Changeset 1643 for draft-ietf-httpbis/latest/p2-semantics.xml
- Timestamp:
- 30/03/12 15:19:59 (11 years ago)
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draft-ietf-httpbis/latest/p2-semantics.xml
r1642 r1643 20 20 <!ENTITY acks "<xref target='Part1' x:rel='#acks' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 21 21 <!ENTITY messaging "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 22 <!ENTITY payload "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">23 22 <!ENTITY conditional "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 24 23 <!ENTITY range "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 25 24 <!ENTITY caching "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 26 25 <!ENTITY auth "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 27 <!ENTITY content-negotiation "<xref target=' Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">28 <!ENTITY agent-driven-negotiation "<xref target=' Part3' x:rel='#agent-driven.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">26 <!ENTITY content-negotiation "<xref target='content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 27 <!ENTITY agent-driven-negotiation "<xref target='agent-driven.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 29 28 <!ENTITY abnf-extension "<xref target='Part1' x:rel='#abnf.extension' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 30 29 <!ENTITY whitespace "<xref target='Part1' x:rel='#whitespace' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 37 36 <!ENTITY http-version "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 38 37 <!ENTITY use100 "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 39 <!ENTITY qvalue "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">40 38 <!ENTITY request-target "<xref target='Part1' x:rel='#request-target' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 41 <!ENTITY header-accept "<xref target=' Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">42 <!ENTITY header-accept-charset "<xref target=' Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">43 <!ENTITY header-accept-encoding "<xref target=' Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">44 <!ENTITY header-accept-language "<xref target=' Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">39 <!ENTITY header-accept "<xref target='header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 40 <!ENTITY header-accept-charset "<xref target='header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 41 <!ENTITY header-accept-encoding "<xref target='header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 42 <!ENTITY header-accept-language "<xref target='header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 45 43 <!ENTITY header-accept-ranges "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 46 44 <!ENTITY header-age "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 48 46 <!ENTITY header-cache-control "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 49 47 <!ENTITY header-connection "<xref target='Part1' x:rel='#header.connection' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 50 <!ENTITY header-content-location "<xref target=' Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">48 <!ENTITY header-content-location "<xref target='header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 51 49 <!ENTITY header-content-range "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 52 <!ENTITY header-content-type "<xref target=' Part3' x:rel='#header.content-type' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">50 <!ENTITY header-content-type "<xref target='header.content-type' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 53 51 <!ENTITY header-etag "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 54 52 <!ENTITY header-expires "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 70 68 <!ENTITY header-warning "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 71 69 <!ENTITY header-www-authenticate "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 72 <!ENTITY media-types "<xref target=' Part3' x:rel='#media.types' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">70 <!ENTITY media-types "<xref target='media.types' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 73 71 <!ENTITY message-body "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 74 72 <!ENTITY media-type-message-http "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 79 77 <!ENTITY status-412 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 80 78 <!ENTITY status-416 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 81 <!ENTITY p3-header-fields "<xref target='Part3' x:rel='#header.field.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">82 79 <!ENTITY p4-status-codes "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 83 80 <!ENTITY p5-status-codes "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 100 97 <!ENTITY header-expires "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 101 98 <!ENTITY header-last-modified "<xref target='Part4' x:rel='#header.last-modified' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 102 <!ENTITY header-user-agent "<xref target=' Part2' x:rel='#header.user-agent' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">99 <!ENTITY header-user-agent "<xref target='header.user-agent' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 103 100 <!ENTITY header-vary "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 104 101 <!ENTITY message-body "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 105 102 <!ENTITY multipart-byteranges "<xref target='Part5' x:rel='#internet.media.type.multipart.byteranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 106 <!ENTITY http-date "<xref target=' Part2' x:rel='#http.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">103 <!ENTITY http-date "<xref target='http.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 107 104 <!ENTITY qvalue "<xref target='Part1' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 108 105 <!ENTITY uri "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> … … 113 110 <!ENTITY deflate-coding "<xref target='Part1' x:rel='#deflate.coding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 114 111 <!ENTITY gzip-coding "<xref target='Part1' x:rel='#gzip.coding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 115 <!ENTITY response-representation "<xref target=' Part2' x:rel='#identifying.response.associated.with.representation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">112 <!ENTITY response-representation "<xref target='identifying.response.associated.with.representation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>"> 116 113 ]> 117 114 <?rfc toc="yes" ?> … … 1830 1827 The resource identified by the request is only capable of generating 1831 1828 response representations which have content characteristics not acceptable 1832 according to the Accept and Accept-* header fields sent in the request 1833 (see &p3-header-fields;). 1829 according to the Accept and Accept-* header fields sent in the request. 1834 1830 </t> 1835 1831 <t> … … 2117 2113 consists of metadata (representation header fields) and data (representation 2118 2114 body). When a complete or partial representation is enclosed in an HTTP message, 2119 it is referred to as the payload of the message. HTTP representations 2120 are defined in &payload;. 2115 it is referred to as the payload of the message. 2121 2116 </t> 2122 2117 <t> … … 3086 3081 <ttcol>Reference</ttcol> 3087 3082 3083 <c>Accept</c> 3084 <c>http</c> 3085 <c>standard</c> 3086 <c> 3087 <xref target="header.accept"/> 3088 </c> 3089 <c>Accept-Charset</c> 3090 <c>http</c> 3091 <c>standard</c> 3092 <c> 3093 <xref target="header.accept-charset"/> 3094 </c> 3095 <c>Accept-Encoding</c> 3096 <c>http</c> 3097 <c>standard</c> 3098 <c> 3099 <xref target="header.accept-encoding"/> 3100 </c> 3101 <c>Accept-Language</c> 3102 <c>http</c> 3103 <c>standard</c> 3104 <c> 3105 <xref target="header.accept-language"/> 3106 </c> 3088 3107 <c>Allow</c> 3089 3108 <c>http</c> … … 3091 3110 <c> 3092 3111 <xref target="header.allow"/> 3112 </c> 3113 <c>Content-Encoding</c> 3114 <c>http</c> 3115 <c>standard</c> 3116 <c> 3117 <xref target="header.content-encoding"/> 3118 </c> 3119 <c>Content-Language</c> 3120 <c>http</c> 3121 <c>standard</c> 3122 <c> 3123 <xref target="header.content-language"/> 3124 </c> 3125 <c>Content-Location</c> 3126 <c>http</c> 3127 <c>standard</c> 3128 <c> 3129 <xref target="header.content-location"/> 3130 </c> 3131 <c>Content-Type</c> 3132 <c>http</c> 3133 <c>standard</c> 3134 <c> 3135 <xref target="header.content-type"/> 3093 3136 </c> 3094 3137 <c>Date</c> … … 3115 3158 <c> 3116 3159 <xref target="header.location"/> 3160 </c> 3161 <c>MIME-Version</c> 3162 <c>http</c> 3163 <c>standard</c> 3164 <c> 3165 <xref target="mime-version"/> 3117 3166 </c> 3118 3167 <c>Max-Forwards</c> … … 3313 3362 </reference> 3314 3363 3315 <reference anchor="Part3">3316 <front>3317 <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>3318 <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">3319 <organization abbrev="Adobe">Adobe Systems Incorporated</organization>3320 <address><email>fielding@gbiv.com</email></address>3321 </author>3322 <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">3323 <organization abbrev="W3C">World Wide Web Consortium</organization>3324 <address><email>ylafon@w3.org</email></address>3325 </author>3326 <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">3327 <organization abbrev="greenbytes">greenbytes GmbH</organization>3328 <address><email>julian.reschke@greenbytes.de</email></address>3329 </author>3330 <date month="&ID-MONTH;" year="&ID-YEAR;"/>3331 </front>3332 <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>3333 <x:source href="p3-payload.xml" basename="p3-payload"/>3334 </reference>3335 3336 3364 <reference anchor="Part4"> 3337 3365 <front> … … 4086 4114 <figure> 4087 4115 <artwork type="abnf" name="p2-semantics.parsed-abnf"> 4116 <x:ref>Accept</x:ref> = [ ( "," / ( media-range [ accept-params ] ) ) *( OWS "," [ 4117 OWS media-range [ accept-params ] ] ) ] 4118 <x:ref>Accept-Charset</x:ref> = *( "," OWS ) ( charset / "*" ) [ OWS ";" OWS "q=" 4119 qvalue ] *( OWS "," [ OWS ( charset / "*" ) [ OWS ";" OWS "q=" 4120 qvalue ] ] ) 4121 <x:ref>Accept-Encoding</x:ref> = [ ( "," / ( codings [ OWS ";" OWS "q=" qvalue ] ) ) 4122 *( OWS "," [ OWS codings [ OWS ";" OWS "q=" qvalue ] ] ) ] 4123 <x:ref>Accept-Language</x:ref> = *( "," OWS ) language-range [ OWS ";" OWS "q=" 4124 qvalue ] *( OWS "," [ OWS language-range [ OWS ";" OWS "q=" qvalue ] 4125 ] ) 4088 4126 <x:ref>Allow</x:ref> = [ ( "," / method ) *( OWS "," [ OWS method ] ) ] 4089 4127 4090 4128 <x:ref>BWS</x:ref> = <BWS, defined in [Part1], Section 3.2.1> 4091 4129 4130 <x:ref>Content-Encoding</x:ref> = *( "," OWS ) content-coding *( OWS "," [ OWS 4131 content-coding ] ) 4132 <x:ref>Content-Language</x:ref> = *( "," OWS ) language-tag *( OWS "," [ OWS 4133 language-tag ] ) 4134 <x:ref>Content-Location</x:ref> = absolute-URI / partial-URI 4135 <x:ref>Content-Type</x:ref> = media-type 4136 4092 4137 <x:ref>Date</x:ref> = HTTP-date 4093 4138 … … 4102 4147 <x:ref>Location</x:ref> = URI-reference 4103 4148 4149 <x:ref>MIME-Version</x:ref> = 1*DIGIT "." 1*DIGIT 4150 4104 4151 <x:ref>Max-Forwards</x:ref> = 1*DIGIT 4105 4152 … … 4107 4154 4108 4155 <x:ref>RWS</x:ref> = <RWS, defined in [Part1], Section 3.2.1> 4156 4109 4157 <x:ref>Referer</x:ref> = absolute-URI / partial-URI 4110 4158 <x:ref>Retry-After</x:ref> = HTTP-date / delta-seconds … … 4113 4161 4114 4162 <x:ref>URI-reference</x:ref> = <URI-reference, defined in [Part1], Section 2.7> 4163 4115 4164 <x:ref>User-Agent</x:ref> = product *( RWS ( product / comment ) ) 4116 4165 4117 4166 <x:ref>absolute-URI</x:ref> = <absolute-URI, defined in [Part1], Section 2.7> 4167 4168 <x:ref>accept-ext</x:ref> = OWS ";" OWS token [ "=" word ] 4169 <x:ref>accept-params</x:ref> = OWS ";" OWS "q=" qvalue *accept-ext 4118 4170 <x:ref>asctime-date</x:ref> = day-name SP date3 SP time-of-day SP year 4119 4171 <x:ref>attribute</x:ref> = token 4172 4173 <x:ref>charset</x:ref> = token 4174 4175 <x:ref>codings</x:ref> = content-coding / "identity" / "*" 4120 4176 <x:ref>comment</x:ref> = <comment, defined in [Part1], Section 3.2.4> 4177 <x:ref>content-coding</x:ref> = token 4121 4178 4122 4179 <x:ref>date1</x:ref> = day SP month SP year 4180 4123 4181 <x:ref>date2</x:ref> = day "-" month "-" 2DIGIT 4124 4182 <x:ref>date3</x:ref> = month SP ( 2DIGIT / ( SP DIGIT ) ) … … 4141 4199 4142 4200 <x:ref>expect-name</x:ref> = token 4201 4143 4202 <x:ref>expect-param</x:ref> = expect-name [ BWS "=" BWS expect-value ] 4144 4203 <x:ref>expect-value</x:ref> = token / quoted-string … … 4148 4207 <x:ref>hour</x:ref> = 2DIGIT 4149 4208 4209 <x:ref>language-range</x:ref> = <language-range, defined in [RFC4647], Section 2.1> 4210 4211 <x:ref>language-tag</x:ref> = <Language-Tag, defined in [RFC5646], Section 2.1> 4212 4150 4213 <x:ref>mailbox</x:ref> = <mailbox, defined in [RFC5322], Section 3.4> 4214 4215 <x:ref>media-range</x:ref> = ( "*/*" / ( type "/*" ) / ( type "/" subtype ) ) *( OWS 4216 ";" OWS parameter ) 4217 <x:ref>media-type</x:ref> = type "/" subtype *( OWS ";" OWS parameter ) 4151 4218 <x:ref>method</x:ref> = token 4152 4219 <x:ref>minute</x:ref> = 2DIGIT … … 4165 4232 4166 4233 <x:ref>obs-date</x:ref> = rfc850-date / asctime-date 4234 4167 4235 <x:ref>obs-text</x:ref> = <obs-text, defined in [Part1], Section 3.2.4> 4236 4237 <x:ref>parameter</x:ref> = attribute "=" value 4168 4238 4169 4239 <x:ref>partial-URI</x:ref> = <partial-URI, defined in [Part1], Section 2.7> … … 4174 4244 4175 4245 <x:ref>rfc1123-date</x:ref> = day-name "," SP date1 SP time-of-day SP GMT 4246 4176 4247 <x:ref>rfc850-date</x:ref> = day-name-l "," SP date2 SP time-of-day SP GMT 4177 4248 4178 4249 <x:ref>second</x:ref> = 2DIGIT 4179 4250 4251 <x:ref>subtype</x:ref> = token 4252 4180 4253 <x:ref>time-of-day</x:ref> = hour ":" minute ":" second 4254 4181 4255 <x:ref>token</x:ref> = <token, defined in [Part1], Section 3.2.4> 4182 4183 word = <word, defined in [Part1], Section 3.2.4> 4256 <x:ref>type</x:ref> = token 4257 4258 <x:ref>value</x:ref> = word 4259 4260 <x:ref>word</x:ref> = <word, defined in [Part1], Section 3.2.4> 4184 4261 4185 4262 <x:ref>year</x:ref> = 4DIGIT … … 4187 4264 </figure> 4188 4265 <figure><preamble>ABNF diagnostics:</preamble><artwork type="inline"> 4266 ; qvalue UNDEFINED 4267 ; Accept defined but not used 4268 ; Accept-Charset defined but not used 4269 ; Accept-Encoding defined but not used 4270 ; Accept-Language defined but not used 4189 4271 ; Allow defined but not used 4272 ; Content-Encoding defined but not used 4273 ; Content-Language defined but not used 4274 ; Content-Location defined but not used 4275 ; Content-Type defined but not used 4190 4276 ; Date defined but not used 4191 4277 ; Expect defined but not used 4192 4278 ; From defined but not used 4193 4279 ; Location defined but not used 4280 ; MIME-Version defined but not used 4194 4281 ; Max-Forwards defined but not used 4195 4282 ; Referer defined but not used … … 4198 4285 ; User-Agent defined but not used 4199 4286 ; obs-text defined but not used 4200 ; word defined but not used4201 4287 </artwork></figure></section> 4202 4288 <?ENDINC p2-semantics.abnf-appendix ?> … … 4844 4930 </section> 4845 4931 4932 <section title="THE TEXT FORMERLY KNOWN AS PART3"> 4933 <section title="Protocol Parameters" anchor="protocol.parameters"> 4934 4935 <section title="Character Encodings (charset)" anchor="character.sets"> 4936 <t> 4937 HTTP uses charset names to indicate the character encoding of a 4938 textual representation. 4939 </t> 4940 <t anchor="rule.charset"> 4941 <x:anchor-alias value="charset"/> 4942 A character encoding is identified by a case-insensitive token. The 4943 complete set of tokens is defined by the IANA Character Set registry 4944 (<eref target="http://www.iana.org/assignments/character-sets"/>). 4945 </t> 4946 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="charset"/> 4947 <x:ref>charset</x:ref> = <x:ref>token</x:ref> 4948 </artwork></figure> 4949 <t> 4950 Although HTTP allows an arbitrary token to be used as a charset 4951 value, any token that has a predefined value within the IANA 4952 Character Set registry &MUST; represent the character encoding defined 4953 by that registry. Applications &SHOULD; limit their use of character 4954 encodings to those defined within the IANA registry. 4955 </t> 4956 <t> 4957 HTTP uses charset in two contexts: within an Accept-Charset request 4958 header field (in which the charset value is an unquoted token) and as the 4959 value of a parameter in a Content-Type header field (within a request or 4960 response), in which case the parameter value of the charset parameter 4961 can be quoted. 4962 </t> 4963 <t> 4964 Implementors need to be aware of IETF character set requirements <xref target="RFC3629"/> 4965 <xref target="RFC2277"/>. 4966 </t> 4967 </section> 4968 4969 <section title="Content Codings" anchor="content.codings"> 4970 <x:anchor-alias value="content-coding"/> 4971 <t> 4972 Content coding values indicate an encoding transformation that has 4973 been or can be applied to a representation. Content codings are primarily 4974 used to allow a representation to be compressed or otherwise usefully 4975 transformed without losing the identity of its underlying media type 4976 and without loss of information. Frequently, the representation is stored in 4977 coded form, transmitted directly, and only decoded by the recipient. 4978 </t> 4979 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="content-coding"/> 4980 <x:ref>content-coding</x:ref> = <x:ref>token</x:ref> 4981 </artwork></figure> 4982 <t> 4983 All content-coding values are case-insensitive. HTTP/1.1 uses 4984 content-coding values in the Accept-Encoding (<xref target="header.accept-encoding"/>) and 4985 Content-Encoding (<xref target="header.content-encoding"/>) header fields. Although the value 4986 describes the content-coding, what is more important is that it 4987 indicates what decoding mechanism will be required to remove the 4988 encoding. 4989 </t> 4990 <t> 4991 compress<iref item="compress (Coding Format)"/><iref item="Coding Format" subitem="compress"/> 4992 <list> 4993 <t> 4994 See &compress-coding;. 4995 </t> 4996 </list> 4997 </t> 4998 <t> 4999 deflate<iref item="deflate (Coding Format)"/><iref item="Coding Format" subitem="deflate"/> 5000 <list> 5001 <t> 5002 See &deflate-coding;. 5003 </t> 5004 </list> 5005 </t> 5006 <t> 5007 gzip<iref item="gzip (Coding Format)"/><iref item="Coding Format" subitem="gzip"/> 5008 <list> 5009 <t> 5010 See &gzip-coding;. 5011 </t> 5012 </list> 5013 </t> 5014 5015 <section title="Content Coding Registry" anchor="content.coding.registry"> 5016 <t> 5017 The HTTP Content Coding Registry defines the name space for the content 5018 coding names. 5019 </t> 5020 <t> 5021 Registrations &MUST; include the following fields: 5022 <list style="symbols"> 5023 <t>Name</t> 5024 <t>Description</t> 5025 <t>Pointer to specification text</t> 5026 </list> 5027 </t> 5028 <t> 5029 Names of content codings &MUST-NOT; overlap with names of transfer codings 5030 (&transfer-codings;), unless the encoding transformation is identical (as 5031 is the case for the compression codings defined in 5032 &compression-codings;). 5033 </t> 5034 <t> 5035 Values to be added to this name space require IETF Review 5036 (see <xref target="RFC5226" x:fmt="of" x:sec="4.1"/>), and &MUST; 5037 conform to the purpose of content coding defined in this section. 5038 </t> 5039 <t> 5040 The registry itself is maintained at 5041 <eref target="http://www.iana.org/assignments/http-parameters"/>. 5042 </t> 5043 </section> 5044 5045 </section> 5046 5047 <section title="Media Types" anchor="media.types"> 5048 <x:anchor-alias value="media-type"/> 5049 <x:anchor-alias value="type"/> 5050 <x:anchor-alias value="subtype"/> 5051 <t> 5052 HTTP uses Internet Media Types <xref target="RFC2046"/> in the Content-Type (<xref target="header.content-type"/>) 5053 and Accept (<xref target="header.accept"/>) header fields in order to provide 5054 open and extensible data typing and type negotiation. 5055 </t> 5056 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="media-type"/><iref primary="true" item="Grammar" subitem="type"/><iref primary="true" item="Grammar" subitem="subtype"/> 5057 <x:ref>media-type</x:ref> = <x:ref>type</x:ref> "/" <x:ref>subtype</x:ref> *( <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>parameter</x:ref> ) 5058 <x:ref>type</x:ref> = <x:ref>token</x:ref> 5059 <x:ref>subtype</x:ref> = <x:ref>token</x:ref> 5060 </artwork></figure> 5061 <t anchor="rule.parameter"> 5062 <x:anchor-alias value="attribute"/> 5063 <x:anchor-alias value="parameter"/> 5064 <x:anchor-alias value="value"/> 5065 The type/subtype &MAY; be followed by parameters in the form of 5066 attribute/value pairs. 5067 </t> 5068 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="parameter"/><iref primary="true" item="Grammar" subitem="attribute"/><iref primary="true" item="Grammar" subitem="value"/> 5069 <x:ref>parameter</x:ref> = <x:ref>attribute</x:ref> "=" <x:ref>value</x:ref> 5070 <x:ref>attribute</x:ref> = <x:ref>token</x:ref> 5071 <x:ref>value</x:ref> = <x:ref>word</x:ref> 5072 </artwork></figure> 5073 <t> 5074 The type, subtype, and parameter attribute names are case-insensitive. 5075 Parameter values might or might not be case-sensitive, depending on the 5076 semantics of the parameter name. The presence or absence of a parameter might 5077 be significant to the processing of a media-type, depending on its 5078 definition within the media type registry. 5079 </t> 5080 <t> 5081 A parameter value that matches the <x:ref>token</x:ref> production can be 5082 transmitted as either a token or within a quoted-string. The quoted and 5083 unquoted values are equivalent. 5084 </t> 5085 <t> 5086 Note that some older HTTP applications do not recognize media type 5087 parameters. When sending data to older HTTP applications, 5088 implementations &SHOULD; only use media type parameters when they are 5089 required by that type/subtype definition. 5090 </t> 5091 <t> 5092 Media-type values are registered with the Internet Assigned Number 5093 Authority (IANA). The media type registration process is 5094 outlined in <xref target="RFC4288"/>. Use of non-registered media types is 5095 discouraged. 5096 </t> 5097 5098 <section title="Canonicalization and Text Defaults" anchor="canonicalization.and.text.defaults"> 5099 <t> 5100 Internet media types are registered with a canonical form. A 5101 representation transferred via HTTP messages &MUST; be in the 5102 appropriate canonical form prior to its transmission except for 5103 "text" types, as defined in the next paragraph. 5104 </t> 5105 <t> 5106 When in canonical form, media subtypes of the "text" type use CRLF as 5107 the text line break. HTTP relaxes this requirement and allows the 5108 transport of text media with plain CR or LF alone representing a line 5109 break when it is done consistently for an entire representation. HTTP 5110 applications &MUST; accept CRLF, bare CR, and bare LF as indicating 5111 a line break in text media received via HTTP. In 5112 addition, if the text is in a character encoding that does not 5113 use octets 13 and 10 for CR and LF respectively, as is the case for 5114 some multi-byte character encodings, HTTP allows the use of whatever octet 5115 sequences are defined by that character encoding to represent the 5116 equivalent of CR and LF for line breaks. This flexibility regarding 5117 line breaks applies only to text media in the payload body; a bare CR 5118 or LF &MUST-NOT; be substituted for CRLF within any of the HTTP control 5119 structures (such as header fields and multipart boundaries). 5120 </t> 5121 <t> 5122 If a representation is encoded with a content-coding, the underlying 5123 data &MUST; be in a form defined above prior to being encoded. 5124 </t> 5125 </section> 5126 5127 <section title="Multipart Types" anchor="multipart.types"> 5128 <t> 5129 MIME provides for a number of "multipart" types — encapsulations of 5130 one or more representations within a single message body. All multipart 5131 types share a common syntax, as defined in <xref target="RFC2046" x:sec="5.1.1" x:fmt="of"/>, 5132 and &MUST; include a boundary parameter as part of the media type 5133 value. The message body is itself a protocol element and &MUST; 5134 therefore use only CRLF to represent line breaks between body-parts. 5135 </t> 5136 <t> 5137 In general, HTTP treats a multipart message body no differently than 5138 any other media type: strictly as payload. HTTP does not use the 5139 multipart boundary as an indicator of message body length. 5140 <!-- jre: re-insert removed text pointing to caching? --> 5141 In all other respects, an HTTP user agent &SHOULD; follow the same or similar 5142 behavior as a MIME user agent would upon receipt of a multipart type. 5143 The MIME header fields within each body-part of a multipart message body 5144 do not have any significance to HTTP beyond that defined by 5145 their MIME semantics. 5146 </t> 5147 <t> 5148 If an application receives an unrecognized multipart subtype, the 5149 application &MUST; treat it as being equivalent to "multipart/mixed". 5150 </t> 5151 <x:note> 5152 <t> 5153 <x:h>Note:</x:h> The "multipart/form-data" type has been specifically defined 5154 for carrying form data suitable for processing via the POST 5155 request method, as described in <xref target="RFC2388"/>. 5156 </t> 5157 </x:note> 5158 </section> 5159 </section> 5160 5161 <section title="Language Tags" anchor="language.tags"> 5162 <x:anchor-alias value="language-tag"/> 5163 <t> 5164 A language tag, as defined in <xref target="RFC5646"/>, identifies a 5165 natural language spoken, written, or otherwise conveyed by human beings for 5166 communication of information to other human beings. Computer languages are 5167 explicitly excluded. HTTP uses language tags within the Accept-Language and 5168 Content-Language fields. 5169 </t> 5170 <t> 5171 In summary, a language tag is composed of one or more parts: A primary 5172 language subtag followed by a possibly empty series of subtags: 5173 </t> 5174 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="language-tag"/> 5175 <x:ref>language-tag</x:ref> = <Language-Tag, defined in <xref target="RFC5646" x:sec="2.1"/>> 5176 </artwork></figure> 5177 <t> 5178 White space is not allowed within the tag and all tags are case-insensitive. 5179 The name space of language subtags is administered by the IANA (see 5180 <eref target="http://www.iana.org/assignments/language-subtag-registry"/>). 5181 </t> 5182 <figure> 5183 <preamble>Example tags include:</preamble> 5184 <artwork type="example"> 5185 en, en-US, es-419, az-Arab, x-pig-latin, man-Nkoo-GN 5186 </artwork> 5187 </figure> 5188 <t> 5189 See <xref target="RFC5646"/> for further information. 5190 </t> 5191 </section> 5192 </section> 5193 5194 <section title="Payload" anchor="payload"> 5195 <t> 5196 HTTP messages &MAY; transfer a payload if not otherwise restricted by 5197 the request method or response status code. The payload consists of 5198 metadata, in the form of header fields, and data, in the form of the 5199 sequence of octets in the message body after any transfer-coding has 5200 been decoded. 5201 </t> 5202 <iref item="payload"/> 5203 <t> 5204 A "<x:dfn>payload</x:dfn>" in HTTP is always a partial or complete 5205 representation of some resource. We use separate terms for payload 5206 and representation because some messages contain only the associated 5207 representation's header fields (e.g., responses to HEAD) or only some 5208 part(s) of the representation (e.g., the 206 status code). 5209 </t> 5210 <section title="Payload Header Fields" anchor="payload.header.fields"> 5211 <x:anchor-alias value="payload-header"/> 5212 <t> 5213 HTTP header fields that specifically define the payload, rather than the 5214 associated representation, are referred to as "payload header fields". 5215 The following payload header fields are defined by HTTP/1.1: 5216 </t> 5217 <texttable align="left"> 5218 <ttcol>Header Field Name</ttcol> 5219 <ttcol>Defined in...</ttcol> 5220 5221 <c>Content-Length</c> <c>&header-content-length;</c> 5222 <c>Content-Range</c> <c>&header-content-range;</c> 5223 </texttable> 5224 </section> 5225 5226 <section title="Payload Body" anchor="payload.body"> 5227 <x:anchor-alias value="payload-body"/> 5228 <t> 5229 A payload body is only present in a message when a message body is 5230 present, as described in &message-body;. The payload body is obtained 5231 from the message body by decoding any Transfer-Encoding that might 5232 have been applied to ensure safe and proper transfer of the message. 5233 </t> 5234 </section> 5235 </section> 5236 5237 <section title="Representation" anchor="representation3"> 5238 <iref item="representation"/> 5239 <t> 5240 A "<x:dfn>representation</x:dfn>" is information in a format that can be readily 5241 communicated from one party to another. A resource representation 5242 is information that reflects the state of that resource, as observed 5243 at some point in the past (e.g., in a response to GET) or to be 5244 desired at some point in the future (e.g., in a PUT request). 5245 </t> 5246 <t> 5247 Most, but not all, representations transferred via HTTP are intended 5248 to be a representation of the target resource (the resource identified 5249 by the effective request URI). The precise semantics of a representation 5250 are determined by the type of message (request or response), the request 5251 method, the response status code, and the representation metadata. 5252 For example, the above semantic is true for the representation in any 5253 200 (OK) response to GET and for the representation in any PUT request. 5254 A 200 response to PUT, in contrast, contains either a representation 5255 that describes the successful action or a representation of the target 5256 resource, with the latter indicated by a Content-Location header field 5257 with the same value as the effective request URI. Likewise, response 5258 messages with an error status code usually contain a representation that 5259 describes the error and what next steps are suggested for resolving it. 5260 </t> 5261 5262 <section title="Representation Header Fields" anchor="representation.header.fields"> 5263 <x:anchor-alias value="representation-header"/> 5264 <t> 5265 Representation header fields define metadata about the representation data 5266 enclosed in the message body or, if no message body is present, about 5267 the representation that would have been transferred in a 200 response 5268 to a simultaneous GET request with the same effective request URI. 5269 </t> 5270 <t> 5271 The following header fields are defined as representation metadata: 5272 </t> 5273 <texttable align="left"> 5274 <ttcol>Header Field Name</ttcol> 5275 <ttcol>Defined in...</ttcol> 5276 5277 <c>Content-Encoding</c> <c><xref target="header.content-encoding"/></c> 5278 <c>Content-Language</c> <c><xref target="header.content-language"/></c> 5279 <c>Content-Location</c> <c><xref target="header.content-location"/></c> 5280 <c>Content-Type</c> <c><xref target="header.content-type"/></c> 5281 <c>Expires</c> <c>&header-expires;</c> 5282 </texttable> 5283 <t> 5284 Additional header fields define metadata about the selected 5285 representation, which might differ from the representation included 5286 in the message for responses to some state-changing methods. 5287 The following header fields are defined as selected representation 5288 metadata: 5289 </t> 5290 <texttable align="left"> 5291 <ttcol>Header Field Name</ttcol> 5292 <ttcol>Defined in...</ttcol> 5293 5294 <c>ETag</c> <c>&header-etag;</c> 5295 <c>Last-Modified</c> <c>&header-last-modified;</c> 5296 </texttable> 5297 </section> 5298 5299 <section title="Representation Data" anchor="representation.data"> 5300 <x:anchor-alias value="representation-data"/> 5301 <t> 5302 The representation body associated with an HTTP message is 5303 either provided as the payload body of the message or 5304 referred to by the message semantics and the effective request 5305 URI. The representation data is in a format and encoding defined by 5306 the representation metadata header fields. 5307 </t> 5308 <t> 5309 The data type of the representation data 5310 is determined via the header fields Content-Type and Content-Encoding. 5311 These define a two-layer, ordered encoding model: 5312 </t> 5313 <figure><artwork type="example"> 5314 representation-data := Content-Encoding( Content-Type( bits ) ) 5315 </artwork></figure> 5316 <t> 5317 Content-Type specifies the media type of the underlying data, which 5318 defines both the data format and how that data &SHOULD; be processed 5319 by the recipient (within the scope of the request method semantics). 5320 Any HTTP/1.1 message containing a payload body &SHOULD; include a 5321 Content-Type header field defining the media type of the associated 5322 representation unless that metadata is unknown to the sender. 5323 If the Content-Type header field is not present, it indicates that 5324 the sender does not know the media type of the representation; 5325 recipients &MAY; either assume that the media type is 5326 "application/octet-stream" (<xref target="RFC2046" x:fmt="," x:sec="4.5.1"/>) 5327 or examine the content to determine its type. 5328 </t> 5329 <t> 5330 In practice, resource owners do not always properly configure their origin 5331 server to provide the correct Content-Type for a given representation, 5332 with the result that some clients will examine a response body's content 5333 and override the specified type. 5334 Clients that do so risk drawing incorrect conclusions, which might expose 5335 additional security risks (e.g., "privilege escalation"). Furthermore, 5336 it is impossible to determine the sender's intent by examining the data 5337 format: many data formats match multiple media types that differ only in 5338 processing semantics. Implementers are encouraged to provide a means of 5339 disabling such "content sniffing" when it is used. 5340 </t> 5341 <t> 5342 Content-Encoding is used to indicate any additional content 5343 codings applied to the data, usually for the purpose of data 5344 compression, that are a property of the representation. If 5345 Content-Encoding is not present, then there is no additional 5346 encoding beyond that defined by the Content-Type. 5347 </t> 5348 </section> 5349 </section> 5350 5351 <section title="Content Negotiation" anchor="content.negotiation"> 5352 <t> 5353 HTTP responses include a representation which contains information for 5354 interpretation, whether by a human user or for further processing. 5355 Often, the server has different ways of representing the 5356 same information; for example, in different formats, languages, 5357 or using different character encodings. 5358 </t> 5359 <t> 5360 HTTP clients and their users might have different or variable 5361 capabilities, characteristics or preferences which would influence 5362 which representation, among those available from the server, 5363 would be best for the server to deliver. For this reason, HTTP 5364 provides mechanisms for "content negotiation" — a process of 5365 allowing selection of a representation of a given resource, 5366 when more than one is available. 5367 </t> 5368 <t> 5369 This specification defines two patterns of content negotiation; 5370 "server-driven", where the server selects the representation based 5371 upon the client's stated preferences, and "agent-driven" negotiation, 5372 where the server provides a list of representations for the client to 5373 choose from, based upon their metadata. In addition, there are 5374 other patterns: some applications use an "active content" pattern, 5375 where the server returns active content which runs on the client 5376 and, based on client available parameters, selects additional 5377 resources to invoke. "Transparent Content Negotiation" (<xref target="RFC2295"/>) 5378 has also been proposed. 5379 </t> 5380 <t> 5381 These patterns are all widely used, and have trade-offs in applicability 5382 and practicality. In particular, when the number of preferences or 5383 capabilities to be expressed by a client are large (such as when many 5384 different formats are supported by a user-agent), server-driven 5385 negotiation becomes unwieldy, and might not be appropriate. Conversely, 5386 when the number of representations to choose from is very large, 5387 agent-driven negotiation might not be appropriate. 5388 </t> 5389 <t> 5390 Note that in all cases, the supplier of representations has the 5391 responsibility for determining which representations might be 5392 considered to be the "same information". 5393 </t> 5394 5395 <section title="Server-driven Negotiation" anchor="server-driven.negotiation"> 5396 <t> 5397 If the selection of the best representation for a response is made by 5398 an algorithm located at the server, it is called server-driven 5399 negotiation. Selection is based on the available representations of 5400 the response (the dimensions over which it can vary; e.g., language, 5401 content-coding, etc.) and the contents of particular header fields in 5402 the request message or on other information pertaining to the request 5403 (such as the network address of the client). 5404 </t> 5405 <t> 5406 Server-driven negotiation is advantageous when the algorithm for 5407 selecting from among the available representations is difficult to 5408 describe to the user agent, or when the server desires to send its 5409 "best guess" to the client along with the first response (hoping to 5410 avoid the round-trip delay of a subsequent request if the "best 5411 guess" is good enough for the user). In order to improve the server's 5412 guess, the user agent &MAY; include request header fields (Accept, 5413 Accept-Language, Accept-Encoding, etc.) which describe its 5414 preferences for such a response. 5415 </t> 5416 <t> 5417 Server-driven negotiation has disadvantages: 5418 <list style="numbers"> 5419 <t> 5420 It is impossible for the server to accurately determine what 5421 might be "best" for any given user, since that would require 5422 complete knowledge of both the capabilities of the user agent 5423 and the intended use for the response (e.g., does the user want 5424 to view it on screen or print it on paper?). 5425 </t> 5426 <t> 5427 Having the user agent describe its capabilities in every 5428 request can be both very inefficient (given that only a small 5429 percentage of responses have multiple representations) and a 5430 potential violation of the user's privacy. 5431 </t> 5432 <t> 5433 It complicates the implementation of an origin server and the 5434 algorithms for generating responses to a request. 5435 </t> 5436 <t> 5437 It might limit a public cache's ability to use the same response 5438 for multiple user's requests. 5439 </t> 5440 </list> 5441 </t> 5442 <t> 5443 Server-driven negotiation allows the user agent to specify its preferences, 5444 but it cannot expect responses to always honor them. For example, the origin 5445 server might not implement server-driven negotiation, or it might decide that 5446 sending a response that doesn't conform to them is better than sending a 406 5447 (Not Acceptable) response. 5448 </t> 5449 <t> 5450 Many of the mechanisms for expressing preferences use quality values to 5451 declare relative preference. See &qvalue; for more information. 5452 </t> 5453 <t> 5454 HTTP/1.1 includes the following header fields for enabling 5455 server-driven negotiation through description of user agent 5456 capabilities and user preferences: Accept (<xref target="header.accept"/>), Accept-Charset 5457 (<xref target="header.accept-charset"/>), Accept-Encoding (<xref target="header.accept-encoding"/>), Accept-Language 5458 (<xref target="header.accept-language"/>), and User-Agent (&header-user-agent;). 5459 However, an origin server is not limited to these dimensions and &MAY; vary 5460 the response based on any aspect of the request, including aspects 5461 of the connection (e.g., IP address) or information within extension 5462 header fields not defined by this specification. 5463 </t> 5464 <x:note> 5465 <t> 5466 <x:h>Note:</x:h> In practice, User-Agent based negotiation is fragile, 5467 because new clients might not be recognized. 5468 </t> 5469 </x:note> 5470 <t> 5471 The Vary header field (&header-vary;) can be used to express the parameters the 5472 server uses to select a representation that is subject to server-driven 5473 negotiation. 5474 </t> 5475 </section> 5476 5477 <section title="Agent-driven Negotiation" anchor="agent-driven.negotiation"> 5478 <t> 5479 With agent-driven negotiation, selection of the best representation 5480 for a response is performed by the user agent after receiving an 5481 initial response from the origin server. Selection is based on a list 5482 of the available representations of the response included within the 5483 header fields or body of the initial response, with each 5484 representation identified by its own URI. Selection from among the 5485 representations can be performed automatically (if the user agent is 5486 capable of doing so) or manually by the user selecting from a 5487 generated (possibly hypertext) menu. 5488 </t> 5489 <t> 5490 Agent-driven negotiation is advantageous when the response would vary 5491 over commonly-used dimensions (such as type, language, or encoding), 5492 when the origin server is unable to determine a user agent's 5493 capabilities from examining the request, and generally when public 5494 caches are used to distribute server load and reduce network usage. 5495 </t> 5496 <t> 5497 Agent-driven negotiation suffers from the disadvantage of needing a 5498 second request to obtain the best alternate representation. This 5499 second request is only efficient when caching is used. In addition, 5500 this specification does not define any mechanism for supporting 5501 automatic selection, though it also does not prevent any such 5502 mechanism from being developed as an extension and used within 5503 HTTP/1.1. 5504 </t> 5505 <t> 5506 This specification defines the 300 (Multiple Choices) and 406 (Not Acceptable) 5507 status codes for enabling agent-driven negotiation when the server is 5508 unwilling or unable to provide a varying response using server-driven 5509 negotiation. 5510 </t> 5511 </section> 5512 </section> 5513 5514 <section title="Header Field Definitions" anchor="header.field.definitions3"> 5515 <t> 5516 This section defines the syntax and semantics of HTTP/1.1 header fields 5517 related to the payload of messages. 5518 </t> 5519 5520 <section title="Accept" anchor="header.accept"> 5521 <iref primary="true" item="Accept header field" x:for-anchor=""/> 5522 <iref primary="true" item="Header Fields" subitem="Accept" x:for-anchor=""/> 5523 <x:anchor-alias value="Accept"/> 5524 <x:anchor-alias value="accept-ext"/> 5525 <x:anchor-alias value="accept-params"/> 5526 <x:anchor-alias value="media-range"/> 5527 <t> 5528 The "Accept" header field can be used by user agents to specify 5529 response media types that are acceptable. Accept header fields can be used to 5530 indicate that the request is specifically limited to a small set of desired 5531 types, as in the case of a request for an in-line image. 5532 </t> 5533 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept"/><iref primary="true" item="Grammar" subitem="media-range"/><iref primary="true" item="Grammar" subitem="accept-params"/><iref primary="true" item="Grammar" subitem="accept-ext"/> 5534 <x:ref>Accept</x:ref> = #( <x:ref>media-range</x:ref> [ <x:ref>accept-params</x:ref> ] ) 5535 5536 <x:ref>media-range</x:ref> = ( "*/*" 5537 / ( <x:ref>type</x:ref> "/" "*" ) 5538 / ( <x:ref>type</x:ref> "/" <x:ref>subtype</x:ref> ) 5539 ) *( <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>parameter</x:ref> ) 5540 <x:ref>accept-params</x:ref> = <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> *( <x:ref>accept-ext</x:ref> ) 5541 <x:ref>accept-ext</x:ref> = <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> <x:ref>token</x:ref> [ "=" <x:ref>word</x:ref> ] 5542 </artwork></figure> 5543 <t> 5544 The asterisk "*" character is used to group media types into ranges, 5545 with "*/*" indicating all media types and "type/*" indicating all 5546 subtypes of that type. The media-range &MAY; include media type 5547 parameters that are applicable to that range. 5548 </t> 5549 <t> 5550 Each media-range &MAY; be followed by one or more accept-params, 5551 beginning with the "q" parameter for indicating a relative quality 5552 factor. The first "q" parameter (if any) separates the media-range 5553 parameter(s) from the accept-params. Quality factors allow the user 5554 or user agent to indicate the relative degree of preference for that 5555 media-range, using the qvalue scale from 0 to 1 (&qvalue;). The 5556 default value is q=1. 5557 </t> 5558 <x:note> 5559 <t> 5560 <x:h>Note:</x:h> Use of the "q" parameter name to separate media type 5561 parameters from Accept extension parameters is due to historical 5562 practice. Although this prevents any media type parameter named 5563 "q" from being used with a media range, such an event is believed 5564 to be unlikely given the lack of any "q" parameters in the IANA 5565 media type registry and the rare usage of any media type 5566 parameters in Accept. Future media types are discouraged from 5567 registering any parameter named "q". 5568 </t> 5569 </x:note> 5570 <t> 5571 The example 5572 </t> 5573 <figure><artwork type="example"> 5574 Accept: audio/*; q=0.2, audio/basic 5575 </artwork></figure> 5576 <t> 5577 &SHOULD; be interpreted as "I prefer audio/basic, but send me any audio 5578 type if it is the best available after an 80% mark-down in quality". 5579 </t> 5580 <t> 5581 A request without any Accept header field implies that the user agent 5582 will accept any media type in response. 5583 If an Accept header field is present in a request and none of the 5584 available representations for the response have a media type that is 5585 listed as acceptable, the origin server &MAY; either 5586 honor the Accept header field by sending a 406 (Not Acceptable) response 5587 or disregard the Accept header field by treating the response as if 5588 it is not subject to content negotiation. 5589 </t> 5590 <t> 5591 A more elaborate example is 5592 </t> 5593 <figure><artwork type="example"> 5594 Accept: text/plain; q=0.5, text/html, 5595 text/x-dvi; q=0.8, text/x-c 5596 </artwork></figure> 5597 <t> 5598 Verbally, this would be interpreted as "text/html and text/x-c are 5599 the preferred media types, but if they do not exist, then send the 5600 text/x-dvi representation, and if that does not exist, send the text/plain 5601 representation". 5602 </t> 5603 <t> 5604 Media ranges can be overridden by more specific media ranges or 5605 specific media types. If more than one media range applies to a given 5606 type, the most specific reference has precedence. For example, 5607 </t> 5608 <figure><artwork type="example"> 5609 Accept: text/*, text/plain, text/plain;format=flowed, */* 5610 </artwork></figure> 5611 <t> 5612 have the following precedence: 5613 <list style="numbers"> 5614 <t>text/plain;format=flowed</t> 5615 <t>text/plain</t> 5616 <t>text/*</t> 5617 <t>*/*</t> 5618 </list> 5619 </t> 5620 <t> 5621 The media type quality factor associated with a given type is 5622 determined by finding the media range with the highest precedence 5623 which matches that type. For example, 5624 </t> 5625 <figure><artwork type="example"> 5626 Accept: text/*;q=0.3, text/html;q=0.7, text/html;level=1, 5627 text/html;level=2;q=0.4, */*;q=0.5 5628 </artwork></figure> 5629 <t> 5630 would cause the following values to be associated: 5631 </t> 5632 <texttable align="left"> 5633 <ttcol>Media Type</ttcol><ttcol>Quality Value</ttcol> 5634 <c>text/html;level=1</c> <c>1</c> 5635 <c>text/html</c> <c>0.7</c> 5636 <c>text/plain</c> <c>0.3</c> 5637 <c>image/jpeg</c> <c>0.5</c> 5638 <c>text/html;level=2</c> <c>0.4</c> 5639 <c>text/html;level=3</c> <c>0.7</c> 5640 </texttable> 5641 <t> 5642 <x:h>Note:</x:h> A user agent might be provided with a default set of quality 5643 values for certain media ranges. However, unless the user agent is 5644 a closed system which cannot interact with other rendering agents, 5645 this default set ought to be configurable by the user. 5646 </t> 5647 </section> 5648 5649 <section title="Accept-Charset" anchor="header.accept-charset"> 5650 <iref primary="true" item="Accept-Charset header field" x:for-anchor=""/> 5651 <iref primary="true" item="Header Fields" subitem="Accept-Charset" x:for-anchor=""/> 5652 <x:anchor-alias value="Accept-Charset"/> 5653 <t> 5654 The "Accept-Charset" header field can be used by user agents to 5655 indicate what character encodings are acceptable in a response 5656 payload. This field allows 5657 clients capable of understanding more comprehensive or special-purpose 5658 character encodings to signal that capability to a server which is capable of 5659 representing documents in those character encodings. 5660 </t> 5661 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Charset"/> 5662 <x:ref>Accept-Charset</x:ref> = 1#( ( <x:ref>charset</x:ref> / "*" ) 5663 [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] ) 5664 </artwork></figure> 5665 <t> 5666 Character encoding values (a.k.a., charsets) are described in 5667 <xref target="character.sets"/>. Each charset &MAY; be given an 5668 associated quality value which represents the user's preference 5669 for that charset. The default value is q=1. An example is 5670 </t> 5671 <figure><artwork type="example"> 5672 Accept-Charset: iso-8859-5, unicode-1-1;q=0.8 5673 </artwork></figure> 5674 <t> 5675 The special value "*", if present in the Accept-Charset field, 5676 matches every character encoding which is not mentioned elsewhere in the 5677 Accept-Charset field. If no "*" is present in an Accept-Charset field, then 5678 all character encodings not explicitly mentioned get a quality value of 0. 5679 </t> 5680 <t> 5681 A request without any Accept-Charset header field implies that the user 5682 agent will accept any character encoding in response. 5683 If an Accept-Charset header field is present in a request and none of the 5684 available representations for the response have a character encoding that 5685 is listed as acceptable, the origin server &MAY; either honor the 5686 Accept-Charset header field by sending a 406 (Not Acceptable) response or 5687 disregard the Accept-Charset header field by treating the response as if 5688 it is not subject to content negotiation. 5689 </t> 5690 </section> 5691 5692 <section title="Accept-Encoding" anchor="header.accept-encoding"> 5693 <iref primary="true" item="Accept-Encoding header field" x:for-anchor=""/> 5694 <iref primary="true" item="Header Fields" subitem="Accept-Encoding" x:for-anchor=""/> 5695 <x:anchor-alias value="Accept-Encoding"/> 5696 <x:anchor-alias value="codings"/> 5697 <t> 5698 The "Accept-Encoding" header field can be used by user agents to 5699 indicate what response content-codings (<xref target="content.codings"/>) 5700 are acceptable in the response. An "identity" token is used as a synonym 5701 for "no encoding" in order to communicate when no encoding is preferred. 5702 </t> 5703 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Encoding"/><iref primary="true" item="Grammar" subitem="codings"/> 5704 <x:ref>Accept-Encoding</x:ref> = #( <x:ref>codings</x:ref> [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] ) 5705 <x:ref>codings</x:ref> = <x:ref>content-coding</x:ref> / "identity" / "*" 5706 </artwork></figure> 5707 <t> 5708 Each codings value &MAY; be given an associated quality value which 5709 represents the preference for that encoding. The default value is q=1. 5710 </t> 5711 <t> 5712 For example, 5713 </t> 5714 <figure><artwork type="example"> 5715 Accept-Encoding: compress, gzip 5716 Accept-Encoding: 5717 Accept-Encoding: * 5718 Accept-Encoding: compress;q=0.5, gzip;q=1.0 5719 Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0 5720 </artwork></figure> 5721 <t> 5722 A server tests whether a content-coding for a given representation is 5723 acceptable, according to an Accept-Encoding field, using these rules: 5724 <list style="numbers"> 5725 <t>The special "*" symbol in an Accept-Encoding field matches any 5726 available content-coding not explicitly listed in the header 5727 field.</t> 5728 5729 <t>If the representation has no content-coding, then it is acceptable 5730 by default unless specifically excluded by the Accept-Encoding field 5731 stating either "identity;q=0" or "*;q=0" without a more specific 5732 entry for "identity".</t> 5733 5734 <t>If the representation's content-coding is one of the content-codings 5735 listed in the Accept-Encoding field, then it is acceptable unless 5736 it is accompanied by a qvalue of 0. (As defined in &qvalue;, a 5737 qvalue of 0 means "not acceptable".)</t> 5738 5739 <t>If multiple content-codings are acceptable, then the acceptable 5740 content-coding with the highest non-zero qvalue is preferred.</t> 5741 </list> 5742 </t> 5743 <t> 5744 An Accept-Encoding header field with a combined field-value that is empty 5745 implies that the user agent does not want any content-coding in response. 5746 If an Accept-Encoding header field is present in a request and none of the 5747 available representations for the response have a content-coding that 5748 is listed as acceptable, the origin server &SHOULD; send a response 5749 without any content-coding. 5750 </t> 5751 <t> 5752 A request without an Accept-Encoding header field implies that the user 5753 agent will accept any content-coding in response, but a representation 5754 without content-coding is preferred for compatibility with the widest 5755 variety of user agents. 5756 </t> 5757 <x:note> 5758 <t> 5759 <x:h>Note:</x:h> Most HTTP/1.0 applications do not recognize or obey qvalues 5760 associated with content-codings. This means that qvalues will not 5761 work and are not permitted with x-gzip or x-compress. 5762 </t> 5763 </x:note> 5764 </section> 5765 5766 <section title="Accept-Language" anchor="header.accept-language"> 5767 <iref primary="true" item="Accept-Language header field" x:for-anchor=""/> 5768 <iref primary="true" item="Header Fields" subitem="Accept-Language" x:for-anchor=""/> 5769 <x:anchor-alias value="Accept-Language"/> 5770 <x:anchor-alias value="language-range"/> 5771 <t> 5772 The "Accept-Language" header field can be used by user agents to 5773 indicate the set of natural languages that are preferred in the response. 5774 Language tags are defined in <xref target="language.tags"/>. 5775 </t> 5776 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Language"/><iref primary="true" item="Grammar" subitem="language-range"/> 5777 <x:ref>Accept-Language</x:ref> = 5778 1#( <x:ref>language-range</x:ref> [ <x:ref>OWS</x:ref> ";" <x:ref>OWS</x:ref> "q=" <x:ref>qvalue</x:ref> ] ) 5779 <x:ref>language-range</x:ref> = 5780 <language-range, defined in <xref target="RFC4647" x:fmt="," x:sec="2.1"/>> 5781 </artwork></figure> 5782 <t> 5783 Each language-range can be given an associated quality value which 5784 represents an estimate of the user's preference for the languages 5785 specified by that range. The quality value defaults to "q=1". For 5786 example, 5787 </t> 5788 <figure><artwork type="example"> 5789 Accept-Language: da, en-gb;q=0.8, en;q=0.7 5790 </artwork></figure> 5791 <t> 5792 would mean: "I prefer Danish, but will accept British English and 5793 other types of English". 5794 (see also <xref target="RFC4647" x:sec="2.3" x:fmt="of"/>) 5795 </t> 5796 <t> 5797 For matching, <xref target="RFC4647" x:sec="3" x:fmt="of"/> defines 5798 several matching schemes. Implementations can offer the most appropriate 5799 matching scheme for their requirements. 5800 </t> 5801 <x:note> 5802 <t> 5803 <x:h>Note:</x:h> The "Basic Filtering" scheme (<xref target="RFC4647" 5804 x:fmt="," x:sec="3.3.1"/>) is identical to the matching scheme that was 5805 previously defined in <xref target="RFC2616" x:fmt="of" x:sec="14.4"/>. 5806 </t> 5807 </x:note> 5808 <t> 5809 It might be contrary to the privacy expectations of the user to send 5810 an Accept-Language header field with the complete linguistic preferences of 5811 the user in every request. For a discussion of this issue, see 5812 <xref target="privacy.issues.connected.to.accept.header.fields"/>. 5813 </t> 5814 <t> 5815 As intelligibility is highly dependent on the individual user, it is 5816 recommended that client applications make the choice of linguistic 5817 preference available to the user. If the choice is not made 5818 available, then the Accept-Language header field &MUST-NOT; be given in 5819 the request. 5820 </t> 5821 <x:note> 5822 <t> 5823 <x:h>Note:</x:h> When making the choice of linguistic preference available to 5824 the user, we remind implementors of the fact that users are not 5825 familiar with the details of language matching as described above, 5826 and ought to be provided appropriate guidance. As an example, users 5827 might assume that on selecting "en-gb", they will be served any 5828 kind of English document if British English is not available. A 5829 user agent might suggest in such a case to add "en" to get the 5830 best matching behavior. 5831 </t> 5832 </x:note> 5833 </section> 5834 5835 <section title="Content-Encoding" anchor="header.content-encoding"> 5836 <iref primary="true" item="Content-Encoding header field" x:for-anchor=""/> 5837 <iref primary="true" item="Header Fields" subitem="Content-Encoding" x:for-anchor=""/> 5838 <x:anchor-alias value="Content-Encoding"/> 5839 <t> 5840 The "Content-Encoding" header field indicates what content-codings 5841 have been applied to the representation beyond those inherent in the media 5842 type, and thus what decoding mechanisms have to be applied in order to obtain 5843 the media-type referenced by the Content-Type header field. 5844 Content-Encoding is primarily used to allow a representation to be 5845 compressed without losing the identity of its underlying media type. 5846 </t> 5847 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Encoding"/> 5848 <x:ref>Content-Encoding</x:ref> = 1#<x:ref>content-coding</x:ref> 5849 </artwork></figure> 5850 <t> 5851 Content codings are defined in <xref target="content.codings"/>. An example of its use is 5852 </t> 5853 <figure><artwork type="example"> 5854 Content-Encoding: gzip 5855 </artwork></figure> 5856 <t> 5857 The content-coding is a characteristic of the representation. 5858 Typically, the representation body is stored with this 5859 encoding and is only decoded before rendering or analogous usage. 5860 However, a transforming proxy &MAY; modify the content-coding if the 5861 new coding is known to be acceptable to the recipient, unless the 5862 "no-transform" cache-control directive is present in the message. 5863 </t> 5864 <t> 5865 If the media type includes an inherent encoding, such as a data format 5866 that is always compressed, then that encoding would not be restated as 5867 a Content-Encoding even if it happens to be the same algorithm as one 5868 of the content-codings. Such a content-coding would only be listed if, 5869 for some bizarre reason, it is applied a second time to form the 5870 representation. Likewise, an origin server might choose to publish the 5871 same payload data as multiple representations that differ only in whether 5872 the coding is defined as part of Content-Type or Content-Encoding, since 5873 some user agents will behave differently in their handling of each 5874 response (e.g., open a "Save as ..." dialog instead of automatic 5875 decompression and rendering of content). 5876 </t> 5877 <t> 5878 A representation that has a content-coding applied to it &MUST; include 5879 a Content-Encoding header field (<xref target="header.content-encoding"/>) 5880 that lists the content-coding(s) applied. 5881 </t> 5882 <t> 5883 If multiple encodings have been applied to a representation, the content 5884 codings &MUST; be listed in the order in which they were applied. 5885 Additional information about the encoding parameters &MAY; be provided 5886 by other header fields not defined by this specification. 5887 </t> 5888 <t> 5889 If the content-coding of a representation in a request message is not 5890 acceptable to the origin server, the server &SHOULD; respond with a 5891 status code of 415 (Unsupported Media Type). 5892 </t> 5893 </section> 5894 5895 <section title="Content-Language" anchor="header.content-language"> 5896 <iref primary="true" item="Content-Language header field" x:for-anchor=""/> 5897 <iref primary="true" item="Header Fields" subitem="Content-Language" x:for-anchor=""/> 5898 <x:anchor-alias value="Content-Language"/> 5899 <t> 5900 The "Content-Language" header field describes the natural 5901 language(s) of the intended audience for the representation. Note that this might 5902 not be equivalent to all the languages used within the representation. 5903 </t> 5904 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Language"/> 5905 <x:ref>Content-Language</x:ref> = 1#<x:ref>language-tag</x:ref> 5906 </artwork></figure> 5907 <t> 5908 Language tags are defined in <xref target="language.tags"/>. The primary purpose of 5909 Content-Language is to allow a user to identify and differentiate 5910 representations according to the user's own preferred language. Thus, if the 5911 body content is intended only for a Danish-literate audience, the 5912 appropriate field is 5913 </t> 5914 <figure><artwork type="example"> 5915 Content-Language: da 5916 </artwork></figure> 5917 <t> 5918 If no Content-Language is specified, the default is that the content 5919 is intended for all language audiences. This might mean that the 5920 sender does not consider it to be specific to any natural language, 5921 or that the sender does not know for which language it is intended. 5922 </t> 5923 <t> 5924 Multiple languages &MAY; be listed for content that is intended for 5925 multiple audiences. For example, a rendition of the "Treaty of 5926 Waitangi", presented simultaneously in the original Maori and English 5927 versions, would call for 5928 </t> 5929 <figure><artwork type="example"> 5930 Content-Language: mi, en 5931 </artwork></figure> 5932 <t> 5933 However, just because multiple languages are present within a representation 5934 does not mean that it is intended for multiple linguistic audiences. 5935 An example would be a beginner's language primer, such as "A First 5936 Lesson in Latin", which is clearly intended to be used by an 5937 English-literate audience. In this case, the Content-Language would 5938 properly only include "en". 5939 </t> 5940 <t> 5941 Content-Language &MAY; be applied to any media type — it is not 5942 limited to textual documents. 5943 </t> 5944 </section> 5945 5946 <section title="Content-Location" anchor="header.content-location"> 5947 <iref primary="true" item="Content-Location header field" x:for-anchor=""/> 5948 <iref primary="true" item="Header Fields" subitem="Content-Location" x:for-anchor=""/> 5949 <x:anchor-alias value="Content-Location"/> 5950 <t> 5951 The "Content-Location" header field supplies a URI that can be used 5952 as a specific identifier for the representation in this message. 5953 In other words, if one were to perform a GET on this URI at the time 5954 of this message's generation, then a 200 response would contain the 5955 same representation that is enclosed as payload in this message. 5956 </t> 5957 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Location"/> 5958 <x:ref>Content-Location</x:ref> = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref> 5959 </artwork></figure> 5960 <t> 5961 The Content-Location value is not a replacement for the effective 5962 Request URI (&effective-request-uri;). It is representation metadata. 5963 It has the same syntax and semantics as the header field of the same name 5964 defined for MIME body parts in <xref target="RFC2557" x:fmt="of" x:sec="4"/>. 5965 However, its appearance in an HTTP message has some special implications 5966 for HTTP recipients. 5967 </t> 5968 <t> 5969 If Content-Location is included in a response message and its value 5970 is the same as the effective request URI, then the response payload 5971 &SHOULD; be considered a current representation of that resource. 5972 For a GET or HEAD request, this is the same as the default semantics 5973 when no Content-Location is provided by the server. For a state-changing 5974 request like PUT or POST, it implies that the server's response contains 5975 the new representation of that resource, thereby distinguishing it from 5976 representations that might only report about the action (e.g., "It worked!"). 5977 This allows authoring applications to update their local copies without 5978 the need for a subsequent GET request. 5979 </t> 5980 <t> 5981 If Content-Location is included in a response message and its value 5982 differs from the effective request URI, then the origin server is 5983 informing recipients that this representation has its own, presumably 5984 more specific, identifier. For a GET or HEAD request, this is an 5985 indication that the effective request URI identifies a resource that 5986 is subject to content negotiation and the selected representation for 5987 this response can also be found at the identified URI. For other 5988 methods, such a Content-Location indicates that this representation 5989 contains a report on the action's status and the same report is 5990 available (for future access with GET) at the given URI. For 5991 example, a purchase transaction made via a POST request might 5992 include a receipt document as the payload of the 200 response; 5993 the Content-Location value provides an identifier for retrieving 5994 a copy of that same receipt in the future. 5995 </t> 5996 <t> 5997 If Content-Location is included in a request message, then it &MAY; 5998 be interpreted by the origin server as an indication of where the 5999 user agent originally obtained the content of the enclosed 6000 representation (prior to any subsequent modification of the content 6001 by that user agent). In other words, the user agent is providing 6002 the same representation metadata that it received with the original 6003 representation. However, such interpretation &MUST-NOT; be used to 6004 alter the semantics of the method requested by the client. For 6005 example, if a client makes a PUT request on a negotiated resource 6006 and the origin server accepts that PUT (without redirection), then the 6007 new set of values for that resource is expected to be consistent with 6008 the one representation supplied in that PUT; the Content-Location 6009 cannot be used as a form of reverse content selection that 6010 identifies only one of the negotiated representations to be updated. 6011 If the user agent had wanted the latter semantics, it would have applied 6012 the PUT directly to the Content-Location URI. 6013 </t> 6014 <t> 6015 A Content-Location field received in a request message is transitory 6016 information that &SHOULD-NOT; be saved with other representation 6017 metadata for use in later responses. The Content-Location's value 6018 might be saved for use in other contexts, such as within source links 6019 or other metadata. 6020 </t> 6021 <t> 6022 A cache cannot assume that a representation with a Content-Location 6023 different from the URI used to retrieve it can be used to respond to 6024 later requests on that Content-Location URI. 6025 </t> 6026 <t> 6027 If the Content-Location value is a partial URI, the partial URI is 6028 interpreted relative to the effective request URI. 6029 </t> 6030 </section> 6031 6032 <section title="Content-Type" anchor="header.content-type"> 6033 <iref primary="true" item="Content-Type header field" x:for-anchor=""/> 6034 <iref primary="true" item="Header Fields" subitem="Content-Type" x:for-anchor=""/> 6035 <x:anchor-alias value="Content-Type"/> 6036 <t> 6037 The "Content-Type" header field indicates the media type of the 6038 representation. In the case of responses to the HEAD method, the media type is 6039 that which would have been sent had the request been a GET. 6040 </t> 6041 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Type"/> 6042 <x:ref>Content-Type</x:ref> = <x:ref>media-type</x:ref> 6043 </artwork></figure> 6044 <t> 6045 Media types are defined in <xref target="media.types"/>. An example of the field is 6046 </t> 6047 <figure><artwork type="example"> 6048 Content-Type: text/html; charset=ISO-8859-4 6049 </artwork></figure> 6050 <t> 6051 Further discussion of Content-Type is provided in <xref target="representation.data"/>. 6052 </t> 6053 </section> 6054 6055 </section> 6056 6057 <section title="IANA Considerations" anchor="IANA.considerations3"> 6058 6059 <section title="Content Coding Registry" anchor="content.coding.registration"> 6060 <t> 6061 The registration procedure for HTTP Content Codings is now defined 6062 by <xref target="content.coding.registry"/> of this document. 6063 </t> 6064 <t> 6065 The HTTP Content Codings Registry located at <eref target="http://www.iana.org/assignments/http-parameters"/> 6066 shall be updated with the registration below: 6067 </t> 6068 <texttable align="left" suppress-title="true" anchor="iana.content.coding.registration.table"> 6069 <ttcol>Name</ttcol> 6070 <ttcol>Description</ttcol> 6071 <ttcol>Reference</ttcol> 6072 <c>compress</c> 6073 <c>UNIX "compress" program method</c> 6074 <c> 6075 &compress-coding; 6076 </c> 6077 <c>deflate</c> 6078 <c>"deflate" compression mechanism (<xref target="RFC1951"/>) used inside 6079 the "zlib" data format (<xref target="RFC1950"/>) 6080 </c> 6081 <c> 6082 &deflate-coding; 6083 </c> 6084 <c>gzip</c> 6085 <c>Same as GNU zip <xref target="RFC1952"/></c> 6086 <c> 6087 &gzip-coding; 6088 </c> 6089 <c>identity</c> 6090 <c>reserved (synonym for "no encoding" in Accept-Encoding header field)</c> 6091 <c> 6092 <xref target="header.accept-encoding"/> 6093 </c> 6094 </texttable> 6095 </section> 6096 6097 </section> 6098 6099 <section title="Security Considerations" anchor="security.considerations3"> 6100 <t> 6101 This section is meant to inform application developers, information 6102 providers, and users of the security limitations in HTTP/1.1 as 6103 described by this document. The discussion does not include 6104 definitive solutions to the problems revealed, though it does make 6105 some suggestions for reducing security risks. 6106 </t> 6107 6108 <section title="Privacy Issues Connected to Accept Header Fields" anchor="privacy.issues.connected.to.accept.header.fields"> 6109 <t> 6110 Accept header fields can reveal information about the user to all 6111 servers which are accessed. The Accept-Language header field in particular 6112 can reveal information the user would consider to be of a private 6113 nature, because the understanding of particular languages is often 6114 strongly correlated to the membership of a particular ethnic group. 6115 User agents which offer the option to configure the contents of an 6116 Accept-Language header field to be sent in every request are strongly 6117 encouraged to let the configuration process include a message which 6118 makes the user aware of the loss of privacy involved. 6119 </t> 6120 <t> 6121 An approach that limits the loss of privacy would be for a user agent 6122 to omit the sending of Accept-Language header fields by default, and to ask 6123 the user whether or not to start sending Accept-Language header fields to a 6124 server if it detects, by looking for any Vary header fields 6125 generated by the server, that such sending could improve the quality 6126 of service. 6127 </t> 6128 <t> 6129 Elaborate user-customized accept header fields sent in every request, 6130 in particular if these include quality values, can be used by servers 6131 as relatively reliable and long-lived user identifiers. Such user 6132 identifiers would allow content providers to do click-trail tracking, 6133 and would allow collaborating content providers to match cross-server 6134 click-trails or form submissions of individual users. Note that for 6135 many users not behind a proxy, the network address of the host 6136 running the user agent will also serve as a long-lived user 6137 identifier. In environments where proxies are used to enhance 6138 privacy, user agents ought to be conservative in offering accept 6139 header configuration options to end users. As an extreme privacy 6140 measure, proxies could filter the accept header fields in relayed requests. 6141 General purpose user agents which provide a high degree of header 6142 configurability &SHOULD; warn users about the loss of privacy which can 6143 be involved. 6144 </t> 6145 </section> 6146 6147 </section> 6148 6149 6150 <section title="Differences between HTTP and MIME" anchor="differences.between.http.and.mime"> 6151 <t> 6152 HTTP/1.1 uses many of the constructs defined for Internet Mail (<xref target="RFC5322"/>) and the Multipurpose Internet Mail Extensions (MIME <xref target="RFC2045"/>) to 6153 allow a message body to be transmitted in an open variety of 6154 representations and with extensible mechanisms. However, RFC 2045 6155 discusses mail, and HTTP has a few features that are different from 6156 those described in MIME. These differences were carefully chosen 6157 to optimize performance over binary connections, to allow greater 6158 freedom in the use of new media types, to make date comparisons 6159 easier, and to acknowledge the practice of some early HTTP servers 6160 and clients. 6161 </t> 6162 <t> 6163 This appendix describes specific areas where HTTP differs from MIME. 6164 Proxies and gateways to strict MIME environments &SHOULD; be 6165 aware of these differences and provide the appropriate conversions 6166 where necessary. Proxies and gateways from MIME environments to HTTP 6167 also need to be aware of the differences because some conversions 6168 might be required. 6169 </t> 6170 6171 <section title="MIME-Version" anchor="mime-version"> 6172 <iref primary="true" item="MIME-Version header field" x:for-anchor=""/> 6173 <iref primary="true" item="Header Fields" subitem="MIME-Version" x:for-anchor=""/> 6174 <x:anchor-alias value="MIME-Version"/> 6175 <t> 6176 HTTP is not a MIME-compliant protocol. However, HTTP/1.1 messages &MAY; 6177 include a single MIME-Version header field to indicate what 6178 version of the MIME protocol was used to construct the message. Use 6179 of the MIME-Version header field indicates that the message is in 6180 full conformance with the MIME protocol (as defined in <xref target="RFC2045"/>). 6181 Proxies/gateways are responsible for ensuring full conformance (where 6182 possible) when exporting HTTP messages to strict MIME environments. 6183 </t> 6184 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="MIME-Version"/> 6185 <x:ref>MIME-Version</x:ref> = 1*<x:ref>DIGIT</x:ref> "." 1*<x:ref>DIGIT</x:ref> 6186 </artwork></figure> 6187 <t> 6188 MIME version "1.0" is the default for use in HTTP/1.1. However, 6189 HTTP/1.1 message parsing and semantics are defined by this document 6190 and not the MIME specification. 6191 </t> 6192 </section> 6193 6194 <section title="Conversion to Canonical Form" anchor="conversion.to.canonical.form"> 6195 <t> 6196 MIME requires that an Internet mail body-part be converted to 6197 canonical form prior to being transferred, as described in <xref target="RFC2049" x:fmt="of" x:sec="4"/>. 6198 <xref target="canonicalization.and.text.defaults"/> of this document describes the forms 6199 allowed for subtypes of the "text" media type when transmitted over 6200 HTTP. <xref target="RFC2046"/> requires that content with a type of "text" represent 6201 line breaks as CRLF and forbids the use of CR or LF outside of line 6202 break sequences. HTTP allows CRLF, bare CR, and bare LF to indicate a 6203 line break within text content when a message is transmitted over 6204 HTTP. 6205 </t> 6206 <t> 6207 Where it is possible, a proxy or gateway from HTTP to a strict MIME 6208 environment &SHOULD; translate all line breaks within the text media 6209 types described in <xref target="canonicalization.and.text.defaults"/> 6210 of this document to the RFC 2049 6211 canonical form of CRLF. Note, however, that this might be complicated 6212 by the presence of a Content-Encoding and by the fact that HTTP 6213 allows the use of some character encodings which do not use octets 13 and 6214 10 to represent CR and LF, respectively, as is the case for some multi-byte 6215 character encodings. 6216 </t> 6217 <t> 6218 Conversion will break any cryptographic 6219 checksums applied to the original content unless the original content 6220 is already in canonical form. Therefore, the canonical form is 6221 recommended for any content that uses such checksums in HTTP. 6222 </t> 6223 </section> 6224 6225 6226 <section title="Conversion of Date Formats" anchor="conversion.of.date.formats"> 6227 <t> 6228 HTTP/1.1 uses a restricted set of date formats (&http-date;) to 6229 simplify the process of date comparison. Proxies and gateways from 6230 other protocols &SHOULD; ensure that any Date header field present in a 6231 message conforms to one of the HTTP/1.1 formats and rewrite the date 6232 if necessary. 6233 </t> 6234 </section> 6235 6236 <section title="Introduction of Content-Encoding" anchor="introduction.of.content-encoding"> 6237 <t> 6238 MIME does not include any concept equivalent to HTTP/1.1's 6239 Content-Encoding header field. Since this acts as a modifier on the 6240 media type, proxies and gateways from HTTP to MIME-compliant 6241 protocols &MUST; either change the value of the Content-Type header 6242 field or decode the representation before forwarding the message. (Some 6243 experimental applications of Content-Type for Internet mail have used 6244 a media-type parameter of ";conversions=<content-coding>" to perform 6245 a function equivalent to Content-Encoding. However, this parameter is 6246 not part of the MIME standards). 6247 </t> 6248 </section> 6249 6250 <section title="No Content-Transfer-Encoding" anchor="no.content-transfer-encoding"> 6251 <iref item="Content-Transfer-Encoding header field" x:for-anchor=""/> 6252 <iref item="Header Fields" subitem="Content-Transfer-Encoding" x:for-anchor=""/> 6253 <t> 6254 HTTP does not use the Content-Transfer-Encoding field of MIME. 6255 Proxies and gateways from MIME-compliant protocols to HTTP &MUST; 6256 remove any Content-Transfer-Encoding 6257 prior to delivering the response message to an HTTP client. 6258 </t> 6259 <t> 6260 Proxies and gateways from HTTP to MIME-compliant protocols are 6261 responsible for ensuring that the message is in the correct format 6262 and encoding for safe transport on that protocol, where "safe 6263 transport" is defined by the limitations of the protocol being used. 6264 Such a proxy or gateway &SHOULD; label the data with an appropriate 6265 Content-Transfer-Encoding if doing so will improve the likelihood of 6266 safe transport over the destination protocol. 6267 </t> 6268 </section> 6269 6270 <section title="Introduction of Transfer-Encoding" anchor="introduction.of.transfer-encoding"> 6271 <t> 6272 HTTP/1.1 introduces the Transfer-Encoding header field (&header-transfer-encoding;). 6273 Proxies/gateways &MUST; remove any transfer-coding prior to 6274 forwarding a message via a MIME-compliant protocol. 6275 </t> 6276 </section> 6277 6278 <section title="MHTML and Line Length Limitations" anchor="mhtml.line.length"> 6279 <t> 6280 HTTP implementations which share code with MHTML <xref target="RFC2557"/> implementations 6281 need to be aware of MIME line length limitations. Since HTTP does not 6282 have this limitation, HTTP does not fold long lines. MHTML messages 6283 being transported by HTTP follow all conventions of MHTML, including 6284 line length limitations and folding, canonicalization, etc., since 6285 HTTP transports all message-bodies as payload (see <xref target="multipart.types"/>) and 6286 does not interpret the content or any MIME header lines that might be 6287 contained therein. 6288 </t> 6289 </section> 6290 </section> 6291 6292 <section title="Additional Features" anchor="additional.features"> 6293 <t> 6294 <xref target="RFC1945"/> and <xref target="RFC2068"/> document protocol elements used by some 6295 existing HTTP implementations, but not consistently and correctly 6296 across most HTTP/1.1 applications. Implementors are advised to be 6297 aware of these features, but cannot rely upon their presence in, or 6298 interoperability with, other HTTP/1.1 applications. Some of these 6299 describe proposed experimental features, and some describe features 6300 that experimental deployment found lacking that are now addressed in 6301 the base HTTP/1.1 specification. 6302 </t> 6303 <t> 6304 A number of other header fields, such as Content-Disposition and Title, 6305 from SMTP and MIME are also often implemented (see <xref target="RFC6266"/> 6306 and <xref target="RFC2076"/>). 6307 </t> 6308 </section> 6309 6310 <section title="Changes from RFC 2616" anchor="changes.from.rfc.2616-3"> 6311 <t> 6312 Clarify contexts that charset is used in. 6313 (<xref target="character.sets"/>) 6314 </t> 6315 <t> 6316 Registration of Content Codings now requires IETF Review 6317 (<xref target="content.coding.registry"/>) 6318 </t> 6319 <t> 6320 Remove the default character encoding for text media types; the default 6321 now is whatever the media type definition says. 6322 (<xref target="canonicalization.and.text.defaults"/>) 6323 </t> 6324 <t> 6325 Change ABNF productions for header fields to only define the field value. 6326 (<xref target="header.field.definitions"/>) 6327 </t> 6328 <t> 6329 Remove definition of Content-MD5 header field because it was inconsistently 6330 implemented with respect to partial responses, and also because of known 6331 deficiencies in the hash algorithm itself (see <xref target="RFC6151"/> for details). 6332 (<xref target="header.field.definitions"/>) 6333 </t> 6334 <t> 6335 Remove ISO-8859-1 special-casing in Accept-Charset. 6336 (<xref target="header.accept-charset"/>) 6337 </t> 6338 <t> 6339 Remove base URI setting semantics for Content-Location due to poor 6340 implementation support, which was caused by too many broken servers emitting 6341 bogus Content-Location header fields, and also the potentially undesirable effect 6342 of potentially breaking relative links in content-negotiated resources. 6343 (<xref target="header.content-location"/>) 6344 </t> 6345 <t> 6346 Remove reference to non-existant identity transfer-coding value tokens. 6347 (<xref target="no.content-transfer-encoding"/>) 6348 </t> 6349 <t> 6350 Remove discussion of Content-Disposition header field, it is now defined 6351 by <xref target="RFC6266"/>. 6352 (<xref target="additional.features"/>) 6353 </t> 6354 </section> 6355 6356 <section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log3"> 6357 6358 <section title="Since RFC 2616"> 6359 <t> 6360 Extracted relevant partitions from <xref target="RFC2616"/>. 6361 </t> 6362 </section> 6363 6364 <section title="Since draft-ietf-httpbis-p3-payload-00"> 6365 <t> 6366 Closed issues: 6367 <list style="symbols"> 6368 <t> 6369 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/8"/>: 6370 "Media Type Registrations" 6371 (<eref target="http://purl.org/NET/http-errata#media-reg"/>) 6372 </t> 6373 <t> 6374 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/14"/>: 6375 "Clarification regarding quoting of charset values" 6376 (<eref target="http://purl.org/NET/http-errata#charactersets"/>) 6377 </t> 6378 <t> 6379 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/16"/>: 6380 "Remove 'identity' token references" 6381 (<eref target="http://purl.org/NET/http-errata#identity"/>) 6382 </t> 6383 <t> 6384 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/25"/>: 6385 "Accept-Encoding BNF" 6386 </t> 6387 <t> 6388 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>: 6389 "Normative and Informative references" 6390 </t> 6391 <t> 6392 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/46"/>: 6393 "RFC1700 references" 6394 </t> 6395 <t> 6396 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/55"/>: 6397 "Updating to RFC4288" 6398 </t> 6399 <t> 6400 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>: 6401 "Informative references" 6402 </t> 6403 <t> 6404 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/66"/>: 6405 "ISO-8859-1 Reference" 6406 </t> 6407 <t> 6408 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/68"/>: 6409 "Encoding References Normative" 6410 </t> 6411 <t> 6412 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/86"/>: 6413 "Normative up-to-date references" 6414 </t> 6415 </list> 6416 </t> 6417 </section> 6418 6419 <section title="Since draft-ietf-httpbis-p3-payload-01"> 6420 <t> 6421 Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>): 6422 <list style="symbols"> 6423 <t> 6424 Add explicit references to BNF syntax and rules imported from other parts of the specification. 6425 </t> 6426 </list> 6427 </t> 6428 </section> 6429 6430 <section title="Since draft-ietf-httpbis-p3-payload-02" anchor="changes.3.since.02"> 6431 <t> 6432 Closed issues: 6433 <list style="symbols"> 6434 <t> 6435 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/67"/>: 6436 "Quoting Charsets" 6437 </t> 6438 <t> 6439 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>: 6440 "Classification for Allow header" 6441 </t> 6442 <t> 6443 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/115"/>: 6444 "missing default for qvalue in description of Accept-Encoding" 6445 </t> 6446 </list> 6447 </t> 6448 <t> 6449 Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>): 6450 <list style="symbols"> 6451 <t> 6452 Reference RFC 3984, and update header field registrations for headers defined 6453 in this document. 6454 </t> 6455 </list> 6456 </t> 6457 </section> 6458 6459 <section title="Since draft-ietf-httpbis-p3-payload-03" anchor="changes.3.since.03"> 6460 <t> 6461 Closed issues: 6462 <list style="symbols"> 6463 <t> 6464 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/67"/>: 6465 "Quoting Charsets" 6466 </t> 6467 <t> 6468 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/113"/>: 6469 "language tag matching (Accept-Language) vs RFC4647" 6470 </t> 6471 <t> 6472 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/121"/>: 6473 "RFC 1806 has been replaced by RFC2183" 6474 </t> 6475 </list> 6476 </t> 6477 <t> 6478 Other changes: 6479 <list style="symbols"> 6480 <t> 6481 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/68"/>: 6482 "Encoding References Normative" — rephrase the annotation and reference 6483 BCP97. 6484 </t> 6485 </list> 6486 </t> 6487 </section> 6488 6489 <section title="Since draft-ietf-httpbis-p3-payload-04" anchor="changes.3.since.04"> 6490 <t> 6491 Closed issues: 6492 <list style="symbols"> 6493 <t> 6494 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>: 6495 "RFC 2822 is updated by RFC 5322" 6496 </t> 6497 </list> 6498 </t> 6499 <t> 6500 Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>): 6501 <list style="symbols"> 6502 <t> 6503 Use "/" instead of "|" for alternatives. 6504 </t> 6505 <t> 6506 Introduce new ABNF rules for "bad" whitespace ("BWS"), optional 6507 whitespace ("OWS") and required whitespace ("RWS"). 6508 </t> 6509 <t> 6510 Rewrite ABNFs to spell out whitespace rules, factor out 6511 header field value format definitions. 6512 </t> 6513 </list> 6514 </t> 6515 </section> 6516 6517 <section title="Since draft-ietf-httpbis-p3-payload-05" anchor="changes.3.since.05"> 6518 <t> 6519 Closed issues: 6520 <list style="symbols"> 6521 <t> 6522 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/118"/>: 6523 "Join "Differences Between HTTP Entities and RFC 2045 Entities"?" 6524 </t> 6525 </list> 6526 </t> 6527 <t> 6528 Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>): 6529 <list style="symbols"> 6530 <t> 6531 Add appendix containing collected and expanded ABNF, reorganize ABNF introduction. 6532 </t> 6533 </list> 6534 </t> 6535 <t> 6536 Other changes: 6537 <list style="symbols"> 6538 <t> 6539 Move definition of quality values into Part 1. 6540 </t> 6541 </list> 6542 </t> 6543 </section> 6544 6545 <section title="Since draft-ietf-httpbis-p3-payload-06" anchor="changes.3.since.06"> 6546 <t> 6547 Closed issues: 6548 <list style="symbols"> 6549 <t> 6550 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/80"/>: 6551 "Content-Location isn't special" 6552 </t> 6553 <t> 6554 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>: 6555 "Content Sniffing" 6556 </t> 6557 </list> 6558 </t> 6559 </section> 6560 6561 <section title="Since draft-ietf-httpbis-p3-payload-07" anchor="changes.3.since.07"> 6562 <t> 6563 Closed issues: 6564 <list style="symbols"> 6565 <t> 6566 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/13"/>: 6567 "Updated reference for language tags" 6568 </t> 6569 <t> 6570 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>: 6571 "Clarify rules for determining what entities a response carries" 6572 </t> 6573 <t> 6574 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/154"/>: 6575 "Content-Location base-setting problems" 6576 </t> 6577 <t> 6578 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>: 6579 "Content Sniffing" 6580 </t> 6581 <t> 6582 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/188"/>: 6583 "pick IANA policy (RFC5226) for Transfer Coding / Content Coding" 6584 </t> 6585 <t> 6586 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/189"/>: 6587 "move definitions of gzip/deflate/compress to part 1" 6588 </t> 6589 </list> 6590 </t> 6591 <t> 6592 Partly resolved issues: 6593 <list style="symbols"> 6594 <t> 6595 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/148"/>: 6596 "update IANA requirements wrt Transfer-Coding values" (add the 6597 IANA Considerations subsection) 6598 </t> 6599 <t> 6600 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/149"/>: 6601 "update IANA requirements wrt Content-Coding values" (add the 6602 IANA Considerations subsection) 6603 </t> 6604 </list> 6605 </t> 6606 </section> 6607 6608 <section title="Since draft-ietf-httpbis-p3-payload-08" anchor="changes.3.since.08"> 6609 <t> 6610 Closed issues: 6611 <list style="symbols"> 6612 <t> 6613 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/81"/>: 6614 "Content Negotiation for media types" 6615 </t> 6616 <t> 6617 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/181"/>: 6618 "Accept-Language: which RFC4647 filtering?" 6619 </t> 6620 </list> 6621 </t> 6622 </section> 6623 6624 <section title="Since draft-ietf-httpbis-p3-payload-09" anchor="changes.3.since.09"> 6625 <t> 6626 Closed issues: 6627 <list style="symbols"> 6628 <t> 6629 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/122"/>: 6630 "MIME-Version not listed in P1, general header fields" 6631 </t> 6632 <t> 6633 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/143"/>: 6634 "IANA registry for content/transfer encodings" 6635 </t> 6636 <t> 6637 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/155"/>: 6638 "Content Sniffing" 6639 </t> 6640 <t> 6641 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/200"/>: 6642 "use of term "word" when talking about header structure" 6643 </t> 6644 </list> 6645 </t> 6646 <t> 6647 Partly resolved issues: 6648 <list style="symbols"> 6649 <t> 6650 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>: 6651 "Term for the requested resource's URI" 6652 </t> 6653 </list> 6654 </t> 6655 </section> 6656 6657 <section title="Since draft-ietf-httpbis-p3-payload-10" anchor="changes.3.since.10"> 6658 <t> 6659 Closed issues: 6660 <list style="symbols"> 6661 <t> 6662 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>: 6663 "Clarify 'Requested Variant'" 6664 </t> 6665 <t> 6666 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/80"/>: 6667 "Content-Location isn't special" 6668 </t> 6669 <t> 6670 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/90"/>: 6671 "Delimiting messages with multipart/byteranges" 6672 </t> 6673 <t> 6674 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>: 6675 "Clarify entity / representation / variant terminology" 6676 </t> 6677 <t> 6678 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/136"/>: 6679 "confusing req. language for Content-Location" 6680 </t> 6681 <t> 6682 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/167"/>: 6683 "Content-Location on 304 responses" 6684 </t> 6685 <t> 6686 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/183"/>: 6687 "'requested resource' in content-encoding definition" 6688 </t> 6689 <t> 6690 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>: 6691 "consider removing the 'changes from 2068' sections" 6692 </t> 6693 </list> 6694 </t> 6695 <t> 6696 Partly resolved issues: 6697 <list style="symbols"> 6698 <t> 6699 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/178"/>: 6700 "Content-MD5 and partial responses" 6701 </t> 6702 </list> 6703 </t> 6704 </section> 6705 6706 <section title="Since draft-ietf-httpbis-p3-payload-11" anchor="changes.3.since.11"> 6707 <t> 6708 Closed issues: 6709 <list style="symbols"> 6710 <t> 6711 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/123"/>: 6712 "Factor out Content-Disposition" 6713 </t> 6714 </list> 6715 </t> 6716 </section> 6717 6718 <section title="Since draft-ietf-httpbis-p3-payload-12" anchor="changes.3.since.12"> 6719 <t> 6720 Closed issues: 6721 <list style="symbols"> 6722 <t> 6723 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>: 6724 "Header Classification" 6725 </t> 6726 <t> 6727 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>: 6728 "untangle ABNFs for header fields" 6729 </t> 6730 <t> 6731 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/277"/>: 6732 "potentially misleading MAY in media-type def" 6733 </t> 6734 </list> 6735 </t> 6736 </section> 6737 6738 <section title="Since draft-ietf-httpbis-p3-payload-13" anchor="changes.3.since.13"> 6739 <t> 6740 Closed issues: 6741 <list style="symbols"> 6742 <t> 6743 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/20"/>: 6744 "Default charsets for text media types" 6745 </t> 6746 <t> 6747 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/178"/>: 6748 "Content-MD5 and partial responses" 6749 </t> 6750 <t> 6751 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>: 6752 "untangle ABNFs for header fields" 6753 </t> 6754 <t> 6755 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/281"/>: 6756 "confusing undefined parameter in media range example" 6757 </t> 6758 </list> 6759 </t> 6760 </section> 6761 6762 <section title="Since draft-ietf-httpbis-p3-payload-14" anchor="changes.3.since.14"> 6763 <t> 6764 None. 6765 </t> 6766 </section> 6767 6768 <section title="Since draft-ietf-httpbis-p3-payload-15" anchor="changes.3.since.15"> 6769 <t> 6770 Closed issues: 6771 <list style="symbols"> 6772 <t> 6773 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/285"/>: 6774 "Strength of requirements on Accept re: 406" 6775 </t> 6776 </list> 6777 </t> 6778 </section> 6779 6780 <section title="Since draft-ietf-httpbis-p3-payload-16" anchor="changes.3.since.16"> 6781 <t> 6782 Closed issues: 6783 <list style="symbols"> 6784 <t> 6785 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/186"/>: 6786 "Document HTTP's error-handling philosophy" 6787 </t> 6788 </list> 6789 </t> 6790 </section> 6791 6792 <section title="Since draft-ietf-httpbis-p3-payload-17" anchor="changes.3.since.17"> 6793 <t> 6794 Closed issues: 6795 <list style="symbols"> 6796 <t> 6797 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/323"/>: 6798 "intended maturity level vs normative references" 6799 </t> 6800 </list> 6801 </t> 6802 </section> 6803 6804 <section title="Since draft-ietf-httpbis-p3-payload-18" anchor="changes.3.since.18"> 6805 <t> 6806 Closed issues: 6807 <list style="symbols"> 6808 <t> 6809 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/330"/>: 6810 "is ETag a representation header field?" 6811 </t> 6812 <t> 6813 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/338"/>: 6814 "Content-Location doesn't constrain the cardinality of representations" 6815 </t> 6816 <t> 6817 <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/346"/>: 6818 "make IANA policy definitions consistent" 6819 </t> 6820 </list> 6821 </t> 6822 </section> 6823 6824 <section title="Since draft-ietf-httpbis-p3-payload-19" anchor="changes.3.since.19"> 6825 <t> 6826 None yet. 6827 </t> 6828 </section> 6829 6830 </section> 6831 </section> 6832 4846 6833 </back> 4847 6834 </rfc>
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