source: draft-ietf-httpbis/21/draft-ietf-httpbis-p5-range-21.xml @ 2132

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<rfc obsoletes="2616" category="std" ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p5-range-21">



<front>

  <title abbrev="HTTP/1.1 Range Requests">Hypertext Transfer Protocol (HTTP/1.1): Range Requests</title>

  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
    <address>
      <postal>
        <street>345 Park Ave</street>
        <city>San Jose</city>
        <region>CA</region>
        <code>95110</code>
        <country>USA</country>
      </postal>
      <email>fielding@gbiv.com</email>
      <uri>http://roy.gbiv.com/</uri>
    </address>
  </author>

  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
    <organization abbrev="W3C">World Wide Web Consortium</organization>
    <address>
      <postal>
        <street>W3C / ERCIM</street>
        <street>2004, rte des Lucioles</street>
        <city>Sophia-Antipolis</city>
        <region>AM</region>
        <code>06902</code>
        <country>France</country>
      </postal>
      <email>ylafon@w3.org</email>
      <uri>http://www.raubacapeu.net/people/yves/</uri>
    </address>
  </author>

  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
    <organization abbrev="greenbytes">greenbytes GmbH</organization>
    <address>
      <postal>
        <street>Hafenweg 16</street>
        <city>Muenster</city><region>NW</region><code>48155</code>
        <country>Germany</country>
      </postal>
      <email>julian.reschke@greenbytes.de</email>
      <uri>http://greenbytes.de/tech/webdav/</uri>
    </address>
  </author>

  <date month="October" year="2012" day="4"/>
  <workgroup>HTTPbis Working Group</workgroup>

<abstract>
<t>
   The Hypertext Transfer Protocol (HTTP) is an application-level protocol for
   distributed, collaborative, hypertext information systems. This document
   defines range requests and the rules for constructing and combining
   responses to those requests.
</t>
</abstract>

<note title="Editorial Note (To be removed by RFC Editor)">
  <t>
    Discussion of this draft takes place on the HTTPBIS working group
    mailing list (ietf-http-wg@w3.org), which is archived at
    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
  </t>
  <t>
    The current issues list is at
    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
    documents (including fancy diffs) can be found at
    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
  </t>
  <t>
    The changes in this draft are summarized in <xref target="changes.since.20"/>.
  </t>
</note>
</front>
<middle>
<section title="Introduction" anchor="introduction">
<t>
   HTTP clients often encounter interrupted data transfers as a result
   of canceled requests or dropped connections.  When a client has stored
   a partial representation, it is desirable to request the remainder
   of that representation in a subsequent request rather than transfer
   the entire representation.
   There are also a number of Web applications that benefit from being
   able to request only a subset of a larger representation, such as a
   single page of a very large document or only part of an image to be
   rendered by a device with limited local storage.
</t>
<t>
   This document defines HTTP/1.1 range requests,
   partial responses, and the multipart/byteranges media type.
   The protocol for range requests is an OPTIONAL feature of HTTP,
   designed so resources or recipients that do not implement this feature
   can respond as if it is a normal GET request without impacting
   interoperability.  Partial responses are indicated by a distinct status
   code to not be mistaken for full responses by intermediate caches
   that might not implement the feature.
</t>
<t>
   Although the HTTP range request mechanism is designed to allow for
   extensible range types, this specification only defines requests for
   byte ranges.
</t>

<section title="Conformance and Error Handling" anchor="conformance">
<t>
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in <xref target="RFC2119"/>.
</t>
<t>
   Conformance criteria and considerations regarding error handling
   are defined in Section 2.5 of <xref target="Part1"/>.
</t>
</section>

<section title="Syntax Notation" anchor="notation">
<t>
   This specification uses the Augmented Backus-Naur Form (ABNF) notation
   of <xref target="RFC5234"/> with the list rule extension defined in
   Section 1.2 of <xref target="Part1"/>. <xref target="imported.abnf"/> describes rules imported from
   other documents. <xref target="collected.abnf"/> shows the collected ABNF
   with the list rule expanded.
</t>
</section>

</section>


<section title="Range Units" anchor="range.units">
  
  
  
<t>
   HTTP/1.1 allows a client to request that only part (a range) of the
   representation be included within the response. HTTP/1.1 uses range
   units in the <xref target="range.retrieval.requests" format="none">Range</xref> (<xref target="header.range"/>) and
   <xref target="header.content-range" format="none">Content-Range</xref> (<xref target="header.content-range"/>)
   header fields. A representation can be broken down into subranges according
   to various structural units.
</t>
<figure><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"/><artwork type="abnf2616"><![CDATA[
  range-unit       = bytes-unit / other-range-unit
  bytes-unit       = "bytes"
  other-range-unit = token
]]></artwork></figure>
<t>
  HTTP/1.1 has been designed to allow implementations of applications
  that do not depend on knowledge of ranges. The only range unit defined
  by HTTP/1.1 is "bytes". Additional specifiers can be defined as described
  in <xref target="range.specifier.registry"/>.
</t>
<t>
  If a range unit is not understood in a request, a server MUST ignore
  the whole <xref target="range.retrieval.requests" format="none">Range</xref> header field (<xref target="header.range"/>).
  If a range unit is not understood in a response, an intermediary 
  SHOULD pass the response to the client; a client MUST fail.
</t>

<section title="Range Specifier Registry" anchor="range.specifier.registry">
<t>
   The HTTP Range Specifier Registry defines the name space for the range
   specifier names.
</t>
<t>
   Registrations MUST include the following fields:
   <list style="symbols">
     <t>Name</t>
     <t>Description</t>
     <t>Pointer to specification text</t>
   </list>
</t>
<t>
  Values to be added to this name space require IETF Review
  (see <xref target="RFC5226"/>, Section 4.1).
</t>
<t>
   The registry itself is maintained at
   <eref target="http://www.iana.org/assignments/http-range-specifiers"/>.
</t>
</section>

</section>

<section title="Status Code Definitions" anchor="status.code.definitions">
<section title="206 Partial Content" anchor="status.206">
  <iref primary="true" item="206 Partial Content (status code)"/>
  
  
<t>
   The server has fulfilled the partial GET request for the resource.
   The request MUST have included a <xref target="range.retrieval.requests" format="none">Range</xref> header field
   (<xref target="header.range"/>) indicating the desired range, and MAY have
   included an <xref target="header.if-range" format="none">If-Range</xref> header field
   (<xref target="header.if-range"/>) to make the request conditional.
</t>
<t>
   The response MUST include the following header fields:
  <list style="symbols">
    <t>
        Either a <xref target="header.content-range" format="none">Content-Range</xref> header field
        (<xref target="header.content-range"/>) indicating
        the range included with this response, or a multipart/byteranges
        Content-Type including Content-Range fields for each
        part. If a Content-Length header field is present in the
        response, its value MUST match the actual number of octets
        transmitted in the message body.
    </t>
    <t>
        Date
    </t>
    <t>
        Cache-Control, ETag,
        Expires, Content-Location and/or
        Vary, if the header field would have been sent in a
        200 (OK) response to the same request
    </t>
  </list>
</t>
<t>
   If a 206 is sent in response to a request with an <xref target="header.if-range" format="none">If-Range</xref>
   header field, it SHOULD NOT include other representation header fields.
   Otherwise, the response MUST include all of the representation header
   fields that would have been returned with a 200 (OK) response
   to the same request.
</t>
<t>
   Caches MAY use a heuristic (see Section 4.1.2 of <xref target="Part6"/>) to determine 
   freshness for 206 responses.
</t>
</section>

<section title="416 Requested Range Not Satisfiable" anchor="status.416">
  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)"/>
  
<t>
   A server SHOULD return a response with this status code if a request
   included a <xref target="range.retrieval.requests" format="none">Range</xref> header field (<xref target="header.range"/>),
   and none of the ranges-specifier values in this field overlap the current
   extent of the selected resource, and the request did not include an
   <xref target="header.if-range" format="none">If-Range</xref> header field (<xref target="header.if-range"/>).
   (For byte-ranges, this means that the first-byte-pos of all of the
   byte-range-spec values were greater than the current length of the selected
   resource.)
</t>
<t>
   When this status code is returned for a byte-range request, the
   response SHOULD include a <xref target="header.content-range" format="none">Content-Range</xref> header field
   specifying the current length of the representation (see <xref target="header.content-range"/>).
   This response MUST NOT use the multipart/byteranges content-type. For example,
</t>
<figure><artwork type="message/http; msgtype=&#34;response&#34;"><![CDATA[
  HTTP/1.1 416 Requested Range Not Satisfiable
  Date: Mon, 20 Jan 2012 15:41:54 GMT
  Content-Range: bytes */47022
  Content-Type: image/gif
  ]]></artwork></figure>
<t><list>
  <t>
    Note: Clients cannot depend on servers to send a <xref target="status.416" format="none">416 (Requested
    Range Not Satisfiable)</xref> response instead of a 200 (OK)
    response for an unsatisfiable <xref target="range.retrieval.requests" format="none">Range</xref> header field, since not
    all servers implement this header field.
  </t>
</list></t>
</section>
</section>

<section title="Responses to a Range Request">
<section title="Response to a Single and Multiple Ranges Request">
<t>
   When an HTTP message includes the content of a single range (for
   example, a response to a request for a single range, or to a request
   for a set of ranges that overlap without any holes), this content is
   transmitted with a <xref target="header.content-range" format="none">Content-Range</xref> header field, and a
   Content-Length header field showing the number of bytes
   actually transferred. For example,
</t>
<figure><artwork type="message/http; msgtype=&#34;response&#34;"><![CDATA[
  HTTP/1.1 206 Partial Content
  Date: Wed, 15 Nov 1995 06:25:24 GMT
  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
  Content-Range: bytes 21010-47021/47022
  Content-Length: 26012
  Content-Type: image/gif
  ]]></artwork></figure>
<t>
   When an HTTP message includes the content of multiple ranges (for
   example, a response to a request for multiple non-overlapping
   ranges), these are transmitted as a multipart message. The multipart
   media type used for this purpose is "multipart/byteranges" as defined
   in <xref target="internet.media.type.multipart.byteranges"/>.
</t>
<t>
   A server MAY combine requested ranges when those ranges are overlapping
   (see <xref target="overlapping.ranges"/>).
</t>
<t>
   A response to a request for a single range MUST NOT be sent using the
   multipart/byteranges media type.  A response to a request for
   multiple ranges, whose result is a single range, MAY be sent as a
   multipart/byteranges media type with one part. A client that cannot
   decode a multipart/byteranges message MUST NOT ask for multiple
   ranges in a single request.
</t>
<t>
   When a client asks for multiple ranges in one request, the
   server SHOULD return them in the order that they appeared in the
   request.
</t>
</section>

<section title="Combining Ranges" anchor="combining.byte.ranges">
<t>
   A response might transfer only a subrange of a representation if the
   connection closed prematurely or if the request used one or more Range
   specifications.  After several such transfers, a client might have
   received several ranges of the same representation.  These ranges can only
   be safely combined if they all have in common the same strong validator,
   where "strong validator" is defined to be either an entity-tag that is
   not marked as weak (Section 2.3 of <xref target="Part4"/>) or, if no entity-tag is provided, a
   Last-Modified value that is strong in the sense defined by
   Section 2.2.2 of <xref target="Part4"/>.
</t>
<t>
   When a client receives an incomplete 200 (OK) or <xref target="status.206" format="none">206 (Partial Content)</xref>
   response and already has one or more stored responses for the same method
   and effective request URI, all of the stored responses with the same
   strong validator MAY be combined with the partial content in this new
   response.  If none of the stored responses contain the same strong
   validator, then this new response corresponds to a new representation
   and MUST NOT be combined with the existing stored responses.
</t>
<t>
   If the new response is an incomplete 200 (OK) response, then the header
   fields of that new response are used for any combined response and replace
   those of the matching stored responses.
</t>
<t>
   If the new response is a <xref target="status.206" format="none">206 (Partial Content)</xref> response and at least one
   of the matching stored responses is a 200 (OK), then the combined response
   header fields consist of the most recent 200 response's header fields.
   If all of the matching stored responses are 206 responses, then the
   stored response with the most header fields is used as the source of
   header fields for the combined response, except that the client MUST
   use other header fields provided in the new response, aside from
   <xref target="header.content-range" format="none">Content-Range</xref>, to replace all instances of the corresponding
   header fields in the stored response.
</t>
<t>
   The combined response message body consists of the union of partial
   content ranges in the new response and each of the selected responses.
   If the union consists of the entire range of the representation, then the
   combined response MUST be recorded as a complete 200 (OK)
   response with a Content-Length header field that reflects the
   complete length. Otherwise, the combined response(s) MUST include a
   <xref target="header.content-range" format="none">Content-Range</xref> header field describing the included range(s)
   and be recorded as incomplete.  If the union consists of a discontinuous
   range of the representation, then the client MAY store it as either a
   multipart range response or as multiple <xref target="status.206" format="none">206</xref> responses with
   one continuous range each.
</t>
</section>
</section>

<section title="Header Field Definitions" anchor="header.field.definitions">
<t>
   This section defines the syntax and semantics of HTTP/1.1 header fields
   related to range requests and partial responses.
</t>

<section title="Accept-Ranges" anchor="header.accept-ranges">
  <iref primary="true" item="Accept-Ranges header field"/>
  
  
<t>
   The "Accept-Ranges" header field allows a resource to indicate
   its acceptance of range requests.
</t>
<figure><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/><artwork type="abnf2616"><![CDATA[
  Accept-Ranges     = acceptable-ranges
  acceptable-ranges = 1#range-unit / "none"
]]></artwork></figure>
<t>
   Origin servers that accept byte-range requests MAY send
</t>
<figure><artwork type="example"><![CDATA[
  Accept-Ranges: bytes
]]></artwork></figure>
<t>
   but are not required to do so. Clients MAY generate range
   requests without having received this header field for the resource
   involved. Range units are defined in <xref target="range.units"/>.
</t>
<t>
   Servers that do not accept any kind of range request for a
   resource MAY send
</t>
<figure><artwork type="example"><![CDATA[
  Accept-Ranges: none
]]></artwork></figure>
<t>
   to advise the client not to attempt a range request.
</t>
</section>

<section title="Content-Range" anchor="header.content-range">
  <iref primary="true" item="Content-Range header field"/>
  
  
  
  
  
  
<t>
   The "Content-Range" header field is sent with a partial representation to
   specify where in the full representation the payload body is intended to be
   applied.
</t>
<t>   
   Range units are defined in <xref target="range.units"/>.
</t>
<figure><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"/><artwork type="abnf2616"><![CDATA[
  Content-Range           = byte-content-range-spec
                          / other-content-range-spec
                          
  byte-content-range-spec = bytes-unit SP
                            byte-range-resp-spec "/"
                            ( instance-length / "*" )
  
  byte-range-resp-spec    = (first-byte-pos "-" last-byte-pos)
                          / "*"
                          
  instance-length         = 1*DIGIT
  
  other-content-range-spec = other-range-unit SP
                             other-range-resp-spec
  other-range-resp-spec    = *CHAR
]]></artwork></figure>
<t>
   The header field SHOULD indicate the total length of the full representation,
   unless this length is unknown or difficult to determine. The asterisk
   "*" character means that the instance-length is unknown at the time
   when the response was generated.
</t>
<t>
   Unlike byte-ranges-specifier values (see <xref target="byte.ranges"/>), a byte-range-resp-spec
   MUST only specify one range, and MUST contain
   absolute byte positions for both the first and last byte of the
   range.
</t>
<t>
   A byte-content-range-spec with a byte-range-resp-spec whose last-byte-pos
   value is less than its first-byte-pos value, or whose
   instance-length value is less than or equal to its last-byte-pos
   value, is invalid. The recipient of an invalid byte-content-range-spec
   MUST ignore it and any content transferred along with it.
</t>
<t>
   In the case of a byte range request:
   A server sending a response with status code <xref target="status.416" format="none">416 (Requested Range Not
   Satisfiable)</xref> SHOULD include a Content-Range field with a byte-range-resp-spec
   of "*". The instance-length specifies the current length of
   the selected resource. A response with status code <xref target="status.206" format="none">206 (Partial Content)</xref>
   MUST NOT include a Content-Range field with a byte-range-resp-spec of "*".
</t>
<t>
  The "Content-Range" header field has no meaning for status codes that do not 
  explicitly describe its semantic. Currently, only status codes
  <xref target="status.206" format="none">206 (Partial Content)</xref> and <xref target="status.416" format="none">416 (Requested Range Not Satisfiable)</xref> describe
  the meaning of this header field.
</t>
<t>
   Examples of byte-content-range-spec values, assuming that the representation
   contains a total of 1234 bytes:
   <list style="symbols">
      <t>
        The first 500 bytes:
<figure><artwork type="example"><![CDATA[
     bytes 0-499/1234
   ]]></artwork></figure>
      </t>    
      <t>
        The second 500 bytes:
<figure><artwork type="example"><![CDATA[
     bytes 500-999/1234
   ]]></artwork></figure>
      </t>    
      <t>
        All except for the first 500 bytes:
<figure><artwork type="example"><![CDATA[
     bytes 500-1233/1234
   ]]></artwork></figure>
      </t>    
      <t>
        The last 500 bytes:
<figure><artwork type="example"><![CDATA[
     bytes 734-1233/1234
   ]]></artwork></figure>
      </t>    
   </list>
</t>
<t>
   If the server ignores a byte-range-spec (for example if it is
   syntactically invalid, or if it might be seen as a denial-of-service
   attack), the server SHOULD treat the request as if the invalid <xref target="range.retrieval.requests" format="none">Range</xref>
   header field did not exist. (Normally, this means return a 200 (OK)
   response containing the full representation).
</t>
</section>

<section title="If-Range" anchor="header.if-range">
  <iref primary="true" item="If-Range header field"/>
  
<t>
   If a client has a partial copy of a representation and wishes
   to have an up-to-date copy of the entire representation, it could use the
   <xref target="range.retrieval.requests" format="none">Range</xref> header field with a conditional GET (using
   either or both of If-Unmodified-Since and
   If-Match.) However, if the condition fails because the
   representation has been modified, the client would then have to make a
   second request to obtain the entire current representation.
</t>
<t>
   The "If-Range" header field allows a client to "short-circuit" the second
   request. Informally, its meaning is "if the representation is unchanged, send
   me the part(s) that I am missing; otherwise, send me the entire new
   representation".
</t>
<figure><iref primary="true" item="Grammar" subitem="If-Range"/><artwork type="abnf2616"><![CDATA[
  If-Range = entity-tag / HTTP-date
]]></artwork></figure>
<t>
   Clients MUST NOT use an entity-tag marked as weak in an If-Range
   field value and MUST NOT use a Last-Modified date in an
   If-Range field value unless it has no entity-tag for the representation and
   the Last-Modified date it does have for the representation is strong
   in the sense defined by Section 2.2.2 of <xref target="Part4"/>.
</t>
<t>
   A server that evaluates a conditional range request that is applicable
   to one of its representations MUST evaluate the condition as false if
   the entity-tag used as a validator is marked as weak or, when an HTTP-date
   is used as the validator, if the date value is not strong in the sense
   defined by Section 2.2.2 of <xref target="Part4"/>. (A server can distinguish between a
   valid HTTP-date and any form of entity-tag by examining the first
   two characters.)
</t>
<t>
   The If-Range header field SHOULD only be sent by clients together with
   a Range header field.  The If-Range header field MUST be ignored if it
   is received in a request that does not include a Range header field.
   The If-Range header field MUST be ignored by a server that does not
   support the sub-range operation.
</t>
<t>
   If the validator given in the If-Range header field matches the current
   validator for the selected representation of the target resource, then
   the server SHOULD send the specified sub-range of the representation
   using a <xref target="status.206" format="none">206 (Partial Content)</xref> response. If the validator does not match,
   then the server SHOULD send the entire representation using a 200 (OK)
   response.
</t>
</section>

<section title="Range" anchor="header.range">
  <iref primary="true" item="Range header field"/>

<section title="Byte Ranges" anchor="byte.ranges">
<t>
   Since all HTTP representations are transferred as sequences
   of bytes, the concept of a byte range is meaningful for any HTTP
   representation. (However, not all clients and servers need to support byte-range
   operations.)
</t>
<t>
   Byte range specifications in HTTP apply to the sequence of bytes in
   the representation data (not necessarily the same as the message body).
</t>
<t anchor="rule.ranges-specifier">
  
  
  
  
  
  
  
  
   A byte range operation MAY specify a single range of bytes, or a set
   of ranges within a single representation.
</t>
<figure><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"/><artwork type="abnf2616"><![CDATA[
  byte-ranges-specifier = bytes-unit "=" byte-range-set
  byte-range-set  = 1#( byte-range-spec / suffix-byte-range-spec )
  byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
  first-byte-pos  = 1*DIGIT
  last-byte-pos   = 1*DIGIT
]]></artwork></figure>
<t>
   The first-byte-pos value in a byte-range-spec gives the byte-offset
   of the first byte in a range. The last-byte-pos value gives the
   byte-offset of the last byte in the range; that is, the byte
   positions specified are inclusive. Byte offsets start at zero.
</t>
<t>
   If the last-byte-pos value is present, it MUST be greater than or
   equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec
   is syntactically invalid. The recipient of a byte-range-set
   that includes one or more syntactically invalid byte-range-spec
   values MUST ignore the header field that includes that byte-range-set.
</t>
<t>
   If the last-byte-pos value is absent, or if the value is greater than
   or equal to the current length of the representation data, last-byte-pos is
   taken to be equal to one less than the current length of the representation
   in bytes.
</t>
<t>
   By its choice of last-byte-pos, a client can limit the number of
   bytes retrieved without knowing the size of the representation.
</t>
<figure><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/><artwork type="abnf2616"><![CDATA[
  suffix-byte-range-spec = "-" suffix-length
  suffix-length = 1*DIGIT
]]></artwork></figure>
<t>
   A suffix-byte-range-spec is used to specify the suffix of the
   representation data, of a length given by the suffix-length value. (That is,
   this form specifies the last N bytes of a representation.) If the
   representation is shorter than the specified suffix-length, the entire
   representation is used.
</t>
<t>
   If a syntactically valid byte-range-set includes at least one byte-range-spec
   whose first-byte-pos is less than the current length of
   the representation, or at least one suffix-byte-range-spec with a non-zero
   suffix-length, then the byte-range-set is satisfiable.
   Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set
   is unsatisfiable, the server SHOULD return a response with a 
   <xref target="status.416" format="none">416 (Requested Range Not Satisfiable)</xref> status code. Otherwise, the server
   SHOULD return a response with a <xref target="status.206" format="none">206 (Partial Content)</xref> status code
   containing the satisfiable ranges of the representation.
</t>
<t>
   In the byte range syntax, <xref target="rule.ranges-specifier" format="none">first-byte-pos</xref>,
   <xref target="rule.ranges-specifier" format="none">last-byte-pos</xref>, and <xref target="rule.ranges-specifier" format="none">suffix-length</xref> are
   expressed as decimal number of octets.  Since there is no predefined limit
   to the length of an HTTP payload, recipients SHOULD anticipate
   potentially large decimal numerals and prevent parsing errors due to integer
   conversion overflows.
</t>
<t>
   Examples of byte-ranges-specifier values (assuming a representation of
   length 10000):
  <list style="symbols">
     <t>The first 500 bytes (byte offsets 0-499, inclusive):
<figure><artwork type="example"><![CDATA[
     bytes=0-499
   ]]></artwork></figure>
    </t>
     <t>The second 500 bytes (byte offsets 500-999, inclusive):
<figure><artwork type="example"><![CDATA[
     bytes=500-999
   ]]></artwork></figure>
    </t>
     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
<figure><artwork type="example"><![CDATA[
     bytes=-500
   ]]></artwork></figure>
    Or:
<figure><artwork type="example"><![CDATA[
     bytes=9500-
   ]]></artwork></figure>
    </t>
     <t>The first and last bytes only (bytes 0 and 9999):
<figure><artwork type="example"><![CDATA[
     bytes=0-0,-1
   ]]></artwork></figure>
     </t>
     <t>Several legal but not canonical specifications of the second 500
        bytes (byte offsets 500-999, inclusive):
<figure><artwork type="example"><![CDATA[
     bytes=500-600,601-999
     bytes=500-700,601-999
   ]]></artwork></figure>
     </t>
  </list>
</t>
</section>

<section title="Range Retrieval Requests" anchor="range.retrieval.requests">
  
  
  
<t>
   The "Range" header field defines the GET method (conditional or
   not) to request one or more sub-ranges of the response representation data, instead
   of the entire representation data.
</t>
<figure><iref primary="true" item="Grammar" subitem="Range"/><artwork type="abnf2616"><![CDATA[
  Range = byte-ranges-specifier / other-ranges-specifier
  other-ranges-specifier = other-range-unit "=" other-range-set
  other-range-set = 1*CHAR
]]></artwork></figure>
<t>
   A server MAY ignore the Range header field. However, origin
   servers and intermediate caches ought to support byte ranges when
   possible, since Range supports efficient recovery from partially
   failed transfers, and supports efficient partial retrieval of large
   representations.
</t>
<t>
   If the server supports the Range header field and the specified range or
   ranges are appropriate for the representation:
  <list style="symbols">
     <t>The presence of a Range header field in an unconditional GET modifies
        what is returned if the GET is otherwise successful. In other
        words, the response carries a status code of <xref target="status.206" format="none">206 (Partial Content)</xref>
        instead of 200 (OK).</t>

     <t>The presence of a Range header field in a conditional GET (a request
        using one or both of If-Modified-Since and
        If-None-Match, or one or both of
        If-Unmodified-Since and If-Match) modifies
        what is returned if the GET is otherwise successful and the
        condition is true. It does not affect the 304 (Not Modified)
        response returned if the conditional is false.</t>
  </list>
</t>
<t>
   In some cases, it might be more appropriate to use the If-Range
   header field (see <xref target="header.if-range"/>) in addition to the Range
   header field.
</t>
<t>
   If a proxy that supports ranges receives a Range request, forwards 
   the request to an inbound server, and receives an entire representation in
   reply, it MAY only return the requested range to its client. 
</t>
</section>
</section>
</section>

<section title="IANA Considerations" anchor="IANA.considerations">

<section title="Status Code Registration" anchor="status.code.registration">
<t>
   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
   shall be updated with the registrations below:
</t>

<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
   <ttcol>Value</ttcol>
   <ttcol>Description</ttcol>
   <ttcol>Reference</ttcol>
   <c>206</c>
   <c>Partial Content</c>
   <c>
      <xref target="status.206"/>
   </c>
   <c>416</c>
   <c>Requested Range Not Satisfiable</c>
   <c>
      <xref target="status.416"/>
   </c>
</texttable>
<!--(END)-->

</section>

<section title="Header Field Registration" anchor="header.field.registration">
<t>
   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
   with the permanent registrations below (see <xref target="RFC3864"/>):
</t>

<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
   <ttcol>Header Field Name</ttcol>
   <ttcol>Protocol</ttcol>
   <ttcol>Status</ttcol>
   <ttcol>Reference</ttcol>

   <c>Accept-Ranges</c>
   <c>http</c>
   <c>standard</c>
   <c>
      <xref target="header.accept-ranges"/>
   </c>
   <c>Content-Range</c>
   <c>http</c>
   <c>standard</c>
   <c>
      <xref target="header.content-range"/>
   </c>
   <c>If-Range</c>
   <c>http</c>
   <c>standard</c>
   <c>
      <xref target="header.if-range"/>
   </c>
   <c>Range</c>
   <c>http</c>
   <c>standard</c>
   <c>
      <xref target="header.range"/>
   </c>
</texttable>
<!--(END)-->

<t>
   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
</t>
</section>

<section title="Range Specifier Registration" anchor="range.specifier.registration">
<t>
  The registration procedure for HTTP Range Specifiers is defined by 
  <xref target="range.specifier.registry"/> of this document.
</t>
<t>
   The HTTP Range Specifier Registry shall be created at <eref target="http://www.iana.org/assignments/http-range-specifiers"/>
   and be populated with the registrations below:
</t>
<texttable align="left" suppress-title="true" anchor="iana.range.specifiers.table">
   <ttcol>Range Specifier Name</ttcol>
   <ttcol>Description</ttcol>
   <ttcol>Reference</ttcol>

   <c>bytes</c>
   <c>a range of octets</c>
   <c><xref target="range.units"/></c>

   <c>none</c>
   <c>reserved as keyword, indicating no ranges are supported</c>
   <c><xref target="header.accept-ranges"/></c>
</texttable>
<t>
   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
</t>
</section>
</section>

<section title="Security Considerations" anchor="security.considerations">
<t>
   This section is meant to inform application developers, information
   providers, and users of the security limitations in HTTP/1.1 as
   described by this document. The discussion does not include
   definitive solutions to the problems revealed, though it does make
   some suggestions for reducing security risks.
</t>
<section title="Overlapping Ranges" anchor="overlapping.ranges">
<t>
   Range requests containing overlapping ranges can lead to the situation
   where a server is sending far more data than the size of the complete
   resource representation.
</t>
</section>
</section>

<section title="Acknowledgments" anchor="acks">
<t>
  See Section 9 of <xref target="Part1"/>.
</t>
</section>
</middle>
<back>

<references title="Normative References">

<reference anchor="Part1">
  <front>
    <title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="October" year="2012"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-21"/>
  
</reference>

<reference anchor="Part2">
  <front>
    <title>Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="October" year="2012"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-21"/>
  
</reference>

<reference anchor="Part4">
  <front>
    <title>Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="October" year="2012"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-21"/>
  
</reference>

<reference anchor="Part6">
  <front>
    <title>Hypertext Transfer Protocol (HTTP/1.1): Caching</title>
    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
      <address><email>fielding@gbiv.com</email></address>
    </author>
    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
      <organization>Akamai</organization>
      <address><email>mnot@mnot.net</email></address>
    </author>
    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
      <organization abbrev="greenbytes">greenbytes GmbH</organization>
      <address><email>julian.reschke@greenbytes.de</email></address>
    </author>
    <date month="October" year="2012"/>
  </front>
  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-21"/>
  
</reference>

<reference anchor="RFC2046">
  <front>
    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
    <author initials="N." surname="Freed" fullname="Ned Freed">
      <organization>Innosoft International, Inc.</organization>
      <address><email>ned@innosoft.com</email></address>
    </author>
    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
      <organization>First Virtual Holdings</organization>
      <address><email>nsb@nsb.fv.com</email></address>
    </author>
    <date month="November" year="1996"/>
  </front>
  <seriesInfo name="RFC" value="2046"/>
</reference>

<reference anchor="RFC2119">
  <front>
    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
    <author initials="S." surname="Bradner" fullname="Scott Bradner">
      <organization>Harvard University</organization>
      <address><email>sob@harvard.edu</email></address>
    </author>
    <date month="March" year="1997"/>
  </front>
  <seriesInfo name="BCP" value="14"/>
  <seriesInfo name="RFC" value="2119"/>
</reference>

<reference anchor="RFC5234">
  <front>
    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
      <organization>Brandenburg InternetWorking</organization>
      <address>
        <email>dcrocker@bbiw.net</email>
      </address>  
    </author>
    <author initials="P." surname="Overell" fullname="Paul Overell">
      <organization>THUS plc.</organization>
      <address>
        <email>paul.overell@thus.net</email>
      </address>
    </author>
    <date month="January" year="2008"/>
  </front>
  <seriesInfo name="STD" value="68"/>
  <seriesInfo name="RFC" value="5234"/>
</reference>

</references>

<references title="Informative References">

<reference anchor="RFC2616">
  <front>
    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
    <author initials="R." surname="Fielding" fullname="R. Fielding">
      <organization>University of California, Irvine</organization>
      <address><email>fielding@ics.uci.edu</email></address>
    </author>
    <author initials="J." surname="Gettys" fullname="J. Gettys">
      <organization>W3C</organization>
      <address><email>jg@w3.org</email></address>
    </author>
    <author initials="J." surname="Mogul" fullname="J. Mogul">
      <organization>Compaq Computer Corporation</organization>
      <address><email>mogul@wrl.dec.com</email></address>
    </author>
    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
      <organization>MIT Laboratory for Computer Science</organization>
      <address><email>frystyk@w3.org</email></address>
    </author>
    <author initials="L." surname="Masinter" fullname="L. Masinter">
      <organization>Xerox Corporation</organization>
      <address><email>masinter@parc.xerox.com</email></address>
    </author>
    <author initials="P." surname="Leach" fullname="P. Leach">
      <organization>Microsoft Corporation</organization>
      <address><email>paulle@microsoft.com</email></address>
    </author>
    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
      <organization>W3C</organization>
      <address><email>timbl@w3.org</email></address>
    </author>
    <date month="June" year="1999"/>
  </front>
  <seriesInfo name="RFC" value="2616"/>
</reference>

<reference anchor="RFC3864">
  <front>
    <title>Registration Procedures for Message Header Fields</title>
    <author initials="G." surname="Klyne" fullname="G. Klyne">
      <organization>Nine by Nine</organization>
      <address><email>GK-IETF@ninebynine.org</email></address>
    </author>
    <author initials="M." surname="Nottingham" fullname="M. Nottingham">
      <organization>BEA Systems</organization>
      <address><email>mnot@pobox.com</email></address>
    </author>
    <author initials="J." surname="Mogul" fullname="J. Mogul">
      <organization>HP Labs</organization>
      <address><email>JeffMogul@acm.org</email></address>
    </author>
    <date year="2004" month="September"/>
  </front>
  <seriesInfo name="BCP" value="90"/>
  <seriesInfo name="RFC" value="3864"/>
</reference>

<reference anchor="RFC4288">
  <front>
    <title>Media Type Specifications and Registration Procedures</title>
    <author initials="N." surname="Freed" fullname="N. Freed">
      <organization>Sun Microsystems</organization>
      <address>
        <email>ned.freed@mrochek.com</email>
      </address>
    </author>
    <author initials="J." surname="Klensin" fullname="J. Klensin">
      <address>
        <email>klensin+ietf@jck.com</email>
      </address>
    </author>
    <date year="2005" month="December"/>
  </front>
  <seriesInfo name="BCP" value="13"/>
  <seriesInfo name="RFC" value="4288"/>
</reference>

<reference anchor="RFC5226">
  <front>
    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
    <author initials="T." surname="Narten" fullname="T. Narten">
      <organization>IBM</organization>
      <address><email>narten@us.ibm.com</email></address>
    </author>
    <author initials="H." surname="Alvestrand" fullname="H. Alvestrand">
      <organization>Google</organization>
      <address><email>Harald@Alvestrand.no</email></address>
    </author>
    <date year="2008" month="May"/>
  </front>
  <seriesInfo name="BCP" value="26"/>
  <seriesInfo name="RFC" value="5226"/>
</reference>

</references>

<section title="Internet Media Type multipart/byteranges" anchor="internet.media.type.multipart.byteranges">
<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
<iref item="multipart/byteranges Media Type" primary="true"/>
<t>
   When an HTTP <xref target="status.206" format="none">206 (Partial Content)</xref> response message includes the
   content of multiple ranges (a response to a request for multiple
   non-overlapping ranges), these are transmitted as a multipart
   message body (<xref target="RFC2046"/>, Section 5.1). The media type for this purpose is called
   "multipart/byteranges".  The following is to be registered with IANA <xref target="RFC4288"/>.
</t>
<t>
   The multipart/byteranges media type includes one or more parts, each
   with its own Content-Type and <xref target="header.content-range" format="none">Content-Range</xref>
   fields. The required boundary parameter specifies the boundary string used
   to separate each body-part.
</t>
<t>
  <list style="hanging">
    <t hangText="Type name:">
      multipart
    </t>
    <t hangText="Subtype name:">
      byteranges
    </t>
    <t hangText="Required parameters:">
      boundary
    </t>
    <t hangText="Optional parameters:">
      none
    </t>
    <t hangText="Encoding considerations:">
      only "7bit", "8bit", or "binary" are permitted
    </t>
    <t hangText="Security considerations:">
      none
    </t>
    <t hangText="Interoperability considerations:">
      none
    </t>
    <t hangText="Published specification:">
      This specification (see <xref target="internet.media.type.multipart.byteranges"/>).
    </t>
    <t hangText="Applications that use this media type:">
      HTTP components supporting multiple ranges in a single request.
    </t>
    <t hangText="Additional information:">
      <list style="hanging">
        <t hangText="Magic number(s):">none</t>
        <t hangText="File extension(s):">none</t>
        <t hangText="Macintosh file type code(s):">none</t>
      </list>
    </t>
    <t hangText="Person and email address to contact for further information:">
      See Authors Section.
    </t>
    <t hangText="Intended usage:">
      COMMON
    </t>
    <t hangText="Restrictions on usage:">
      none
    </t>
    <t hangText="Author/Change controller:">
      IESG
    </t>
  </list>
</t>
<t><list>
  <t>
    Note: Despite the name "multipart/byteranges" is not limited to the byte ranges only.
  </t>
</list></t>
<figure><preamble>
   For example:
</preamble><artwork type="example"><![CDATA[
  HTTP/1.1 206 Partial Content
  Date: Wed, 15 Nov 1995 06:25:24 GMT
  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
  
  --THIS_STRING_SEPARATES
  Content-type: application/pdf
  Content-range: bytes 500-999/8000
  
  ...the first range...
  --THIS_STRING_SEPARATES
  Content-type: application/pdf
  Content-range: bytes 7000-7999/8000
  
  ...the second range
  --THIS_STRING_SEPARATES--
]]></artwork></figure>
<figure><preamble>
   Another example, using the "exampleunit" range unit:
</preamble>
<artwork type="example"><![CDATA[
  HTTP/1.1 206 Partial Content
  Date: Tue, 14 Nov 1995 06:25:24 GMT
  Last-Modified: Tue, 14 July 04:58:08 GMT
  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
  
  --THIS_STRING_SEPARATES
  Content-type: video/example
  Content-range: exampleunit 1.2-4.3/25
  
  ...the first range...
  --THIS_STRING_SEPARATES
  Content-type: video/example
  Content-range: exampleunit 11.2-14.3/25
  
  ...the second range
  --THIS_STRING_SEPARATES--
]]></artwork>
</figure>
<t>
  Notes:
  <list style="numbers">
      <t>Additional CRLFs MAY precede the first boundary string in the body.</t>

      <t>Although <xref target="RFC2046"/> permits the boundary string to be
         quoted, some existing implementations handle a quoted boundary
         string incorrectly.</t>

      <t>A number of clients and servers were coded to an early draft
         of the byteranges specification to use a media type of
         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>, which is almost, but not quite
         compatible with the version documented in HTTP/1.1.</t>
  </list>
</t>
</section>

<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
<t>
  Introduce Range Specifier Registry.
  (<xref target="range.specifier.registry"/>)
</t>
<t>
  Clarify that it is not ok to use a weak validator in a <xref target="status.206" format="none">206</xref> response.
  (<xref target="status.206"/>)
</t>
<t>
  Clarify that multipart/byteranges can consist of a single part.
  (<xref target="internet.media.type.multipart.byteranges"/>)
</t>
</section>

<section title="Imported ABNF" anchor="imported.abnf">
  
  
  
  
  
  
  
  
  
  
  
  
<t>
  The following core rules are included by
  reference, as defined in Appendix B.1 of <xref target="RFC5234"/>:
  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
  DIGIT (decimal 0-9), DQUOTE (double quote),
  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
  OCTET (any 8-bit sequence of data), SP (space), and
  VCHAR (any visible US-ASCII character).
</t>
<t>
  Note that all rules derived from <xref target="imported.abnf" format="none">token</xref> are to
  be compared case-insensitively, like <xref target="range.units" format="none">range-unit</xref> and
  <xref target="header.accept-ranges" format="none">acceptable-ranges</xref>.
</t>
<t>
  The rules below are defined in <xref target="Part1"/>:
</t>
<figure><artwork type="abnf2616"><![CDATA[
  OWS        = <OWS, defined in [Part1], Section 3.2.1>
  token      = <token, defined in [Part1], Section 3.2.4>
]]></artwork></figure>
<t>
  The rules below are defined in other parts: 
</t>
<figure><artwork type="abnf2616"><![CDATA[
  HTTP-date  = <HTTP-date, defined in [Part2], Section 8.1.1.1>
  entity-tag = <entity-tag, defined in [Part4], Section 2.3>
]]></artwork></figure>
</section> 


<section title="Collected ABNF" anchor="collected.abnf">
<figure>
<artwork type="abnf" name="p5-range.parsed-abnf"><![CDATA[
Accept-Ranges = acceptable-ranges

Content-Range = byte-content-range-spec / other-content-range-spec

HTTP-date = <HTTP-date, defined in [Part2], Section 8.1.1.1>

If-Range = entity-tag / HTTP-date

OWS = <OWS, defined in [Part1], Section 3.2.1>

Range = byte-ranges-specifier / other-ranges-specifier

acceptable-ranges = ( *( "," OWS ) range-unit *( OWS "," [ OWS
 range-unit ] ) ) / "none"

byte-content-range-spec = bytes-unit SP byte-range-resp-spec "/" (
 instance-length / "*" )
byte-range-resp-spec = ( first-byte-pos "-" last-byte-pos ) / "*"
byte-range-set = *( "," OWS ) ( byte-range-spec /
 suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
 suffix-byte-range-spec ) ] )
byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
byte-ranges-specifier = bytes-unit "=" byte-range-set
bytes-unit = "bytes"

entity-tag = <entity-tag, defined in [Part4], Section 2.3>

first-byte-pos = 1*DIGIT

instance-length = 1*DIGIT

last-byte-pos = 1*DIGIT

other-content-range-spec = other-range-unit SP other-range-resp-spec
other-range-resp-spec = *CHAR
other-range-set = 1*CHAR
other-range-unit = token
other-ranges-specifier = other-range-unit "=" other-range-set

range-unit = bytes-unit / other-range-unit

suffix-byte-range-spec = "-" suffix-length
suffix-length = 1*DIGIT

token = <token, defined in [Part1], Section 3.2.4>
]]></artwork>
</figure>
</section>



<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
<t>
  Changes up to the first Working Group Last Call draft are summarized
  in <eref target="http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#appendix-D"/>.
</t>

<section title="Since draft-ietf-httpbis-p5-range-19" anchor="changes.since.19">
<t>
  Closed issues:
  <list style="symbols"> 
    <t>
      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/358"/>:
      "ABNF list expansion code problem"
    </t>
    <t>
      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/361"/>:
      "ABNF requirements for recipients"
    </t>
    <t>
      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/367"/>:
      "reserve 'none' as byte range unit"
    </t>
    <t>
      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/368"/>:
      "note introduction of new IANA registries as normative changes"
    </t>
    <t>
      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/369"/>:
      "range units vs leading zeroes vs size"
    </t>
  </list>
</t>
</section>

<section title="Since draft-ietf-httpbis-p5-range-20" anchor="changes.since.20">
<t>
  <list style="symbols">
    <t>
      Conformance criteria and considerations regarding error handling are
      now defined in Part 1.
    </t>
  </list>
</t>
</section>

</section>

</back>
</rfc>