source: draft-ietf-httpbis/latest/p5-range.xml @ 1431

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bump up document dates; update to latest version of rfc2629.xslt, refresh appendices.

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