HTTP/1.1, part 5: Range Requests and Partial Responses

HTTP/1.1, part 5: Range Requests and Partial Responses Adobe Systems Incorporated

345 Park Ave San Jose CA 95110 USA fielding@gbiv.com http://roy.gbiv.com/

Alcatel-Lucent Bell Labs

21 Oak Knoll Road Carlisle MA 01741 USA jg@freedesktop.org http://gettys.wordpress.com/

Hewlett-Packard Company

HP Labs, Large Scale Systems Group 1501 Page Mill Road, MS 1177 Palo Alto CA 94304 USA JeffMogul@acm.org

Microsoft Corporation

1 Microsoft Way Redmond WA 98052 USA henrikn@microsoft.com

Adobe Systems Incorporated

345 Park Ave San Jose CA 95110 USA LMM@acm.org http://larry.masinter.net/

Microsoft Corporation

1 Microsoft Way Redmond WA 98052 paulle@microsoft.com

World Wide Web Consortium

MIT Computer Science and Artificial Intelligence Laboratory The Stata Center, Building 32 32 Vassar Street Cambridge MA 02139 USA timbl@w3.org http://www.w3.org/People/Berners-Lee/

World Wide Web Consortium

W3C / ERCIM 2004, rte des Lucioles Sophia-Antipolis AM 06902 France ylafon@w3.org http://www.raubacapeu.net/people/yves/

greenbytes GmbH

Hafenweg 16 MuensterNW48155 Germany +49 251 2807760 +49 251 2807761 julian.reschke@greenbytes.de http://greenbytes.de/tech/webdav/

HTTPbis Working Group The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document is Part 5 of the seven-part specification that defines the protocol referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 5 defines range-specific requests and the rules for constructing and combining responses to those requests. Discussion of this draft should take place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org). The current issues list is at and related documents (including fancy diffs) can be found at . The changes in this draft are summarized in .

HTTP clients often encounter interrupted data transfers as a result of cancelled requests or dropped connections. When a cache 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. 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. Although the HTTP range request mechanism is designed to allow for extensible range types, this specification only defines requests for byte ranges.

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 . An implementation is not compliant if it fails to satisfy one or more of the "MUST" or "REQUIRED" level requirements for the protocols it implements. An implementation that satisfies all the "MUST" or "REQUIRED" level and all the "SHOULD" level requirements for its protocols is said to be "unconditionally compliant"; one that satisfies all the "MUST" level requirements but not all the "SHOULD" level requirements for its protocols is said to be "conditionally compliant".

This specification uses the ABNF syntax defined in ¬ation; (which extends the syntax defined in with a list rule). shows the collected ABNF, with the list rule expanded. The following core rules are included by reference, as defined in : 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), VCHAR (any visible USASCII character), and WSP (whitespace).

The core rules below are defined in &basic-rules;:

token = <token, defined in &basic-rules;> OWS = <OWS, defined in &basic-rules;>

The ABNF rules below are defined in other parts:

HTTP-date = <HTTP-date, defined in &full-date;>

entity-tag = <entity-tag, defined in &entity-tags;>

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 Range () and Content-Range () header fields. A representation can be broken down into subranges according to various structural units.

range-unit = bytes-unit / other-range-unit bytes-unit = "bytes" other-range-unit = token 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 . If a range unit is not understood in a request, a server &MUST; ignore the whole Range header field (). If a range unit is not understood in a response, an intermediary &SHOULD; pass the response to the client; a client &MUST; fail.

The HTTP Ranger Specifier Registry defines the name space for the range specifier names. Registrations &MUST; include the following fields: Name Description Pointer to specification text Values to be added to this name space are subject to IETF review (). The registry itself is maintained at .

The server has fulfilled the partial GET request for the resource. The request &MUST; have included a Range header field () indicating the desired range, and &MAY; have included an If-Range header field () to make the request conditional. The response &MUST; include the following header fields: Either a Content-Range header field () 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. Date Cache-Control, ETag, Expires, Content-Location, Last-Modified, and/or Vary, if the header field would have been sent in a 200 response to the same request If the 206 response is the result of an If-Range request, the response &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. A cache &MUST-NOT; combine a 206 response with other previously cached content if the ETag or Last-Modified header fields do not match exactly, see . A cache that does not support the Range and Content-Range header fields &MUST-NOT; cache 206 (Partial Content) responses. Furthermore, if a response uses a range unit that is not understood by the cache, then it &MUST-NOT; be cached either.

A server &SHOULD; return a response with this status code if a request included a Range header field (), 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 If-Range header field (). (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.) When this status code is returned for a byte-range request, the response &SHOULD; include a Content-Range header field specifying the current length of the representation (see ). This response &MUST-NOT; use the multipart/byteranges content-type.

A response might transfer only a subrange of a representation, either because the request included one or more Range specifications, or because a connection closed prematurely. After several such transfers, a cache might have received several ranges of the same representation. If a cache has a stored non-empty set of subranges for a representation, and an incoming response transfers another subrange, the cache &MAY; combine the new subrange with the existing set if both the following conditions are met: Both the incoming response and the cache entry have a cache validator. The two cache validators match using the strong comparison function (see &weak-and-strong-validators;). If either requirement is not met, the cache &MUST; use only the most recent partial response (based on the Date values transmitted with every response, and using the incoming response if these values are equal or missing), and &MUST; discard the other partial information.

This section defines the syntax and semantics of HTTP/1.1 header fields related to range requests and partial responses.

The "Accept-Ranges" header field allows a resource to indicate its acceptance of range requests.

Accept-Ranges = "Accept-Ranges" ":" OWS Accept-Ranges-v Accept-Ranges-v = acceptable-ranges acceptable-ranges = 1#range-unit / "none" Origin servers that accept byte-range requests &MAY; send

Accept-Ranges: bytes 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 . Servers that do not accept any kind of range request for a resource &MAY; send

Accept-Ranges: none to advise the client not to attempt a range request.

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. Range units are defined in .

Content-Range = "Content-Range" ":" OWS Content-Range-v Content-Range-v = content-range-spec content-range-spec = 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 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. Unlike byte-ranges-specifier values (see ), 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. 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. In the case of a byte range request: A server sending a response with status code 416 (Requested range not satisfiable) &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 206 (Partial Content) &MUST-NOT; include a Content-Range field with a byte-range-resp-spec of "*". Examples of byte-content-range-spec values, assuming that the representation contains a total of 1234 bytes: The first 500 bytes:

bytes 0-499/1234 The second 500 bytes:

bytes 500-999/1234 All except for the first 500 bytes:

bytes 500-1233/1234 The last 500 bytes:

bytes 734-1233/1234 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 Content-Range header field, and a Content-Length header field showing the number of bytes actually transferred. For example,

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 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 . 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. When a client requests multiple ranges in one request, the server &SHOULD; return them in the order that they appeared in the request. If the server ignores a byte-range-spec because it is syntactically invalid, the server &SHOULD; treat the request as if the invalid Range header field did not exist. (Normally, this means return a 200 response containing the full representation). If the server receives a request (other than one including an If-Range header field) with an unsatisfiable Range header field (that is, all of whose byte-range-spec values have a first-byte-pos value greater than the current length of the selected resource), it &SHOULD; return a response code of 416 (Requested range not satisfiable) (). Note: Clients cannot depend on servers to send a 416 (Requested range not satisfiable) response instead of a 200 (OK) response for an unsatisfiable Range header field, since not all servers implement this header field.

If a client has a partial copy of a representation in its cache, and wishes to have an up-to-date copy of the entire representation in its cache, it could use the Range 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. 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".

If-Range = "If-Range" ":" OWS If-Range-v If-Range-v = entity-tag / HTTP-date If the client has no entity-tag for a representation, but does have a Last-Modified date, it &MAY; use that date in an If-Range header field. (The server can distinguish between a valid HTTP-date and any form of entity-tag by examining no more than two characters.) The If-Range header field &SHOULD; only be used together with a Range header field, and &MUST; be ignored if the request does not include a Range header field, or if the server does not support the sub-range operation. If the entity-tag given in the If-Range header field matches the current cache validator for the representation, then the server &SHOULD; provide the specified sub-range of the representation using a 206 (Partial Content) response. If the cache validator does not match, then the server &SHOULD; return the entire representation using a 200 (OK) response.

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.) Byte range specifications in HTTP apply to the sequence of bytes in the representation body (not necessarily the same as the message-body).

A byte range operation &MAY; specify a single range of bytes, or a set of ranges within a single representation.

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 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. 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. If the last-byte-pos value is absent, or if the value is greater than or equal to the current length of the representation body, last-byte-pos is taken to be equal to one less than the current length of the representation in bytes. By its choice of last-byte-pos, a client can limit the number of bytes retrieved without knowing the size of the representation.

suffix-byte-range-spec = "-" suffix-length suffix-length = 1*DIGIT A suffix-byte-range-spec is used to specify the suffix of the representation body, 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. 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 416 (Requested range not satisfiable) status code. Otherwise, the server &SHOULD; return a response with a 206 (Partial Content) status code containing the satisfiable ranges of the representation. Examples of byte-ranges-specifier values (assuming a representation of length 10000): The first 500 bytes (byte offsets 0-499, inclusive):

bytes=0-499 The second 500 bytes (byte offsets 500-999, inclusive):

bytes=500-999 The final 500 bytes (byte offsets 9500-9999, inclusive):

bytes=-500 Or:

bytes=9500- The first and last bytes only (bytes 0 and 9999):

bytes=0-0,-1 Several legal but not canonical specifications of the second 500 bytes (byte offsets 500-999, inclusive):

bytes=500-600,601-999 bytes=500-700,601-999

The "Range" header field defines the GET method (conditional or not) to request one or more sub-ranges of the response representation body, instead of the entire representation body.

Range = "Range" ":" OWS Range-v Range-v = byte-ranges-specifier / other-ranges-specifier other-ranges-specifier = other-range-unit "=" other-range-set other-range-set = 1*CHAR A server &MAY; ignore the Range header field. However, HTTP/1.1 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. If the server supports the Range header field and the specified range or ranges are appropriate for the representation: 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 206 (Partial Content) instead of 200 (OK). 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. In some cases, it might be more appropriate to use the If-Range header field (see ) in addition to the Range header field. 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.

The HTTP Status Code Registry located at shall be updated with the registrations below: Value Description Reference 206 Partial Content 416 Requested Range Not Satisfiable

The Message Header Field Registry located at shall be updated with the permanent registrations below (see ): Header Field Name Protocol Status Reference Accept-Ranges http standard Content-Range http standard If-Range http standard Range http standard The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".

The registration procedure for HTTP Range Specifiers is defined by of this document. The HTTP Range Specifier Registry shall be created at and be populated with the registrations below: Range Specifier Name Description Reference bytes a range of octets (this specification) The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".

No additional security considerations have been identified beyond those applicable to HTTP in general &messaging;.

Most of the specification of ranges is based on work originally done by Ari Luotonen and John Franks, with additional input from Steve Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin Hamilton, Koen Holtman, Shel Kaplan, Paul Leach, Alex Lopez-Ortiz, Larry Masinter, Jeff Mogul, Lou Montulli, David W. Morris, Luigi Rizzo, and Bill Weihl.

HTTP/1.1, part 1: URIs, Connections, and Message Parsing Adobe Systems Incorporated

fielding@gbiv.com

Alcatel-Lucent Bell Labs

jg@freedesktop.org

Hewlett-Packard Company

JeffMogul@acm.org

Microsoft Corporation

henrikn@microsoft.com

Adobe Systems Incorporated

LMM@acm.org

Microsoft Corporation

paulle@microsoft.com

World Wide Web Consortium

timbl@w3.org

World Wide Web Consortium

ylafon@w3.org

greenbytes GmbH

julian.reschke@greenbytes.de

HTTP/1.1, part 4: Conditional Requests Adobe Systems Incorporated

fielding@gbiv.com

Alcatel-Lucent Bell Labs

jg@freedesktop.org

Hewlett-Packard Company

JeffMogul@acm.org

Microsoft Corporation

henrikn@microsoft.com

Adobe Systems Incorporated

LMM@acm.org

Microsoft Corporation

paulle@microsoft.com

World Wide Web Consortium

timbl@w3.org

World Wide Web Consortium

ylafon@w3.org

greenbytes GmbH

julian.reschke@greenbytes.de

Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types Innosoft International, Inc.

ned@innosoft.com

First Virtual Holdings

nsb@nsb.fv.com

Key words for use in RFCs to Indicate Requirement Levels Harvard University

sob@harvard.edu

Augmented BNF for Syntax Specifications: ABNF Brandenburg InternetWorking

dcrocker@bbiw.net

THUS plc.

paul.overell@thus.net

Hypertext Transfer Protocol -- HTTP/1.1 University of California, Irvine

fielding@ics.uci.edu

W3C

jg@w3.org

Compaq Computer Corporation

mogul@wrl.dec.com

MIT Laboratory for Computer Science

frystyk@w3.org

Xerox Corporation

masinter@parc.xerox.com

Microsoft Corporation

paulle@microsoft.com

W3C

timbl@w3.org

Registration Procedures for Message Header Fields Nine by Nine

GK-IETF@ninebynine.org

BEA Systems

mnot@pobox.com

HP Labs

JeffMogul@acm.org

Media Type Specifications and Registration Procedures Sun Microsystems

ned.freed@mrochek.com

klensin+ietf@jck.com

Guidelines for Writing an IANA Considerations Section in RFCs IBM

narten@us.ibm.com

Google

Harald@Alvestrand.no

When an HTTP 206 (Partial Content) 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 (). The media type for this purpose is called "multipart/byteranges". The following is to be registered with IANA . Note: Despite the name "multipart/byteranges" is not limited to the byte ranges only. The multipart/byteranges media type includes one or more parts, each with its own Content-Type and Content-Range fields. The required boundary parameter specifies the boundary string used to separate each body-part. multipart byteranges boundary none only "7bit", "8bit", or "binary" are permitted none none This specification (see ). none none none See Authors Section. COMMON none IESG

For example: 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--

Other example: 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-- Notes: Additional CRLFs &MAY; precede the first boundary string in the body. Although permits the boundary string to be quoted, some existing implementations handle a quoted boundary string incorrectly. A number of browsers and servers were coded to an early draft of the byteranges specification to use a media type of multipart/x-byteranges, which is almost, but not quite compatible with the version documented in HTTP/1.1.

Clarify that it is not ok to use a weak cache validator in a 206 response. () Clarify that multipart/byteranges can consist of a single part. ()

Accept-Ranges = "Accept-Ranges:" OWS Accept-Ranges-v Accept-Ranges-v = acceptable-ranges Content-Range = "Content-Range:" OWS Content-Range-v Content-Range-v = content-range-spec HTTP-date = <HTTP-date, defined in [Part1], Section 6.1> If-Range = "If-Range:" OWS If-Range-v If-Range-v = entity-tag / HTTP-date OWS = <OWS, defined in [Part1], Section 1.2.2> Range = "Range:" OWS Range-v Range-v = 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" content-range-spec = byte-content-range-spec / other-content-range-spec entity-tag = <entity-tag, defined in [Part4], Section 2> 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 1.2.2>

ABNF diagnostics: ; Accept-Ranges defined but not used ; Content-Range defined but not used ; If-Range defined but not used ; Range defined but not used

Extracted relevant partitions from .

Closed issues: : "Cache validators in 206 responses" () : "Normative and Informative references" : "Normative up-to-date references"

Closed issues: : "Updating to RFC4288" Ongoing work on ABNF conversion (): Add explicit references to BNF syntax and rules imported from other parts of the specification.

Ongoing work on IANA Message Header Field Registration (): Reference RFC 3984, and update header field registrations for headers defined in this document.

Closed issues: : "multipart/byteranges minimum number of parts" Ongoing work on ABNF conversion (): Use "/" instead of "|" for alternatives. Introduce new ABNF rules for "bad" whitespace ("BWS"), optional whitespace ("OWS") and required whitespace ("RWS"). Rewrite ABNFs to spell out whitespace rules, factor out header field value format definitions.

Closed issues: : "State base for *-byte-pos and suffix-length" Ongoing work on Custom Ranges (): Remove bias in favor of byte ranges; allow custom ranges in ABNF. Final work on ABNF conversion (): Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.

Closed issues: : "base for numeric protocol elements"

Closed issues: Fixed discrepancy in the If-Range definition about allowed validators. : "multipart/byteranges for custom range units" : "range unit missing from other-ranges-specifier in Range header" : "move IANA registrations for optional status codes"

No significant changes.

Closed issues: : "Clarify 'Requested Variant'" : "Clarify entity / representation / variant terminology" : "consider removing the 'changes from 2068' sections" Ongoing work on Custom Ranges (): Add IANA registry.

Closed issues: : "Caches can't be required to serve ranges"

Closed issues: : "Header Classification"