source: draft-ietf-httpbis/latest/p5-range.xml @ 154

Last change on this file since 154 was 153, checked in by julian.reschke@…, 12 years ago

Update "Editorial Note" stating that we now have incorporated everything that was in draft-lafon-rfc2616bis-03.

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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "January">
16  <!ENTITY ID-YEAR "2008">
17  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY weak-and-strong-validators "<xref target='Part4' x:rel='#weak.and.strong.validators' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19]>
20<?rfc toc="yes" ?>
21<?rfc symrefs="yes" ?>
22<?rfc sortrefs="yes" ?>
23<?rfc compact="yes"?>
24<?rfc subcompact="no" ?>
25<?rfc linkmailto="no" ?>
26<?rfc editing="no" ?>
27<?rfc-ext allow-markup-in-artwork="yes" ?>
28<?rfc-ext include-references-in-index="yes" ?>
29<rfc obsoletes="2616" category="std"
30     ipr="full3978" docName="draft-ietf-httpbis-p5-range-&ID-VERSION;"
31     xmlns:x='http://purl.org/net/xml2rfc/ext'>
32<front>
33
34  <title abbrev="HTTP/1.1, Part 5">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
35
36  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
37    <organization abbrev="Day Software">Day Software</organization>
38    <address>
39      <postal>
40        <street>23 Corporate Plaza DR, Suite 280</street>
41        <city>Newport Beach</city>
42        <region>CA</region>
43        <code>92660</code>
44        <country>USA</country>
45      </postal>
46      <phone>+1-949-706-5300</phone>
47      <facsimile>+1-949-706-5305</facsimile>
48      <email>fielding@gbiv.com</email>
49      <uri>http://roy.gbiv.com/</uri>
50    </address>
51  </author>
52
53  <author initials="J." surname="Gettys" fullname="Jim Gettys">
54    <organization>One Laptop per Child</organization>
55    <address>
56      <postal>
57        <street>21 Oak Knoll Road</street>
58        <city>Carlisle</city>
59        <region>MA</region>
60        <code>01741</code>
61        <country>USA</country>
62      </postal>
63      <email>jg@laptop.org</email>
64      <uri>http://www.laptop.org/</uri>
65    </address>
66  </author>
67 
68  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
69    <organization abbrev="HP">Hewlett-Packard Company</organization>
70    <address>
71      <postal>
72        <street>HP Labs, Large Scale Systems Group</street>
73        <street>1501 Page Mill Road, MS 1177</street>
74        <city>Palo Alto</city>
75        <region>CA</region>
76        <code>94304</code>
77        <country>USA</country>
78      </postal>
79      <email>JeffMogul@acm.org</email>
80    </address>
81  </author>
82
83  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
84    <organization abbrev="Microsoft">Microsoft Corporation</organization>
85    <address>
86      <postal>
87        <street>1 Microsoft Way</street>
88        <city>Redmond</city>
89        <region>WA</region>
90        <code>98052</code>
91        <country>USA</country>
92      </postal>
93      <email>henrikn@microsoft.com</email>
94    </address>
95  </author>
96
97  <author initials="L." surname="Masinter" fullname="Larry Masinter">
98    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
99    <address>
100      <postal>
101        <street>345 Park Ave</street>
102        <city>San Jose</city>
103        <region>CA</region>
104        <code>95110</code>
105        <country>USA</country>
106      </postal>
107      <email>LMM@acm.org</email>
108      <uri>http://larry.masinter.net/</uri>
109    </address>
110  </author>
111 
112  <author initials="P." surname="Leach" fullname="Paul J. Leach">
113    <organization abbrev="Microsoft">Microsoft Corporation</organization>
114    <address>
115      <postal>
116        <street>1 Microsoft Way</street>
117        <city>Redmond</city>
118        <region>WA</region>
119        <code>98052</code>
120      </postal>
121      <email>paulle@microsoft.com</email>
122    </address>
123  </author>
124   
125  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
126    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
127    <address>
128      <postal>
129        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
130        <street>The Stata Center, Building 32</street>
131        <street>32 Vassar Street</street>
132        <city>Cambridge</city>
133        <region>MA</region>
134        <code>02139</code>
135        <country>USA</country>
136      </postal>
137      <email>timbl@w3.org</email>
138      <uri>http://www.w3.org/People/Berners-Lee/</uri>
139    </address>
140  </author>
141
142  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
143    <organization abbrev="W3C">World Wide Web Consortium</organization>
144    <address>
145      <postal>
146        <street>W3C / ERCIM</street>
147        <street>2004, rte des Lucioles</street>
148        <city>Sophia-Antipolis</city>
149        <region>AM</region>
150        <code>06902</code>
151        <country>France</country>
152      </postal>
153      <email>ylafon@w3.org</email>
154      <uri>http://www.raubacapeu.net/people/yves/</uri>
155    </address>
156  </author>
157
158  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
159    <organization abbrev="greenbytes">greenbytes GmbH</organization>
160    <address>
161      <postal>
162        <street>Hafenweg 16</street>
163        <city>Muenster</city><region>NW</region><code>48155</code>
164        <country>Germany</country>
165      </postal>
166      <phone>+49 251 2807760</phone>   
167      <facsimile>+49 251 2807761</facsimile>   
168      <email>julian.reschke@greenbytes.de</email>       
169      <uri>http://greenbytes.de/tech/webdav/</uri>     
170    </address>
171  </author>
172
173  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
174
175<abstract>
176<t>
177   The Hypertext Transfer Protocol (HTTP) is an application-level
178   protocol for distributed, collaborative, hypermedia information
179   systems. HTTP has been in use by the World Wide Web global information
180   initiative since 1990. This document is Part 5 of the seven-part specification
181   that defines the protocol referred to as "HTTP/1.1" and, taken together,
182   obsoletes RFC 2616.  Part 5 defines range-specific requests and
183   the rules for constructing and combining responses to those requests.
184</t>
185</abstract>
186
187<note title="Editorial Note (To be removed by RFC Editor)">
188  <t>
189    Discussion of this draft should take place on the HTTPBIS working group
190    mailing list (ietf-http-wg@w3.org). The current issues list is
191    at <eref target="http://www.tools.ietf.org/wg/httpbis/trac/report/11"/>
192    and related documents (including fancy diffs) can be found at
193    <eref target="http://www.tools.ietf.org/wg/httpbis/"/>.
194  </t>
195  <t>
196    This draft incorporates those issue resolutions that were either
197    collected in the original RFC2616 errata list (<eref target="http://purl.org/NET/http-errata"/>),
198    or which were agreed upon on the mailing list between October 2006 and
199    November 2007 (as published in "draft-lafon-rfc2616bis-03").
200  </t>
201</note>
202</front>
203<middle>
204<section title="Introduction" anchor="introduction">
205<t>
206   This document will define aspects of HTTP related to range requests,
207   partial responses, and the multipart/byteranges media type.  Right now
208   it only includes the extracted relevant sections of
209   <xref target="RFC2616">RFC 2616</xref> without edit.
210</t>
211
212<section title="Requirements" anchor="intro.requirements">
213<t>
214   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
215   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
216   document are to be interpreted as described in <xref target="RFC2119"/>.
217</t>
218<t>
219   An implementation is not compliant if it fails to satisfy one or more
220   of the &MUST; or &REQUIRED; level requirements for the protocols it
221   implements. An implementation that satisfies all the &MUST; or &REQUIRED;
222   level and all the &SHOULD; level requirements for its protocols is said
223   to be "unconditionally compliant"; one that satisfies all the &MUST;
224   level requirements but not all the &SHOULD; level requirements for its
225   protocols is said to be "conditionally compliant."
226</t>
227</section>
228</section>
229
230<section title="Range Units" anchor="range.units">
231<t>
232   HTTP/1.1 allows a client to request that only part (a range of) the
233   response entity be included within the response. HTTP/1.1 uses range
234   units in the Range (<xref target="header.range"/>) and Content-Range (<xref target="header.content-range"/>)
235   header fields. An entity can be broken down into subranges according
236   to various structural units.
237</t>
238<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="range-unit"/><iref primary="true" item="Grammar" subitem="bytes-unit"/><iref primary="true" item="Grammar" subitem="other-range-unit"/>
239  range-unit       = bytes-unit | other-range-unit
240  bytes-unit       = "bytes"
241  other-range-unit = token
242</artwork></figure>
243<t>
244   The only range unit defined by HTTP/1.1 is "bytes". HTTP/1.1
245   implementations &MAY; ignore ranges specified using other units.
246</t>
247<t>
248   HTTP/1.1 has been designed to allow implementations of applications
249   that do not depend on knowledge of ranges.
250</t>
251</section>
252
253<section title="Status Code Definitions">
254<section title="206 Partial Content" anchor="status.206">
255  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
256  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
257<t>
258   The server has fulfilled the partial GET request for the resource.
259   The request &MUST; have included a Range header field (<xref target="header.range"/>)
260   indicating the desired range, and &MAY; have included an If-Range
261   header field (<xref target="header.if-range"/>) to make the request conditional.
262</t>
263<t>
264   The response &MUST; include the following header fields:
265  <list style="symbols">
266    <t>
267        Either a Content-Range header field (<xref target="header.content-range"/>) indicating
268        the range included with this response, or a multipart/byteranges
269        Content-Type including Content-Range fields for each part. If a
270        Content-Length header field is present in the response, its
271        value &MUST; match the actual number of OCTETs transmitted in the
272        message-body.
273    </t>
274    <t>
275        Date
276    </t>
277    <t>
278        ETag and/or Content-Location, if the header would have been sent
279        in a 200 response to the same request
280    </t>
281    <t>
282        Expires, Cache-Control, and/or Vary, if the field-value might
283        differ from that sent in any previous response for the same
284        variant
285    </t>
286  </list>
287</t>
288<t>
289   If the 206 response is the result of an If-Range request, the response
290   &SHOULD-NOT; include other entity-headers. Otherwise, the response
291   &MUST; include all of the entity-headers that would have been returned
292   with a 200 (OK) response to the same request.
293</t>
294<t>
295   A cache &MUST-NOT; combine a 206 response with other previously cached
296   content if the ETag or Last-Modified headers do not match exactly,
297   see <xref target="combining.byte.ranges"/>.
298</t>
299<t>
300   A cache that does not support the Range and Content-Range headers
301   &MUST-NOT; cache 206 (Partial Content) responses.
302</t>
303</section>
304
305<section title="416 Requested Range Not Satisfiable" anchor="status.416">
306  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
307  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
308<t>
309   A server &SHOULD; return a response with this status code if a request
310   included a Range request-header field (<xref target="header.range"/>), and none of
311   the range-specifier values in this field overlap the current extent
312   of the selected resource, and the request did not include an If-Range
313   request-header field. (For byte-ranges, this means that the first-byte-pos
314   of all of the byte-range-spec values were greater than the
315   current length of the selected resource.)
316</t>
317<t>
318   When this status code is returned for a byte-range request, the
319   response &SHOULD; include a Content-Range entity-header field
320   specifying the current length of the selected resource (see <xref target="header.content-range"/>).
321   This response &MUST-NOT; use the multipart/byteranges content-type.
322</t>
323</section>
324</section>
325
326<section title="Combining Byte Ranges" anchor="combining.byte.ranges">
327<t>
328   A response might transfer only a subrange of the bytes of an entity-body,
329   either because the request included one or more Range
330   specifications, or because a connection was broken prematurely. After
331   several such transfers, a cache might have received several ranges of
332   the same entity-body.
333</t>
334<t>
335   If a cache has a stored non-empty set of subranges for an entity, and
336   an incoming response transfers another subrange, the cache &MAY;
337   combine the new subrange with the existing set if both the following
338   conditions are met:
339  <list style="symbols">
340    <t>Both the incoming response and the cache entry have a cache
341        validator.</t>
342    <t>The two cache validators match using the strong comparison
343        function (see &weak-and-strong-validators;).</t>
344  </list>
345</t>
346<t>
347   If either requirement is not met, the cache &MUST; use only the most
348   recent partial response (based on the Date values transmitted with
349   every response, and using the incoming response if these values are
350   equal or missing), and &MUST; discard the other partial information.
351</t>
352</section>
353
354<section title="Header Field Definitions" anchor="header.fields">
355<t>
356   This section defines the syntax and semantics of HTTP/1.1 header fields
357   related to range requests and partial responses.
358</t>
359<t>
360   For entity-header fields, both sender and recipient refer to either the
361   client or the server, depending on who sends and who receives the entity.
362</t>
363
364<section title="Accept-Ranges" anchor="header.accept-ranges">
365  <iref primary="true" item="Accept-Ranges header" x:for-anchor=""/>
366  <iref primary="true" item="Headers" subitem="Accept-Ranges" x:for-anchor=""/>
367<t>
368      The Accept-Ranges response-header field allows the server to
369      indicate its acceptance of range requests for a resource:
370</t>
371<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/>
372  Accept-Ranges     = "Accept-Ranges" ":" acceptable-ranges
373  acceptable-ranges = 1#range-unit | "none"
374</artwork></figure>
375<t>
376      Origin servers that accept byte-range requests &MAY; send
377</t>
378<figure><artwork type="example">
379       Accept-Ranges: bytes
380</artwork></figure>
381<t>
382      but are not required to do so. Clients &MAY; generate byte-range
383      requests without having received this header for the resource
384      involved. Range units are defined in <xref target="range.units"/>.
385</t>
386<t>
387      Servers that do not accept any kind of range request for a
388      resource &MAY; send
389</t>
390<figure><artwork type="example">
391       Accept-Ranges: none
392</artwork></figure>
393<t>
394      to advise the client not to attempt a range request.
395</t>
396</section>
397
398<section title="Content-Range" anchor="header.content-range">
399  <iref primary="true" item="Content-Range header" x:for-anchor=""/>
400  <iref primary="true" item="Headers" subitem="Content-Range" x:for-anchor=""/>
401<t>
402   The Content-Range entity-header is sent with a partial entity-body to
403   specify where in the full entity-body the partial body should be
404   applied. Range units are defined in <xref target="range.units"/>.
405</t>
406<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Range"/><iref primary="true" item="Grammar" subitem="content-range-spec"/><iref primary="true" item="Grammar" subitem="byte-content-range-spec"/><iref primary="true" item="Grammar" subitem="byte-range-resp-spec"/><iref primary="true" item="Grammar" subitem="instance-length"/>
407  Content-Range = "Content-Range" ":" content-range-spec
408 
409  content-range-spec      = byte-content-range-spec
410  byte-content-range-spec = bytes-unit SP
411                            byte-range-resp-spec "/"
412                            ( instance-length | "*" )
413 
414  byte-range-resp-spec = (first-byte-pos "-" last-byte-pos)
415                                 | "*"
416  instance-length           = 1*DIGIT
417</artwork></figure>
418<t>
419   The header &SHOULD; indicate the total length of the full entity-body,
420   unless this length is unknown or difficult to determine. The asterisk
421   "*" character means that the instance-length is unknown at the time
422   when the response was generated.
423</t>
424<t>
425   Unlike byte-ranges-specifier values (see <xref target="byte.ranges"/>), a byte-range-resp-spec
426   &MUST; only specify one range, and &MUST; contain
427   absolute byte positions for both the first and last byte of the
428   range.
429</t>
430<t>
431   A byte-content-range-spec with a byte-range-resp-spec whose last-byte-pos
432   value is less than its first-byte-pos value, or whose
433   instance-length value is less than or equal to its last-byte-pos
434   value, is invalid. The recipient of an invalid byte-content-range-spec
435   &MUST; ignore it and any content transferred along with it.
436</t>
437<t>
438   A server sending a response with status code 416 (Requested range not
439   satisfiable) &SHOULD; include a Content-Range field with a byte-range-resp-spec
440   of "*". The instance-length specifies the current length of
441   the selected resource. A response with status code 206 (Partial
442   Content) &MUST-NOT; include a Content-Range field with a byte-range-resp-spec of "*".
443</t>
444<t>
445   Examples of byte-content-range-spec values, assuming that the entity
446   contains a total of 1234 bytes:
447   <list style="symbols">
448      <t>
449        The first 500 bytes:
450<figure><artwork type="text/plain">
451   bytes 0-499/1234
452</artwork></figure>
453      </t>   
454      <t>
455        The second 500 bytes:
456<figure><artwork type="text/plain">
457   bytes 500-999/1234
458</artwork></figure>
459      </t>   
460      <t>
461        All except for the first 500 bytes:
462<figure><artwork type="text/plain">
463   bytes 500-1233/1234
464</artwork></figure>
465      </t>   
466      <t>
467        The last 500 bytes:
468<figure><artwork type="text/plain">
469   bytes 734-1233/1234
470</artwork></figure>
471      </t>   
472   </list>
473</t>
474<t>
475   When an HTTP message includes the content of a single range (for
476   example, a response to a request for a single range, or to a request
477   for a set of ranges that overlap without any holes), this content is
478   transmitted with a Content-Range header, and a Content-Length header
479   showing the number of bytes actually transferred. For example,
480</t>
481<figure><artwork type="example">
482    HTTP/1.1 206 Partial Content
483    Date: Wed, 15 Nov 1995 06:25:24 GMT
484    Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
485    Content-Range: bytes 21010-47021/47022
486    Content-Length: 26012
487    Content-Type: image/gif
488</artwork></figure>
489<t>
490   When an HTTP message includes the content of multiple ranges (for
491   example, a response to a request for multiple non-overlapping
492   ranges), these are transmitted as a multipart message. The multipart
493   media type used for this purpose is "multipart/byteranges" as defined
494   in <xref target="internet.media.type.multipart.byteranges"/>. See <xref target="changes.from.rfc.2068"/> for a compatibility issue.
495</t>
496<t>
497   A response to a request for a single range &MUST-NOT; be sent using the
498   multipart/byteranges media type.  A response to a request for
499   multiple ranges, whose result is a single range, &MAY; be sent as a
500   multipart/byteranges media type with one part. A client that cannot
501   decode a multipart/byteranges message &MUST-NOT; ask for multiple
502   byte-ranges in a single request.
503</t>
504<t>
505   When a client requests multiple byte-ranges in one request, the
506   server &SHOULD; return them in the order that they appeared in the
507   request.
508</t>
509<t>
510   If the server ignores a byte-range-spec because it is syntactically
511   invalid, the server &SHOULD; treat the request as if the invalid Range
512   header field did not exist. (Normally, this means return a 200
513   response containing the full entity).
514</t>
515<t>
516   If the server receives a request (other than one including an If-Range
517   request-header field) with an unsatisfiable Range request-header
518   field (that is, all of whose byte-range-spec values have a
519   first-byte-pos value greater than the current length of the selected
520   resource), it &SHOULD; return a response code of 416 (Requested range
521   not satisfiable) (<xref target="status.416"/>).
522  <list><t>
523      <x:h>Note:</x:h> clients cannot depend on servers to send a 416 (Requested
524      range not satisfiable) response instead of a 200 (OK) response for
525      an unsatisfiable Range request-header, since not all servers
526      implement this request-header.
527  </t></list>
528</t>
529</section>
530
531<section title="If-Range" anchor="header.if-range">
532  <iref primary="true" item="If-Range header" x:for-anchor=""/>
533  <iref primary="true" item="Headers" subitem="If-Range" x:for-anchor=""/>
534<t>
535   If a client has a partial copy of an entity in its cache, and wishes
536   to have an up-to-date copy of the entire entity in its cache, it
537   could use the Range request-header with a conditional GET (using
538   either or both of If-Unmodified-Since and If-Match.) However, if the
539   condition fails because the entity has been modified, the client
540   would then have to make a second request to obtain the entire current
541   entity-body.
542</t>
543<t>
544   The If-Range header allows a client to "short-circuit" the second
545   request. Informally, its meaning is `if the entity is unchanged, send
546   me the part(s) that I am missing; otherwise, send me the entire new
547   entity'.
548</t>
549<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="If-Range"/>
550  If-Range = "If-Range" ":" ( entity-tag | HTTP-date )
551</artwork></figure>
552<t>
553   If the client has no entity tag for an entity, but does have a Last-Modified
554   date, it &MAY; use that date in an If-Range header. (The
555   server can distinguish between a valid HTTP-date and any form of
556   entity-tag by examining no more than two characters.) The If-Range
557   header &SHOULD; only be used together with a Range header, and &MUST; be
558   ignored if the request does not include a Range header, or if the
559   server does not support the sub-range operation.
560</t>
561<t>
562   If the entity tag given in the If-Range header matches the current
563   entity tag for the entity, then the server &SHOULD; provide the
564   specified sub-range of the entity using a 206 (Partial Content)
565   response. If the entity tag does not match, then the server &SHOULD;
566   return the entire entity using a 200 (OK) response.
567</t>
568</section>
569
570<section title="Range" anchor="header.range">
571  <iref primary="true" item="Range header" x:for-anchor=""/>
572  <iref primary="true" item="Headers" subitem="Range" x:for-anchor=""/>
573
574<section title="Byte Ranges" anchor="byte.ranges">
575<t>
576   Since all HTTP entities are represented in HTTP messages as sequences
577   of bytes, the concept of a byte range is meaningful for any HTTP
578   entity. (However, not all clients and servers need to support byte-range
579   operations.)
580</t>
581<t>
582   Byte range specifications in HTTP apply to the sequence of bytes in
583   the entity-body (not necessarily the same as the message-body).
584</t>
585<t>
586   A byte range operation &MAY; specify a single range of bytes, or a set
587   of ranges within a single entity.
588</t>
589<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="ranges-specifier"/><iref primary="true" item="Grammar" subitem="byte-ranges-specifier"/><iref primary="true" item="Grammar" subitem="byte-range-set"/><iref primary="true" item="Grammar" subitem="byte-range-spec"/><iref primary="true" item="Grammar" subitem="first-byte-pos"/><iref primary="true" item="Grammar" subitem="last-byte-pos"/>
590  ranges-specifier = byte-ranges-specifier
591  byte-ranges-specifier = bytes-unit "=" byte-range-set
592  byte-range-set  = 1#( byte-range-spec | suffix-byte-range-spec )
593  byte-range-spec = first-byte-pos "-" [last-byte-pos]
594  first-byte-pos  = 1*DIGIT
595  last-byte-pos   = 1*DIGIT
596</artwork></figure>
597<t>
598   The first-byte-pos value in a byte-range-spec gives the byte-offset
599   of the first byte in a range. The last-byte-pos value gives the
600   byte-offset of the last byte in the range; that is, the byte
601   positions specified are inclusive. Byte offsets start at zero.
602</t>
603<t>
604   If the last-byte-pos value is present, it &MUST; be greater than or
605   equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec
606   is syntactically invalid. The recipient of a byte-range-set
607   that includes one or more syntactically invalid byte-range-spec
608   values &MUST; ignore the header field that includes that byte-range-set.
609</t>
610<t>
611   If the last-byte-pos value is absent, or if the value is greater than
612   or equal to the current length of the entity-body, last-byte-pos is
613   taken to be equal to one less than the current length of the entity-body
614   in bytes.
615</t>
616<t>
617   By its choice of last-byte-pos, a client can limit the number of
618   bytes retrieved without knowing the size of the entity.
619</t>
620<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/>
621  suffix-byte-range-spec = "-" suffix-length
622  suffix-length = 1*DIGIT
623</artwork></figure>
624<t>
625   A suffix-byte-range-spec is used to specify the suffix of the
626   entity-body, of a length given by the suffix-length value. (That is,
627   this form specifies the last N bytes of an entity-body.) If the
628   entity is shorter than the specified suffix-length, the entire
629   entity-body is used.
630</t>
631<t>
632   If a syntactically valid byte-range-set includes at least one byte-range-spec
633   whose first-byte-pos is less than the current length of
634   the entity-body, or at least one suffix-byte-range-spec with a non-zero
635   suffix-length, then the byte-range-set is satisfiable.
636   Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set
637   is unsatisfiable, the server &SHOULD; return a response with a status
638   of 416 (Requested range not satisfiable). Otherwise, the server
639   &SHOULD; return a response with a status of 206 (Partial Content)
640   containing the satisfiable ranges of the entity-body.
641</t>
642<t>
643   Examples of byte-ranges-specifier values (assuming an entity-body of
644   length 10000):
645  <list style="symbols">
646     <t>The first 500 bytes (byte offsets 0-499, inclusive):  bytes=0-499</t>
647
648     <t>The second 500 bytes (byte offsets 500-999, inclusive):
649        bytes=500-999</t>
650
651     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
652        bytes=-500</t>
653
654     <t>Or bytes=9500-</t>
655
656     <t>The first and last bytes only (bytes 0 and 9999):  bytes=0-0,-1</t>
657
658     <t>Several legal but not canonical specifications of the second 500
659        bytes (byte offsets 500-999, inclusive):
660        <vspace/>
661         bytes=500-600,601-999<vspace/>
662         bytes=500-700,601-999</t>
663  </list>
664</t>
665</section>
666
667<section title="Range Retrieval Requests" anchor="range.retrieval.requests">
668<t>
669   HTTP retrieval requests using conditional or unconditional GET
670   methods &MAY; request one or more sub-ranges of the entity, instead of
671   the entire entity, using the Range request header, which applies to
672   the entity returned as the result of the request:
673</t>
674<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Range"/>
675  Range = "Range" ":" ranges-specifier
676</artwork></figure>
677<t>
678   A server &MAY; ignore the Range header. However, HTTP/1.1 origin
679   servers and intermediate caches ought to support byte ranges when
680   possible, since Range supports efficient recovery from partially
681   failed transfers, and supports efficient partial retrieval of large
682   entities.
683</t>
684<t>
685   If the server supports the Range header and the specified range or
686   ranges are appropriate for the entity:
687  <list style="symbols">
688     <t>The presence of a Range header in an unconditional GET modifies
689        what is returned if the GET is otherwise successful. In other
690        words, the response carries a status code of 206 (Partial
691        Content) instead of 200 (OK).</t>
692
693     <t>The presence of a Range header in a conditional GET (a request
694        using one or both of If-Modified-Since and If-None-Match, or
695        one or both of If-Unmodified-Since and If-Match) modifies what
696        is returned if the GET is otherwise successful and the
697        condition is true. It does not affect the 304 (Not Modified)
698        response returned if the conditional is false.</t>
699  </list>
700</t>
701<t>
702   In some cases, it might be more appropriate to use the If-Range
703   header (see <xref target="header.if-range"/>) in addition to the Range header.
704</t>
705<t>
706   If a proxy that supports ranges receives a Range request, forwards
707   the request to an inbound server, and receives an entire entity in
708   reply, it &SHOULD; only return the requested range to its client. It
709   &SHOULD; store the entire received response in its cache if that is
710   consistent with its cache allocation policies.
711</t>
712</section>
713</section>
714</section>
715
716<section title="IANA Considerations" anchor="IANA.considerations">
717<t>
718   TBD.
719</t>
720</section>
721
722<section title="Security Considerations" anchor="security.considerations">
723<t>
724   No additional security considerations have been identified beyond
725   those applicable to HTTP in general &messaging;.
726</t>
727</section>
728
729<section title="Acknowledgments" anchor="ack">
730<t>
731   Most of the specification of ranges is based on work originally done
732   by Ari Luotonen and John Franks, with additional input from Steve
733   Zilles.
734</t>
735</section>
736</middle>
737<back>
738
739<references title="Normative References">
740
741<reference anchor="Part1">
742  <front>
743    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
744    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
745      <organization abbrev="Day Software">Day Software</organization>
746      <address><email>fielding@gbiv.com</email></address>
747    </author>
748    <author initials="J." surname="Gettys" fullname="Jim Gettys">
749      <organization>One Laptop per Child</organization>
750      <address><email>jg@laptop.org</email></address>
751    </author>
752    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
753      <organization abbrev="HP">Hewlett-Packard Company</organization>
754      <address><email>JeffMogul@acm.org</email></address>
755    </author>
756    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
757      <organization abbrev="Microsoft">Microsoft Corporation</organization>
758      <address><email>henrikn@microsoft.com</email></address>
759    </author>
760    <author initials="L." surname="Masinter" fullname="Larry Masinter">
761      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
762      <address><email>LMM@acm.org</email></address>
763    </author>
764    <author initials="P." surname="Leach" fullname="Paul J. Leach">
765      <organization abbrev="Microsoft">Microsoft Corporation</organization>
766      <address><email>paulle@microsoft.com</email></address>
767    </author>
768    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
769      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
770      <address><email>timbl@w3.org</email></address>
771    </author>
772    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
773      <organization abbrev="W3C">World Wide Web Consortium</organization>
774      <address><email>ylafon@w3.org</email></address>
775    </author>
776    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
777      <organization abbrev="greenbytes">greenbytes GmbH</organization>
778      <address><email>julian.reschke@greenbytes.de</email></address>
779    </author>
780    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
781  </front>
782  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
783  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
784</reference>
785
786<reference anchor="Part3">
787  <front>
788    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
789    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
790      <organization abbrev="Day Software">Day Software</organization>
791      <address><email>fielding@gbiv.com</email></address>
792    </author>
793    <author initials="J." surname="Gettys" fullname="Jim Gettys">
794      <organization>One Laptop per Child</organization>
795      <address><email>jg@laptop.org</email></address>
796    </author>
797    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
798      <organization abbrev="HP">Hewlett-Packard Company</organization>
799      <address><email>JeffMogul@acm.org</email></address>
800    </author>
801    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
802      <organization abbrev="Microsoft">Microsoft Corporation</organization>
803      <address><email>henrikn@microsoft.com</email></address>
804    </author>
805    <author initials="L." surname="Masinter" fullname="Larry Masinter">
806      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
807      <address><email>LMM@acm.org</email></address>
808    </author>
809    <author initials="P." surname="Leach" fullname="Paul J. Leach">
810      <organization abbrev="Microsoft">Microsoft Corporation</organization>
811      <address><email>paulle@microsoft.com</email></address>
812    </author>
813    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
814      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
815      <address><email>timbl@w3.org</email></address>
816    </author>
817    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
818      <organization abbrev="W3C">World Wide Web Consortium</organization>
819      <address><email>ylafon@w3.org</email></address>
820    </author>
821    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
822      <organization abbrev="greenbytes">greenbytes GmbH</organization>
823      <address><email>julian.reschke@greenbytes.de</email></address>
824    </author>
825    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
826  </front>
827  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
828  <x:source href="p3-payload.xml" basename="p3-payload"/>
829</reference>
830
831<reference anchor="Part4">
832  <front>
833    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
834    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
835      <organization abbrev="Day Software">Day Software</organization>
836      <address><email>fielding@gbiv.com</email></address>
837    </author>
838    <author initials="J." surname="Gettys" fullname="Jim Gettys">
839      <organization>One Laptop per Child</organization>
840      <address><email>jg@laptop.org</email></address>
841    </author>
842    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
843      <organization abbrev="HP">Hewlett-Packard Company</organization>
844      <address><email>JeffMogul@acm.org</email></address>
845    </author>
846    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
847      <organization abbrev="Microsoft">Microsoft Corporation</organization>
848      <address><email>henrikn@microsoft.com</email></address>
849    </author>
850    <author initials="L." surname="Masinter" fullname="Larry Masinter">
851      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
852      <address><email>LMM@acm.org</email></address>
853    </author>
854    <author initials="P." surname="Leach" fullname="Paul J. Leach">
855      <organization abbrev="Microsoft">Microsoft Corporation</organization>
856      <address><email>paulle@microsoft.com</email></address>
857    </author>
858    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
859      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
860      <address><email>timbl@w3.org</email></address>
861    </author>
862    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
863      <organization abbrev="W3C">World Wide Web Consortium</organization>
864      <address><email>ylafon@w3.org</email></address>
865    </author>
866    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
867      <organization abbrev="greenbytes">greenbytes GmbH</organization>
868      <address><email>julian.reschke@greenbytes.de</email></address>
869    </author>
870    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
871  </front>
872  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
873  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
874</reference>
875
876<reference anchor="Part6">
877  <front>
878    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
879    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
880      <organization abbrev="Day Software">Day Software</organization>
881      <address><email>fielding@gbiv.com</email></address>
882    </author>
883    <author initials="J." surname="Gettys" fullname="Jim Gettys">
884      <organization>One Laptop per Child</organization>
885      <address><email>jg@laptop.org</email></address>
886    </author>
887    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
888      <organization abbrev="HP">Hewlett-Packard Company</organization>
889      <address><email>JeffMogul@acm.org</email></address>
890    </author>
891    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
892      <organization abbrev="Microsoft">Microsoft Corporation</organization>
893      <address><email>henrikn@microsoft.com</email></address>
894    </author>
895    <author initials="L." surname="Masinter" fullname="Larry Masinter">
896      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
897      <address><email>LMM@acm.org</email></address>
898    </author>
899    <author initials="P." surname="Leach" fullname="Paul J. Leach">
900      <organization abbrev="Microsoft">Microsoft Corporation</organization>
901      <address><email>paulle@microsoft.com</email></address>
902    </author>
903    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
904      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
905      <address><email>timbl@w3.org</email></address>
906    </author>
907    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
908      <organization abbrev="W3C">World Wide Web Consortium</organization>
909      <address><email>ylafon@w3.org</email></address>
910    </author>
911    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
912      <organization abbrev="greenbytes">greenbytes GmbH</organization>
913      <address><email>julian.reschke@greenbytes.de</email></address>
914    </author>
915    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
916  </front>
917  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
918  <x:source href="p6-cache.xml" basename="p6-cache"/>
919</reference>
920
921<reference anchor="RFC2046">
922  <front>
923    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
924    <author initials="N." surname="Freed" fullname="Ned Freed">
925      <organization>Innosoft International, Inc.</organization>
926      <address><email>ned@innosoft.com</email></address>
927    </author>
928    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
929      <organization>First Virtual Holdings</organization>
930      <address><email>nsb@nsb.fv.com</email></address>
931    </author>
932    <date month="November" year="1996"/>
933  </front>
934  <seriesInfo name="RFC" value="2046"/>
935</reference>
936
937<reference anchor="RFC2119">
938  <front>
939    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
940    <author initials="S." surname="Bradner" fullname="Scott Bradner">
941      <organization>Harvard University</organization>
942      <address><email>sob@harvard.edu</email></address>
943    </author>
944    <date month="March" year="1997"/>
945  </front>
946  <seriesInfo name="BCP" value="14"/>
947  <seriesInfo name="RFC" value="2119"/>
948</reference>
949
950</references>
951
952<references title="Informative References">
953
954<reference anchor="RFC2616">
955  <front>
956    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
957    <author initials="R." surname="Fielding" fullname="R. Fielding">
958      <organization>University of California, Irvine</organization>
959      <address><email>fielding@ics.uci.edu</email></address>
960    </author>
961    <author initials="J." surname="Gettys" fullname="J. Gettys">
962      <organization>W3C</organization>
963      <address><email>jg@w3.org</email></address>
964    </author>
965    <author initials="J." surname="Mogul" fullname="J. Mogul">
966      <organization>Compaq Computer Corporation</organization>
967      <address><email>mogul@wrl.dec.com</email></address>
968    </author>
969    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
970      <organization>MIT Laboratory for Computer Science</organization>
971      <address><email>frystyk@w3.org</email></address>
972    </author>
973    <author initials="L." surname="Masinter" fullname="L. Masinter">
974      <organization>Xerox Corporation</organization>
975      <address><email>masinter@parc.xerox.com</email></address>
976    </author>
977    <author initials="P." surname="Leach" fullname="P. Leach">
978      <organization>Microsoft Corporation</organization>
979      <address><email>paulle@microsoft.com</email></address>
980    </author>
981    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
982      <organization>W3C</organization>
983      <address><email>timbl@w3.org</email></address>
984    </author>
985    <date month="June" year="1999"/>
986  </front>
987  <seriesInfo name="RFC" value="2616"/>
988</reference>
989
990</references>
991
992<section title="Internet Media Type multipart/byteranges" anchor="internet.media.type.multipart.byteranges">
993<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
994<iref item="multipart/byteranges Media Type" primary="true"/>
995<t>
996   When an HTTP 206 (Partial Content) response message includes the
997   content of multiple ranges (a response to a request for multiple
998   non-overlapping ranges), these are transmitted as a multipart
999   message-body. The media type for this purpose is called
1000   "multipart/byteranges".
1001</t><t>
1002   The multipart/byteranges media type includes two or more parts, each
1003   with its own Content-Type and Content-Range fields. The required
1004   boundary parameter specifies the boundary string used to separate
1005   each body-part.
1006</t>
1007<t>
1008  <list style="hanging" x:indent="12em">
1009    <t hangText="Media Type name:">
1010      multipart
1011    </t>
1012    <t hangText="Media subtype name:">
1013      byteranges
1014    </t>
1015    <t hangText="Required parameters:">
1016      boundary
1017    </t>
1018    <t hangText="Optional parameters:">
1019      none
1020    </t>
1021    <t hangText="Encoding considerations:">
1022      only "7bit", "8bit", or "binary" are permitted
1023    </t>
1024    <t hangText="Security considerations:">
1025      none
1026    </t>
1027  </list>
1028</t>
1029<figure><preamble>
1030   For example:
1031</preamble><artwork type="example">
1032   HTTP/1.1 206 Partial Content
1033   Date: Wed, 15 Nov 1995 06:25:24 GMT
1034   Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
1035   Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1036
1037   --THIS_STRING_SEPARATES
1038   Content-type: application/pdf
1039   Content-range: bytes 500-999/8000
1040
1041   ...the first range...
1042   --THIS_STRING_SEPARATES
1043   Content-type: application/pdf
1044   Content-range: bytes 7000-7999/8000
1045
1046   ...the second range
1047   --THIS_STRING_SEPARATES--
1048</artwork></figure>
1049<t>
1050      Notes:
1051  <list style="numbers">
1052      <t>Additional CRLFs may precede the first boundary string in the
1053         entity.</t>
1054
1055      <t>Although <xref target="RFC2046"/> permits the boundary string to be
1056         quoted, some existing implementations handle a quoted boundary
1057         string incorrectly.</t>
1058
1059      <t>A number of browsers and servers were coded to an early draft
1060         of the byteranges specification to use a media type of
1061         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>, which is almost, but not quite
1062         compatible with the version documented in HTTP/1.1.</t>
1063  </list>
1064</t>
1065</section>
1066
1067<section title="Compatibility with Previous Versions" anchor="compatibility">
1068<section title="Changes from RFC 2068" anchor="changes.from.rfc.2068">
1069<t>
1070   Transfer-coding and message lengths all interact in ways that
1071   required fixing exactly when chunked encoding is used (to allow for
1072   transfer encoding that may not be self delimiting); it was important
1073   to straighten out exactly how message lengths are computed.
1074   (<xref target="header.content-range"/>,
1075   see also <xref target="Part1"/>, <xref target="Part3"/> and <xref target="Part6"/>)
1076</t>
1077<t>
1078   There are situations where a server (especially a proxy) does not
1079   know the full length of a response but is capable of serving a
1080   byterange request. We therefore need a mechanism to allow byteranges
1081   with a content-range not indicating the full length of the message.
1082   (<xref target="header.content-range"/>)
1083</t>
1084<t>
1085   Range request responses would become very verbose if all meta-data
1086   were always returned; by allowing the server to only send needed
1087   headers in a 206 response, this problem can be avoided.
1088   (Section <xref target="status.206" format="counter"/>
1089   and <xref target="header.if-range" format="counter"/>)
1090</t>
1091<t>
1092   Fix problem with unsatisfiable range requests; there are two cases:
1093   syntactic problems, and range doesn't exist in the document. The 416
1094   status code was needed to resolve this ambiguity needed to indicate
1095   an error for a byte range request that falls outside of the actual
1096   contents of a document. (Section <xref target="status.416" format="counter"/>, <xref target="header.content-range" format="counter"/>)
1097</t>
1098</section>
1099
1100<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
1101<t>
1102  Clarify that it is not ok to use a weak cache validator in a 206 response.
1103  (<xref target="status.206"/>)
1104</t>
1105</section>
1106
1107</section>
1108
1109<section title="Change Log (to be removed by RFC Editor before publication)">
1110
1111<section title="Since RFC2616">
1112<t>
1113  Extracted relevant partitions from <xref target="RFC2616"/>.
1114</t>
1115</section>
1116
1117<section title="Since draft-ietf-httpbis-p5-range-00">
1118<t>
1119  Closed issues:
1120  <list style="symbols"> 
1121    <t>
1122      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/18"/>:
1123      "Cache validators in 206 responses"
1124      (<eref target="http://purl.org/NET/http-errata#ifrange206"/>)
1125    </t>
1126    <t>
1127      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
1128      "Normative and Informative references"
1129    </t>
1130    <t>
1131      <eref target="http://www3.tools.ietf.org/wg/httpbis/trac/ticket/86"/>:
1132      "Normative up-to-date references"
1133    </t>
1134  </list>
1135</t>
1136</section>
1137
1138</section>
1139
1140</back>
1141</rfc>
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