source: draft-ietf-httpbis/latest/p5-range.xml @ 1396

Last change on this file since 1396 was 1396, checked in by julian.reschke@…, 8 years ago

fix ABNF links (see [1393])

  • Property svn:eol-style set to native
File size: 65.3 KB
Line 
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 "August">
16  <!ENTITY ID-YEAR "2011">
17  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY acks                       "<xref target='Part1' x:rel='#acks' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY field-rules                "<xref target='Part1' x:rel='#field.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY entity-tags                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY weak-and-strong-validators "<xref target='Part4' x:rel='#weak.and.strong.validators' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY lastmod-comparison         "<xref target='Part4' x:rel='#lastmod.comparison' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27]>
28<?rfc toc="yes" ?>
29<?rfc symrefs="yes" ?>
30<?rfc sortrefs="yes" ?>
31<?rfc compact="yes"?>
32<?rfc subcompact="no" ?>
33<?rfc linkmailto="no" ?>
34<?rfc editing="no" ?>
35<?rfc comments="yes"?>
36<?rfc inline="yes"?>
37<?rfc rfcedstyle="yes"?>
38<?rfc-ext allow-markup-in-artwork="yes" ?>
39<?rfc-ext include-references-in-index="yes" ?>
40<rfc obsoletes="2616" category="std" x:maturity-level="draft"
41     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p5-range-&ID-VERSION;"     xmlns:x='http://purl.org/net/xml2rfc/ext'>
42<front>
43
44  <title abbrev="HTTP/1.1, Part 5">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
45
46  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
47    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
48    <address>
49      <postal>
50        <street>345 Park Ave</street>
51        <city>San Jose</city>
52        <region>CA</region>
53        <code>95110</code>
54        <country>USA</country>
55      </postal>
56      <email>fielding@gbiv.com</email>
57      <uri>http://roy.gbiv.com/</uri>
58    </address>
59  </author>
60
61  <author initials="J." surname="Gettys" fullname="Jim Gettys">
62    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
63    <address>
64      <postal>
65        <street>21 Oak Knoll Road</street>
66        <city>Carlisle</city>
67        <region>MA</region>
68        <code>01741</code>
69        <country>USA</country>
70      </postal>
71      <email>jg@freedesktop.org</email>
72      <uri>http://gettys.wordpress.com/</uri>
73    </address>
74  </author>
75 
76  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
77    <organization abbrev="HP">Hewlett-Packard Company</organization>
78    <address>
79      <postal>
80        <street>HP Labs, Large Scale Systems Group</street>
81        <street>1501 Page Mill Road, MS 1177</street>
82        <city>Palo Alto</city>
83        <region>CA</region>
84        <code>94304</code>
85        <country>USA</country>
86      </postal>
87      <email>JeffMogul@acm.org</email>
88    </address>
89  </author>
90
91  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
92    <organization abbrev="Microsoft">Microsoft Corporation</organization>
93    <address>
94      <postal>
95        <street>1 Microsoft Way</street>
96        <city>Redmond</city>
97        <region>WA</region>
98        <code>98052</code>
99        <country>USA</country>
100      </postal>
101      <email>henrikn@microsoft.com</email>
102    </address>
103  </author>
104
105  <author initials="L." surname="Masinter" fullname="Larry Masinter">
106    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
107    <address>
108      <postal>
109        <street>345 Park Ave</street>
110        <city>San Jose</city>
111        <region>CA</region>
112        <code>95110</code>
113        <country>USA</country>
114      </postal>
115      <email>LMM@acm.org</email>
116      <uri>http://larry.masinter.net/</uri>
117    </address>
118  </author>
119 
120  <author initials="P." surname="Leach" fullname="Paul J. Leach">
121    <organization abbrev="Microsoft">Microsoft Corporation</organization>
122    <address>
123      <postal>
124        <street>1 Microsoft Way</street>
125        <city>Redmond</city>
126        <region>WA</region>
127        <code>98052</code>
128      </postal>
129      <email>paulle@microsoft.com</email>
130    </address>
131  </author>
132   
133  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
134    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
135    <address>
136      <postal>
137        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
138        <street>The Stata Center, Building 32</street>
139        <street>32 Vassar Street</street>
140        <city>Cambridge</city>
141        <region>MA</region>
142        <code>02139</code>
143        <country>USA</country>
144      </postal>
145      <email>timbl@w3.org</email>
146      <uri>http://www.w3.org/People/Berners-Lee/</uri>
147    </address>
148  </author>
149
150  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
151    <organization abbrev="W3C">World Wide Web Consortium</organization>
152    <address>
153      <postal>
154        <street>W3C / ERCIM</street>
155        <street>2004, rte des Lucioles</street>
156        <city>Sophia-Antipolis</city>
157        <region>AM</region>
158        <code>06902</code>
159        <country>France</country>
160      </postal>
161      <email>ylafon@w3.org</email>
162      <uri>http://www.raubacapeu.net/people/yves/</uri>
163    </address>
164  </author>
165
166  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
167    <organization abbrev="greenbytes">greenbytes GmbH</organization>
168    <address>
169      <postal>
170        <street>Hafenweg 16</street>
171        <city>Muenster</city><region>NW</region><code>48155</code>
172        <country>Germany</country>
173      </postal>
174      <phone>+49 251 2807760</phone>
175      <facsimile>+49 251 2807761</facsimile>
176      <email>julian.reschke@greenbytes.de</email>
177      <uri>http://greenbytes.de/tech/webdav/</uri>
178    </address>
179  </author>
180
181  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
182  <workgroup>HTTPbis Working Group</workgroup>
183
184<abstract>
185<t>
186   The Hypertext Transfer Protocol (HTTP) is an application-level protocol for
187   distributed, collaborative, hypertext information systems. HTTP has been in
188   use by the World Wide Web global information initiative since 1990. This
189   document is Part 5 of the seven-part specification that defines the protocol
190   referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616.
191</t>
192<t>
193   Part 5 defines range-specific requests and the rules for constructing and
194   combining responses to those requests.
195</t>
196</abstract>
197
198<note title="Editorial Note (To be removed by RFC Editor)">
199  <t>
200    Discussion of this draft should take place on the HTTPBIS working group
201    mailing list (ietf-http-wg@w3.org), which is archived at
202    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
203  </t>
204  <t>
205    The current issues list is at
206    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
207    documents (including fancy diffs) can be found at
208    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
209  </t>
210  <t>
211    The changes in this draft are summarized in <xref target="changes.since.15"/>.
212  </t>
213</note>
214</front>
215<middle>
216<section title="Introduction" anchor="introduction">
217<t>
218   HTTP clients often encounter interrupted data transfers as a result
219   of cancelled requests or dropped connections.  When a client has stored
220   a partial representation, it is desirable to request the remainder
221   of that representation in a subsequent request rather than transfer
222   the entire representation.
223   There are also a number of Web applications that benefit from being
224   able to request only a subset of a larger representation, such as a
225   single page of a very large document or only part of an image to be
226   rendered by a device with limited local storage.
227</t>
228<t>
229   This document defines HTTP/1.1 range requests,
230   partial responses, and the multipart/byteranges media type.
231   The protocol for range requests is an &OPTIONAL; feature of HTTP,
232   designed so resources or recipients that do not implement this feature
233   can respond as if it is a normal GET request without impacting
234   interoperability.  Partial responses are indicated by a distinct status
235   code to not be mistaken for full responses by intermediate caches
236   that might not implement the feature.
237</t>
238<t>
239   Although the HTTP range request mechanism is designed to allow for
240   extensible range types, this specification only defines requests for
241   byte ranges.
242</t>
243
244<section title="Requirements" anchor="intro.requirements">
245<t>
246   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
247   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
248   document are to be interpreted as described in <xref target="RFC2119"/>.
249</t>
250<t>
251   An implementation is not compliant if it fails to satisfy one or more
252   of the "MUST" or "REQUIRED" level requirements for the protocols it
253   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
254   level and all the "SHOULD" level requirements for its protocols is said
255   to be "unconditionally compliant"; one that satisfies all the "MUST"
256   level requirements but not all the "SHOULD" level requirements for its
257   protocols is said to be "conditionally compliant".
258</t>
259</section>
260
261<section title="Syntax Notation" anchor="notation">
262  <x:anchor-alias value="ALPHA"/>
263  <x:anchor-alias value="CHAR"/>
264  <x:anchor-alias value="CR"/>
265  <x:anchor-alias value="DIGIT"/>
266  <x:anchor-alias value="LF"/>
267  <x:anchor-alias value="OCTET"/>
268  <x:anchor-alias value="SP"/>
269  <x:anchor-alias value="VCHAR"/>
270  <x:anchor-alias value="WSP"/>
271<t>
272  This specification uses the ABNF syntax defined in &notation; (which
273  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
274  <xref target="collected.abnf"/> shows the collected ABNF, with the list
275  rule expanded.
276</t>
277<t>
278  The following core rules are included by
279  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
280  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
281  DIGIT (decimal 0-9), DQUOTE (double quote),
282  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
283  OCTET (any 8-bit sequence of data), SP (space),
284  VCHAR (any visible USASCII character),
285  and WSP (whitespace).
286</t>
287
288<section title="Core Rules" anchor="core.rules">
289  <x:anchor-alias value="token"/>
290  <x:anchor-alias value="OWS"/>
291<t>
292  The core rules below are defined in <xref target="Part1"/>:
293</t>
294<figure><artwork type="abnf2616">
295  <x:ref>OWS</x:ref>        = &lt;OWS, defined in &basic-rules;&gt;
296  <x:ref>token</x:ref>      = &lt;token, defined in &field-rules;&gt;
297</artwork></figure>
298</section>
299
300<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
301  <x:anchor-alias value="entity-tag"/>
302  <x:anchor-alias value="HTTP-date"/>
303<t>
304  The ABNF rules below are defined in other parts:
305</t>
306<figure><!--Part1--><artwork type="abnf2616">
307  <x:ref>HTTP-date</x:ref>  = &lt;HTTP-date, defined in &full-date;&gt;
308</artwork></figure>
309<figure><!--Part4--><artwork type="abnf2616">
310  <x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in &entity-tags;&gt;
311</artwork></figure>
312</section>
313
314</section>
315
316</section>
317
318
319<section title="Range Units" anchor="range.units">
320  <x:anchor-alias value="bytes-unit"/>
321  <x:anchor-alias value="other-range-unit"/>
322  <x:anchor-alias value="range-unit"/>
323<t>
324   HTTP/1.1 allows a client to request that only part (a range) of the
325   representation be included within the response. HTTP/1.1 uses range
326   units in the Range (<xref target="header.range"/>) and Content-Range (<xref target="header.content-range"/>)
327   header fields. A representation can be broken down into subranges according
328   to various structural units.
329</t>
330<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"/>
331  <x:ref>range-unit</x:ref>       = <x:ref>bytes-unit</x:ref> / <x:ref>other-range-unit</x:ref>
332  <x:ref>bytes-unit</x:ref>       = "bytes"
333  <x:ref>other-range-unit</x:ref> = <x:ref>token</x:ref>
334</artwork></figure>
335<t>
336  HTTP/1.1 has been designed to allow implementations of applications
337  that do not depend on knowledge of ranges. The only range unit defined
338  by HTTP/1.1 is "bytes". Additional specifiers can be defined as described
339  in <xref target="range.specifier.registry"/>.
340</t>
341<t>
342  If a range unit is not understood in a request, a server &MUST; ignore
343  the whole Range header field (<xref target="header.range"/>).
344  If a range unit is not understood in a response, an intermediary
345  &SHOULD; pass the response to the client; a client &MUST; fail.
346</t>
347
348<section title="Range Specifier Registry" anchor="range.specifier.registry">
349<t>
350   The HTTP Range Specifier Registry defines the name space for the range
351   specifier names.
352</t>
353<t>
354   Registrations &MUST; include the following fields:
355   <list style="symbols">
356     <t>Name</t>
357     <t>Description</t>
358     <t>Pointer to specification text</t>
359   </list>
360</t>
361<t>
362  Values to be added to this name space are subject to IETF review
363  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
364</t>
365<t>
366   The registry itself is maintained at
367   <eref target="http://www.iana.org/assignments/http-range-specifiers"/>.
368</t>
369</section>
370
371</section>
372
373<section title="Status Code Definitions" anchor="status.code.definitions">
374<section title="206 Partial Content" anchor="status.206">
375  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
376  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
377<t>
378   The server has fulfilled the partial GET request for the resource.
379   The request &MUST; have included a Range header field (<xref target="header.range"/>)
380   indicating the desired range, and &MAY; have included an If-Range
381   header field (<xref target="header.if-range"/>) to make the request conditional.
382</t>
383<t>
384   The response &MUST; include the following header fields:
385  <list style="symbols">
386    <t>
387        Either a Content-Range header field (<xref target="header.content-range"/>) indicating
388        the range included with this response, or a multipart/byteranges
389        Content-Type including Content-Range fields for each part. If a
390        Content-Length header field is present in the response, its
391        value &MUST; match the actual number of octets transmitted in the
392        message-body.
393    </t>
394    <t>
395        Date
396    </t>
397    <t>
398        Cache-Control, ETag, Expires, Content-Location, Last-Modified,
399        and/or Vary, if the header field would have been sent in a 200
400        response to the same request
401    </t>
402  </list>
403</t>
404<t>
405   If the 206 response is the result of an If-Range request, the response
406   &SHOULD-NOT; include other representation header fields. Otherwise, the response
407   &MUST; include all of the representation header fields that would have been returned
408   with a 200 (OK) response to the same request.
409</t>
410</section>
411
412<section title="416 Requested Range Not Satisfiable" anchor="status.416">
413  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
414  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
415<t>
416   A server &SHOULD; return a response with this status code if a request
417   included a Range header field (<xref target="header.range"/>), and none of
418   the ranges-specifier values in this field overlap the current extent
419   of the selected resource, and the request did not include an If-Range
420   header field (<xref target="header.if-range"/>). (For byte-ranges,
421   this means that the first-byte-pos of all of the byte-range-spec values were
422   greater than the current length of the selected resource.)
423</t>
424<t>
425   When this status code is returned for a byte-range request, the
426   response &SHOULD; include a Content-Range header field
427   specifying the current length of the representation (see <xref target="header.content-range"/>).
428   This response &MUST-NOT; use the multipart/byteranges content-type.
429</t>
430</section>
431</section>
432
433<section title="Combining Ranges" anchor="combining.byte.ranges">
434<t>
435   A response might transfer only a subrange of a representation if the
436   connection closed prematurely or if the request used one or more Range
437   specifications.  After several such transfers, a client might have
438   received several ranges of the same representation.  These ranges can only
439   be safely combined if they all have in common the same strong validator,
440   where "strong validator" is defined to be either an entity-tag that is
441   not marked as weak (&entity-tags;) or, if no entity-tag is provided, a
442   Last-Modified value that is strong in the sense defined by
443   &lastmod-comparison;.
444</t>
445<t>
446   When a client receives an incomplete 200 (OK) or 206 (Partial Content)
447   response and already has one or more stored responses for the same method
448   and effective request URI, all of the stored responses with the same
449   strong validator &MAY; be combined with the partial content in this new
450   response.  If none of the stored responses contain the same strong
451   validator, then this new response corresponds to a new representation
452   and &MUST-NOT; be combined with the existing stored responses.
453</t>
454<t>
455   If the new response is an incomplete 200 (OK) response, then the header
456   fields of that new response are used for any combined response and replace
457   those of the matching stored responses.
458</t>
459<t>
460   If the new response is a 206 (Partial Content) response and at least one
461   of the matching stored responses is a 200 (OK), then the combined response
462   header fields consist of the most recent 200 response's header fields.
463   If all of the matching stored responses are 206 responses, then the
464   stored response with the most header fields is used as the source of
465   header fields for the combined response, except that the client &MUST;
466   use other header fields provided in the new response, aside from
467   Content-Range, to replace all instances of the corresponding header
468   fields in the stored response.
469</t>
470<t>
471   The combined response message-body consists of the union of partial
472   content ranges in the new response and each of the selected responses.
473   If the union consists of the entire range of the representation, then the
474   combined response &MUST; be recorded as a complete 200 (OK) response
475   with a Content-Length header field that reflects the complete length.
476   Otherwise, the combined response(s) &MUST; include a Content-Range
477   header field describing the included range(s) and be recorded as
478   incomplete.  If the union consists of a discontinuous range of the
479   representation, then the client &MAY; store it as either a multipart range
480   response or as multiple 206 responses with one continuous range each.
481</t>
482</section>
483
484<section title="Header Field Definitions" anchor="header.fields">
485<t>
486   This section defines the syntax and semantics of HTTP/1.1 header fields
487   related to range requests and partial responses.
488</t>
489
490<section title="Accept-Ranges" anchor="header.accept-ranges">
491  <iref primary="true" item="Accept-Ranges header field" x:for-anchor=""/>
492  <iref primary="true" item="Header Fields" subitem="Accept-Ranges" x:for-anchor=""/>
493  <x:anchor-alias value="Accept-Ranges"/>
494  <x:anchor-alias value="acceptable-ranges"/>
495<t>
496   The "Accept-Ranges" header field allows a resource to indicate
497   its acceptance of range requests.
498</t>
499<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/>
500  <x:ref>Accept-Ranges</x:ref>     = <x:ref>acceptable-ranges</x:ref>
501  <x:ref>acceptable-ranges</x:ref> = 1#<x:ref>range-unit</x:ref> / "none"
502</artwork></figure>
503<t>
504      Origin servers that accept byte-range requests &MAY; send
505</t>
506<figure><artwork type="example">
507  Accept-Ranges: bytes
508</artwork></figure>
509<t>
510      but are not required to do so. Clients &MAY; generate range
511      requests without having received this header field for the resource
512      involved. Range units are defined in <xref target="range.units"/>.
513</t>
514<t>
515      Servers that do not accept any kind of range request for a
516      resource &MAY; send
517</t>
518<figure><artwork type="example">
519  Accept-Ranges: none
520</artwork></figure>
521<t>
522      to advise the client not to attempt a range request.
523</t>
524</section>
525
526<section title="Content-Range" anchor="header.content-range">
527  <iref primary="true" item="Content-Range header field" x:for-anchor=""/>
528  <iref primary="true" item="Header Fields" subitem="Content-Range" x:for-anchor=""/>
529  <x:anchor-alias value="byte-content-range-spec"/>
530  <x:anchor-alias value="byte-range-resp-spec"/>
531  <x:anchor-alias value="Content-Range"/>
532  <x:anchor-alias value="content-range-spec"/>
533  <x:anchor-alias value="instance-length"/>
534  <x:anchor-alias value="other-content-range-spec"/>
535  <x:anchor-alias value="other-range-resp-spec"/>
536<t>
537   The "Content-Range" header field is sent with a partial representation to
538   specify where in the full representation the payload body is intended to be
539   applied.
540</t>
541<t>   
542   Range units are defined in <xref target="range.units"/>.
543</t>
544<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"/>
545  <x:ref>Content-Range</x:ref> = <x:ref>content-range-spec</x:ref>
546 
547  <x:ref>content-range-spec</x:ref>      = <x:ref>byte-content-range-spec</x:ref>
548                          / <x:ref>other-content-range-spec</x:ref>
549  <x:ref>byte-content-range-spec</x:ref> = <x:ref>bytes-unit</x:ref> <x:ref>SP</x:ref>
550                            <x:ref>byte-range-resp-spec</x:ref> "/"
551                            ( <x:ref>instance-length</x:ref> / "*" )
552 
553  <x:ref>byte-range-resp-spec</x:ref>    = (<x:ref>first-byte-pos</x:ref> "-" <x:ref>last-byte-pos</x:ref>)
554                          / "*"
555                         
556  <x:ref>instance-length</x:ref>         = 1*<x:ref>DIGIT</x:ref>
557 
558  <x:ref>other-content-range-spec</x:ref> = <x:ref>other-range-unit</x:ref> <x:ref>SP</x:ref>
559                             <x:ref>other-range-resp-spec</x:ref>
560  <x:ref>other-range-resp-spec</x:ref>    = *<x:ref>CHAR</x:ref>
561</artwork></figure>
562<t>
563   The header field &SHOULD; indicate the total length of the full representation,
564   unless this length is unknown or difficult to determine. The asterisk
565   "*" character means that the instance-length is unknown at the time
566   when the response was generated.
567</t>
568<t>
569   Unlike byte-ranges-specifier values (see <xref target="byte.ranges"/>), a byte-range-resp-spec
570   &MUST; only specify one range, and &MUST; contain
571   absolute byte positions for both the first and last byte of the
572   range.
573</t>
574<t>
575   A byte-content-range-spec with a byte-range-resp-spec whose last-byte-pos
576   value is less than its first-byte-pos value, or whose
577   instance-length value is less than or equal to its last-byte-pos
578   value, is invalid. The recipient of an invalid byte-content-range-spec
579   &MUST; ignore it and any content transferred along with it.
580</t>
581<t>
582   In the case of a byte range request:
583   A server sending a response with status code 416 (Requested range not
584   satisfiable) &SHOULD; include a Content-Range field with a byte-range-resp-spec
585   of "*". The instance-length specifies the current length of
586   the selected resource. A response with status code 206 (Partial
587   Content) &MUST-NOT; include a Content-Range field with a byte-range-resp-spec of "*".
588</t>
589<t>
590   Examples of byte-content-range-spec values, assuming that the representation
591   contains a total of 1234 bytes:
592   <list style="symbols">
593      <t>
594        The first 500 bytes:
595<figure><artwork type="example" x:indent-with="   ">
596  bytes 0-499/1234
597</artwork></figure>
598      </t>   
599      <t>
600        The second 500 bytes:
601<figure><artwork type="example" x:indent-with="   ">
602  bytes 500-999/1234
603</artwork></figure>
604      </t>   
605      <t>
606        All except for the first 500 bytes:
607<figure><artwork type="example" x:indent-with="   ">
608  bytes 500-1233/1234
609</artwork></figure>
610      </t>   
611      <t>
612        The last 500 bytes:
613<figure><artwork type="example" x:indent-with="   ">
614  bytes 734-1233/1234
615</artwork></figure>
616      </t>   
617   </list>
618</t>
619<t>
620   When an HTTP message includes the content of a single range (for
621   example, a response to a request for a single range, or to a request
622   for a set of ranges that overlap without any holes), this content is
623   transmitted with a Content-Range header field, and a Content-Length header
624   field showing the number of bytes actually transferred. For example,
625</t>
626<figure><artwork type="example">
627  HTTP/1.1 206 Partial Content
628  Date: Wed, 15 Nov 1995 06:25:24 GMT
629  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
630  Content-Range: bytes 21010-47021/47022
631  Content-Length: 26012
632  Content-Type: image/gif
633</artwork></figure>
634<t>
635   When an HTTP message includes the content of multiple ranges (for
636   example, a response to a request for multiple non-overlapping
637   ranges), these are transmitted as a multipart message. The multipart
638   media type used for this purpose is "multipart/byteranges" as defined
639   in <xref target="internet.media.type.multipart.byteranges"/>.
640</t>
641<t>
642   A response to a request for a single range &MUST-NOT; be sent using the
643   multipart/byteranges media type.  A response to a request for
644   multiple ranges, whose result is a single range, &MAY; be sent as a
645   multipart/byteranges media type with one part. A client that cannot
646   decode a multipart/byteranges message &MUST-NOT; ask for multiple
647   ranges in a single request.
648</t>
649<t>
650   When a client requests multiple ranges in one request, the
651   server &SHOULD; return them in the order that they appeared in the
652   request.
653</t>
654<t>
655   If the server ignores a byte-range-spec because it is syntactically
656   invalid, the server &SHOULD; treat the request as if the invalid Range
657   header field did not exist. (Normally, this means return a 200
658   response containing the full representation).
659</t>
660<t>
661   If the server receives a request (other than one including an If-Range
662   header field) with an unsatisfiable Range header
663   field (that is, all of whose byte-range-spec values have a
664   first-byte-pos value greater than the current length of the selected
665   resource), it &SHOULD; return a response code of 416 (Requested range
666   not satisfiable) (<xref target="status.416"/>).
667</t>
668<x:note>
669  <t>
670    <x:h>Note:</x:h> Clients cannot depend on servers to send a 416 (Requested
671    range not satisfiable) response instead of a 200 (OK) response for
672    an unsatisfiable Range header field, since not all servers
673    implement this header field.
674  </t>
675</x:note>
676</section>
677
678<section title="If-Range" anchor="header.if-range">
679  <iref primary="true" item="If-Range header field" x:for-anchor=""/>
680  <iref primary="true" item="Header Fields" subitem="If-Range" x:for-anchor=""/>
681  <x:anchor-alias value="If-Range"/>
682<t>
683   If a client has a partial copy of a representation and wishes
684   to have an up-to-date copy of the entire representation, it
685   could use the Range header field with a conditional GET (using
686   either or both of If-Unmodified-Since and If-Match.) However, if the
687   condition fails because the representation has been modified, the client
688   would then have to make a second request to obtain the entire current
689   representation.
690</t>
691<t>
692   The "If-Range" header field allows a client to "short-circuit" the second
693   request. Informally, its meaning is "if the representation is unchanged, send
694   me the part(s) that I am missing; otherwise, send me the entire new
695   representation".
696</t>
697<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="If-Range"/>
698  <x:ref>If-Range</x:ref> = <x:ref>entity-tag</x:ref> / <x:ref>HTTP-date</x:ref>
699</artwork></figure>
700<t>
701   Clients &MUST-NOT; use an entity-tag marked as weak in an If-Range
702   field value and &MUST-NOT; use a Last-Modified date in an If-Range
703   field value unless it has no entity-tag for the representation and
704   the Last-Modified date it does have for the representation is strong
705   in the sense defined by &lastmod-comparison;.
706</t>
707<t>
708   A server that evaluates a conditional range request that is applicable
709   to one of its representations &MUST; evaluate the condition as false if
710   the entity-tag used as a validator is marked as weak or, when an HTTP-date
711   is used as the validator, if the date value is not strong in the sense
712   defined by &lastmod-comparison;. (A server can distinguish between a
713   valid HTTP-date and any form of entity-tag by examining the first
714   two characters.)
715</t>
716<t>
717   The If-Range header field &SHOULD; only be sent by clients together with
718   a Range header field.  The If-Range header field &MUST; be ignored if it
719   is received in a request that does not include a Range header field.
720   The If-Range header field &MUST; be ignored by a server that does not
721   support the sub-range operation.
722</t>
723<t>
724   If the validator given in the If-Range header field matches the current
725   validator for the selected representation of the target resource, then
726   the server &SHOULD; send the specified sub-range of the representation
727   using a 206 (Partial Content) response. If the validator does not match,
728   then the server &SHOULD; send the entire representation using a 200 (OK)
729   response.
730</t>
731</section>
732
733<section title="Range" anchor="header.range">
734  <iref primary="true" item="Range header field" x:for-anchor=""/>
735  <iref primary="true" item="Header Fields" subitem="Range" x:for-anchor=""/>
736
737<section title="Byte Ranges" anchor="byte.ranges">
738<t>
739   Since all HTTP representations are transferred as sequences
740   of bytes, the concept of a byte range is meaningful for any HTTP
741   representation. (However, not all clients and servers need to support byte-range
742   operations.)
743</t>
744<t>
745   Byte range specifications in HTTP apply to the sequence of bytes in
746   the representation body (not necessarily the same as the message-body).
747</t>
748<t anchor="rule.ranges-specifier">
749  <x:anchor-alias value="byte-range-set"/>
750  <x:anchor-alias value="byte-range-spec"/>
751  <x:anchor-alias value="byte-ranges-specifier"/>
752  <x:anchor-alias value="first-byte-pos"/>
753  <x:anchor-alias value="last-byte-pos"/>
754  <x:anchor-alias value="ranges-specifier"/>
755  <x:anchor-alias value="suffix-byte-range-spec"/>
756  <x:anchor-alias value="suffix-length"/>
757
758   A byte range operation &MAY; specify a single range of bytes, or a set
759   of ranges within a single representation.
760</t>
761<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"/>
762  <x:ref>byte-ranges-specifier</x:ref> = <x:ref>bytes-unit</x:ref> "=" <x:ref>byte-range-set</x:ref>
763  <x:ref>byte-range-set</x:ref>  = 1#( <x:ref>byte-range-spec</x:ref> / <x:ref>suffix-byte-range-spec</x:ref> )
764  <x:ref>byte-range-spec</x:ref> = <x:ref>first-byte-pos</x:ref> "-" [ <x:ref>last-byte-pos</x:ref> ]
765  <x:ref>first-byte-pos</x:ref>  = 1*<x:ref>DIGIT</x:ref>
766  <x:ref>last-byte-pos</x:ref>   = 1*<x:ref>DIGIT</x:ref>
767</artwork></figure>
768<t>
769   The first-byte-pos value in a byte-range-spec gives the byte-offset
770   of the first byte in a range. The last-byte-pos value gives the
771   byte-offset of the last byte in the range; that is, the byte
772   positions specified are inclusive. Byte offsets start at zero.
773</t>
774<t>
775   If the last-byte-pos value is present, it &MUST; be greater than or
776   equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec
777   is syntactically invalid. The recipient of a byte-range-set
778   that includes one or more syntactically invalid byte-range-spec
779   values &MUST; ignore the header field that includes that byte-range-set.
780</t>
781<t>
782   If the last-byte-pos value is absent, or if the value is greater than
783   or equal to the current length of the representation body, last-byte-pos is
784   taken to be equal to one less than the current length of the representation
785   in bytes.
786</t>
787<t>
788   By its choice of last-byte-pos, a client can limit the number of
789   bytes retrieved without knowing the size of the representation.
790</t>
791<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/>
792  <x:ref>suffix-byte-range-spec</x:ref> = "-" <x:ref>suffix-length</x:ref>
793  <x:ref>suffix-length</x:ref> = 1*<x:ref>DIGIT</x:ref>
794</artwork></figure>
795<t>
796   A suffix-byte-range-spec is used to specify the suffix of the
797   representation body, of a length given by the suffix-length value. (That is,
798   this form specifies the last N bytes of a representation.) If the
799   representation is shorter than the specified suffix-length, the entire
800   representation is used.
801</t>
802<t>
803   If a syntactically valid byte-range-set includes at least one byte-range-spec
804   whose first-byte-pos is less than the current length of
805   the representation, or at least one suffix-byte-range-spec with a non-zero
806   suffix-length, then the byte-range-set is satisfiable.
807   Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set
808   is unsatisfiable, the server &SHOULD; return a response with a
809   416 (Requested range not satisfiable) status code. Otherwise, the server
810   &SHOULD; return a response with a 206 (Partial Content) status code
811   containing the satisfiable ranges of the representation.
812</t>
813<t>
814   Examples of byte-ranges-specifier values (assuming a representation of
815   length 10000):
816  <list style="symbols">
817     <t>The first 500 bytes (byte offsets 0-499, inclusive):
818<figure><artwork type="example" x:indent-with="   ">
819  bytes=0-499
820</artwork></figure>
821    </t>
822     <t>The second 500 bytes (byte offsets 500-999, inclusive):
823<figure><artwork type="example" x:indent-with="   ">
824  bytes=500-999
825</artwork></figure>
826    </t>
827     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
828<figure><artwork type="example" x:indent-with="   ">
829  bytes=-500
830</artwork></figure>
831    Or:
832<figure><artwork type="example" x:indent-with="   ">
833  bytes=9500-
834</artwork></figure>
835    </t>
836     <t>The first and last bytes only (bytes 0 and 9999):
837<figure><artwork type="example" x:indent-with="   ">
838  bytes=0-0,-1
839</artwork></figure>
840     </t>
841     <t>Several legal but not canonical specifications of the second 500
842        bytes (byte offsets 500-999, inclusive):
843<figure><artwork type="example" x:indent-with="   ">
844  bytes=500-600,601-999
845  bytes=500-700,601-999
846</artwork></figure>
847     </t>
848  </list>
849</t>
850</section>
851
852<section title="Range Retrieval Requests" anchor="range.retrieval.requests">
853  <x:anchor-alias value="Range"/>
854  <x:anchor-alias value="other-ranges-specifier"/>
855  <x:anchor-alias value="other-range-set"/>
856<t>
857   The "Range" header field defines the GET method (conditional or
858   not) to request one or more sub-ranges of the response representation body, instead
859   of the entire representation body.
860</t>
861<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Range"/>
862  <x:ref>Range</x:ref> = <x:ref>byte-ranges-specifier</x:ref> / <x:ref>other-ranges-specifier</x:ref>
863  <x:ref>other-ranges-specifier</x:ref> = <x:ref>other-range-unit</x:ref> "=" <x:ref>other-range-set</x:ref>
864  <x:ref>other-range-set</x:ref> = 1*<x:ref>CHAR</x:ref>
865</artwork></figure>
866<t>
867   A server &MAY; ignore the Range header field. However, origin
868   servers and intermediate caches ought to support byte ranges when
869   possible, since Range supports efficient recovery from partially
870   failed transfers, and supports efficient partial retrieval of large
871   representations.
872</t>
873<t>
874   If the server supports the Range header field and the specified range or
875   ranges are appropriate for the representation:
876  <list style="symbols">
877     <t>The presence of a Range header field in an unconditional GET modifies
878        what is returned if the GET is otherwise successful. In other
879        words, the response carries a status code of 206 (Partial
880        Content) instead of 200 (OK).</t>
881
882     <t>The presence of a Range header field in a conditional GET (a request
883        using one or both of If-Modified-Since and If-None-Match, or
884        one or both of If-Unmodified-Since and If-Match) modifies what
885        is returned if the GET is otherwise successful and the
886        condition is true. It does not affect the 304 (Not Modified)
887        response returned if the conditional is false.</t>
888  </list>
889</t>
890<t>
891   In some cases, it might be more appropriate to use the If-Range
892   header field (see <xref target="header.if-range"/>) in addition to the Range
893   header field.
894</t>
895<t>
896   If a proxy that supports ranges receives a Range request, forwards
897   the request to an inbound server, and receives an entire representation in
898   reply, it &MAY; only return the requested range to its client.
899</t>
900</section>
901</section>
902</section>
903
904<section title="IANA Considerations" anchor="IANA.considerations">
905
906<section title="Status Code Registration" anchor="status.code.registration">
907<t>
908   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
909   shall be updated with the registrations below:
910</t>
911<?BEGININC p5-range.iana-status-codes ?>
912<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
913<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
914   <ttcol>Value</ttcol>
915   <ttcol>Description</ttcol>
916   <ttcol>Reference</ttcol>
917   <c>206</c>
918   <c>Partial Content</c>
919   <c>
920      <xref target="status.206"/>
921   </c>
922   <c>416</c>
923   <c>Requested Range Not Satisfiable</c>
924   <c>
925      <xref target="status.416"/>
926   </c>
927</texttable>
928<!--(END)-->
929<?ENDINC p5-range.iana-status-codes ?>
930</section>
931
932<section title="Header Field Registration" anchor="header.field.registration">
933<t>
934   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
935   with the permanent registrations below (see <xref target="RFC3864"/>):
936</t>
937<?BEGININC p5-range.iana-headers ?>
938<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
939<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
940   <ttcol>Header Field Name</ttcol>
941   <ttcol>Protocol</ttcol>
942   <ttcol>Status</ttcol>
943   <ttcol>Reference</ttcol>
944
945   <c>Accept-Ranges</c>
946   <c>http</c>
947   <c>standard</c>
948   <c>
949      <xref target="header.accept-ranges"/>
950   </c>
951   <c>Content-Range</c>
952   <c>http</c>
953   <c>standard</c>
954   <c>
955      <xref target="header.content-range"/>
956   </c>
957   <c>If-Range</c>
958   <c>http</c>
959   <c>standard</c>
960   <c>
961      <xref target="header.if-range"/>
962   </c>
963   <c>Range</c>
964   <c>http</c>
965   <c>standard</c>
966   <c>
967      <xref target="header.range"/>
968   </c>
969</texttable>
970<!--(END)-->
971<?ENDINC p5-range.iana-headers ?>
972<t>
973   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
974</t>
975</section>
976
977<section title="Range Specifier Registration" anchor="range.specifier.registration">
978<t>
979  The registration procedure for HTTP Range Specifiers is defined by
980  <xref target="range.specifier.registry"/> of this document.
981</t>
982<t>
983   The HTTP Range Specifier Registry shall be created at <eref target="http://www.iana.org/assignments/http-range-specifiers"/>
984   and be populated with the registrations below:
985</t>
986<texttable align="left" suppress-title="true" anchor="iana.range.specifiers.table">
987   <ttcol>Range Specifier Name</ttcol>
988   <ttcol>Description</ttcol>
989   <ttcol>Reference</ttcol>
990
991   <c>bytes</c>
992   <c>a range of octets</c>
993   <c>(this specification)</c>
994</texttable>
995<t>
996   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
997</t>
998</section>
999</section>
1000
1001<section title="Security Considerations" anchor="security.considerations">
1002<t>
1003   This section is meant to inform application developers, information
1004   providers, and users of the security limitations in HTTP/1.1 as
1005   described by this document. The discussion does not include
1006   definitive solutions to the problems revealed, though it does make
1007   some suggestions for reducing security risks.
1008</t>
1009<section title="Overlapping Ranges" anchor="overlapping.ranges">
1010<t>
1011   Range requests containing overlapping ranges may lead to the situation
1012   where a server is sending far more data than the size of the complete
1013   resource representation.
1014</t>
1015</section>
1016</section>
1017
1018<section title="Acknowledgments" anchor="acks">
1019<t>
1020  See &acks;.
1021</t>
1022</section>
1023</middle>
1024<back>
1025
1026<references title="Normative References">
1027
1028<reference anchor="Part1">
1029  <front>
1030    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
1031    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1032      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1033      <address><email>fielding@gbiv.com</email></address>
1034    </author>
1035    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1036      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1037      <address><email>jg@freedesktop.org</email></address>
1038    </author>
1039    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1040      <organization abbrev="HP">Hewlett-Packard Company</organization>
1041      <address><email>JeffMogul@acm.org</email></address>
1042    </author>
1043    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1044      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1045      <address><email>henrikn@microsoft.com</email></address>
1046    </author>
1047    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1048      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1049      <address><email>LMM@acm.org</email></address>
1050    </author>
1051    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1052      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1053      <address><email>paulle@microsoft.com</email></address>
1054    </author>
1055    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1056      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1057      <address><email>timbl@w3.org</email></address>
1058    </author>
1059    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1060      <organization abbrev="W3C">World Wide Web Consortium</organization>
1061      <address><email>ylafon@w3.org</email></address>
1062    </author>
1063    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1064      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1065      <address><email>julian.reschke@greenbytes.de</email></address>
1066    </author>
1067    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1068  </front>
1069  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
1070  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
1071</reference>
1072
1073<reference anchor="Part4">
1074  <front>
1075    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
1076    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1077      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1078      <address><email>fielding@gbiv.com</email></address>
1079    </author>
1080    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1081      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1082      <address><email>jg@freedesktop.org</email></address>
1083    </author>
1084    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1085      <organization abbrev="HP">Hewlett-Packard Company</organization>
1086      <address><email>JeffMogul@acm.org</email></address>
1087    </author>
1088    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1089      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1090      <address><email>henrikn@microsoft.com</email></address>
1091    </author>
1092    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1093      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1094      <address><email>LMM@acm.org</email></address>
1095    </author>
1096    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1097      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1098      <address><email>paulle@microsoft.com</email></address>
1099    </author>
1100    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1101      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1102      <address><email>timbl@w3.org</email></address>
1103    </author>
1104    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1105      <organization abbrev="W3C">World Wide Web Consortium</organization>
1106      <address><email>ylafon@w3.org</email></address>
1107    </author>
1108    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1109      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1110      <address><email>julian.reschke@greenbytes.de</email></address>
1111    </author>
1112    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1113  </front>
1114  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
1115  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
1116</reference>
1117
1118<reference anchor="RFC2046">
1119  <front>
1120    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1121    <author initials="N." surname="Freed" fullname="Ned Freed">
1122      <organization>Innosoft International, Inc.</organization>
1123      <address><email>ned@innosoft.com</email></address>
1124    </author>
1125    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1126      <organization>First Virtual Holdings</organization>
1127      <address><email>nsb@nsb.fv.com</email></address>
1128    </author>
1129    <date month="November" year="1996"/>
1130  </front>
1131  <seriesInfo name="RFC" value="2046"/>
1132</reference>
1133
1134<reference anchor="RFC2119">
1135  <front>
1136    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1137    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1138      <organization>Harvard University</organization>
1139      <address><email>sob@harvard.edu</email></address>
1140    </author>
1141    <date month="March" year="1997"/>
1142  </front>
1143  <seriesInfo name="BCP" value="14"/>
1144  <seriesInfo name="RFC" value="2119"/>
1145</reference>
1146
1147<reference anchor="RFC5234">
1148  <front>
1149    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
1150    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
1151      <organization>Brandenburg InternetWorking</organization>
1152      <address>
1153        <email>dcrocker@bbiw.net</email>
1154      </address> 
1155    </author>
1156    <author initials="P." surname="Overell" fullname="Paul Overell">
1157      <organization>THUS plc.</organization>
1158      <address>
1159        <email>paul.overell@thus.net</email>
1160      </address>
1161    </author>
1162    <date month="January" year="2008"/>
1163  </front>
1164  <seriesInfo name="STD" value="68"/>
1165  <seriesInfo name="RFC" value="5234"/>
1166</reference>
1167
1168</references>
1169
1170<references title="Informative References">
1171
1172<reference anchor="RFC2616">
1173  <front>
1174    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
1175    <author initials="R." surname="Fielding" fullname="R. Fielding">
1176      <organization>University of California, Irvine</organization>
1177      <address><email>fielding@ics.uci.edu</email></address>
1178    </author>
1179    <author initials="J." surname="Gettys" fullname="J. Gettys">
1180      <organization>W3C</organization>
1181      <address><email>jg@w3.org</email></address>
1182    </author>
1183    <author initials="J." surname="Mogul" fullname="J. Mogul">
1184      <organization>Compaq Computer Corporation</organization>
1185      <address><email>mogul@wrl.dec.com</email></address>
1186    </author>
1187    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
1188      <organization>MIT Laboratory for Computer Science</organization>
1189      <address><email>frystyk@w3.org</email></address>
1190    </author>
1191    <author initials="L." surname="Masinter" fullname="L. Masinter">
1192      <organization>Xerox Corporation</organization>
1193      <address><email>masinter@parc.xerox.com</email></address>
1194    </author>
1195    <author initials="P." surname="Leach" fullname="P. Leach">
1196      <organization>Microsoft Corporation</organization>
1197      <address><email>paulle@microsoft.com</email></address>
1198    </author>
1199    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
1200      <organization>W3C</organization>
1201      <address><email>timbl@w3.org</email></address>
1202    </author>
1203    <date month="June" year="1999"/>
1204  </front>
1205  <seriesInfo name="RFC" value="2616"/>
1206</reference>
1207
1208<reference anchor='RFC3864'>
1209  <front>
1210    <title>Registration Procedures for Message Header Fields</title>
1211    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
1212      <organization>Nine by Nine</organization>
1213      <address><email>GK-IETF@ninebynine.org</email></address>
1214    </author>
1215    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
1216      <organization>BEA Systems</organization>
1217      <address><email>mnot@pobox.com</email></address>
1218    </author>
1219    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
1220      <organization>HP Labs</organization>
1221      <address><email>JeffMogul@acm.org</email></address>
1222    </author>
1223    <date year='2004' month='September' />
1224  </front>
1225  <seriesInfo name='BCP' value='90' />
1226  <seriesInfo name='RFC' value='3864' />
1227</reference>
1228
1229<reference anchor="RFC4288">
1230  <front>
1231    <title>Media Type Specifications and Registration Procedures</title>
1232    <author initials="N." surname="Freed" fullname="N. Freed">
1233      <organization>Sun Microsystems</organization>
1234      <address>
1235        <email>ned.freed@mrochek.com</email>
1236      </address>
1237    </author>
1238    <author initials="J." surname="Klensin" fullname="J. Klensin">
1239      <address>
1240        <email>klensin+ietf@jck.com</email>
1241      </address>
1242    </author>
1243    <date year="2005" month="December"/>
1244  </front>
1245  <seriesInfo name="BCP" value="13"/>
1246  <seriesInfo name="RFC" value="4288"/>
1247</reference>
1248
1249<reference anchor='RFC5226'>
1250  <front>
1251    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
1252    <author initials='T.' surname='Narten' fullname='T. Narten'>
1253      <organization>IBM</organization>
1254      <address><email>narten@us.ibm.com</email></address>
1255    </author>
1256    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
1257      <organization>Google</organization>
1258      <address><email>Harald@Alvestrand.no</email></address>
1259    </author>
1260    <date year='2008' month='May' />
1261  </front>
1262  <seriesInfo name='BCP' value='26' />
1263  <seriesInfo name='RFC' value='5226' />
1264</reference>
1265
1266</references>
1267
1268<section title="Internet Media Type multipart/byteranges" anchor="internet.media.type.multipart.byteranges">
1269<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
1270<iref item="multipart/byteranges Media Type" primary="true"/>
1271<t>
1272   When an HTTP 206 (Partial Content) response message includes the
1273   content of multiple ranges (a response to a request for multiple
1274   non-overlapping ranges), these are transmitted as a multipart
1275   message-body (<xref target="RFC2046" x:fmt="," x:sec="5.1"/>). The media type for this purpose is called
1276   "multipart/byteranges".  The following is to be registered with IANA <xref target="RFC4288"/>.
1277</t>
1278<x:note>
1279  <t>
1280    <x:h>Note:</x:h> Despite the name "multipart/byteranges" is not limited to the byte ranges only.
1281  </t>
1282</x:note>
1283<t>
1284   The multipart/byteranges media type includes one or more parts, each
1285   with its own Content-Type and Content-Range fields. The required
1286   boundary parameter specifies the boundary string used to separate
1287   each body-part.
1288</t>
1289<t>
1290  <list style="hanging" x:indent="12em">
1291    <t hangText="Type name:">
1292      multipart
1293    </t>
1294    <t hangText="Subtype name:">
1295      byteranges
1296    </t>
1297    <t hangText="Required parameters:">
1298      boundary
1299    </t>
1300    <t hangText="Optional parameters:">
1301      none
1302    </t>
1303    <t hangText="Encoding considerations:">
1304      only "7bit", "8bit", or "binary" are permitted
1305    </t>
1306    <t hangText="Security considerations:">
1307      none
1308    </t>
1309    <t hangText="Interoperability considerations:">
1310      none
1311    </t>
1312    <t hangText="Published specification:">
1313      This specification (see <xref target="internet.media.type.multipart.byteranges"/>).
1314    </t>
1315    <t hangText="Applications that use this media type:">
1316    </t>
1317    <t hangText="Additional information:">
1318      <list style="hanging">
1319        <t hangText="Magic number(s):">none</t>
1320        <t hangText="File extension(s):">none</t>
1321        <t hangText="Macintosh file type code(s):">none</t>
1322      </list>
1323    </t>
1324    <t hangText="Person and email address to contact for further information:">
1325      See Authors Section.
1326    </t>
1327    <t hangText="Intended usage:">
1328      COMMON
1329    </t>
1330    <t hangText="Restrictions on usage:">
1331      none
1332    </t>
1333    <t hangText="Author/Change controller:">
1334      IESG
1335    </t>
1336  </list>
1337</t>
1338<figure><preamble>
1339   For example:
1340</preamble><artwork type="example">
1341  HTTP/1.1 206 Partial Content
1342  Date: Wed, 15 Nov 1995 06:25:24 GMT
1343  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
1344  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1345 
1346  --THIS_STRING_SEPARATES
1347  Content-type: application/pdf
1348  Content-range: bytes 500-999/8000
1349 
1350  ...the first range...
1351  --THIS_STRING_SEPARATES
1352  Content-type: application/pdf
1353  Content-range: bytes 7000-7999/8000
1354 
1355  ...the second range
1356  --THIS_STRING_SEPARATES--
1357</artwork></figure>
1358<figure><preamble>
1359   Other example:
1360</preamble>
1361<artwork type="example">
1362  HTTP/1.1 206 Partial Content
1363  Date: Tue, 14 Nov 1995 06:25:24 GMT
1364  Last-Modified: Tue, 14 July 04:58:08 GMT
1365  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1366 
1367  --THIS_STRING_SEPARATES
1368  Content-type: video/example
1369  Content-range: exampleunit 1.2-4.3/25
1370 
1371  ...the first range...
1372  --THIS_STRING_SEPARATES
1373  Content-type: video/example
1374  Content-range: exampleunit 11.2-14.3/25
1375 
1376  ...the second range
1377  --THIS_STRING_SEPARATES--
1378</artwork>
1379</figure>
1380<t>
1381      Notes:
1382  <list style="numbers">
1383      <t>Additional CRLFs &MAY; precede the first boundary string in the body.</t>
1384
1385      <t>Although <xref target="RFC2046"/> permits the boundary string to be
1386         quoted, some existing implementations handle a quoted boundary
1387         string incorrectly.</t>
1388
1389      <t>A number of browsers and servers were coded to an early draft
1390         of the byteranges specification to use a media type of
1391         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>, which is almost, but not quite
1392         compatible with the version documented in HTTP/1.1.</t>
1393  </list>
1394</t>
1395</section>
1396
1397<section title="Compatibility with Previous Versions" anchor="compatibility">
1398<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
1399<t>
1400  Clarify that it is not ok to use a weak validator in a 206 response.
1401  (<xref target="status.206"/>)
1402</t>
1403<t>
1404  Change ABNF productions for header fields to only define the field value.
1405  (<xref target="header.fields"/>)
1406</t>
1407<t>
1408  Clarify that multipart/byteranges can consist of a single part.
1409  (<xref target="internet.media.type.multipart.byteranges"/>)
1410</t>
1411</section>
1412
1413</section>
1414
1415<?BEGININC p5-range.abnf-appendix ?>
1416<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
1417<figure>
1418<artwork type="abnf" name="p5-range.parsed-abnf">
1419<x:ref>Accept-Ranges</x:ref> = acceptable-ranges
1420
1421<x:ref>Content-Range</x:ref> = content-range-spec
1422
1423<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
1424
1425<x:ref>If-Range</x:ref> = entity-tag / HTTP-date
1426
1427<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
1428
1429<x:ref>Range</x:ref> = byte-ranges-specifier / other-ranges-specifier
1430
1431<x:ref>acceptable-ranges</x:ref> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
1432 range-unit ] ) ) / "none"
1433
1434<x:ref>byte-content-range-spec</x:ref> = bytes-unit SP byte-range-resp-spec "/" (
1435 instance-length / "*" )
1436<x:ref>byte-range-resp-spec</x:ref> = ( first-byte-pos "-" last-byte-pos ) / "*"
1437<x:ref>byte-range-set</x:ref> = ( *( "," OWS ) byte-range-spec ) / (
1438 suffix-byte-range-spec *( OWS "," [ ( OWS byte-range-spec ) /
1439 suffix-byte-range-spec ] ) )
1440<x:ref>byte-range-spec</x:ref> = first-byte-pos "-" [ last-byte-pos ]
1441<x:ref>byte-ranges-specifier</x:ref> = bytes-unit "=" byte-range-set
1442<x:ref>bytes-unit</x:ref> = "bytes"
1443
1444<x:ref>content-range-spec</x:ref> = byte-content-range-spec /
1445 other-content-range-spec
1446
1447<x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in [Part4], Section 2.3&gt;
1448
1449<x:ref>first-byte-pos</x:ref> = 1*DIGIT
1450
1451<x:ref>instance-length</x:ref> = 1*DIGIT
1452
1453<x:ref>last-byte-pos</x:ref> = 1*DIGIT
1454
1455<x:ref>other-content-range-spec</x:ref> = other-range-unit SP other-range-resp-spec
1456<x:ref>other-range-resp-spec</x:ref> = *CHAR
1457<x:ref>other-range-set</x:ref> = 1*CHAR
1458<x:ref>other-range-unit</x:ref> = token
1459<x:ref>other-ranges-specifier</x:ref> = other-range-unit "=" other-range-set
1460
1461<x:ref>range-unit</x:ref> = bytes-unit / other-range-unit
1462
1463<x:ref>suffix-byte-range-spec</x:ref> = "-" suffix-length
1464<x:ref>suffix-length</x:ref> = 1*DIGIT
1465
1466<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 3.2.3&gt;
1467</artwork>
1468</figure>
1469<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
1470; Accept-Ranges defined but not used
1471; Content-Range defined but not used
1472; If-Range defined but not used
1473; Range defined but not used
1474</artwork></figure></section>
1475<?ENDINC p5-range.abnf-appendix ?>
1476
1477
1478<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
1479
1480<section title="Since RFC 2616">
1481<t>
1482  Extracted relevant partitions from <xref target="RFC2616"/>.
1483</t>
1484</section>
1485
1486<section title="Since draft-ietf-httpbis-p5-range-00">
1487<t>
1488  Closed issues:
1489  <list style="symbols"> 
1490    <t>
1491      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/18"/>:
1492      "Cache validators in 206 responses"
1493      (<eref target="http://purl.org/NET/http-errata#ifrange206"/>)
1494    </t>
1495    <t>
1496      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
1497      "Normative and Informative references"
1498    </t>
1499    <t>
1500      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/86"/>:
1501      "Normative up-to-date references"
1502    </t>
1503  </list>
1504</t>
1505</section>
1506
1507<section title="Since draft-ietf-httpbis-p5-range-01">
1508<t>
1509  Closed issues:
1510  <list style="symbols"> 
1511    <t>
1512      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/55"/>:
1513      "Updating to RFC4288"
1514    </t>
1515  </list>
1516</t>
1517<t>
1518  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1519  <list style="symbols"> 
1520    <t>
1521      Add explicit references to BNF syntax and rules imported from other parts of the specification.
1522    </t>
1523  </list>
1524</t>
1525</section>
1526
1527<section title="Since draft-ietf-httpbis-p5-range-02" anchor="changes.since.02">
1528<t>
1529  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
1530  <list style="symbols"> 
1531    <t>
1532      Reference RFC 3984, and update header field registrations for headers defined
1533      in this document.
1534    </t>
1535  </list>
1536</t>
1537</section>
1538
1539<section title="Since draft-ietf-httpbis-p5-range-03" anchor="changes.since.03">
1540<t>
1541  None.
1542</t>
1543</section>
1544
1545<section title="Since draft-ietf-httpbis-p5-range-04" anchor="changes.since.04">
1546<t>
1547  Closed issues:
1548  <list style="symbols"> 
1549    <t>
1550      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/133"/>:
1551      "multipart/byteranges minimum number of parts"
1552    </t>
1553  </list>
1554</t>
1555<t>
1556  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1557  <list style="symbols"> 
1558    <t>
1559      Use "/" instead of "|" for alternatives.
1560    </t>
1561    <t>
1562      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
1563      whitespace ("OWS") and required whitespace ("RWS").
1564    </t>
1565    <t>
1566      Rewrite ABNFs to spell out whitespace rules, factor out
1567      header field value format definitions.
1568    </t>
1569  </list>
1570</t>
1571</section>
1572
1573<section title="Since draft-ietf-httpbis-p5-range-05" anchor="changes.since.05">
1574<t>
1575  Closed issues:
1576  <list style="symbols"> 
1577    <t>
1578      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/142"/>:
1579      "State base for *-byte-pos and suffix-length"
1580    </t>
1581  </list>
1582</t>
1583<t>
1584  Ongoing work on Custom Ranges (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/85"/>):
1585  <list style="symbols"> 
1586    <t>
1587      Remove bias in favor of byte ranges; allow custom ranges in ABNF.
1588    </t>
1589  </list>
1590</t>
1591<t>
1592  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1593  <list style="symbols"> 
1594    <t>
1595      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
1596    </t>
1597  </list>
1598</t>
1599</section>
1600
1601<section title="Since draft-ietf-httpbis-p5-range-06" anchor="changes.since.06">
1602<t>
1603  Closed issues:
1604  <list style="symbols"> 
1605    <t>
1606      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/161"/>:
1607      "base for numeric protocol elements"
1608    </t>
1609  </list>
1610</t>
1611</section>
1612
1613<section title="Since draft-ietf-httpbis-p5-range-07" anchor="changes.since.07">
1614<t>
1615  Closed issues:
1616  <list style="symbols">
1617    <t>
1618      Fixed discrepancy in the If-Range definition about allowed validators.
1619    </t>
1620    <t>
1621      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/150" />: "multipart/byteranges for custom range units"
1622    </t>
1623    <t>
1624      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/151" />: "range unit missing from other-ranges-specifier in Range header"
1625    </t>
1626    <t>
1627      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
1628      "move IANA registrations for optional status codes"
1629    </t>
1630  </list>
1631</t>
1632</section>
1633
1634<section title="Since draft-ietf-httpbis-p5-range-08" anchor="changes.since.08">
1635<t>
1636  No significant changes.
1637</t>
1638</section>
1639
1640<section title="Since draft-ietf-httpbis-p5-range-09" anchor="changes.since.09">
1641<t>
1642 No significant changes.
1643</t>
1644</section>
1645
1646<section title="Since draft-ietf-httpbis-p5-range-10" anchor="changes.since.10">
1647<t>
1648  Closed issues:
1649  <list style="symbols"> 
1650    <t>
1651      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
1652      "Clarify 'Requested Variant'"
1653    </t>
1654    <t>
1655      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
1656      "Clarify entity / representation / variant terminology"
1657    </t>
1658    <t>
1659      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
1660      "consider removing the 'changes from 2068' sections"
1661    </t>
1662  </list>
1663</t>
1664<t>
1665  Ongoing work on Custom Ranges (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/85"/>):
1666  <list style="symbols"> 
1667    <t>
1668      Add IANA registry.
1669    </t>
1670  </list>
1671</t>
1672</section>
1673
1674<section title="Since draft-ietf-httpbis-p5-range-11" anchor="changes.since.11">
1675<t>
1676  Closed issues:
1677  <list style="symbols"> 
1678    <t>
1679      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/217"/>:
1680      "Caches can't be required to serve ranges"
1681    </t>
1682  </list>
1683</t>
1684</section>
1685
1686<section title="Since draft-ietf-httpbis-p5-range-12" anchor="changes.since.12">
1687<t>
1688  Closed issues:
1689  <list style="symbols"> 
1690    <t>
1691      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>:
1692      "Header Classification"
1693    </t>
1694  </list>
1695</t>
1696</section>
1697
1698<section title="Since draft-ietf-httpbis-p5-range-13" anchor="changes.since.13">
1699<t>
1700  Closed issues:
1701  <list style="symbols">
1702    <t>
1703      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
1704      "untangle ABNFs for header fields"
1705    </t>
1706  </list>
1707</t>
1708</section>
1709
1710<section title="Since draft-ietf-httpbis-p5-range-14" anchor="changes.since.14">
1711<t>
1712  None.
1713</t>
1714</section>
1715
1716<section title="Since draft-ietf-httpbis-p5-range-15" anchor="changes.since.15">
1717<t>
1718  Closed issues:
1719  <list style="symbols">
1720    <t>
1721      <eref target="http://trac.tools.ietf.org/wg/httpbis/trac/ticket/175"/>:
1722      "Security consideration: range flooding"
1723    </t>
1724  </list>
1725</t>
1726</section>
1727
1728</section>
1729
1730</back>
1731</rfc>
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