (<a href="#header.range" id="rfc.xref.header.range.5" title="Range">Section&nbsp;3.1</a>)
1281         </p>
1282         <p id="rfc.section.B.p.2">A weak validator cannot be used in a <a href="#status.206" class="smpl">206</a> response. (<a href="#status.206" id="rfc.xref.status.206.2" title="206 Partial Content">Section&nbsp;4.1</a>)
1283         </p>
1284         <p id="rfc.section.B.p.3">The Content-Range header field only has meaning when the status code explicitly defines its use. (<a href="#header.content-range" id="rfc.xref.header.content-range.4" title="Content-Range">Section&nbsp;4.2</a>)
1285         </p>
1286         <p id="rfc.section.B.p.4">This specification introduces a Range Unit Registry. (<a href="#range.unit.registry" title="Range Unit Registry">Section&nbsp;5.1</a>)
1287         </p>
1288         <p id="rfc.section.B.p.5">multipart/byteranges can consist of a single part. (<a href="" title="Internet Media Type multipart/byteranges">Appendix&nbsp;A</a>)
1289         </p>
1290      </div>
1291      <div id="imported.abnf">
1292         <h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a>&nbsp;<a href="#imported.abnf">Imported ABNF</a></h1>
1293         <p id="rfc.section.C.p.1">The following core rules are included by reference, as defined in <a href="">Appendix B.1</a> of <a href="#RFC5234" id="rfc.xref.RFC5234.2"><cite title="Augmented BNF for Syntax Specifications: ABNF">[RFC5234]</cite></a>: ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote), HEXDIG
1294            (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
1295            character).
1296         </p>
1297         <p id="rfc.section.C.p.2">Note that all rules derived from <a href="#imported.abnf" class="smpl">token</a> are to be compared case-insensitively, like <a href="#range.units" class="smpl">range-unit</a> and <a href="#header.accept-ranges" class="smpl">acceptable-ranges</a>.
1298         </p>
1299         <p id="rfc.section.C.p.3">The rules below are defined in <a href="#Part1" id="rfc.xref.Part1.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>:
1300         </p>
1301         <div id="rfc.figure.u.29"></div><pre class="inline">  <a href="#imported.abnf" class="smpl">OWS</a>        = &lt;OWS, defined in <a href="#Part1" id="rfc.xref.Part1.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>, <a href="p1-messaging.html#whitespace" title="Whitespace">Section 3.2.3</a>&gt;
1302  <a href="#imported.abnf" class="smpl">token</a>      = &lt;token, defined in <a href="#Part1" id="rfc.xref.Part1.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>, <a href="p1-messaging.html#field.components" title="Field value components">Section 3.2.6</a>&gt;
1303</pre><p id="rfc.section.C.p.5">The rules below are defined in other parts:</p>
1304         <div id="rfc.figure.u.30"></div><pre class="inline">  <a href="#imported.abnf" class="smpl">HTTP-date</a>  = &lt;HTTP-date, defined in <a href="#Part2" id="rfc.xref.Part2.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, <a href="" title="Date/Time Formats">Section</a>&gt;
1305  <a href="#imported.abnf" class="smpl">entity-tag</a> = &lt;entity-tag, defined in <a href="#Part4" id="rfc.xref.Part4.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>, <a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a>&gt;
1307      <div id="collected.abnf">
1308         <h1 id="rfc.section.D"><a href="#rfc.section.D">D.</a>&nbsp;<a href="#collected.abnf">Collected ABNF</a></h1>
1309         <p id="rfc.section.D.p.1">In the collected ABNF below, list rules are expanded as per <a href="p1-messaging.html#notation" title="Syntax Notation">Section 1.2</a> of <a href="#Part1" id="rfc.xref.Part1.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>.
1310         </p>
1311         <div id="rfc.figure.u.31"></div><pre class="inline"><a href="#header.accept-ranges" class="smpl">Accept-Ranges</a> = acceptable-ranges
1313<a href="#header.content-range" class="smpl">Content-Range</a> = byte-content-range / other-content-range
1315<a href="#imported.abnf" class="smpl">HTTP-date</a> = &lt;HTTP-date, defined in [Part2], Section;
1317<a href="#header.if-range" class="smpl">If-Range</a> = entity-tag / HTTP-date
1319<a href="#imported.abnf" class="smpl">OWS</a> = &lt;OWS, defined in [Part1], Section 3.2.3&gt;
1321<a href="#header.range" class="smpl">Range</a> = byte-ranges-specifier / other-ranges-specifier
1323<a href="#header.accept-ranges" class="smpl">acceptable-ranges</a> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
1324 range-unit ] ) ) / "none"
1326<a href="#header.content-range" class="smpl">byte-content-range</a> = bytes-unit SP ( byte-range-resp /
1327 unsatisfied-range )
1328<a href="#header.content-range" class="smpl">byte-range</a> = first-byte-pos "-" last-byte-pos
1329<a href="#header.content-range" class="smpl">byte-range-resp</a> = byte-range "/" ( complete-length / "*" )
1330<a href="#rule.ranges-specifier" class="smpl">byte-range-set</a> = *( "," OWS ) ( byte-range-spec /
1331 suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
1332 suffix-byte-range-spec ) ] )
1333<a href="#rule.ranges-specifier" class="smpl">byte-range-spec</a> = first-byte-pos "-" [ last-byte-pos ]
1334<a href="#rule.ranges-specifier" class="smpl">byte-ranges-specifier</a> = bytes-unit "=" byte-range-set
1335<a href="#byte.ranges" class="smpl">bytes-unit</a> = "bytes"
1337<a href="#header.content-range" class="smpl">complete-length</a> = 1*DIGIT
1339<a href="#imported.abnf" class="smpl">entity-tag</a> = &lt;entity-tag, defined in [Part4], Section 2.3&gt;
1341<a href="#rule.ranges-specifier" class="smpl">first-byte-pos</a> = 1*DIGIT
1343<a href="#rule.ranges-specifier" class="smpl">last-byte-pos</a> = 1*DIGIT
1345<a href="#header.content-range" class="smpl">other-content-range</a> = other-range-unit SP other-range-resp
1346<a href="#header.content-range" class="smpl">other-range-resp</a> = *CHAR
1347<a href="#header.range" class="smpl">other-range-set</a> = 1*CHAR
1348<a href="#range.units.other" class="smpl">other-range-unit</a> = token
1349<a href="#header.range" class="smpl">other-ranges-specifier</a> = other-range-unit "=" other-range-set
1351<a href="#range.units" class="smpl">range-unit</a> = bytes-unit / other-range-unit
1353<a href="#rule.ranges-specifier" class="smpl">suffix-byte-range-spec</a> = "-" suffix-length
1354<a href="#rule.ranges-specifier" class="smpl">suffix-length</a> = 1*DIGIT
1356<a href="#imported.abnf" class="smpl">token</a> = &lt;token, defined in [Part1], Section 3.2.6&gt;
1358<a href="#header.content-range" class="smpl">unsatisfied-range</a> = "*/" complete-length
1360      <div id="change.log">
1361         <h1 id="rfc.section.E"><a href="#rfc.section.E">E.</a>&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
1362         <p id="rfc.section.E.p.1">Changes up to the first Working Group Last Call draft are summarized in &lt;<a href=""></a>&gt;.
1363         </p>
1364         <div id="changes.since.19">
1365            <h2 id="rfc.section.E.1"><a href="#rfc.section.E.1">E.1</a>&nbsp;<a href="#changes.since.19">Since draft-ietf-httpbis-p5-range-19</a></h2>
1366            <p id="rfc.section.E.1.p.1">Closed issues: </p>
1367            <ul>
1368               <li>&lt;<a href=""></a>&gt;: "ABNF list expansion code problem"
1369               </li>
1370               <li>&lt;<a href=""></a>&gt;: "ABNF requirements for recipients"
1371               </li>
1372               <li>&lt;<a href=""></a>&gt;: "reserve 'none' as byte range unit"
1373               </li>
1374               <li>&lt;<a href=""></a>&gt;: "note introduction of new IANA registries as normative changes"
1375               </li>
1376               <li>&lt;<a href=""></a>&gt;: "range units vs leading zeroes vs size"
1377               </li>
1378            </ul>
1379         </div>
1380         <div id="changes.since.20">
1381            <h2 id="rfc.section.E.2"><a href="#rfc.section.E.2">E.2</a>&nbsp;<a href="#changes.since.20">Since draft-ietf-httpbis-p5-range-20</a></h2>
1382            <p id="rfc.section.E.2.p.1"></p>
1383            <ul>
1384               <li>Conformance criteria and considerations regarding error handling are now defined in Part 1.</li>
1385            </ul>
1386         </div>
1387         <div id="changes.since.21">
1388            <h2 id="rfc.section.E.3"><a href="#rfc.section.E.3">E.3</a>&nbsp;<a href="#changes.since.21">Since draft-ietf-httpbis-p5-range-21</a></h2>
1389            <p id="rfc.section.E.3.p.1">Closed issues: </p>
1390            <ul>
1391               <li>&lt;<a href=""></a>&gt;: "Security consideration: range flooding"
1392               </li>
1393               <li>&lt;<a href=""></a>&gt;: "Allowing heuristic caching for new status codes"
1394               </li>
1395               <li>&lt;<a href=""></a>&gt;: "Add limitations to Range to reduce its use as a denial-of-service tool"
1396               </li>
1397               <li>&lt;<a href=""></a>&gt;: "416 and multipart/byteranges"
1398               </li>
1399            </ul>
1400         </div>
1401         <div id="changes.since.22">
1402            <h2 id="rfc.section.E.4"><a href="#rfc.section.E.4">E.4</a>&nbsp;<a href="#changes.since.22">Since draft-ietf-httpbis-p5-range-22</a></h2>
1403            <p id="rfc.section.E.4.p.1">Closed issues: </p>
1404            <ul>
1405               <li>&lt;<a href=""></a>&gt;: "explain list expansion in ABNF appendices"
1406               </li>
1407               <li>&lt;<a href=""></a>&gt;: "incorrect example dates"
1408               </li>
1409               <li>&lt;<a href=""></a>&gt;: "media type registration template issues"
1410               </li>
1411               <li>&lt;<a href=""></a>&gt;: "Editorial suggestions"
1412               </li>
1413               <li>&lt;<a href=""></a>&gt;: "MUSTs and other feedback"
1414               </li>
1415            </ul>
1416         </div>
1417         <div id="changes.since.23">
1418            <h2 id="rfc.section.E.5"><a href="#rfc.section.E.5">E.5</a>&nbsp;<a href="#changes.since.23">Since draft-ietf-httpbis-p5-range-23</a></h2>
1419            <p id="rfc.section.E.5.p.1">Closed issues: </p>
1420            <ul>
1421               <li>&lt;<a href=""></a>&gt;: "is P5's definition of strong validator consistent with P4?"
1422               </li>
1423               <li>&lt;<a href=""></a>&gt;: "p5 editorial comments"
1424               </li>
1425            </ul>
1426         </div>
1427      </div>
1428      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
1429      <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.B">B</a> <a href="#rfc.index.C">C</a> <a href="#rfc.index.G">G</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>
1430      </p>
1431      <div class="print2col">
1432         <ul class="ind">
1433            <li><a id="rfc.index.2" href="#rfc.index.2"><b>2</b></a><ul>
1434                  <li>206 Partial Content (status code)&nbsp;&nbsp;<a href="#rfc.iref.20"><b>4.1</b></a>, <a href="#rfc.xref.status.206.1">5.2</a>, <a href="#rfc.xref.status.206.2">B</a></li>
1435               </ul>
1436            </li>
1437            <li><a id="rfc.index.4" href="#rfc.index.4"><b>4</b></a><ul>
1438                  <li>416 Range Not Satisfiable (status code)&nbsp;&nbsp;<a href="#rfc.iref.29"><b>4.4</b></a>, <a href="#rfc.xref.status.416.1">5.2</a></li>
1439               </ul>
1440            </li>
1441            <li><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul>
1442                  <li>Accept-Ranges header field&nbsp;&nbsp;<a href="#rfc.xref.header.accept-ranges.1">2</a>, <a href="#rfc.iref.a.1"><b>2.3</b></a>, <a href="#rfc.xref.header.accept-ranges.2">5.1.2</a>, <a href="#rfc.xref.header.accept-ranges.3">5.3</a></li>
1443               </ul>
1444            </li>
1445            <li><a id="rfc.index.B" href="#rfc.index.B"><b>B</b></a><ul>
1446                  <li><em>BCP13</em>&nbsp;&nbsp;<a href="#BCP13"><b>8.2</b></a>, <a href="#rfc.xref.BCP13.1">A</a></li>
1447                  <li><em>BCP90</em>&nbsp;&nbsp;<a href="#rfc.xref.BCP90.1">5.3</a>, <a href="#BCP90"><b>8.2</b></a></li>
1448               </ul>
1449            </li>
1450            <li><a id="rfc.index.C" href="#rfc.index.C"><b>C</b></a><ul>
1451                  <li>Content-Range header field&nbsp;&nbsp;<a href="#rfc.xref.header.content-range.1">2</a>, <a href="#rfc.iref.c.1"><b>4.2</b></a>, <a href="#rfc.xref.header.content-range.2">4.4</a>, <a href="#rfc.xref.header.content-range.3">5.3</a>, <a href="#rfc.xref.header.content-range.4">B</a></li>
1452               </ul>
1453            </li>
1454            <li><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul>
1455                  <li><tt>Grammar</tt>&nbsp;&nbsp;
1456                     <ul>
1457                        <li><tt>Accept-Ranges</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.14"><b>2.3</b></a></li>
1458                        <li><tt>acceptable-ranges</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.15"><b>2.3</b></a></li>
1459                        <li><tt>byte-content-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.19"><b>4.2</b></a></li>
1460                        <li><tt>byte-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.21"><b>4.2</b></a></li>
1461                        <li><tt>byte-range-resp</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.20"><b>4.2</b></a></li>
1462                        <li><tt>byte-range-set</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.7"><b>2.1</b></a></li>
1463                        <li><tt>byte-range-spec</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.8"><b>2.1</b></a></li>
1464                        <li><tt>byte-ranges-specifier</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.6"><b>2.1</b></a></li>
1465                        <li><tt>bytes-unit</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2">2</a>, <a href="#rfc.iref.g.4"><b>2.1</b></a></li>
1466                        <li><tt>complete-length</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.25"><b>4.2</b></a></li>
1467                        <li><tt>Content-Range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.18"><b>4.2</b></a></li>
1468                        <li><tt>first-byte-pos</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.9"><b>2.1</b></a></li>
1469                        <li><tt>If-Range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.17"><b>3.2</b></a></li>
1470                        <li><tt>last-byte-pos</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.10"><b>2.1</b></a></li>
1471                        <li><tt>other-content-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.23"><b>4.2</b></a></li>
1472                        <li><tt>other-range-resp</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.24"><b>4.2</b></a></li>
1473                        <li><tt>other-range-unit</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.3">2</a>, <a href="#rfc.iref.g.13"><b>2.2</b></a></li>
1474                        <li><tt>Range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.16"><b>3.1</b></a></li>
1475                        <li><tt>range-unit</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>2</b></a></li>
1476                        <li><tt>ranges-specifier</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.5"><b>2.1</b></a></li>
1477                        <li><tt>suffix-byte-range-spec</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.11"><b>2.1</b></a></li>
1478                        <li><tt>suffix-length</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.12"><b>2.1</b></a></li>
1479                        <li><tt>unsatisfied-range</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.22"><b>4.2</b></a></li>
1480                     </ul>
1481                  </li>
1482               </ul>
1483            </li>
1484            <li><a id="rfc.index.I" href="#rfc.index.I"><b>I</b></a><ul>
1485                  <li>If-Range header field&nbsp;&nbsp;<a href="#rfc.xref.header.if-range.1">3.1</a>, <a href="#rfc.iref.i.1"><b>3.2</b></a>, <a href="#rfc.xref.header.if-range.2">5.3</a></li>
1486               </ul>
1487            </li>
1488            <li><a id="rfc.index.M" href="#rfc.index.M"><b>M</b></a><ul>
1489                  <li>Media Type&nbsp;&nbsp;
1490                     <ul>
1491                        <li>multipart/byteranges&nbsp;&nbsp;<a href="#rfc.iref.m.1"><b>A</b></a></li>
1492                        <li>multipart/x-byteranges&nbsp;&nbsp;<a href="#rfc.iref.m.4">A</a></li>
1493                     </ul>
1494                  </li>
1495                  <li>multipart/byteranges Media Type&nbsp;&nbsp;<a href="#rfc.iref.m.2"><b>A</b></a></li>
1496                  <li>multipart/x-byteranges Media Type&nbsp;&nbsp;<a href="#rfc.iref.m.3">A</a></li>
1497               </ul>
1498            </li>
1499            <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul>
1500                  <li><em>Part1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.1">1.1</a>, <a href="#rfc.xref.Part1.2">1.2</a>, <a href="#rfc.xref.Part1.3">6</a>, <a href="#rfc.xref.Part1.4">7</a>, <a href="#Part1"><b>8.1</b></a>, <a href="#rfc.xref.Part1.5">C</a>, <a href="#rfc.xref.Part1.6">C</a>, <a href="#rfc.xref.Part1.7">C</a>, <a href="#rfc.xref.Part1.8">D</a><ul>
1501                        <li><em>Section 1.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.8">D</a></li>
1502                        <li><em>Section 2.5</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.1">1.1</a></li>
1503                        <li><em>Section 3.2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.6">C</a></li>
1504                        <li><em>Section 3.2.6</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.7">C</a></li>
1505                        <li><em>Section 7</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.2">1.2</a></li>
1506                        <li><em>Section 10</em>&nbsp;&nbsp;<a href="#rfc.xref.Part1.4">7</a></li>
1507                     </ul>
1508                  </li>
1509                  <li><em>Part2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part2.1">2.1</a>, <a href="#rfc.xref.Part2.2">6</a>, <a href="#Part2"><b>8.1</b></a>, <a href="#rfc.xref.Part2.3">C</a><ul>
1510                        <li><em>Section 3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part2.1">2.1</a></li>
1511                        <li><em>Section</em>&nbsp;&nbsp;<a href="#rfc.xref.Part2.3">C</a></li>
1512                     </ul>
1513                  </li>
1514                  <li><em>Part4</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.1">3.1</a>, <a href="#rfc.xref.Part4.2">3.2</a>, <a href="#rfc.xref.Part4.3">3.2</a>, <a href="#rfc.xref.Part4.4">3.2</a>, <a href="#rfc.xref.Part4.5">4.3</a>, <a href="#Part4"><b>8.1</b></a>, <a href="#rfc.xref.Part4.6">C</a><ul>
1515                        <li><em>Section 2.1</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.5">4.3</a></li>
1516                        <li><em>Section 2.2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.2">3.2</a>, <a href="#rfc.xref.Part4.4">3.2</a></li>
1517                        <li><em>Section 2.3</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.6">C</a></li>
1518                        <li><em>Section 2.3.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part4.3">3.2</a></li>
1519                     </ul>
1520                  </li>
1521                  <li><em>Part6</em>&nbsp;&nbsp;<a href="#rfc.xref.Part6.1">4.1</a>, <a href="#Part6"><b>8.1</b></a><ul>
1522                        <li><em>Section 4.2.2</em>&nbsp;&nbsp;<a href="#rfc.xref.Part6.1">4.1</a></li>
1523                     </ul>
1524                  </li>
1525               </ul>
1526            </li>
1527            <li><a id="rfc.index.R" href="#rfc.index.R"><b>R</b></a><ul>
1528                  <li>Range header field&nbsp;&nbsp;<a href="#rfc.xref.header.range.1">2</a>, <a href="#rfc.iref.r.1"><b>3.1</b></a>, <a href="#rfc.xref.header.range.2">4.1</a>, <a href="#rfc.xref.header.range.3">4.4</a>, <a href="#rfc.xref.header.range.4">5.3</a>, <a href="#rfc.xref.header.range.5">B</a></li>
1529                  <li><em>RFC2046</em>&nbsp;&nbsp;<a href="#RFC2046"><b>8.1</b></a>, <a href="#rfc.xref.RFC2046.1">A</a>, <a href="#rfc.xref.RFC2046.2">A</a><ul>
1530                        <li><em>Section 5.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2046.1">A</a></li>
1531                     </ul>
1532                  </li>
1533                  <li><em>RFC2119</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC2119.1">1.1</a>, <a href="#RFC2119"><b>8.1</b></a></li>
1534                  <li><em>RFC2616</em>&nbsp;&nbsp;<a href="#RFC2616"><b>8.2</b></a></li>
1535                  <li><em>RFC5226</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">5.1.1</a>, <a href="#RFC5226"><b>8.2</b></a><ul>
1536                        <li><em>Section 4.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5226.1">5.1.1</a></li>
1537                     </ul>
1538                  </li>
1539                  <li><em>RFC5234</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.1">1.2</a>, <a href="#RFC5234"><b>8.1</b></a>, <a href="#rfc.xref.RFC5234.2">C</a><ul>
1540                        <li><em>Appendix B.1</em>&nbsp;&nbsp;<a href="#rfc.xref.RFC5234.2">C</a></li>
1541                     </ul>
1542                  </li>
1543               </ul>
1544            </li>
1545         </ul>
1546      </div>
1547   </body>
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