Changeset 1920
- Timestamp:
- 01/10/12 01:14:48 (10 years ago)
- Location:
- draft-ietf-httpbis/latest
- Files:
-
- 2 edited
Legend:
- Unmodified
- Added
- Removed
-
draft-ietf-httpbis/latest/p2-semantics.html
r1919 r1920 587 587 </ul> 588 588 </li> 589 <li><a href="#rfc.section.3.2">3.2</a> <a href="#selected.representation">Selected Representation Header Fields</a></li> 590 <li><a href="#rfc.section.3.3">3.3</a> <a href="#representation.data">Representation Data</a></li> 591 <li><a href="#rfc.section.3.4">3.4</a> <a href="#payload">Message Payload</a><ul> 592 <li><a href="#rfc.section.3.4.1">3.4.1</a> <a href="#payload.header.fields">Payload Header Fields</a></li> 593 <li><a href="#rfc.section.3.4.2">3.4.2</a> <a href="#identifying.payload">Identifying the Payload</a></li> 589 <li><a href="#rfc.section.3.2">3.2</a> <a href="#representation.data">Representation Data</a></li> 590 <li><a href="#rfc.section.3.3">3.3</a> <a href="#payload">Message Payload</a><ul> 591 <li><a href="#rfc.section.3.3.1">3.3.1</a> <a href="#payload.header.fields">Payload Header Fields</a></li> 592 <li><a href="#rfc.section.3.3.2">3.3.2</a> <a href="#identifying.payload">Identifying the Payload</a></li> 594 593 </ul> 595 594 </li> 596 <li><a href="#rfc.section.3. 5">3.5</a> <a href="#content.negotiation">Content Negotiation</a><ul>597 <li><a href="#rfc.section.3. 5.1">3.5.1</a> <a href="#proactive.negotiation">Proactive Negotiation</a></li>598 <li><a href="#rfc.section.3. 5.2">3.5.2</a> <a href="#reactive.negotiation">Reactive Negotiation</a></li>595 <li><a href="#rfc.section.3.4">3.4</a> <a href="#content.negotiation">Content Negotiation</a><ul> 596 <li><a href="#rfc.section.3.4.1">3.4.1</a> <a href="#proactive.negotiation">Proactive Negotiation</a></li> 597 <li><a href="#rfc.section.3.4.2">3.4.2</a> <a href="#reactive.negotiation">Reactive Negotiation</a></li> 599 598 </ul> 600 599 </li> … … 706 705 <li><a href="#rfc.section.7">7.</a> <a href="#response.header.fields">Response Header Fields</a><ul> 707 706 <li><a href="#rfc.section.7.1">7.1</a> <a href="#response.control.data">Control Data</a><ul> 708 <li><a href="#rfc.section.7.1.1">7.1.1</a> <a href="#header.location">Location</a></li> 709 <li><a href="#rfc.section.7.1.2">7.1.2</a> <a href="#header.retry-after">Retry-After</a></li> 707 <li><a href="#rfc.section.7.1.1">7.1.1</a> <a href="#header.date">Date</a></li> 708 <li><a href="#rfc.section.7.1.2">7.1.2</a> <a href="#header.location">Location</a></li> 709 <li><a href="#rfc.section.7.1.3">7.1.3</a> <a href="#header.retry-after">Retry-After</a></li> 710 710 </ul> 711 711 </li> 712 <li><a href="#rfc.section.7.2">7.2</a> <a href="#response.cache.related">Cache-related</a><ul> 713 <li><a href="#rfc.section.7.2.1">7.2.1</a> <a href="#header.date">Date</a></li> 714 <li><a href="#rfc.section.7.2.2">7.2.2</a> <a href="#header.vary">Vary</a></li> 712 <li><a href="#rfc.section.7.2">7.2</a> <a href="#selected.representation">Selected Representation Header Fields</a><ul> 713 <li><a href="#rfc.section.7.2.1">7.2.1</a> <a href="#header.vary">Vary</a></li> 715 714 </ul> 716 715 </li> … … 926 925 </p> 927 926 <div id="rfc.figure.u.2"></div><pre class="text"> Content-Type: text/html; charset=ISO-8859-4 928 </pre><p id="rfc.section.3.1.1.p.5">Further discussion of Content-Type is provided in <a href="#representation.data" title="Representation Data">Section 3. 3</a>.927 </pre><p id="rfc.section.3.1.1.p.5">Further discussion of Content-Type is provided in <a href="#representation.data" title="Representation Data">Section 3.2</a>. 929 928 </p> 930 929 <div id="rfc.iref.c.3"></div> … … 1019 1018 </p> 1020 1019 <p id="rfc.section.3.1.4.p.9">If the Content-Location value is a partial URI, the partial URI is interpreted relative to the effective request URI.</p> 1021 <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a> <a id="selected.representation" href="#selected.representation">Selected Representation Header Fields</a></h2> 1022 <p id="rfc.section.3.2.p.1"><span id="rfc.iref.s.1"></span> We use the term "<dfn>selected representation</dfn>" to refer to the the current representation of a target resource that would have been selected in a successful response if 1023 the same request had used the method GET and excluded any conditional request header fields. 1024 </p> 1025 <p id="rfc.section.3.2.p.2">Additional header fields define metadata about the selected representation, which might differ from the representation included 1026 in the message for responses to some state-changing methods. The following header fields are defined as selected representation 1027 metadata: 1028 </p> 1029 <div id="rfc.table.u.2"> 1030 <table class="tt full left" cellpadding="3" cellspacing="0"> 1031 <thead> 1032 <tr> 1033 <th>Header Field Name</th> 1034 <th>Defined in...</th> 1035 </tr> 1036 </thead> 1037 <tbody> 1038 <tr> 1039 <td class="left">ETag</td> 1040 <td class="left"><a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1041 </tr> 1042 <tr> 1043 <td class="left">Last-Modified</td> 1044 <td class="left"><a href="p4-conditional.html#header.last-modified" title="Last-Modified">Section 2.2</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1045 </tr> 1046 </tbody> 1047 </table> 1048 </div> 1049 <h2 id="rfc.section.3.3"><a href="#rfc.section.3.3">3.3</a> <a id="representation.data" href="#representation.data">Representation Data</a></h2> 1050 <p id="rfc.section.3.3.p.1">The representation data associated with an HTTP message is either provided as the payload body of the message or referred 1020 <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a> <a id="representation.data" href="#representation.data">Representation Data</a></h2> 1021 <p id="rfc.section.3.2.p.1">The representation data associated with an HTTP message is either provided as the payload body of the message or referred 1051 1022 to by the message semantics and the effective request URI. The representation data is in a format and encoding defined by 1052 1023 the representation metadata header fields. 1053 1024 </p> 1054 <p id="rfc.section.3. 3.p.2">The data type of the representation data is determined via the header fields <a href="#header.content-type" class="smpl">Content-Type</a> and <a href="#header.content-encoding" class="smpl">Content-Encoding</a>. These define a two-layer, ordered encoding model:1025 <p id="rfc.section.3.2.p.2">The data type of the representation data is determined via the header fields <a href="#header.content-type" class="smpl">Content-Type</a> and <a href="#header.content-encoding" class="smpl">Content-Encoding</a>. These define a two-layer, ordered encoding model: 1055 1026 </p> 1056 1027 <div id="rfc.figure.u.9"></div><pre class="text"> representation-data := Content-Encoding( Content-Type( bits ) ) 1057 </pre><p id="rfc.section.3. 3.p.4"> <a href="#header.content-type" class="smpl">Content-Type</a> specifies the media type of the underlying data, which defines both the data format and how that data <em class="bcp14">SHOULD</em> be processed by the recipient (within the scope of the request method semantics). Any HTTP/1.1 message containing a payload1028 </pre><p id="rfc.section.3.2.p.4"> <a href="#header.content-type" class="smpl">Content-Type</a> specifies the media type of the underlying data, which defines both the data format and how that data <em class="bcp14">SHOULD</em> be processed by the recipient (within the scope of the request method semantics). Any HTTP/1.1 message containing a payload 1058 1029 body <em class="bcp14">SHOULD</em> include a Content-Type header field defining the media type of the associated representation unless that metadata is unknown 1059 1030 to the sender. If the Content-Type header field is not present, it indicates that the sender does not know the media type 1060 1031 of the representation; recipients <em class="bcp14">MAY</em> either assume that the media type is "application/octet-stream" (<a href="#RFC2046" id="rfc.xref.RFC2046.1"><cite title="Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types">[RFC2046]</cite></a>, <a href="http://tools.ietf.org/html/rfc2046#section-4.5.1">Section 4.5.1</a>) or examine the content to determine its type. 1061 1032 </p> 1062 <p id="rfc.section.3. 3.p.5">In practice, resource owners do not always properly configure their origin server to provide the correct Content-Type for1033 <p id="rfc.section.3.2.p.5">In practice, resource owners do not always properly configure their origin server to provide the correct Content-Type for 1063 1034 a given representation, with the result that some clients will examine a payload's content and override the specified type. 1064 1035 Clients that do so risk drawing incorrect conclusions, which might expose additional security risks (e.g., "privilege escalation"). … … 1067 1038 sniffing" when it is used. 1068 1039 </p> 1069 <p id="rfc.section.3. 3.p.6"> <a href="#header.content-encoding" class="smpl">Content-Encoding</a> is used to indicate any additional content codings applied to the data, usually for the purpose of data compression, that1040 <p id="rfc.section.3.2.p.6"> <a href="#header.content-encoding" class="smpl">Content-Encoding</a> is used to indicate any additional content codings applied to the data, usually for the purpose of data compression, that 1070 1041 are a property of the representation. If Content-Encoding is not present, then there is no additional encoding beyond that 1071 1042 defined by the <a href="#header.content-type" class="smpl">Content-Type</a> header field. 1072 1043 </p> 1073 1044 <div id="rfc.iref.p.1"></div> 1074 <h2 id="rfc.section.3. 4"><a href="#rfc.section.3.4">3.4</a> <a id="payload" href="#payload">Message Payload</a></h2>1075 <p id="rfc.section.3. 4.p.1">Some HTTP messages transfer a complete or partial representation as the message "<dfn>payload</dfn>". In some cases, a payload might only contain the associated representation's header fields (e.g., responses to HEAD) or1045 <h2 id="rfc.section.3.3"><a href="#rfc.section.3.3">3.3</a> <a id="payload" href="#payload">Message Payload</a></h2> 1046 <p id="rfc.section.3.3.p.1">Some HTTP messages transfer a complete or partial representation as the message "<dfn>payload</dfn>". In some cases, a payload might only contain the associated representation's header fields (e.g., responses to HEAD) or 1076 1047 only some part(s) of the representation data (e.g., the <a href="p5-range.html#status.206" class="smpl">206 (Partial Content)</a> status code). 1077 1048 </p> 1078 <p id="rfc.section.3. 4.p.2">The purpose of a payload in a request is defined by the method semantics. In a response, the payload's purpose is defined1049 <p id="rfc.section.3.3.p.2">The purpose of a payload in a request is defined by the method semantics. In a response, the payload's purpose is defined 1079 1050 by both the request method and the response status code. 1080 1051 </p> 1081 <p id="rfc.section.3. 4.p.3">For example, a representation in the payload of a PUT request (<a href="#PUT" id="rfc.xref.PUT.1" title="PUT">Section 4.3.4</a>) represents the desired state of the target resource if the request is successfully applied, whereas a representation in1052 <p id="rfc.section.3.3.p.3">For example, a representation in the payload of a PUT request (<a href="#PUT" id="rfc.xref.PUT.1" title="PUT">Section 4.3.4</a>) represents the desired state of the target resource if the request is successfully applied, whereas a representation in 1082 1053 the payload of a POST request (<a href="#POST" id="rfc.xref.POST.1" title="POST">Section 4.3.3</a>) represents an anonymous resource for providing data to be processed, such as the information that a user entered within 1083 1054 an HTML form. 1084 1055 </p> 1085 <p id="rfc.section.3. 4.p.4">Likewise, the payload of a <a href="#status.200" class="smpl">200 (OK)</a> response to GET (<a href="#GET" id="rfc.xref.GET.1" title="GET">Section 4.3.1</a>) contains a representation of the target resource, as observed at the time of the message origination date (<a href="#header.date" id="rfc.xref.header.date.1" title="Date">Section 7.2.1</a>), whereas the same status code in a response to POST might contain either a representation of the processing result or a1056 <p id="rfc.section.3.3.p.4">Likewise, the payload of a <a href="#status.200" class="smpl">200 (OK)</a> response to GET (<a href="#GET" id="rfc.xref.GET.1" title="GET">Section 4.3.1</a>) contains a representation of the target resource, as observed at the time of the message origination date (<a href="#header.date" id="rfc.xref.header.date.1" title="Date">Section 7.1.1</a>), whereas the same status code in a response to POST might contain either a representation of the processing result or a 1086 1057 current representation of the target resource after applying the processing. Response messages with an error status code usually 1087 1058 contain a representation that describes the error and what next steps are suggested for resolving it. 1088 1059 </p> 1089 <h3 id="rfc.section.3. 4.1"><a href="#rfc.section.3.4.1">3.4.1</a> <a id="payload.header.fields" href="#payload.header.fields">Payload Header Fields</a></h3>1090 <p id="rfc.section.3. 4.1.p.1">Header fields that specifically describe the payload, rather than the associated representation, are referred to as "payload1060 <h3 id="rfc.section.3.3.1"><a href="#rfc.section.3.3.1">3.3.1</a> <a id="payload.header.fields" href="#payload.header.fields">Payload Header Fields</a></h3> 1061 <p id="rfc.section.3.3.1.p.1">Header fields that specifically describe the payload, rather than the associated representation, are referred to as "payload 1091 1062 header fields". Payload header fields are defined in other parts of this specification, due to their impact on message parsing. 1092 1063 </p> 1093 <div id="rfc.table.u. 3">1064 <div id="rfc.table.u.2"> 1094 1065 <table class="tt full left" cellpadding="3" cellspacing="0"> 1095 1066 <thead> … … 1115 1086 </table> 1116 1087 </div> 1117 <h3 id="rfc.section.3. 4.2"><a href="#rfc.section.3.4.2">3.4.2</a> <a id="identifying.payload" href="#identifying.payload">Identifying the Payload</a></h3>1118 <p id="rfc.section.3. 4.2.p.1">When a complete or partial representation is transferred in a message payload, it is often desirable for the sender to supply,1088 <h3 id="rfc.section.3.3.2"><a href="#rfc.section.3.3.2">3.3.2</a> <a id="identifying.payload" href="#identifying.payload">Identifying the Payload</a></h3> 1089 <p id="rfc.section.3.3.2.p.1">When a complete or partial representation is transferred in a message payload, it is often desirable for the sender to supply, 1119 1090 or the recipient to determine, an identifier for the resource corresponding to that representation. 1120 1091 </p> 1121 <p id="rfc.section.3. 4.2.p.2">The following rules are used to determine such a URI for the payload of a request message: </p>1092 <p id="rfc.section.3.3.2.p.2">The following rules are used to determine such a URI for the payload of a request message: </p> 1122 1093 <ul> 1123 1094 <li>If the request has a <a href="#header.content-location" class="smpl">Content-Location</a> header field, then the sender asserts that the payload is a representation of the resource identified by the Content-Location … … 1127 1098 <li>Otherwise, the payload is unidentified.</li> 1128 1099 </ul> 1129 <p id="rfc.section.3. 4.2.p.3">The following rules, to be applied in order until a match is found, are used to determine such a URI for the payload of a1100 <p id="rfc.section.3.3.2.p.3">The following rules, to be applied in order until a match is found, are used to determine such a URI for the payload of a 1130 1101 response message: 1131 1102 </p> … … 1145 1116 <li>Otherwise, the payload is unidentified.</li> 1146 1117 </ol> 1147 <h2 id="rfc.section.3. 5"><a href="#rfc.section.3.5">3.5</a> <a id="content.negotiation" href="#content.negotiation">Content Negotiation</a></h2>1148 <p id="rfc.section.3. 5.p.1">HTTP responses include a representation which contains information for interpretation, whether by a human user or for further1118 <h2 id="rfc.section.3.4"><a href="#rfc.section.3.4">3.4</a> <a id="content.negotiation" href="#content.negotiation">Content Negotiation</a></h2> 1119 <p id="rfc.section.3.4.p.1">HTTP responses include a representation which contains information for interpretation, whether by a human user or for further 1149 1120 processing. Often, the server has different ways of representing the same information; for example, in different formats, 1150 1121 languages, or using different character encodings. 1151 1122 </p> 1152 <p id="rfc.section.3. 5.p.2">HTTP clients and their users might have different or variable capabilities, characteristics or preferences which would influence1123 <p id="rfc.section.3.4.p.2">HTTP clients and their users might have different or variable capabilities, characteristics or preferences which would influence 1153 1124 which representation, among those available from the server, would be best for the server to deliver. For this reason, HTTP 1154 1125 provides mechanisms for "content negotiation" — a process of allowing selection of a representation of a given resource, when 1155 1126 more than one is available. 1156 1127 </p> 1157 <p id="rfc.section.3. 5.p.3">This specification defines two patterns of content negotiation; "proactive", where the server selects the representation based1128 <p id="rfc.section.3.4.p.3">This specification defines two patterns of content negotiation; "proactive", where the server selects the representation based 1158 1129 upon the client's stated preferences, and "reactive" negotiation, where the server provides a list of representations for 1159 1130 the client to choose from, based upon their metadata. In addition, there are other patterns: some applications use an "active … … 1161 1132 selects additional resources to invoke. "Transparent Content Negotiation" (<a href="#RFC2295" id="rfc.xref.RFC2295.1"><cite title="Transparent Content Negotiation in HTTP">[RFC2295]</cite></a>) has also been proposed. 1162 1133 </p> 1163 <p id="rfc.section.3. 5.p.4">These patterns are all widely used, and have trade-offs in applicability and practicality. In particular, when the number1134 <p id="rfc.section.3.4.p.4">These patterns are all widely used, and have trade-offs in applicability and practicality. In particular, when the number 1164 1135 of preferences or capabilities to be expressed by a client are large (such as when many different formats are supported by 1165 1136 a user-agent), proactive negotiation becomes unwieldy, and might not be appropriate. Conversely, when the number of representations 1166 1137 to choose from is very large, reactive negotiation might not be appropriate. 1167 1138 </p> 1168 <p id="rfc.section.3. 5.p.5">Note that, in all cases, the supplier of representations has the responsibility for determining which representations might1139 <p id="rfc.section.3.4.p.5">Note that, in all cases, the supplier of representations has the responsibility for determining which representations might 1169 1140 be considered to be the "same information". 1170 1141 </p> 1171 <h3 id="rfc.section.3. 5.1"><a href="#rfc.section.3.5.1">3.5.1</a> <a id="proactive.negotiation" href="#proactive.negotiation">Proactive Negotiation</a></h3>1172 <p id="rfc.section.3. 5.1.p.1">If the selection of the best representation for a response is made by an algorithm located at the server, it is called proactive1142 <h3 id="rfc.section.3.4.1"><a href="#rfc.section.3.4.1">3.4.1</a> <a id="proactive.negotiation" href="#proactive.negotiation">Proactive Negotiation</a></h3> 1143 <p id="rfc.section.3.4.1.p.1">If the selection of the best representation for a response is made by an algorithm located at the server, it is called proactive 1173 1144 negotiation. Selection is based on the available representations of the response (the dimensions over which it can vary; e.g., 1174 1145 language, content-coding, etc.) and the contents of particular header fields in the request message or on other information 1175 1146 pertaining to the request (such as the network address of the client). 1176 1147 </p> 1177 <p id="rfc.section.3. 5.1.p.2">Proactive negotiation is advantageous when the algorithm for selecting from among the available representations is difficult1148 <p id="rfc.section.3.4.1.p.2">Proactive negotiation is advantageous when the algorithm for selecting from among the available representations is difficult 1178 1149 to describe to the user agent, or when the server desires to send its "best guess" to the client along with the first response 1179 1150 (hoping to avoid the round-trip delay of a subsequent request if the "best guess" is good enough for the user). In order to 1180 1151 improve the server's guess, the user agent <em class="bcp14">MAY</em> include request header fields (<a href="#header.accept" class="smpl">Accept</a>, <a href="#header.accept-language" class="smpl">Accept-Language</a>, <a href="#header.accept-encoding" class="smpl">Accept-Encoding</a>, etc.) which describe its preferences for such a response. 1181 1152 </p> 1182 <p id="rfc.section.3. 5.1.p.3">Proactive negotiation has disadvantages: </p>1153 <p id="rfc.section.3.4.1.p.3">Proactive negotiation has disadvantages: </p> 1183 1154 <ol> 1184 1155 <li>It is impossible for the server to accurately determine what might be "best" for any given user, since that would require … … 1192 1163 <li>It might limit a public cache's ability to use the same response for multiple user's requests.</li> 1193 1164 </ol> 1194 <p id="rfc.section.3. 5.1.p.4">Proactive negotiation allows the user agent to specify its preferences, but it cannot expect responses to always honor them.1165 <p id="rfc.section.3.4.1.p.4">Proactive negotiation allows the user agent to specify its preferences, but it cannot expect responses to always honor them. 1195 1166 For example, the origin server might not implement proactive negotiation, or it might decide that sending a response that 1196 1167 doesn't conform to them is better than sending a <a href="#status.406" class="smpl">406 1197 1168 (Not Acceptable)</a> response. 1198 1169 </p> 1199 <p id="rfc.section.3. 5.1.p.5">HTTP/1.1 includes the following header fields for enabling proactive negotiation through description of user agent capabilities1170 <p id="rfc.section.3.4.1.p.5">HTTP/1.1 includes the following header fields for enabling proactive negotiation through description of user agent capabilities 1200 1171 and user preferences: <a href="#header.accept" class="smpl">Accept</a> (<a href="#header.accept" id="rfc.xref.header.accept.1" title="Accept">Section 5.3.2</a>), <a href="#header.accept-charset" class="smpl">Accept-Charset</a> (<a href="#header.accept-charset" id="rfc.xref.header.accept-charset.1" title="Accept-Charset">Section 5.3.3</a>), <a href="#header.accept-encoding" class="smpl">Accept-Encoding</a> (<a href="#header.accept-encoding" id="rfc.xref.header.accept-encoding.1" title="Accept-Encoding">Section 5.3.4</a>), <a href="#header.accept-language" class="smpl">Accept-Language</a> (<a href="#header.accept-language" id="rfc.xref.header.accept-language.1" title="Accept-Language">Section 5.3.5</a>), and <a href="#header.user-agent" class="smpl">User-Agent</a> (<a href="#header.user-agent" id="rfc.xref.header.user-agent.1" title="User-Agent">Section 5.5.3</a>). However, an origin server is not limited to these dimensions and <em class="bcp14">MAY</em> vary the response based on any aspect of the request, including aspects of the connection (e.g., IP address) or information 1201 1172 within extension header fields not defined by this specification. 1202 1173 </p> 1203 <div class="note" id="rfc.section.3. 5.1.p.6">1174 <div class="note" id="rfc.section.3.4.1.p.6"> 1204 1175 <p> <b>Note:</b> In practice, <a href="#header.user-agent" class="smpl">User-Agent</a> based negotiation is fragile, because new clients might not be recognized. 1205 1176 </p> 1206 1177 </div> 1207 <p id="rfc.section.3. 5.1.p.7">The <a href="#header.vary" class="smpl">Vary</a> header field (<a href="#header.vary" id="rfc.xref.header.vary.1" title="Vary">Section 7.2.2</a>) can be used to express the parameters the server uses to select a representation that is subject to proactive negotiation.1208 </p> 1209 <h3 id="rfc.section.3. 5.2"><a href="#rfc.section.3.5.2">3.5.2</a> <a id="reactive.negotiation" href="#reactive.negotiation">Reactive Negotiation</a></h3>1210 <p id="rfc.section.3. 5.2.p.1">With reactive negotiation, selection of the best representation for a response is performed by the user agent after receiving1178 <p id="rfc.section.3.4.1.p.7">The <a href="#header.vary" class="smpl">Vary</a> header field (<a href="#header.vary" id="rfc.xref.header.vary.1" title="Vary">Section 7.2.1</a>) can be used to express the parameters the server uses to select a representation that is subject to proactive negotiation. 1179 </p> 1180 <h3 id="rfc.section.3.4.2"><a href="#rfc.section.3.4.2">3.4.2</a> <a id="reactive.negotiation" href="#reactive.negotiation">Reactive Negotiation</a></h3> 1181 <p id="rfc.section.3.4.2.p.1">With reactive negotiation, selection of the best representation for a response is performed by the user agent after receiving 1211 1182 an initial response from the origin server. Selection is based on a list of the available representations of the response 1212 1183 included within the header fields or body of the initial response, with each representation identified by its own URI. Selection … … 1214 1185 user selecting from a generated (possibly hypertext) menu. 1215 1186 </p> 1216 <p id="rfc.section.3. 5.2.p.2">Reactive negotiation is advantageous when the response would vary over commonly-used dimensions (such as type, language, or1187 <p id="rfc.section.3.4.2.p.2">Reactive negotiation is advantageous when the response would vary over commonly-used dimensions (such as type, language, or 1217 1188 encoding), when the origin server is unable to determine a user agent's capabilities from examining the request, and generally 1218 1189 when public caches are used to distribute server load and reduce network usage. 1219 1190 </p> 1220 <p id="rfc.section.3. 5.2.p.3">Reactive negotiation suffers from the disadvantage of needing a second request to obtain the best alternate representation.1191 <p id="rfc.section.3.4.2.p.3">Reactive negotiation suffers from the disadvantage of needing a second request to obtain the best alternate representation. 1221 1192 This second request is only efficient when caching is used. In addition, this specification does not define any mechanism 1222 1193 for supporting automatic selection, though it also does not prevent any such mechanism from being developed as an extension 1223 1194 and used within HTTP/1.1. 1224 1195 </p> 1225 <p id="rfc.section.3. 5.2.p.4">This specification defines the <a href="#status.300" class="smpl">300 (Multiple Choices)</a> and <a href="#status.406" class="smpl">406 (Not Acceptable)</a> status codes for enabling reactive negotiation when the server is unwilling or unable to provide a varying response using1196 <p id="rfc.section.3.4.2.p.4">This specification defines the <a href="#status.300" class="smpl">300 (Multiple Choices)</a> and <a href="#status.406" class="smpl">406 (Not Acceptable)</a> status codes for enabling reactive negotiation when the server is unwilling or unable to provide a varying response using 1226 1197 proactive negotiation. 1227 1198 </p> … … 1308 1279 </p> 1309 1280 <h2 id="rfc.section.4.2"><a href="#rfc.section.4.2">4.2</a> <a id="method.properties" href="#method.properties">Common Method Properties</a></h2> 1310 <div id="rfc.iref.s. 2"></div>1281 <div id="rfc.iref.s.1"></div> 1311 1282 <h3 id="rfc.section.4.2.1"><a href="#rfc.section.4.2.1">4.2.1</a> <a id="safe.methods" href="#safe.methods">Safe Methods</a></h3> 1312 1283 <p id="rfc.section.4.2.1.p.1">Request methods are considered "<dfn id="safe">safe</dfn>" if their defined semantics are essentially read-only; i.e., the client does not request, and does not expect, any state … … 1365 1336 in the response and not the source text of the process, unless that text happens to be the output of the process. 1366 1337 </p> 1367 <p id="rfc.section.4.3.1.p.3">The semantics of the GET method change to a "conditional GET" if the request message includes an <a href="p4-conditional.html#header.if-modified-since" class="smpl">If-Modified-Since</a>, <a href="p4-conditional.html#header.if-unmodified-since" class="smpl">If-Unmodified-Since</a>, <a href="p4-conditional.html#header.if-match" class="smpl">If-Match</a>, <a href="p4-conditional.html#header.if-none-match" class="smpl">If-None-Match</a>, or <a href="p5-range.html#header.if-range" class="smpl">If-Range</a> header field (<a href="#Part4" id="rfc.xref.Part4. 3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>). A conditional GET requests that the representation be transferred only under the circumstances described by the conditional1338 <p id="rfc.section.4.3.1.p.3">The semantics of the GET method change to a "conditional GET" if the request message includes an <a href="p4-conditional.html#header.if-modified-since" class="smpl">If-Modified-Since</a>, <a href="p4-conditional.html#header.if-unmodified-since" class="smpl">If-Unmodified-Since</a>, <a href="p4-conditional.html#header.if-match" class="smpl">If-Match</a>, <a href="p4-conditional.html#header.if-none-match" class="smpl">If-None-Match</a>, or <a href="p5-range.html#header.if-range" class="smpl">If-Range</a> header field (<a href="#Part4" id="rfc.xref.Part4.1"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>). A conditional GET requests that the representation be transferred only under the circumstances described by the conditional 1368 1339 header field(s). The conditional GET request is intended to reduce unnecessary network usage by allowing cached representations 1369 1340 to be refreshed without requiring multiple requests or transferring data already held by the client. … … 1407 1378 the result. 1408 1379 </p> 1409 <p id="rfc.section.4.3.3.p.4">If a resource has been created on the origin server, the response <em class="bcp14">SHOULD</em> be <a href="#status.201" class="smpl">201 (Created)</a> and contain a representation which describes the status of the request and refers to the new resource, and a <a href="#header.location" class="smpl">Location</a> header field (see <a href="#header.location" id="rfc.xref.header.location.1" title="Location">Section 7.1. 1</a>).1380 <p id="rfc.section.4.3.3.p.4">If a resource has been created on the origin server, the response <em class="bcp14">SHOULD</em> be <a href="#status.201" class="smpl">201 (Created)</a> and contain a representation which describes the status of the request and refers to the new resource, and a <a href="#header.location" class="smpl">Location</a> header field (see <a href="#header.location" id="rfc.xref.header.location.1" title="Location">Section 7.1.2</a>). 1410 1381 </p> 1411 1382 <p id="rfc.section.4.3.3.p.5">Responses to POST requests are only cacheable when they include explicit freshness information (see <a href="p6-cache.html#calculating.freshness.lifetime" title="Calculating Freshness Lifetime">Section 4.1.1</a> of <a href="#Part6" id="rfc.xref.Part6.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>). A cached POST response with a <a href="#header.content-location" class="smpl">Content-Location</a> header field (see <a href="#header.content-location" id="rfc.xref.header.content-location.2" title="Content-Location">Section 3.1.4</a>) whose value is the effective Request URI <em class="bcp14">MAY</em> be used to satisfy subsequent GET and HEAD (not POST) requests. … … 1572 1543 <h2 id="rfc.section.5.1"><a href="#rfc.section.5.1">5.1</a> <a id="request.controls" href="#request.controls">Controls</a></h2> 1573 1544 <p id="rfc.section.5.1.p.1">Controls are request header fields that direct specific handling of the request.</p> 1574 <div id="rfc.table.u. 4">1545 <div id="rfc.table.u.3"> 1575 1546 <table class="tt full left" cellpadding="3" cellspacing="0"> 1576 1547 <thead> … … 1626 1597 </p> 1627 1598 <p id="rfc.section.5.1.2.p.4">The only expectation defined by this specification is:</p> 1628 <p id="rfc.section.5.1.2.p.5"><span id="rfc.iref.3 2"></span><span id="rfc.iref.e.2"></span> 100-continue1599 <p id="rfc.section.5.1.2.p.5"><span id="rfc.iref.31"></span><span id="rfc.iref.e.2"></span> 100-continue 1629 1600 </p> 1630 1601 <ul class="empty"> … … 1688 1659 <p id="rfc.section.5.2.p.1">Conditionals are request header fields that indicate a precondition to be tested before applying the method semantics to the 1689 1660 target resource. Each precondition is based on metadata that is expected to change if the selected representation of the target 1690 resource is changed. The HTTP/1.1 conditional request mechanisms are defined in <a href="#Part4" id="rfc.xref.Part4. 4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>.1691 </p> 1692 <div id="rfc.table.u. 5">1661 resource is changed. The HTTP/1.1 conditional request mechanisms are defined in <a href="#Part4" id="rfc.xref.Part4.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>. 1662 </p> 1663 <div id="rfc.table.u.4"> 1693 1664 <table class="tt full left" cellpadding="3" cellspacing="0"> 1694 1665 <thead> … … 1701 1672 <tr> 1702 1673 <td class="left">If-Match</td> 1703 <td class="left"><a href="p4-conditional.html#header.if-match" title="If-Match">Section 3.1</a> of <a href="#Part4" id="rfc.xref.Part4. 5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>1674 <td class="left"><a href="p4-conditional.html#header.if-match" title="If-Match">Section 3.1</a> of <a href="#Part4" id="rfc.xref.Part4.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1704 1675 </tr> 1705 1676 <tr> 1706 1677 <td class="left">If-None-Match</td> 1707 <td class="left"><a href="p4-conditional.html#header.if-none-match" title="If-None-Match">Section 3.2</a> of <a href="#Part4" id="rfc.xref.Part4. 6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>1678 <td class="left"><a href="p4-conditional.html#header.if-none-match" title="If-None-Match">Section 3.2</a> of <a href="#Part4" id="rfc.xref.Part4.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1708 1679 </tr> 1709 1680 <tr> 1710 1681 <td class="left">If-Modified-Since</td> 1711 <td class="left"><a href="p4-conditional.html#header.if-modified-since" title="If-Modified-Since">Section 3.3</a> of <a href="#Part4" id="rfc.xref.Part4. 7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>1682 <td class="left"><a href="p4-conditional.html#header.if-modified-since" title="If-Modified-Since">Section 3.3</a> of <a href="#Part4" id="rfc.xref.Part4.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1712 1683 </tr> 1713 1684 <tr> 1714 1685 <td class="left">If-Unmodified-Since</td> 1715 <td class="left"><a href="p4-conditional.html#header.if-unmodified-since" title="If-Unmodified-Since">Section 3.4</a> of <a href="#Part4" id="rfc.xref.Part4. 8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>1686 <td class="left"><a href="p4-conditional.html#header.if-unmodified-since" title="If-Unmodified-Since">Section 3.4</a> of <a href="#Part4" id="rfc.xref.Part4.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 1716 1687 </tr> 1717 1688 <tr> … … 1723 1694 </div> 1724 1695 <h2 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a> <a id="request.conneg" href="#request.conneg">Content Negotiation</a></h2> 1725 <div id="rfc.table.u. 6">1696 <div id="rfc.table.u.5"> 1726 1697 <table class="tt full left" cellpadding="3" cellspacing="0"> 1727 1698 <thead> … … 1824 1795 text/html;level=2;q=0.4, */*;q=0.5 1825 1796 </pre><p id="rfc.section.5.3.2.p.18">would cause the following values to be associated:</p> 1826 <div id="rfc.table.u. 7">1797 <div id="rfc.table.u.6"> 1827 1798 <table class="tt full left" cellpadding="3" cellspacing="0"> 1828 1799 <thead> … … 1955 1926 </div> 1956 1927 <h2 id="rfc.section.5.4"><a href="#rfc.section.5.4">5.4</a> <a id="request.auth" href="#request.auth">Authentication</a></h2> 1957 <div id="rfc.table.u. 8">1928 <div id="rfc.table.u.7"> 1958 1929 <table class="tt full left" cellpadding="3" cellspacing="0"> 1959 1930 <thead> … … 1976 1947 </div> 1977 1948 <h2 id="rfc.section.5.5"><a href="#rfc.section.5.5">5.5</a> <a id="request.context" href="#request.context">Context</a></h2> 1978 <div id="rfc.table.u. 9">1949 <div id="rfc.table.u.8"> 1979 1950 <table class="tt full left" cellpadding="3" cellspacing="0"> 1980 1951 <thead> … … 2089 2060 </p> 2090 2061 <h2 id="rfc.section.6.1"><a href="#rfc.section.6.1">6.1</a> <a id="overview.of.status.codes" href="#overview.of.status.codes">Overview of Status Codes</a></h2> 2091 <p id="rfc.section.6.1.p.1">The status codes listed below are defined in this specification, <a href="p4-conditional.html#status.code.definitions" title="Status Code Definitions">Section 4</a> of <a href="#Part4" id="rfc.xref.Part4. 9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>, <a href="p5-range.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part5" id="rfc.xref.Part5.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Range Requests">[Part5]</cite></a>, and <a href="p7-auth.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part7" id="rfc.xref.Part7.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Authentication">[Part7]</cite></a>. The reason phrases listed here are only recommendations — they can be replaced by local equivalents without affecting the2062 <p id="rfc.section.6.1.p.1">The status codes listed below are defined in this specification, <a href="p4-conditional.html#status.code.definitions" title="Status Code Definitions">Section 4</a> of <a href="#Part4" id="rfc.xref.Part4.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>, <a href="p5-range.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part5" id="rfc.xref.Part5.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Range Requests">[Part5]</cite></a>, and <a href="p7-auth.html#status.code.definitions" title="Status Code Definitions">Section 3</a> of <a href="#Part7" id="rfc.xref.Part7.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Authentication">[Part7]</cite></a>. The reason phrases listed here are only recommendations — they can be replaced by local equivalents without affecting the 2092 2063 protocol. 2093 2064 </p> 2094 <div id="rfc.table.u. 10">2065 <div id="rfc.table.u.9"> 2095 2066 <table class="tt full left" cellpadding="3" cellspacing="0"> 2096 2067 <thead> … … 2170 2141 <td class="left">304</td> 2171 2142 <td class="left">Not Modified</td> 2172 <td id="status.304" class="left"><a href="p4-conditional.html#status.304" title="304 Not Modified">Section 4.1</a> of <a href="#Part4" id="rfc.xref.Part4. 10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>2143 <td id="status.304" class="left"><a href="p4-conditional.html#status.304" title="304 Not Modified">Section 4.1</a> of <a href="#Part4" id="rfc.xref.Part4.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 2173 2144 </tr> 2174 2145 <tr> … … 2245 2216 <td class="left">412</td> 2246 2217 <td class="left">Precondition Failed</td> 2247 <td id="status.412" class="left"><a href="p4-conditional.html#status.412" title="412 Precondition Failed">Section 4.2</a> of <a href="#Part4" id="rfc.xref.Part4. 11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td>2218 <td id="status.412" class="left"><a href="p4-conditional.html#status.412" title="412 Precondition Failed">Section 4.2</a> of <a href="#Part4" id="rfc.xref.Part4.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 2248 2219 </tr> 2249 2220 <tr> … … 2312 2283 <p id="rfc.section.6.1.p.2">Note that this list is not exhaustive — it does not include extension status codes defined in other specifications.</p> 2313 2284 <h2 id="rfc.section.6.2"><a href="#rfc.section.6.2">6.2</a> <a id="status.1xx" href="#status.1xx">Informational 1xx</a></h2> 2314 <div id="rfc.iref.5 4"></div>2315 <div id="rfc.iref.s. 3"></div>2285 <div id="rfc.iref.53"></div> 2286 <div id="rfc.iref.s.2"></div> 2316 2287 <p id="rfc.section.6.2.p.1">This class of status code indicates a provisional response, consisting only of the status-line and optional header fields, 2317 2288 and is terminated by an empty line. There are no required header fields for this class of status code. Since HTTP/1.0 did … … 2325 2296 a request, then it need not forward the corresponding <a href="#status.100" class="smpl">100 (Continue)</a> response(s).) 2326 2297 </p> 2327 <div id="rfc.iref.5 5"></div>2298 <div id="rfc.iref.54"></div> 2328 2299 <h3 id="rfc.section.6.2.1"><a href="#rfc.section.6.2.1">6.2.1</a> <a id="status.100" href="#status.100">100 Continue</a></h3> 2329 2300 <p id="rfc.section.6.2.1.p.1">The client <em class="bcp14">SHOULD</em> continue with its request. This interim response is used to inform the client that the initial part of the request has been … … 2331 2302 server <em class="bcp14">MUST</em> send a final response after the request has been completed. See <a href="#use.of.the.100.status" title="Use of the 100 (Continue) Status">Section 5.1.2.1</a> for detailed discussion of the use and handling of this status code. 2332 2303 </p> 2333 <div id="rfc.iref.5 5"></div>2304 <div id="rfc.iref.54"></div> 2334 2305 <h3 id="rfc.section.6.2.2"><a href="#rfc.section.6.2.2">6.2.2</a> <a id="status.101" href="#status.101">101 Switching Protocols</a></h3> 2335 2306 <p id="rfc.section.6.2.2.p.1">The server understands and is willing to comply with the client's request, via the <a href="p1-messaging.html#header.upgrade" class="smpl">Upgrade</a> message header field (<a href="p1-messaging.html#header.upgrade" title="Upgrade">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.18"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>), for a change in the application protocol being used on this connection. The server will switch protocols to those defined … … 2341 2312 </p> 2342 2313 <h2 id="rfc.section.6.3"><a href="#rfc.section.6.3">6.3</a> <a id="status.2xx" href="#status.2xx">Successful 2xx</a></h2> 2314 <div id="rfc.iref.54"></div> 2315 <div id="rfc.iref.s.3"></div> 2316 <p id="rfc.section.6.3.p.1">This class of status code indicates that the client's request was successfully received, understood, and accepted.</p> 2343 2317 <div id="rfc.iref.55"></div> 2344 <div id="rfc.iref.s.4"></div>2345 <p id="rfc.section.6.3.p.1">This class of status code indicates that the client's request was successfully received, understood, and accepted.</p>2346 <div id="rfc.iref.56"></div>2347 2318 <h3 id="rfc.section.6.3.1"><a href="#rfc.section.6.3.1">6.3.1</a> <a id="status.200" href="#status.200">200 OK</a></h3> 2348 2319 <p id="rfc.section.6.3.1.p.1">The request has succeeded. The payload returned with the response is dependent on the method used in the request, for example: </p> … … 2359 2330 <p id="rfc.section.6.3.1.p.2">Caches <em class="bcp14">MAY</em> use a heuristic (see <a href="p6-cache.html#heuristic.freshness" title="Calculating Heuristic Freshness">Section 4.1.2</a> of <a href="#Part6" id="rfc.xref.Part6.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) to determine freshness for 200 responses. 2360 2331 </p> 2361 <div id="rfc.iref.5 6"></div>2332 <div id="rfc.iref.55"></div> 2362 2333 <h3 id="rfc.section.6.3.2"><a href="#rfc.section.6.3.2">6.3.2</a> <a id="status.201" href="#status.201">201 Created</a></h3> 2363 2334 <p id="rfc.section.6.3.2.p.1">The request has been fulfilled and has resulted in one or more new resources being created.</p> … … 2369 2340 </p> 2370 2341 <p id="rfc.section.6.3.2.p.4">A 201 response <em class="bcp14">MAY</em> contain an <a href="p4-conditional.html#header.etag" class="smpl">ETag</a> response header field indicating the current value of the entity-tag for the representation of the resource identified by 2371 the <a href="#header.location" class="smpl">Location</a> header field or, in case the Location header field was omitted, by the Effective Request URI (see <a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.1 2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>).2372 </p> 2373 <div id="rfc.iref.5 6"></div>2342 the <a href="#header.location" class="smpl">Location</a> header field or, in case the Location header field was omitted, by the Effective Request URI (see <a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>). 2343 </p> 2344 <div id="rfc.iref.55"></div> 2374 2345 <h3 id="rfc.section.6.3.3"><a href="#rfc.section.6.3.3">6.3.3</a> <a id="status.202" href="#status.202">202 Accepted</a></h3> 2375 2346 <p id="rfc.section.6.3.3.p.1">The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually … … 2382 2353 user can expect the request to be fulfilled. 2383 2354 </p> 2384 <div id="rfc.iref.5 6"></div>2355 <div id="rfc.iref.55"></div> 2385 2356 <h3 id="rfc.section.6.3.4"><a href="#rfc.section.6.3.4">6.3.4</a> <a id="status.203" href="#status.203">203 Non-Authoritative Information</a></h3> 2386 2357 <p id="rfc.section.6.3.4.p.1">The representation in the response has been transformed or otherwise modified by a transforming proxy (<a href="p1-messaging.html#intermediaries" title="Intermediaries">Section 2.3</a> of <a href="#Part1" id="rfc.xref.Part1.19"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>). Note that the behavior of transforming intermediaries is controlled by the no-transform Cache-Control directive (<a href="p6-cache.html#header.cache-control" title="Cache-Control">Section 7.2</a> of <a href="#Part6" id="rfc.xref.Part6.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>). … … 2391 2362 <p id="rfc.section.6.3.4.p.3">Caches <em class="bcp14">MAY</em> use a heuristic (see <a href="p6-cache.html#heuristic.freshness" title="Calculating Heuristic Freshness">Section 4.1.2</a> of <a href="#Part6" id="rfc.xref.Part6.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) to determine freshness for 203 responses. 2392 2363 </p> 2393 <div id="rfc.iref.5 6"></div>2364 <div id="rfc.iref.55"></div> 2394 2365 <h3 id="rfc.section.6.3.5"><a href="#rfc.section.6.3.5">6.3.5</a> <a id="status.204" href="#status.204">204 No Content</a></h3> 2395 2366 <p id="rfc.section.6.3.5.p.1">The 204 (No Content) status code indicates that the server has successfully fulfilled the request and that there is no additional … … 2411 2382 <p id="rfc.section.6.3.5.p.5">The 204 response <em class="bcp14">MUST NOT</em> include a message body, and thus is always terminated by the first empty line after the header fields. 2412 2383 </p> 2413 <div id="rfc.iref.5 6"></div>2384 <div id="rfc.iref.55"></div> 2414 2385 <h3 id="rfc.section.6.3.6"><a href="#rfc.section.6.3.6">6.3.6</a> <a id="status.205" href="#status.205">205 Reset Content</a></h3> 2415 2386 <p id="rfc.section.6.3.6.p.1">The server has fulfilled the request and the user agent <em class="bcp14">SHOULD</em> reset the document view which caused the request to be sent. This response is primarily intended to allow input for actions … … 2420 2391 </p> 2421 2392 <h2 id="rfc.section.6.4"><a href="#rfc.section.6.4">6.4</a> <a id="status.3xx" href="#status.3xx">Redirection 3xx</a></h2> 2422 <div id="rfc.iref.5 6"></div>2423 <div id="rfc.iref.s. 5"></div>2393 <div id="rfc.iref.55"></div> 2394 <div id="rfc.iref.s.4"></div> 2424 2395 <p id="rfc.section.6.4.p.1">This class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request. 2425 2396 If the required action involves a subsequent HTTP request, it <em class="bcp14">MAY</em> be carried out by the user agent without interaction with the user if and only if the method used in the second request is … … 2440 2411 </li> 2441 2412 <li> 2442 <p>Redirection offering a choice of matching resources for use by reactive content negotiation (<a href="#reactive.negotiation" title="Reactive Negotiation">Section 3. 5.2</a>). This is status code <a href="#status.300" class="smpl">300 (Multiple Choices)</a>.2413 <p>Redirection offering a choice of matching resources for use by reactive content negotiation (<a href="#reactive.negotiation" title="Reactive Negotiation">Section 3.4.2</a>). This is status code <a href="#status.300" class="smpl">300 (Multiple Choices)</a>. 2443 2414 </p> 2444 2415 </li> 2445 2416 <li> 2446 2417 <p>Other kinds of redirection, such as to a cached result (status code <a href="p4-conditional.html#status.304" class="smpl">304 2447 (Not Modified)</a>, see <a href="p4-conditional.html#status.304" title="304 Not Modified">Section 4.1</a> of <a href="#Part4" id="rfc.xref.Part4.1 3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>).2418 (Not Modified)</a>, see <a href="p4-conditional.html#status.304" title="304 Not Modified">Section 4.1</a> of <a href="#Part4" id="rfc.xref.Part4.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a>). 2448 2419 </p> 2449 2420 </li> … … 2455 2426 </p> 2456 2427 </div> 2457 <p id="rfc.section.6.4.p.4">A <a href="#header.location" class="smpl">Location</a> header field on a 3xx response indicates that a client <em class="bcp14">MAY</em> automatically redirect to the URI provided; see <a href="#header.location" id="rfc.xref.header.location.2" title="Location">Section 7.1. 1</a>.2428 <p id="rfc.section.6.4.p.4">A <a href="#header.location" class="smpl">Location</a> header field on a 3xx response indicates that a client <em class="bcp14">MAY</em> automatically redirect to the URI provided; see <a href="#header.location" id="rfc.xref.header.location.2" title="Location">Section 7.1.2</a>. 2458 2429 </p> 2459 2430 <p id="rfc.section.6.4.p.5">Note that for methods not known to be "safe", as defined in <a href="#safe.methods" title="Safe Methods">Section 4.2.1</a>, automatic redirection needs to done with care, since the redirect might change the conditions under which the request was … … 2466 2437 </p> 2467 2438 </div> 2468 <div id="rfc.iref.5 7"></div>2439 <div id="rfc.iref.56"></div> 2469 2440 <h3 id="rfc.section.6.4.1"><a href="#rfc.section.6.4.1">6.4.1</a> <a id="status.300" href="#status.300">300 Multiple Choices</a></h3> 2470 2441 <p id="rfc.section.6.4.1.p.1">The target resource has more than one representation, each with its own specific location, and reactive negotiation information 2471 (<a href="#content.negotiation" title="Content Negotiation">Section 3. 5</a>) is being provided so that the user (or user agent) can select a preferred representation by redirecting its request to that2442 (<a href="#content.negotiation" title="Content Negotiation">Section 3.4</a>) is being provided so that the user (or user agent) can select a preferred representation by redirecting its request to that 2472 2443 location. 2473 2444 </p> … … 2480 2451 <p id="rfc.section.6.4.1.p.4">Caches <em class="bcp14">MAY</em> use a heuristic (see <a href="p6-cache.html#heuristic.freshness" title="Calculating Heuristic Freshness">Section 4.1.2</a> of <a href="#Part6" id="rfc.xref.Part6.12"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) to determine freshness for 300 responses. 2481 2452 </p> 2482 <div id="rfc.iref.5 7"></div>2453 <div id="rfc.iref.56"></div> 2483 2454 <h3 id="rfc.section.6.4.2"><a href="#rfc.section.6.4.2">6.4.2</a> <a id="status.301" href="#status.301">301 Moved Permanently</a></h3> 2484 2455 <p id="rfc.section.6.4.2.p.1">The target resource has been assigned a new permanent URI and any future references to this resource <em class="bcp14">SHOULD</em> use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the effective … … 2493 2464 </p> 2494 2465 </div> 2495 <div id="rfc.iref.5 7"></div>2466 <div id="rfc.iref.56"></div> 2496 2467 <h3 id="rfc.section.6.4.3"><a href="#rfc.section.6.4.3">6.4.3</a> <a id="status.302" href="#status.302">302 Found</a></h3> 2497 2468 <p id="rfc.section.6.4.3.p.1">The target resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client <em class="bcp14">SHOULD</em> continue to use the effective request URI for future requests. … … 2503 2474 </p> 2504 2475 </div> 2505 <div id="rfc.iref.5 7"></div>2476 <div id="rfc.iref.56"></div> 2506 2477 <h3 id="rfc.section.6.4.4"><a href="#rfc.section.6.4.4">6.4.4</a> <a id="status.303" href="#status.303">303 See Other</a></h3> 2507 2478 <p id="rfc.section.6.4.4.p.1">The 303 status code indicates that the server is redirecting the user agent to a different resource, as indicated by a URI … … 2523 2494 <p id="rfc.section.6.4.4.p.4">Except for responses to a HEAD request, the representation of a 303 response <em class="bcp14">SHOULD</em> contain a short hypertext note with a hyperlink to the <a href="#header.location" class="smpl">Location</a> URI. 2524 2495 </p> 2525 <div id="rfc.iref.5 7"></div>2496 <div id="rfc.iref.56"></div> 2526 2497 <h3 id="rfc.section.6.4.5"><a href="#rfc.section.6.4.5">6.4.5</a> <a id="status.305" href="#status.305">305 Use Proxy</a></h3> 2527 2498 <p id="rfc.section.6.4.5.p.1">The 305 status code was defined in a previous version of this specification (see <a href="#changes.from.rfc.2616" title="Changes from RFC 2616">Appendix C</a>), and is now deprecated. 2528 2499 </p> 2529 <div id="rfc.iref.5 7"></div>2500 <div id="rfc.iref.56"></div> 2530 2501 <h3 id="rfc.section.6.4.6"><a href="#rfc.section.6.4.6">6.4.6</a> <a id="status.306" href="#status.306">306 (Unused)</a></h3> 2531 2502 <p id="rfc.section.6.4.6.p.1">The 306 status code was used in a previous version of the specification, is no longer used, and the code is reserved.</p> 2532 <div id="rfc.iref.5 7"></div>2503 <div id="rfc.iref.56"></div> 2533 2504 <h3 id="rfc.section.6.4.7"><a href="#rfc.section.6.4.7">6.4.7</a> <a id="status.307" href="#status.307">307 Temporary Redirect</a></h3> 2534 2505 <p id="rfc.section.6.4.7.p.1">The target resource resides temporarily under a different URI. Since the redirection can change over time, the client <em class="bcp14">SHOULD</em> continue to use the effective request URI for future requests. … … 2543 2514 </div> 2544 2515 <h2 id="rfc.section.6.5"><a href="#rfc.section.6.5">6.5</a> <a id="status.4xx" href="#status.4xx">Client Error 4xx</a></h2> 2545 <div id="rfc.iref.5 7"></div>2546 <div id="rfc.iref.s. 6"></div>2516 <div id="rfc.iref.56"></div> 2517 <div id="rfc.iref.s.5"></div> 2547 2518 <p id="rfc.section.6.5.p.1">The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD 2548 2519 request, the server <em class="bcp14">SHOULD</em> include a representation containing an explanation of the error situation, and whether it is a temporary or permanent condition. 2549 2520 These status codes are applicable to any request method. User agents <em class="bcp14">SHOULD</em> display any included representation to the user. 2550 2521 </p> 2551 <div id="rfc.iref.5 8"></div>2522 <div id="rfc.iref.57"></div> 2552 2523 <h3 id="rfc.section.6.5.1"><a href="#rfc.section.6.5.1">6.5.1</a> <a id="status.400" href="#status.400">400 Bad Request</a></h3> 2553 2524 <p id="rfc.section.6.5.1.p.1">The server cannot or will not process the request, due to a client error (e.g., malformed syntax).</p> 2554 <div id="rfc.iref.5 8"></div>2525 <div id="rfc.iref.57"></div> 2555 2526 <h3 id="rfc.section.6.5.2"><a href="#rfc.section.6.5.2">6.5.2</a> <a id="status.402" href="#status.402">402 Payment Required</a></h3> 2556 2527 <p id="rfc.section.6.5.2.p.1">This code is reserved for future use.</p> 2557 <div id="rfc.iref.5 8"></div>2528 <div id="rfc.iref.57"></div> 2558 2529 <h3 id="rfc.section.6.5.3"><a href="#rfc.section.6.5.3">6.5.3</a> <a id="status.403" href="#status.403">403 Forbidden</a></h3> 2559 2530 <p id="rfc.section.6.5.3.p.1">The server understood the request, but refuses to authorize it. Providing different user authentication credentials might … … 2564 2535 (Not Found)</a> <em class="bcp14">MAY</em> be used instead. 2565 2536 </p> 2566 <div id="rfc.iref.5 8"></div>2537 <div id="rfc.iref.57"></div> 2567 2538 <h3 id="rfc.section.6.5.4"><a href="#rfc.section.6.5.4">6.5.4</a> <a id="status.404" href="#status.404">404 Not Found</a></h3> 2568 2539 <p id="rfc.section.6.5.4.p.1">The server has not found anything matching the effective request URI. No indication is given of whether the condition is temporary … … 2571 2542 has been refused, or when no other response is applicable. 2572 2543 </p> 2573 <div id="rfc.iref.5 8"></div>2544 <div id="rfc.iref.57"></div> 2574 2545 <h3 id="rfc.section.6.5.5"><a href="#rfc.section.6.5.5">6.5.5</a> <a id="status.405" href="#status.405">405 Method Not Allowed</a></h3> 2575 2546 <p id="rfc.section.6.5.5.p.1">The method specified in the request-line is not allowed for the target resource. The response <em class="bcp14">MUST</em> include an <a href="#header.allow" class="smpl">Allow</a> header field containing a list of valid methods for the requested resource. 2576 2547 </p> 2577 <div id="rfc.iref.5 8"></div>2548 <div id="rfc.iref.57"></div> 2578 2549 <h3 id="rfc.section.6.5.6"><a href="#rfc.section.6.5.6">6.5.6</a> <a id="status.406" href="#status.406">406 Not Acceptable</a></h3> 2579 2550 <p id="rfc.section.6.5.6.p.1">The resource identified by the request is only capable of generating response representations which have content characteristics … … 2592 2563 <p id="rfc.section.6.5.6.p.4">If the response could be unacceptable, a user agent <em class="bcp14">SHOULD</em> temporarily stop receipt of more data and query the user for a decision on further actions. 2593 2564 </p> 2594 <div id="rfc.iref.5 8"></div>2565 <div id="rfc.iref.57"></div> 2595 2566 <h3 id="rfc.section.6.5.7"><a href="#rfc.section.6.5.7">6.5.7</a> <a id="status.408" href="#status.408">408 Request Timeout</a></h3> 2596 2567 <p id="rfc.section.6.5.7.p.1">The client did not produce a request within the time that the server was prepared to wait. The client <em class="bcp14">MAY</em> repeat the request without modifications at any later time. 2597 2568 </p> 2598 <div id="rfc.iref.5 8"></div>2569 <div id="rfc.iref.57"></div> 2599 2570 <h3 id="rfc.section.6.5.8"><a href="#rfc.section.6.5.8">6.5.8</a> <a id="status.409" href="#status.409">409 Conflict</a></h3> 2600 2571 <p id="rfc.section.6.5.8.p.1">The request could not be completed due to a conflict with the current state of the resource. This code is only allowed in … … 2607 2578 contain a list of the differences between the two versions. 2608 2579 </p> 2609 <div id="rfc.iref.5 8"></div>2580 <div id="rfc.iref.57"></div> 2610 2581 <h3 id="rfc.section.6.5.9"><a href="#rfc.section.6.5.9">6.5.9</a> <a id="status.410" href="#status.410">410 Gone</a></h3> 2611 2582 <p id="rfc.section.6.5.9.p.1">The target resource is no longer available at the server and no forwarding address is known. This condition is expected to … … 2621 2592 <p id="rfc.section.6.5.9.p.3">Caches <em class="bcp14">MAY</em> use a heuristic (see <a href="p6-cache.html#heuristic.freshness" title="Calculating Heuristic Freshness">Section 4.1.2</a> of <a href="#Part6" id="rfc.xref.Part6.14"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) to determine freshness for 410 responses. 2622 2593 </p> 2623 <div id="rfc.iref.5 8"></div>2594 <div id="rfc.iref.57"></div> 2624 2595 <h3 id="rfc.section.6.5.10"><a href="#rfc.section.6.5.10">6.5.10</a> <a id="status.411" href="#status.411">411 Length Required</a></h3> 2625 2596 <p id="rfc.section.6.5.10.p.1">The server refuses to accept the request without a defined <a href="p1-messaging.html#header.content-length" class="smpl">Content-Length</a>. The client <em class="bcp14">MAY</em> repeat the request if it adds a valid Content-Length header field containing the length of the message body in the request 2626 2597 message. 2627 2598 </p> 2628 <div id="rfc.iref.5 8"></div>2599 <div id="rfc.iref.57"></div> 2629 2600 <h3 id="rfc.section.6.5.11"><a href="#rfc.section.6.5.11">6.5.11</a> <a id="status.413" href="#status.413">413 Request Representation Too Large</a></h3> 2630 2601 <p id="rfc.section.6.5.11.p.1">The server is refusing to process a request because the request representation is larger than the server is willing or able … … 2633 2604 <p id="rfc.section.6.5.11.p.2">If the condition is temporary, the server <em class="bcp14">SHOULD</em> include a <a href="#header.retry-after" class="smpl">Retry-After</a> header field to indicate that it is temporary and after what time the client <em class="bcp14">MAY</em> try again. 2634 2605 </p> 2635 <div id="rfc.iref.5 8"></div>2606 <div id="rfc.iref.57"></div> 2636 2607 <h3 id="rfc.section.6.5.12"><a href="#rfc.section.6.5.12">6.5.12</a> <a id="status.414" href="#status.414">414 URI Too Long</a></h3> 2637 2608 <p id="rfc.section.6.5.12.p.1">The server is refusing to service the request because the effective request URI is longer than the server is willing to interpret. … … 2641 2612 in some servers using fixed-length buffers for reading or manipulating the request-target. 2642 2613 </p> 2643 <div id="rfc.iref.5 8"></div>2614 <div id="rfc.iref.57"></div> 2644 2615 <h3 id="rfc.section.6.5.13"><a href="#rfc.section.6.5.13">6.5.13</a> <a id="status.415" href="#status.415">415 Unsupported Media Type</a></h3> 2645 2616 <p id="rfc.section.6.5.13.p.1">The server is refusing to service the request because the request payload is in a format not supported by this request method 2646 2617 on the target resource. 2647 2618 </p> 2648 <div id="rfc.iref.5 8"></div>2619 <div id="rfc.iref.57"></div> 2649 2620 <h3 id="rfc.section.6.5.14"><a href="#rfc.section.6.5.14">6.5.14</a> <a id="status.417" href="#status.417">417 Expectation Failed</a></h3> 2650 2621 <p id="rfc.section.6.5.14.p.1">The expectation given in an <a href="#header.expect" class="smpl">Expect</a> header field (see <a href="#header.expect" id="rfc.xref.header.expect.2" title="Expect">Section 5.1.2</a>) could not be met by this server, or, if the server is a proxy, the server has unambiguous evidence that the request could 2651 2622 not be met by the next-hop server. 2652 2623 </p> 2653 <div id="rfc.iref.5 8"></div>2624 <div id="rfc.iref.57"></div> 2654 2625 <h3 id="rfc.section.6.5.15"><a href="#rfc.section.6.5.15">6.5.15</a> <a id="status.426" href="#status.426">426 Upgrade Required</a></h3> 2655 2626 <p id="rfc.section.6.5.15.p.1">The request can not be completed without a prior protocol upgrade. This response <em class="bcp14">MUST</em> include an <a href="p1-messaging.html#header.upgrade" class="smpl">Upgrade</a> header field (<a href="p1-messaging.html#header.upgrade" title="Upgrade">Section 6.3</a> of <a href="#Part1" id="rfc.xref.Part1.21"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>) specifying the required protocols. … … 2667 2638 </p> 2668 2639 <h2 id="rfc.section.6.6"><a href="#rfc.section.6.6">6.6</a> <a id="status.5xx" href="#status.5xx">Server Error 5xx</a></h2> 2669 <div id="rfc.iref.5 8"></div>2670 <div id="rfc.iref.s. 7"></div>2640 <div id="rfc.iref.57"></div> 2641 <div id="rfc.iref.s.6"></div> 2671 2642 <p id="rfc.section.6.6.p.1">Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has erred or is incapable 2672 2643 of performing the request. Except when responding to a HEAD request, the server <em class="bcp14">SHOULD</em> include a representation containing an explanation of the error situation, and whether it is a temporary or permanent condition. 2673 2644 User agents <em class="bcp14">SHOULD</em> display any included representation to the user. These response codes are applicable to any request method. 2674 2645 </p> 2675 <div id="rfc.iref.5 9"></div>2646 <div id="rfc.iref.58"></div> 2676 2647 <h3 id="rfc.section.6.6.1"><a href="#rfc.section.6.6.1">6.6.1</a> <a id="status.500" href="#status.500">500 Internal Server Error</a></h3> 2677 2648 <p id="rfc.section.6.6.1.p.1">The server encountered an unexpected condition which prevented it from fulfilling the request.</p> 2678 <div id="rfc.iref.5 9"></div>2649 <div id="rfc.iref.58"></div> 2679 2650 <h3 id="rfc.section.6.6.2"><a href="#rfc.section.6.6.2">6.6.2</a> <a id="status.501" href="#status.501">501 Not Implemented</a></h3> 2680 2651 <p id="rfc.section.6.6.2.p.1">The server does not support the functionality required to fulfill the request. This is the appropriate response when the server 2681 2652 does not recognize the request method and is not capable of supporting it for any resource. 2682 2653 </p> 2683 <div id="rfc.iref.5 9"></div>2654 <div id="rfc.iref.58"></div> 2684 2655 <h3 id="rfc.section.6.6.3"><a href="#rfc.section.6.6.3">6.6.3</a> <a id="status.502" href="#status.502">502 Bad Gateway</a></h3> 2685 2656 <p id="rfc.section.6.6.3.p.1">The server, while acting as a gateway or proxy, received an invalid response from the upstream server it accessed in attempting 2686 2657 to fulfill the request. 2687 2658 </p> 2688 <div id="rfc.iref.5 9"></div>2659 <div id="rfc.iref.58"></div> 2689 2660 <h3 id="rfc.section.6.6.4"><a href="#rfc.section.6.6.4">6.6.4</a> <a id="status.503" href="#status.503">503 Service Unavailable</a></h3> 2690 2661 <p id="rfc.section.6.6.4.p.1">The server is currently unable to handle the request due to a temporary overloading or maintenance of the server.</p> 2691 2662 <p id="rfc.section.6.6.4.p.2">The implication is that this is a temporary condition which will be alleviated after some delay. If known, the length of the 2692 delay <em class="bcp14">MAY</em> be indicated in a <a href="#header.retry-after" class="smpl">Retry-After</a> header field (<a href="#header.retry-after" id="rfc.xref.header.retry-after.1" title="Retry-After">Section 7.1. 2</a>). If no Retry-After is given, the client <em class="bcp14">SHOULD</em> handle the response as it would for a <a href="#status.500" class="smpl">500 (Internal2663 delay <em class="bcp14">MAY</em> be indicated in a <a href="#header.retry-after" class="smpl">Retry-After</a> header field (<a href="#header.retry-after" id="rfc.xref.header.retry-after.1" title="Retry-After">Section 7.1.3</a>). If no Retry-After is given, the client <em class="bcp14">SHOULD</em> handle the response as it would for a <a href="#status.500" class="smpl">500 (Internal 2693 2664 Server Error)</a> response. 2694 2665 </p> … … 2698 2669 </p> 2699 2670 </div> 2700 <div id="rfc.iref.5 9"></div>2671 <div id="rfc.iref.58"></div> 2701 2672 <h3 id="rfc.section.6.6.5"><a href="#rfc.section.6.6.5">6.6.5</a> <a id="status.504" href="#status.504">504 Gateway Timeout</a></h3> 2702 2673 <p id="rfc.section.6.6.5.p.1">The server, while acting as a gateway or proxy, did not receive a timely response from the upstream server specified by the … … 2708 2679 </p> 2709 2680 </div> 2710 <div id="rfc.iref.5 9"></div>2681 <div id="rfc.iref.58"></div> 2711 2682 <h3 id="rfc.section.6.6.6"><a href="#rfc.section.6.6.6">6.6.6</a> <a id="status.505" href="#status.505">505 HTTP Version Not Supported</a></h3> 2712 2683 <p id="rfc.section.6.6.6.p.1">The server does not support, or refuses to support, the protocol version that was used in the request message. The server … … 2720 2691 <h2 id="rfc.section.7.1"><a href="#rfc.section.7.1">7.1</a> <a id="response.control.data" href="#response.control.data">Control Data</a></h2> 2721 2692 <p id="rfc.section.7.1.p.1">Response header fields can supply control data that supplements the status code or instructs the client where to go next.</p> 2722 <div id="rfc.table.u.1 1">2693 <div id="rfc.table.u.10"> 2723 2694 <table class="tt full left" cellpadding="3" cellspacing="0"> 2724 2695 <thead> … … 2730 2701 <tbody> 2731 2702 <tr> 2703 <td class="left">Age</td> 2704 <td class="left"><a href="p6-cache.html#header.age" title="Age">Section 7.1</a> of <a href="#Part6" id="rfc.xref.Part6.15"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a></td> 2705 </tr> 2706 <tr> 2707 <td class="left">Date</td> 2708 <td class="left"><a href="#header.date" id="rfc.xref.header.date.2" title="Date">Section 7.1.1</a></td> 2709 </tr> 2710 <tr> 2732 2711 <td class="left">Location</td> 2733 <td class="left"><a href="#header.location" id="rfc.xref.header.location.3" title="Location">Section 7.1. 1</a></td>2712 <td class="left"><a href="#header.location" id="rfc.xref.header.location.3" title="Location">Section 7.1.2</a></td> 2734 2713 </tr> 2735 2714 <tr> 2736 2715 <td class="left">Retry-After</td> 2737 <td class="left"><a href="#header.retry-after" id="rfc.xref.header.retry-after.2" title="Retry-After">Section 7.1. 2</a></td>2716 <td class="left"><a href="#header.retry-after" id="rfc.xref.header.retry-after.2" title="Retry-After">Section 7.1.3</a></td> 2738 2717 </tr> 2739 2718 </tbody> 2740 2719 </table> 2741 2720 </div> 2721 <div id="rfc.iref.d.2"></div> 2722 <h3 id="rfc.section.7.1.1"><a href="#rfc.section.7.1.1">7.1.1</a> <a id="header.date" href="#header.date">Date</a></h3> 2723 <p id="rfc.section.7.1.1.p.1">The "Date" header field represents the date and time at which the message was originated, having the same semantics as the 2724 Origination Date Field (orig-date) defined in <a href="http://tools.ietf.org/html/rfc5322#section-3.6.1">Section 3.6.1</a> of <a href="#RFC5322" id="rfc.xref.RFC5322.3"><cite title="Internet Message Format">[RFC5322]</cite></a>. The field value is an HTTP-date, as defined in <a href="#http.date" title="Date/Time Formats">Section 8.1</a>; it <em class="bcp14">MUST</em> be sent in rfc1123-date format. 2725 </p> 2726 <div id="rfc.figure.u.34"></div><pre class="inline"><span id="rfc.iref.g.27"></span> <a href="#header.date" class="smpl">Date</a> = <a href="#http.date" class="smpl">HTTP-date</a> 2727 </pre><p id="rfc.section.7.1.1.p.3">An example is</p> 2728 <div id="rfc.figure.u.35"></div><pre class="text"> Date: Tue, 15 Nov 1994 08:12:31 GMT 2729 </pre><p id="rfc.section.7.1.1.p.5">Origin servers <em class="bcp14">MUST</em> include a Date header field in all responses, except in these cases: 2730 </p> 2731 <ol> 2732 <li>If the response status code is <a href="#status.100" class="smpl">100 (Continue)</a> or <a href="#status.101" class="smpl">101 (Switching Protocols)</a>, the response <em class="bcp14">MAY</em> include a Date header field, at the server's option. 2733 </li> 2734 <li>If the response status code conveys a server error, e.g., <a href="#status.500" class="smpl">500 2735 (Internal Server Error)</a> or <a href="#status.503" class="smpl">503 (Service Unavailable)</a>, and it is inconvenient or impossible to generate a valid Date. 2736 </li> 2737 <li>If the server does not have a clock that can provide a reasonable approximation of the current time, its responses <em class="bcp14">MUST NOT</em> include a Date header field. 2738 </li> 2739 </ol> 2740 <p id="rfc.section.7.1.1.p.6">A received message that does not have a Date header field <em class="bcp14">MUST</em> be assigned one by the recipient if the message will be cached by that recipient. 2741 </p> 2742 <p id="rfc.section.7.1.1.p.7">Clients can use the Date header field as well; in order to keep request messages small, they are advised not to include it 2743 when it doesn't convey any useful information (as is usually the case for requests that do not contain a payload). 2744 </p> 2745 <p id="rfc.section.7.1.1.p.8">The HTTP-date sent in a Date header field <em class="bcp14">SHOULD NOT</em> represent a date and time subsequent to the generation of the message. It <em class="bcp14">SHOULD</em> represent the best available approximation of the date and time of message generation, unless the implementation has no means 2746 of generating a reasonably accurate date and time. In theory, the date ought to represent the moment just before the payload 2747 is generated. In practice, the date can be generated at any time during the message origination without affecting its semantic 2748 value. 2749 </p> 2742 2750 <div id="rfc.iref.l.1"></div> 2743 <h3 id="rfc.section.7.1. 1"><a href="#rfc.section.7.1.1">7.1.1</a> <a id="header.location" href="#header.location">Location</a></h3>2744 <p id="rfc.section.7.1. 1.p.1">The "Location" header field <em class="bcp14">MAY</em> be sent in responses to refer to a specific resource in accordance with the semantics of the status code.2745 </p> 2746 <div id="rfc.figure.u.3 4"></div><pre class="inline"><span id="rfc.iref.g.27"></span> <a href="#header.location" class="smpl">Location</a> = <a href="#imported.abnf" class="smpl">URI-reference</a>2747 </pre><p id="rfc.section.7.1. 1.p.3">For <a href="#status.201" class="smpl">201 (Created)</a> responses, the Location is the URI of the new resource which was created by the request. For <a href="#status.3xx" class="smpl">3xx (Redirection)</a> responses, the location <em class="bcp14">SHOULD</em> indicate the server's preferred URI for automatic redirection to the resource.2748 </p> 2749 <p id="rfc.section.7.1. 1.p.4">The field value consists of a single URI-reference. When it has the form of a relative reference (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-4.2">Section 4.2</a>), the final value is computed by resolving it against the effective request URI (<a href="#RFC3986" id="rfc.xref.RFC3986.2"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-5">Section 5</a>). If the original URI, as navigated to by the user agent, did contain a fragment identifier, and the final value does not,2751 <h3 id="rfc.section.7.1.2"><a href="#rfc.section.7.1.2">7.1.2</a> <a id="header.location" href="#header.location">Location</a></h3> 2752 <p id="rfc.section.7.1.2.p.1">The "Location" header field <em class="bcp14">MAY</em> be sent in responses to refer to a specific resource in accordance with the semantics of the status code. 2753 </p> 2754 <div id="rfc.figure.u.36"></div><pre class="inline"><span id="rfc.iref.g.28"></span> <a href="#header.location" class="smpl">Location</a> = <a href="#imported.abnf" class="smpl">URI-reference</a> 2755 </pre><p id="rfc.section.7.1.2.p.3">For <a href="#status.201" class="smpl">201 (Created)</a> responses, the Location is the URI of the new resource which was created by the request. For <a href="#status.3xx" class="smpl">3xx (Redirection)</a> responses, the location <em class="bcp14">SHOULD</em> indicate the server's preferred URI for automatic redirection to the resource. 2756 </p> 2757 <p id="rfc.section.7.1.2.p.4">The field value consists of a single URI-reference. When it has the form of a relative reference (<a href="#RFC3986" id="rfc.xref.RFC3986.1"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-4.2">Section 4.2</a>), the final value is computed by resolving it against the effective request URI (<a href="#RFC3986" id="rfc.xref.RFC3986.2"><cite title="Uniform Resource Identifier (URI): Generic Syntax">[RFC3986]</cite></a>, <a href="http://tools.ietf.org/html/rfc3986#section-5">Section 5</a>). If the original URI, as navigated to by the user agent, did contain a fragment identifier, and the final value does not, 2750 2758 then the original URI's fragment identifier is added to the final value. 2751 2759 </p> 2752 <div id="rfc.figure.u.3 5"></div>2760 <div id="rfc.figure.u.37"></div> 2753 2761 <p>For example, the original URI "http://www.example.org/~tim", combined with a field value given as:</p> <pre class="text"> Location: /pub/WWW/People.html#tim 2754 2762 </pre> <p>would result in a final value of "http://www.example.org/pub/WWW/People.html#tim"</p> 2755 <div id="rfc.figure.u.3 6"></div>2763 <div id="rfc.figure.u.38"></div> 2756 2764 <p>An original URI "http://www.example.org/index.html#larry", combined with a field value given as:</p> <pre class="text"> Location: http://www.example.net/index.html 2757 2765 </pre> <p>would result in a final value of "http://www.example.net/index.html#larry", preserving the original fragment identifier.</p> 2758 <div class="note" id="rfc.section.7.1. 1.p.7">2766 <div class="note" id="rfc.section.7.1.2.p.7"> 2759 2767 <p> <b>Note:</b> Some recipients attempt to recover from Location fields that are not valid URI references. This specification does not mandate 2760 2768 or define such processing, but does allow it. 2761 2769 </p> 2762 2770 </div> 2763 <p id="rfc.section.7.1. 1.p.8">There are circumstances in which a fragment identifier in a Location URI would not be appropriate. For instance, when it appears2771 <p id="rfc.section.7.1.2.p.8">There are circumstances in which a fragment identifier in a Location URI would not be appropriate. For instance, when it appears 2764 2772 in a <a href="#status.201" class="smpl">201 2765 2773 (Created)</a> response, where the Location header field specifies the URI for the entire created resource. 2766 2774 </p> 2767 <div class="note" id="rfc.section.7.1. 1.p.9">2775 <div class="note" id="rfc.section.7.1.2.p.9"> 2768 2776 <p> <b>Note:</b> The <a href="#header.content-location" class="smpl">Content-Location</a> header field (<a href="#header.content-location" id="rfc.xref.header.content-location.3" title="Content-Location">Section 3.1.4</a>) differs from Location in that the Content-Location identifies the most specific resource corresponding to the enclosed representation. 2769 2777 It is therefore possible for a response to contain header fields for both Location and Content-Location. … … 2771 2779 </div> 2772 2780 <div id="rfc.iref.r.3"></div> 2773 <h3 id="rfc.section.7.1. 2"><a href="#rfc.section.7.1.2">7.1.2</a> <a id="header.retry-after" href="#header.retry-after">Retry-After</a></h3>2774 <p id="rfc.section.7.1. 2.p.1">The header "Retry-After" field can be used with a <a href="#status.503" class="smpl">503 (Service2781 <h3 id="rfc.section.7.1.3"><a href="#rfc.section.7.1.3">7.1.3</a> <a id="header.retry-after" href="#header.retry-after">Retry-After</a></h3> 2782 <p id="rfc.section.7.1.3.p.1">The header "Retry-After" field can be used with a <a href="#status.503" class="smpl">503 (Service 2775 2783 Unavailable)</a> response to indicate how long the service is expected to be unavailable to the requesting client. This field <em class="bcp14">MAY</em> also be used with any <a href="#status.3xx" class="smpl">3xx (Redirection)</a> response to indicate the minimum time the user-agent is asked to wait before issuing the redirected request. 2776 2784 </p> 2777 <p id="rfc.section.7.1. 2.p.2">The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response.</p>2778 <div id="rfc.figure.u.3 7"></div><pre class="inline"><span id="rfc.iref.g.28"></span> <a href="#header.retry-after" class="smpl">Retry-After</a> = <a href="#http.date" class="smpl">HTTP-date</a> / <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>2785 <p id="rfc.section.7.1.3.p.2">The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response.</p> 2786 <div id="rfc.figure.u.39"></div><pre class="inline"><span id="rfc.iref.g.29"></span> <a href="#header.retry-after" class="smpl">Retry-After</a> = <a href="#http.date" class="smpl">HTTP-date</a> / <a href="#rule.delta-seconds" class="smpl">delta-seconds</a> 2779 2787 </pre><div id="rule.delta-seconds"> 2780 <p id="rfc.section.7.1. 2.p.4"> Time spans are non-negative decimal integers, representing time in seconds.</p>2788 <p id="rfc.section.7.1.3.p.4"> Time spans are non-negative decimal integers, representing time in seconds.</p> 2781 2789 </div> 2782 <div id="rfc.figure.u. 38"></div><pre class="inline"><span id="rfc.iref.g.29"></span> <a href="#rule.delta-seconds" class="smpl">delta-seconds</a> = 1*<a href="#imported.abnf" class="smpl">DIGIT</a>2783 </pre><p id="rfc.section.7.1. 2.p.6">Two examples of its use are</p>2784 <div id="rfc.figure.u. 39"></div><pre class="text"> Retry-After: Fri, 31 Dec 1999 23:59:59 GMT2790 <div id="rfc.figure.u.40"></div><pre class="inline"><span id="rfc.iref.g.30"></span> <a href="#rule.delta-seconds" class="smpl">delta-seconds</a> = 1*<a href="#imported.abnf" class="smpl">DIGIT</a> 2791 </pre><p id="rfc.section.7.1.3.p.6">Two examples of its use are</p> 2792 <div id="rfc.figure.u.41"></div><pre class="text"> Retry-After: Fri, 31 Dec 1999 23:59:59 GMT 2785 2793 Retry-After: 120 2786 </pre><p id="rfc.section.7.1.2.p.8">In the latter example, the delay is 2 minutes.</p> 2787 <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a> <a id="response.cache.related" href="#response.cache.related">Cache-related</a></h2> 2788 <p id="rfc.section.7.2.p.1">Cache-related response header fields provide metadata about the message in order to assist downstream caches.</p> 2789 <div id="rfc.table.u.12"> 2794 </pre><p id="rfc.section.7.1.3.p.8">In the latter example, the delay is 2 minutes.</p> 2795 <h2 id="rfc.section.7.2"><a href="#rfc.section.7.2">7.2</a> <a id="selected.representation" href="#selected.representation">Selected Representation Header Fields</a></h2> 2796 <p id="rfc.section.7.2.p.1"><span id="rfc.iref.s.7"></span> We use the term "<dfn>selected representation</dfn>" to refer to the the current representation of a target resource that would have been selected in a successful response if 2797 the same request had used the method GET and excluded any conditional request header fields. 2798 </p> 2799 <p id="rfc.section.7.2.p.2">Additional header fields define metadata about the selected representation, which might differ from the representation included 2800 in the message for responses to some state-changing methods. The following header fields are defined as selected representation 2801 metadata: 2802 </p> 2803 <div id="rfc.table.u.11"> 2790 2804 <table class="tt full left" cellpadding="3" cellspacing="0"> 2791 2805 <thead> … … 2797 2811 <tbody> 2798 2812 <tr> 2799 <td class="left"> Age</td>2800 <td class="left"><a href="p 6-cache.html#header.age" title="Age">Section 7.1</a> of <a href="#Part6" id="rfc.xref.Part6.15"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a></td>2801 </tr> 2802 <tr> 2803 <td class="left"> Date</td>2804 <td class="left"><a href=" #header.date" id="rfc.xref.header.date.2" title="Date">Section 7.2.1</a></td>2813 <td class="left">ETag</td> 2814 <td class="left"><a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.12"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 2815 </tr> 2816 <tr> 2817 <td class="left">Last-Modified</td> 2818 <td class="left"><a href="p4-conditional.html#header.last-modified" title="Last-Modified">Section 2.2</a> of <a href="#Part4" id="rfc.xref.Part4.13"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests">[Part4]</cite></a></td> 2805 2819 </tr> 2806 2820 <tr> 2807 2821 <td class="left">Vary</td> 2808 <td class="left"><a href="#header.vary" id="rfc.xref.header.vary.2" title="Vary">Section 7.2. 2</a></td>2822 <td class="left"><a href="#header.vary" id="rfc.xref.header.vary.2" title="Vary">Section 7.2.1</a></td> 2809 2823 </tr> 2810 2824 </tbody> 2811 2825 </table> 2812 2826 </div> 2813 <div id="rfc.iref.d.2"></div>2814 <h3 id="rfc.section.7.2.1"><a href="#rfc.section.7.2.1">7.2.1</a> <a id="header.date" href="#header.date">Date</a></h3>2815 <p id="rfc.section.7.2.1.p.1">The "Date" header field represents the date and time at which the message was originated, having the same semantics as the2816 Origination Date Field (orig-date) defined in <a href="http://tools.ietf.org/html/rfc5322#section-3.6.1">Section 3.6.1</a> of <a href="#RFC5322" id="rfc.xref.RFC5322.3"><cite title="Internet Message Format">[RFC5322]</cite></a>. The field value is an HTTP-date, as defined in <a href="#http.date" title="Date/Time Formats">Section 8.1</a>; it <em class="bcp14">MUST</em> be sent in rfc1123-date format.2817 </p>2818 <div id="rfc.figure.u.40"></div><pre class="inline"><span id="rfc.iref.g.30"></span> <a href="#header.date" class="smpl">Date</a> = <a href="#http.date" class="smpl">HTTP-date</a>2819 </pre><p id="rfc.section.7.2.1.p.3">An example is</p>2820 <div id="rfc.figure.u.41"></div><pre class="text"> Date: Tue, 15 Nov 1994 08:12:31 GMT2821 </pre><p id="rfc.section.7.2.1.p.5">Origin servers <em class="bcp14">MUST</em> include a Date header field in all responses, except in these cases:2822 </p>2823 <ol>2824 <li>If the response status code is <a href="#status.100" class="smpl">100 (Continue)</a> or <a href="#status.101" class="smpl">101 (Switching Protocols)</a>, the response <em class="bcp14">MAY</em> include a Date header field, at the server's option.2825 </li>2826 <li>If the response status code conveys a server error, e.g., <a href="#status.500" class="smpl">5002827 (Internal Server Error)</a> or <a href="#status.503" class="smpl">503 (Service Unavailable)</a>, and it is inconvenient or impossible to generate a valid Date.2828 </li>2829 <li>If the server does not have a clock that can provide a reasonable approximation of the current time, its responses <em class="bcp14">MUST NOT</em> include a Date header field.2830 </li>2831 </ol>2832 <p id="rfc.section.7.2.1.p.6">A received message that does not have a Date header field <em class="bcp14">MUST</em> be assigned one by the recipient if the message will be cached by that recipient.2833 </p>2834 <p id="rfc.section.7.2.1.p.7">Clients can use the Date header field as well; in order to keep request messages small, they are advised not to include it2835 when it doesn't convey any useful information (as is usually the case for requests that do not contain a payload).2836 </p>2837 <p id="rfc.section.7.2.1.p.8">The HTTP-date sent in a Date header field <em class="bcp14">SHOULD NOT</em> represent a date and time subsequent to the generation of the message. It <em class="bcp14">SHOULD</em> represent the best available approximation of the date and time of message generation, unless the implementation has no means2838 of generating a reasonably accurate date and time. In theory, the date ought to represent the moment just before the payload2839 is generated. In practice, the date can be generated at any time during the message origination without affecting its semantic2840 value.2841 </p>2842 2827 <div id="rfc.iref.v.1"></div> 2843 <h3 id="rfc.section.7.2. 2"><a href="#rfc.section.7.2.2">7.2.2</a> <a id="header.vary" href="#header.vary">Vary</a></h3>2844 <p id="rfc.section.7.2. 2.p.1">The "Vary" header field conveys the set of header fields that were used to select the representation.</p>2845 <p id="rfc.section.7.2. 2.p.2">Caches use this information as part of determining whether a stored response can be used to satisfy a given request (<a href="p6-cache.html#caching.negotiated.responses" title="Using Negotiated Responses">Section 4.3</a> of <a href="#Part6" id="rfc.xref.Part6.16"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>).2846 </p> 2847 <p id="rfc.section.7.2. 2.p.3">In uncacheable or stale responses, the Vary field value advises the user agent about the criteria that were used to select2828 <h3 id="rfc.section.7.2.1"><a href="#rfc.section.7.2.1">7.2.1</a> <a id="header.vary" href="#header.vary">Vary</a></h3> 2829 <p id="rfc.section.7.2.1.p.1">The "Vary" header field conveys the set of header fields that were used to select the representation.</p> 2830 <p id="rfc.section.7.2.1.p.2">Caches use this information as part of determining whether a stored response can be used to satisfy a given request (<a href="p6-cache.html#caching.negotiated.responses" title="Using Negotiated Responses">Section 4.3</a> of <a href="#Part6" id="rfc.xref.Part6.16"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>). 2831 </p> 2832 <p id="rfc.section.7.2.1.p.3">In uncacheable or stale responses, the Vary field value advises the user agent about the criteria that were used to select 2848 2833 the representation. 2849 2834 </p> 2850 2835 <div id="rfc.figure.u.42"></div><pre class="inline"><span id="rfc.iref.g.31"></span> <a href="#header.vary" class="smpl">Vary</a> = "*" / 1#<a href="#imported.abnf" class="smpl">field-name</a> 2851 </pre><p id="rfc.section.7.2. 2.p.5">The set of header fields named by the Vary field value is known as the selecting header fields.</p>2852 <p id="rfc.section.7.2. 2.p.6">A server <em class="bcp14">SHOULD</em> include a Vary header field with any cacheable response that is subject to proactive negotiation. Doing so allows a cache2836 </pre><p id="rfc.section.7.2.1.p.5">The set of header fields named by the Vary field value is known as the selecting header fields.</p> 2837 <p id="rfc.section.7.2.1.p.6">A server <em class="bcp14">SHOULD</em> include a Vary header field with any cacheable response that is subject to proactive negotiation. Doing so allows a cache 2853 2838 to properly interpret future requests on that resource and informs the user agent about the presence of negotiation on that 2854 2839 resource. A server <em class="bcp14">MAY</em> include a Vary header field with a non-cacheable response that is subject to proactive negotiation, since this might provide 2855 2840 the user agent with useful information about the dimensions over which the response varies at the time of the response. 2856 2841 </p> 2857 <p id="rfc.section.7.2. 2.p.7">A Vary field value of "*" signals that unspecified parameters not limited to the header fields (e.g., the network address2842 <p id="rfc.section.7.2.1.p.7">A Vary field value of "*" signals that unspecified parameters not limited to the header fields (e.g., the network address 2858 2843 of the client), play a role in the selection of the response representation; therefore, a cache cannot determine whether this 2859 2844 response is appropriate. A proxy <em class="bcp14">MUST NOT</em> generate the "*" value. 2860 2845 </p> 2861 <p id="rfc.section.7.2. 2.p.8">The field-names given are not limited to the set of standard header fields defined by this specification. Field names are2846 <p id="rfc.section.7.2.1.p.8">The field-names given are not limited to the set of standard header fields defined by this specification. Field names are 2862 2847 case-insensitive. 2863 2848 </p> … … 2866 2851 requests. 2867 2852 </p> 2868 <div id="rfc.table.u.1 3">2853 <div id="rfc.table.u.12"> 2869 2854 <table class="tt full left" cellpadding="3" cellspacing="0"> 2870 2855 <thead> … … 2888 2873 <h2 id="rfc.section.7.4"><a href="#rfc.section.7.4">7.4</a> <a id="response.inform" href="#response.inform">Informative</a></h2> 2889 2874 <p id="rfc.section.7.4.p.1">The remaining response header fields provide more information about the target resource for potential use in later requests.</p> 2890 <div id="rfc.table.u.1 4">2875 <div id="rfc.table.u.13"> 2891 2876 <table class="tt full left" cellpadding="3" cellspacing="0"> 2892 2877 <thead> … … 3273 3258 code (e.g., combinations of request header fields and/or method(s)) along with any dependencies on response header fields 3274 3259 (e.g., what fields are required and what fields can modify the semantics). A response that can transfer a payload ought to 3275 specify expected cache behavior (e.g., cacheability and freshness criteria, as described in <a href="#Part6" id="rfc.xref.Part6.17"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) and whether the payload has any implied association with an identified resource (<a href="#identifying.payload" title="Identifying the Payload">Section 3. 4.2</a>).3260 specify expected cache behavior (e.g., cacheability and freshness criteria, as described in <a href="#Part6" id="rfc.xref.Part6.17"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Caching">[Part6]</cite></a>) and whether the payload has any implied association with an identified resource (<a href="#identifying.payload" title="Identifying the Payload">Section 3.3.2</a>). 3276 3261 </p> 3277 3262 <h3 id="rfc.section.9.2.3"><a href="#rfc.section.9.2.3">9.2.3</a> <a id="status.code.registration" href="#status.code.registration">Registrations</a></h3> … … 3655 3640 <td class="left">http</td> 3656 3641 <td class="left">standard</td> 3657 <td class="left"> <a href="#header.date" id="rfc.xref.header.date.3" title="Date">Section 7. 2.1</a>3642 <td class="left"> <a href="#header.date" id="rfc.xref.header.date.3" title="Date">Section 7.1.1</a> 3658 3643 </td> 3659 3644 </tr> … … 3676 3661 <td class="left">http</td> 3677 3662 <td class="left">standard</td> 3678 <td class="left"> <a href="#header.location" id="rfc.xref.header.location.4" title="Location">Section 7.1. 1</a>3663 <td class="left"> <a href="#header.location" id="rfc.xref.header.location.4" title="Location">Section 7.1.2</a> 3679 3664 </td> 3680 3665 </tr> … … 3704 3689 <td class="left">http</td> 3705 3690 <td class="left">standard</td> 3706 <td class="left"> <a href="#header.retry-after" id="rfc.xref.header.retry-after.3" title="Retry-After">Section 7.1. 2</a>3691 <td class="left"> <a href="#header.retry-after" id="rfc.xref.header.retry-after.3" title="Retry-After">Section 7.1.3</a> 3707 3692 </td> 3708 3693 </tr> … … 3725 3710 <td class="left">http</td> 3726 3711 <td class="left">standard</td> 3727 <td class="left"> <a href="#header.vary" id="rfc.xref.header.vary.3" title="Vary">Section 7.2. 2</a>3712 <td class="left"> <a href="#header.vary" id="rfc.xref.header.vary.3" title="Vary">Section 7.2.1</a> 3728 3713 </td> 3729 3714 </tr> … … 4170 4155 </p> 4171 4156 <p id="rfc.section.C.p.14">Correct syntax of "<a href="#header.location" class="smpl">Location</a>" header field to allow URI references (including relative references and fragments), as referred symbol "absoluteURI" wasn't 4172 what was expected, and add some clarifications as to when use of fragments would not be appropriate. (<a href="#header.location" id="rfc.xref.header.location.5" title="Location">Section 7.1. 1</a>)4157 what was expected, and add some clarifications as to when use of fragments would not be appropriate. (<a href="#header.location" id="rfc.xref.header.location.5" title="Location">Section 7.1.2</a>) 4173 4158 </p> 4174 4159 <p id="rfc.section.C.p.15">Reclassify "<a href="#header.allow" class="smpl">Allow</a>" as response header field, removing the option to specify it in a PUT request. Relax the server requirement on the contents … … 4942 4927 <ul class="ind"> 4943 4928 <li><a id="rfc.index.1" href="#rfc.index.1"><b>1</b></a><ul> 4944 <li>100 Continue (status code) <a href="#rfc.xref.status.100.1">5.1.2.1</a>, <a href="#rfc.xref.status.100.2">5.1.2.1</a>, <a href="#rfc.xref.status.100.3">6.1</a>, <a href="#rfc.iref.5 5"><b>6.2.1</b></a>, <a href="#rfc.xref.status.100.4">9.2.3</a></li>4945 <li>100-continue (expect value) <a href="#rfc.iref.3 2"><b>5.1.2</b></a></li>4946 <li>101 Switching Protocols (status code) <a href="#rfc.xref.status.101.1">6.1</a>, <a href="#rfc.iref.5 5"><b>6.2.2</b></a>, <a href="#rfc.xref.status.101.2">9.2.3</a></li>4947 <li>1xx Informational (status code class) <a href="#rfc.iref.5 4"><b>6.2</b></a></li>4929 <li>100 Continue (status code) <a href="#rfc.xref.status.100.1">5.1.2.1</a>, <a href="#rfc.xref.status.100.2">5.1.2.1</a>, <a href="#rfc.xref.status.100.3">6.1</a>, <a href="#rfc.iref.54"><b>6.2.1</b></a>, <a href="#rfc.xref.status.100.4">9.2.3</a></li> 4930 <li>100-continue (expect value) <a href="#rfc.iref.31"><b>5.1.2</b></a></li> 4931 <li>101 Switching Protocols (status code) <a href="#rfc.xref.status.101.1">6.1</a>, <a href="#rfc.iref.54"><b>6.2.2</b></a>, <a href="#rfc.xref.status.101.2">9.2.3</a></li> 4932 <li>1xx Informational (status code class) <a href="#rfc.iref.53"><b>6.2</b></a></li> 4948 4933 </ul> 4949 4934 </li> 4950 4935 <li><a id="rfc.index.2" href="#rfc.index.2"><b>2</b></a><ul> 4951 <li>200 OK (status code) <a href="#rfc.xref.status.200.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.1</b></a>, <a href="#rfc.xref.status.200.2">9.2.3</a></li>4952 <li>201 Created (status code) <a href="#rfc.xref.status.201.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.2</b></a>, <a href="#rfc.xref.status.201.2">9.2.3</a></li>4953 <li>202 Accepted (status code) <a href="#rfc.xref.status.202.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.3</b></a>, <a href="#rfc.xref.status.202.2">9.2.3</a></li>4954 <li>203 Non-Authoritative Information (status code) <a href="#rfc.xref.status.203.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.4</b></a>, <a href="#rfc.xref.status.203.2">9.2.3</a>, <a href="#rfc.xref.status.203.3">C</a></li>4955 <li>204 No Content (status code) <a href="#rfc.xref.status.204.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.5</b></a>, <a href="#rfc.xref.status.204.2">9.2.3</a></li>4956 <li>205 Reset Content (status code) <a href="#rfc.xref.status.205.1">6.1</a>, <a href="#rfc.iref.5 6"><b>6.3.6</b></a>, <a href="#rfc.xref.status.205.2">9.2.3</a></li>4957 <li>2xx Successful (status code class) <a href="#rfc.iref.5 5"><b>6.3</b></a></li>4936 <li>200 OK (status code) <a href="#rfc.xref.status.200.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.1</b></a>, <a href="#rfc.xref.status.200.2">9.2.3</a></li> 4937 <li>201 Created (status code) <a href="#rfc.xref.status.201.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.2</b></a>, <a href="#rfc.xref.status.201.2">9.2.3</a></li> 4938 <li>202 Accepted (status code) <a href="#rfc.xref.status.202.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.3</b></a>, <a href="#rfc.xref.status.202.2">9.2.3</a></li> 4939 <li>203 Non-Authoritative Information (status code) <a href="#rfc.xref.status.203.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.4</b></a>, <a href="#rfc.xref.status.203.2">9.2.3</a>, <a href="#rfc.xref.status.203.3">C</a></li> 4940 <li>204 No Content (status code) <a href="#rfc.xref.status.204.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.5</b></a>, <a href="#rfc.xref.status.204.2">9.2.3</a></li> 4941 <li>205 Reset Content (status code) <a href="#rfc.xref.status.205.1">6.1</a>, <a href="#rfc.iref.55"><b>6.3.6</b></a>, <a href="#rfc.xref.status.205.2">9.2.3</a></li> 4942 <li>2xx Successful (status code class) <a href="#rfc.iref.54"><b>6.3</b></a></li> 4958 4943 </ul> 4959 4944 </li> 4960 4945 <li><a id="rfc.index.3" href="#rfc.index.3"><b>3</b></a><ul> 4961 <li>300 Multiple Choices (status code) <a href="#rfc.xref.status.300.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.1</b></a>, <a href="#rfc.xref.status.300.2">9.2.3</a></li>4962 <li>301 Moved Permanently (status code) <a href="#rfc.xref.status.301.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.2</b></a>, <a href="#rfc.xref.status.301.2">9.2.3</a>, <a href="#rfc.xref.status.301.3">C</a></li>4963 <li>302 Found (status code) <a href="#rfc.xref.status.302.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.3</b></a>, <a href="#rfc.xref.status.302.2">9.2.3</a>, <a href="#rfc.xref.status.302.3">C</a></li>4964 <li>303 See Other (status code) <a href="#rfc.xref.status.303.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.4</b></a>, <a href="#rfc.xref.status.303.2">9.2.3</a></li>4965 <li>305 Use Proxy (status code) <a href="#rfc.xref.status.305.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.5</b></a>, <a href="#rfc.xref.status.305.2">9.2.3</a>, <a href="#rfc.xref.status.305.3">C</a></li>4966 <li>306 (Unused) (status code) <a href="#rfc.iref.5 7"><b>6.4.6</b></a>, <a href="#rfc.xref.status.306.1">9.2.3</a></li>4967 <li>307 Temporary Redirect (status code) <a href="#rfc.xref.status.307.1">6.1</a>, <a href="#rfc.iref.5 7"><b>6.4.7</b></a>, <a href="#rfc.xref.status.307.2">9.2.3</a>, <a href="#rfc.xref.status.307.3">C</a></li>4968 <li>3xx Redirection (status code class) <a href="#rfc.iref.5 6"><b>6.4</b></a>, <a href="#rfc.xref.status.3xx.1">C</a></li>4946 <li>300 Multiple Choices (status code) <a href="#rfc.xref.status.300.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.1</b></a>, <a href="#rfc.xref.status.300.2">9.2.3</a></li> 4947 <li>301 Moved Permanently (status code) <a href="#rfc.xref.status.301.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.2</b></a>, <a href="#rfc.xref.status.301.2">9.2.3</a>, <a href="#rfc.xref.status.301.3">C</a></li> 4948 <li>302 Found (status code) <a href="#rfc.xref.status.302.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.3</b></a>, <a href="#rfc.xref.status.302.2">9.2.3</a>, <a href="#rfc.xref.status.302.3">C</a></li> 4949 <li>303 See Other (status code) <a href="#rfc.xref.status.303.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.4</b></a>, <a href="#rfc.xref.status.303.2">9.2.3</a></li> 4950 <li>305 Use Proxy (status code) <a href="#rfc.xref.status.305.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.5</b></a>, <a href="#rfc.xref.status.305.2">9.2.3</a>, <a href="#rfc.xref.status.305.3">C</a></li> 4951 <li>306 (Unused) (status code) <a href="#rfc.iref.56"><b>6.4.6</b></a>, <a href="#rfc.xref.status.306.1">9.2.3</a></li> 4952 <li>307 Temporary Redirect (status code) <a href="#rfc.xref.status.307.1">6.1</a>, <a href="#rfc.iref.56"><b>6.4.7</b></a>, <a href="#rfc.xref.status.307.2">9.2.3</a>, <a href="#rfc.xref.status.307.3">C</a></li> 4953 <li>3xx Redirection (status code class) <a href="#rfc.iref.55"><b>6.4</b></a>, <a href="#rfc.xref.status.3xx.1">C</a></li> 4969 4954 </ul> 4970 4955 </li> 4971 4956 <li><a id="rfc.index.4" href="#rfc.index.4"><b>4</b></a><ul> 4972 <li>400 Bad Request (status code) <a href="#rfc.xref.status.400.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.1</b></a>, <a href="#rfc.xref.status.400.2">9.2.3</a></li>4973 <li>402 Payment Required (status code) <a href="#rfc.xref.status.402.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.2</b></a>, <a href="#rfc.xref.status.402.2">9.2.3</a></li>4974 <li>403 Forbidden (status code) <a href="#rfc.xref.status.403.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.3</b></a>, <a href="#rfc.xref.status.403.2">9.2.3</a></li>4975 <li>404 Not Found (status code) <a href="#rfc.xref.status.404.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.4</b></a>, <a href="#rfc.xref.status.404.2">9.2.3</a></li>4976 <li>405 Method Not Allowed (status code) <a href="#rfc.xref.status.405.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.5</b></a>, <a href="#rfc.xref.status.405.2">9.2.3</a></li>4977 <li>406 Not Acceptable (status code) <a href="#rfc.xref.status.406.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.6</b></a>, <a href="#rfc.xref.status.406.2">9.2.3</a></li>4978 <li>408 Request Timeout (status code) <a href="#rfc.xref.status.408.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.7</b></a>, <a href="#rfc.xref.status.408.2">9.2.3</a></li>4979 <li>409 Conflict (status code) <a href="#rfc.xref.status.409.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.8</b></a>, <a href="#rfc.xref.status.409.2">9.2.3</a></li>4980 <li>410 Gone (status code) <a href="#rfc.xref.status.410.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.9</b></a>, <a href="#rfc.xref.status.410.2">9.2.3</a></li>4981 <li>411 Length Required (status code) <a href="#rfc.xref.status.411.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.10</b></a>, <a href="#rfc.xref.status.411.2">9.2.3</a></li>4982 <li>413 Request Representation Too Large (status code) <a href="#rfc.xref.status.413.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.11</b></a>, <a href="#rfc.xref.status.413.2">9.2.3</a></li>4983 <li>414 URI Too Long (status code) <a href="#rfc.xref.status.414.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.12</b></a>, <a href="#rfc.xref.status.414.2">9.2.3</a></li>4984 <li>415 Unsupported Media Type (status code) <a href="#rfc.xref.status.415.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.13</b></a>, <a href="#rfc.xref.status.415.2">9.2.3</a></li>4985 <li>417 Expectation Failed (status code) <a href="#rfc.xref.status.417.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.14</b></a>, <a href="#rfc.xref.status.417.2">9.2.3</a></li>4986 <li>426 Upgrade Required (status code) <a href="#rfc.xref.status.426.1">6.1</a>, <a href="#rfc.iref.5 8"><b>6.5.15</b></a>, <a href="#rfc.xref.status.426.2">9.2.3</a>, <a href="#rfc.xref.status.426.3">C</a></li>4987 <li>4xx Client Error (status code class) <a href="#rfc.iref.5 7"><b>6.5</b></a></li>4957 <li>400 Bad Request (status code) <a href="#rfc.xref.status.400.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.1</b></a>, <a href="#rfc.xref.status.400.2">9.2.3</a></li> 4958 <li>402 Payment Required (status code) <a href="#rfc.xref.status.402.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.2</b></a>, <a href="#rfc.xref.status.402.2">9.2.3</a></li> 4959 <li>403 Forbidden (status code) <a href="#rfc.xref.status.403.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.3</b></a>, <a href="#rfc.xref.status.403.2">9.2.3</a></li> 4960 <li>404 Not Found (status code) <a href="#rfc.xref.status.404.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.4</b></a>, <a href="#rfc.xref.status.404.2">9.2.3</a></li> 4961 <li>405 Method Not Allowed (status code) <a href="#rfc.xref.status.405.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.5</b></a>, <a href="#rfc.xref.status.405.2">9.2.3</a></li> 4962 <li>406 Not Acceptable (status code) <a href="#rfc.xref.status.406.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.6</b></a>, <a href="#rfc.xref.status.406.2">9.2.3</a></li> 4963 <li>408 Request Timeout (status code) <a href="#rfc.xref.status.408.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.7</b></a>, <a href="#rfc.xref.status.408.2">9.2.3</a></li> 4964 <li>409 Conflict (status code) <a href="#rfc.xref.status.409.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.8</b></a>, <a href="#rfc.xref.status.409.2">9.2.3</a></li> 4965 <li>410 Gone (status code) <a href="#rfc.xref.status.410.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.9</b></a>, <a href="#rfc.xref.status.410.2">9.2.3</a></li> 4966 <li>411 Length Required (status code) <a href="#rfc.xref.status.411.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.10</b></a>, <a href="#rfc.xref.status.411.2">9.2.3</a></li> 4967 <li>413 Request Representation Too Large (status code) <a href="#rfc.xref.status.413.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.11</b></a>, <a href="#rfc.xref.status.413.2">9.2.3</a></li> 4968 <li>414 URI Too Long (status code) <a href="#rfc.xref.status.414.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.12</b></a>, <a href="#rfc.xref.status.414.2">9.2.3</a></li> 4969 <li>415 Unsupported Media Type (status code) <a href="#rfc.xref.status.415.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.13</b></a>, <a href="#rfc.xref.status.415.2">9.2.3</a></li> 4970 <li>417 Expectation Failed (status code) <a href="#rfc.xref.status.417.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.14</b></a>, <a href="#rfc.xref.status.417.2">9.2.3</a></li> 4971 <li>426 Upgrade Required (status code) <a href="#rfc.xref.status.426.1">6.1</a>, <a href="#rfc.iref.57"><b>6.5.15</b></a>, <a href="#rfc.xref.status.426.2">9.2.3</a>, <a href="#rfc.xref.status.426.3">C</a></li> 4972 <li>4xx Client Error (status code class) <a href="#rfc.iref.56"><b>6.5</b></a></li> 4988 4973 </ul> 4989 4974 </li> 4990 4975 <li><a id="rfc.index.5" href="#rfc.index.5"><b>5</b></a><ul> 4991 <li>500 Internal Server Error (status code) <a href="#rfc.xref.status.500.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.1</b></a>, <a href="#rfc.xref.status.500.2">9.2.3</a></li>4992 <li>501 Not Implemented (status code) <a href="#rfc.xref.status.501.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.2</b></a>, <a href="#rfc.xref.status.501.2">9.2.3</a></li>4993 <li>502 Bad Gateway (status code) <a href="#rfc.xref.status.502.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.3</b></a>, <a href="#rfc.xref.status.502.2">9.2.3</a></li>4994 <li>503 Service Unavailable (status code) <a href="#rfc.xref.status.503.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.4</b></a>, <a href="#rfc.xref.status.503.2">9.2.3</a></li>4995 <li>504 Gateway Timeout (status code) <a href="#rfc.xref.status.504.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.5</b></a>, <a href="#rfc.xref.status.504.2">9.2.3</a></li>4996 <li>505 HTTP Version Not Supported (status code) <a href="#rfc.xref.status.505.1">6.1</a>, <a href="#rfc.iref.5 9"><b>6.6.6</b></a>, <a href="#rfc.xref.status.505.2">9.2.3</a></li>4997 <li>5xx Server Error (status code class) <a href="#rfc.iref.5 8"><b>6.6</b></a></li>4976 <li>500 Internal Server Error (status code) <a href="#rfc.xref.status.500.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.1</b></a>, <a href="#rfc.xref.status.500.2">9.2.3</a></li> 4977 <li>501 Not Implemented (status code) <a href="#rfc.xref.status.501.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.2</b></a>, <a href="#rfc.xref.status.501.2">9.2.3</a></li> 4978 <li>502 Bad Gateway (status code) <a href="#rfc.xref.status.502.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.3</b></a>, <a href="#rfc.xref.status.502.2">9.2.3</a></li> 4979 <li>503 Service Unavailable (status code) <a href="#rfc.xref.status.503.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.4</b></a>, <a href="#rfc.xref.status.503.2">9.2.3</a></li> 4980 <li>504 Gateway Timeout (status code) <a href="#rfc.xref.status.504.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.5</b></a>, <a href="#rfc.xref.status.504.2">9.2.3</a></li> 4981 <li>505 HTTP Version Not Supported (status code) <a href="#rfc.xref.status.505.1">6.1</a>, <a href="#rfc.iref.58"><b>6.6.6</b></a>, <a href="#rfc.xref.status.505.2">9.2.3</a></li> 4982 <li>5xx Server Error (status code class) <a href="#rfc.iref.57"><b>6.6</b></a></li> 4998 4983 </ul> 4999 4984 </li> 5000 4985 <li><a id="rfc.index.A" href="#rfc.index.A"><b>A</b></a><ul> 5001 <li>Accept header field <a href="#rfc.xref.header.accept.1">3. 5.1</a>, <a href="#rfc.xref.header.accept.2">5.3</a>, <a href="#rfc.iref.a.1"><b>5.3.2</b></a>, <a href="#rfc.xref.header.accept.3">8.5</a>, <a href="#rfc.xref.header.accept.4">9.3.2</a></li>5002 <li>Accept-Charset header field <a href="#rfc.xref.header.accept-charset.1">3. 5.1</a>, <a href="#rfc.xref.header.accept-charset.2">5.3</a>, <a href="#rfc.iref.a.2"><b>5.3.3</b></a>, <a href="#rfc.xref.header.accept-charset.3">9.3.2</a>, <a href="#rfc.xref.header.accept-charset.4">C</a></li>5003 <li>Accept-Encoding header field <a href="#rfc.xref.header.accept-encoding.1">3. 5.1</a>, <a href="#rfc.xref.header.accept-encoding.2">5.3</a>, <a href="#rfc.iref.a.3"><b>5.3.4</b></a>, <a href="#rfc.xref.header.accept-encoding.3">8.4</a>, <a href="#rfc.xref.header.accept-encoding.4">9.3.2</a>, <a href="#rfc.xref.header.accept-encoding.5">9.4.2</a></li>5004 <li>Accept-Language header field <a href="#rfc.xref.header.accept-language.1">3. 5.1</a>, <a href="#rfc.xref.header.accept-language.2">5.3</a>, <a href="#rfc.iref.a.4"><b>5.3.5</b></a>, <a href="#rfc.xref.header.accept-language.3">9.3.2</a></li>4986 <li>Accept header field <a href="#rfc.xref.header.accept.1">3.4.1</a>, <a href="#rfc.xref.header.accept.2">5.3</a>, <a href="#rfc.iref.a.1"><b>5.3.2</b></a>, <a href="#rfc.xref.header.accept.3">8.5</a>, <a href="#rfc.xref.header.accept.4">9.3.2</a></li> 4987 <li>Accept-Charset header field <a href="#rfc.xref.header.accept-charset.1">3.4.1</a>, <a href="#rfc.xref.header.accept-charset.2">5.3</a>, <a href="#rfc.iref.a.2"><b>5.3.3</b></a>, <a href="#rfc.xref.header.accept-charset.3">9.3.2</a>, <a href="#rfc.xref.header.accept-charset.4">C</a></li> 4988 <li>Accept-Encoding header field <a href="#rfc.xref.header.accept-encoding.1">3.4.1</a>, <a href="#rfc.xref.header.accept-encoding.2">5.3</a>, <a href="#rfc.iref.a.3"><b>5.3.4</b></a>, <a href="#rfc.xref.header.accept-encoding.3">8.4</a>, <a href="#rfc.xref.header.accept-encoding.4">9.3.2</a>, <a href="#rfc.xref.header.accept-encoding.5">9.4.2</a></li> 4989 <li>Accept-Language header field <a href="#rfc.xref.header.accept-language.1">3.4.1</a>, <a href="#rfc.xref.header.accept-language.2">5.3</a>, <a href="#rfc.iref.a.4"><b>5.3.5</b></a>, <a href="#rfc.xref.header.accept-language.3">9.3.2</a></li> 5005 4990 <li>Allow header field <a href="#rfc.xref.header.allow.1">4.1</a>, <a href="#rfc.xref.header.allow.2">7.4</a>, <a href="#rfc.iref.a.5"><b>7.4.1</b></a>, <a href="#rfc.xref.header.allow.3">9.3.2</a>, <a href="#rfc.xref.header.allow.4">C</a></li> 5006 4991 </ul> … … 5013 4998 <li>Content-Encoding header field <a href="#rfc.xref.header.content-encoding.1">3.1</a>, <a href="#rfc.iref.c.3"><b>3.1.2</b></a>, <a href="#rfc.xref.header.content-encoding.2">8.4</a>, <a href="#rfc.xref.header.content-encoding.3">9.3.2</a></li> 5014 4999 <li>Content-Language header field <a href="#rfc.xref.header.content-language.1">3.1</a>, <a href="#rfc.iref.c.4"><b>3.1.3</b></a>, <a href="#rfc.xref.header.content-language.2">9.3.2</a></li> 5015 <li>Content-Location header field <a href="#rfc.xref.header.content-location.1">3.1</a>, <a href="#rfc.iref.c.5"><b>3.1.4</b></a>, <a href="#rfc.xref.header.content-location.2">4.3.3</a>, <a href="#rfc.xref.header.content-location.3">7.1. 1</a>, <a href="#rfc.xref.header.content-location.4">9.3.2</a>, <a href="#rfc.xref.header.content-location.5">C</a></li>5000 <li>Content-Location header field <a href="#rfc.xref.header.content-location.1">3.1</a>, <a href="#rfc.iref.c.5"><b>3.1.4</b></a>, <a href="#rfc.xref.header.content-location.2">4.3.3</a>, <a href="#rfc.xref.header.content-location.3">7.1.2</a>, <a href="#rfc.xref.header.content-location.4">9.3.2</a>, <a href="#rfc.xref.header.content-location.5">C</a></li> 5016 5001 <li>Content-Transfer-Encoding header field <a href="#rfc.iref.c.9">A.5</a>, <a href="#rfc.xref.no.content-transfer-encoding.1">C</a></li> 5017 5002 <li>Content-Type header field <a href="#rfc.xref.header.content-type.1">3.1</a>, <a href="#rfc.iref.c.2"><b>3.1.1</b></a>, <a href="#rfc.xref.header.content-type.2">6</a>, <a href="#rfc.xref.header.content-type.3">8.5</a>, <a href="#rfc.xref.header.content-type.4">9.3.1</a>, <a href="#rfc.xref.header.content-type.5">9.3.2</a></li> … … 5019 5004 </li> 5020 5005 <li><a id="rfc.index.D" href="#rfc.index.D"><b>D</b></a><ul> 5021 <li>Date header field <a href="#rfc.xref.header.date.1">3. 4</a>, <a href="#rfc.xref.header.date.2">7.2</a>, <a href="#rfc.iref.d.2"><b>7.2.1</b></a>, <a href="#rfc.xref.header.date.3">9.3.2</a></li>5006 <li>Date header field <a href="#rfc.xref.header.date.1">3.3</a>, <a href="#rfc.xref.header.date.2">7.1</a>, <a href="#rfc.iref.d.2"><b>7.1.1</b></a>, <a href="#rfc.xref.header.date.3">9.3.2</a></li> 5022 5007 <li>deflate (Coding Format) <a href="#rfc.iref.d.3">8.4</a></li> 5023 5008 <li>DELETE method <a href="#rfc.xref.DELETE.1">4.1</a>, <a href="#rfc.iref.d.1"><b>4.3.5</b></a>, <a href="#rfc.xref.DELETE.2">9.1.3</a></li> … … 5038 5023 </li> 5039 5024 <li><a id="rfc.index.G" href="#rfc.index.G"><b>G</b></a><ul> 5040 <li>GET method <a href="#rfc.xref.GET.1">3. 4</a>, <a href="#rfc.xref.GET.2">4.1</a>, <a href="#rfc.iref.g.6"><b>4.3.1</b></a>, <a href="#rfc.xref.GET.3">9.1.3</a></li>5025 <li>GET method <a href="#rfc.xref.GET.1">3.3</a>, <a href="#rfc.xref.GET.2">4.1</a>, <a href="#rfc.iref.g.6"><b>4.3.1</b></a>, <a href="#rfc.xref.GET.3">9.1.3</a></li> 5041 5026 <li><tt>Grammar</tt> 5042 5027 <ul> … … 5057 5042 <li><tt>Content-Location</tt> <a href="#rfc.iref.g.4"><b>3.1.4</b></a></li> 5058 5043 <li><tt>Content-Type</tt> <a href="#rfc.iref.g.1"><b>3.1.1</b></a></li> 5059 <li><tt>Date</tt> <a href="#rfc.iref.g. 30"><b>7.2.1</b></a></li>5044 <li><tt>Date</tt> <a href="#rfc.iref.g.27"><b>7.1.1</b></a></li> 5060 5045 <li><tt>date1</tt> <a href="#rfc.iref.g.36"><b>8.1</b></a></li> 5061 5046 <li><tt>day</tt> <a href="#rfc.iref.g.43"><b>8.1</b></a></li> 5062 5047 <li><tt>day-name</tt> <a href="#rfc.iref.g.41"><b>8.1</b></a></li> 5063 5048 <li><tt>day-name-l</tt> <a href="#rfc.iref.g.42"><b>8.1</b></a></li> 5064 <li><tt>delta-seconds</tt> <a href="#rfc.iref.g. 29"><b>7.1.2</b></a></li>5049 <li><tt>delta-seconds</tt> <a href="#rfc.iref.g.30"><b>7.1.3</b></a></li> 5065 5050 <li><tt>Expect</tt> <a href="#rfc.iref.g.8"><b>5.1.2</b></a></li> 5066 5051 <li><tt>expect-name</tt> <a href="#rfc.iref.g.12"><b>5.1.2</b></a></li> … … 5074 5059 <li><tt>language-range</tt> <a href="#rfc.iref.g.23"><b>5.3.5</b></a></li> 5075 5060 <li><tt>language-tag</tt> <a href="#rfc.iref.g.61"><b>8.6</b></a></li> 5076 <li><tt>Location</tt> <a href="#rfc.iref.g.2 7"><b>7.1.1</b></a></li>5061 <li><tt>Location</tt> <a href="#rfc.iref.g.28"><b>7.1.2</b></a></li> 5077 5062 <li><tt>Max-Forwards</tt> <a href="#rfc.iref.g.7"><b>5.1.1</b></a></li> 5078 5063 <li><tt>media-range</tt> <a href="#rfc.iref.g.16"><b>5.3.2</b></a></li> … … 5088 5073 <li><tt>qvalue</tt> <a href="#rfc.iref.g.14"><b>5.3.1</b></a></li> 5089 5074 <li><tt>Referer</tt> <a href="#rfc.iref.g.25"><b>5.5.2</b></a></li> 5090 <li><tt>Retry-After</tt> <a href="#rfc.iref.g.2 8"><b>7.1.2</b></a></li>5075 <li><tt>Retry-After</tt> <a href="#rfc.iref.g.29"><b>7.1.3</b></a></li> 5091 5076 <li><tt>rfc1123-date</tt> <a href="#rfc.iref.g.35"><b>8.1</b></a></li> 5092 5077 <li><tt>rfc850-date</tt> <a href="#rfc.iref.g.48"><b>8.1</b></a></li> … … 5098 5083 <li><tt>User-Agent</tt> <a href="#rfc.iref.g.26"><b>5.5.3</b></a></li> 5099 5084 <li><tt>value</tt> <a href="#rfc.iref.g.60"><b>8.5</b></a></li> 5100 <li><tt>Vary</tt> <a href="#rfc.iref.g.31"><b>7.2. 2</b></a></li>5085 <li><tt>Vary</tt> <a href="#rfc.iref.g.31"><b>7.2.1</b></a></li> 5101 5086 <li><tt>weight</tt> <a href="#rfc.iref.g.13"><b>5.3.1</b></a></li> 5102 5087 <li><tt>year</tt> <a href="#rfc.iref.g.45"><b>8.1</b></a></li> … … 5115 5100 </li> 5116 5101 <li><a id="rfc.index.L" href="#rfc.index.L"><b>L</b></a><ul> 5117 <li>Location header field <a href="#rfc.xref.header.location.1">4.3.3</a>, <a href="#rfc.xref.header.location.2">6.4</a>, <a href="#rfc.xref.header.location.3">7.1</a>, <a href="#rfc.iref.l.1"><b>7.1. 1</b></a>, <a href="#rfc.xref.header.location.4">9.3.2</a>, <a href="#rfc.xref.header.location.5">C</a></li>5102 <li>Location header field <a href="#rfc.xref.header.location.1">4.3.3</a>, <a href="#rfc.xref.header.location.2">6.4</a>, <a href="#rfc.xref.header.location.3">7.1</a>, <a href="#rfc.iref.l.1"><b>7.1.2</b></a>, <a href="#rfc.xref.header.location.4">9.3.2</a>, <a href="#rfc.xref.header.location.5">C</a></li> 5118 5103 </ul> 5119 5104 </li> … … 5128 5113 </li> 5129 5114 <li><a id="rfc.index.P" href="#rfc.index.P"><b>P</b></a><ul> 5130 <li><em>Part1</em> <a href="#rfc.xref.Part1.1">1</a>, <a href="#rfc.xref.Part1.2">1.1</a>, <a href="#rfc.xref.Part1.3">1.2</a>, <a href="#rfc.xref.Part1.4">2</a>, <a href="#rfc.xref.Part1.5">2</a>, <a href="#rfc.xref.Part1.6">2</a>, <a href="#rfc.xref.Part1.7">3.1.4</a>, <a href="#rfc.xref.Part1.8">3. 4.1</a>, <a href="#rfc.xref.Part1.9">3.4.1</a>, <a href="#rfc.xref.Part1.10">3.4.2</a>, <a href="#rfc.xref.Part1.11">4.3.6</a>, <a href="#rfc.xref.Part1.12">4.3.7</a>, <a href="#rfc.xref.Part1.13">4.3.8</a>, <a href="#rfc.xref.Part1.14">4.3.8</a>, <a href="#rfc.xref.Part1.15">5.1</a>, <a href="#rfc.xref.Part1.16">5.5</a>, <a href="#rfc.xref.Part1.17">5.5.3</a>, <a href="#rfc.xref.Part1.18">6.2.2</a>, <a href="#rfc.xref.Part1.19">6.3.4</a>, <a href="#rfc.xref.Part1.20">6.3.6</a>, <a href="#rfc.xref.Part1.21">6.5.15</a>, <a href="#rfc.xref.Part1.22">6.6.6</a>, <a href="#rfc.xref.Part1.23">7</a>, <a href="#rfc.xref.Part1.24">7.4.2</a>, <a href="#rfc.xref.Part1.25">7.4.2</a>, <a href="#rfc.xref.Part1.26">8.4</a>, <a href="#rfc.xref.Part1.27">8.4</a>, <a href="#rfc.xref.Part1.28">8.4</a>, <a href="#rfc.xref.Part1.29">9.1.2</a>, <a href="#rfc.xref.Part1.30">9.3.1</a>, <a href="#rfc.xref.Part1.31">9.3.1</a>, <a href="#rfc.xref.Part1.32">9.3.1</a>, <a href="#rfc.xref.Part1.33">9.3.1</a>, <a href="#rfc.xref.Part1.34">9.3.1</a>, <a href="#rfc.xref.Part1.35">9.3.1</a>, <a href="#rfc.xref.Part1.36">9.4</a>, <a href="#rfc.xref.Part1.37">9.4.1</a>, <a href="#rfc.xref.Part1.38">9.4.1</a>, <a href="#rfc.xref.Part1.39">9.4.2</a>, <a href="#rfc.xref.Part1.40">9.4.2</a>, <a href="#rfc.xref.Part1.41">9.4.2</a>, <a href="#rfc.xref.Part1.42">11</a>, <a href="#Part1"><b>12.1</b></a>, <a href="#rfc.xref.Part1.43">C</a>, <a href="#rfc.xref.Part1.44">D</a>, <a href="#rfc.xref.Part1.45">D</a>, <a href="#rfc.xref.Part1.46">D</a>, <a href="#rfc.xref.Part1.47">D</a>, <a href="#rfc.xref.Part1.48">D</a>, <a href="#rfc.xref.Part1.49">D</a>, <a href="#rfc.xref.Part1.50">D</a>, <a href="#rfc.xref.Part1.51">D</a>, <a href="#rfc.xref.Part1.52">D</a>, <a href="#rfc.xref.Part1.53">D</a>, <a href="#rfc.xref.Part1.54">D</a>, <a href="#rfc.xref.Part1.55">D</a><ul>5115 <li><em>Part1</em> <a href="#rfc.xref.Part1.1">1</a>, <a href="#rfc.xref.Part1.2">1.1</a>, <a href="#rfc.xref.Part1.3">1.2</a>, <a href="#rfc.xref.Part1.4">2</a>, <a href="#rfc.xref.Part1.5">2</a>, <a href="#rfc.xref.Part1.6">2</a>, <a href="#rfc.xref.Part1.7">3.1.4</a>, <a href="#rfc.xref.Part1.8">3.3.1</a>, <a href="#rfc.xref.Part1.9">3.3.1</a>, <a href="#rfc.xref.Part1.10">3.3.2</a>, <a href="#rfc.xref.Part1.11">4.3.6</a>, <a href="#rfc.xref.Part1.12">4.3.7</a>, <a href="#rfc.xref.Part1.13">4.3.8</a>, <a href="#rfc.xref.Part1.14">4.3.8</a>, <a href="#rfc.xref.Part1.15">5.1</a>, <a href="#rfc.xref.Part1.16">5.5</a>, <a href="#rfc.xref.Part1.17">5.5.3</a>, <a href="#rfc.xref.Part1.18">6.2.2</a>, <a href="#rfc.xref.Part1.19">6.3.4</a>, <a href="#rfc.xref.Part1.20">6.3.6</a>, <a href="#rfc.xref.Part1.21">6.5.15</a>, <a href="#rfc.xref.Part1.22">6.6.6</a>, <a href="#rfc.xref.Part1.23">7</a>, <a href="#rfc.xref.Part1.24">7.4.2</a>, <a href="#rfc.xref.Part1.25">7.4.2</a>, <a href="#rfc.xref.Part1.26">8.4</a>, <a href="#rfc.xref.Part1.27">8.4</a>, <a href="#rfc.xref.Part1.28">8.4</a>, <a href="#rfc.xref.Part1.29">9.1.2</a>, <a href="#rfc.xref.Part1.30">9.3.1</a>, <a href="#rfc.xref.Part1.31">9.3.1</a>, <a href="#rfc.xref.Part1.32">9.3.1</a>, <a href="#rfc.xref.Part1.33">9.3.1</a>, <a href="#rfc.xref.Part1.34">9.3.1</a>, <a href="#rfc.xref.Part1.35">9.3.1</a>, <a href="#rfc.xref.Part1.36">9.4</a>, <a href="#rfc.xref.Part1.37">9.4.1</a>, <a href="#rfc.xref.Part1.38">9.4.1</a>, <a href="#rfc.xref.Part1.39">9.4.2</a>, <a href="#rfc.xref.Part1.40">9.4.2</a>, <a href="#rfc.xref.Part1.41">9.4.2</a>, <a href="#rfc.xref.Part1.42">11</a>, <a href="#Part1"><b>12.1</b></a>, <a href="#rfc.xref.Part1.43">C</a>, <a href="#rfc.xref.Part1.44">D</a>, <a href="#rfc.xref.Part1.45">D</a>, <a href="#rfc.xref.Part1.46">D</a>, <a href="#rfc.xref.Part1.47">D</a>, <a href="#rfc.xref.Part1.48">D</a>, <a href="#rfc.xref.Part1.49">D</a>, <a href="#rfc.xref.Part1.50">D</a>, <a href="#rfc.xref.Part1.51">D</a>, <a href="#rfc.xref.Part1.52">D</a>, <a href="#rfc.xref.Part1.53">D</a>, <a href="#rfc.xref.Part1.54">D</a>, <a href="#rfc.xref.Part1.55">D</a><ul> 5131 5116 <li><em>Section 1.2</em> <a href="#rfc.xref.Part1.3">1.2</a></li> 5132 5117 <li><em>Section 2.3</em> <a href="#rfc.xref.Part1.19">6.3.4</a></li> … … 5137 5122 <li><em>Section 3.2.1</em> <a href="#rfc.xref.Part1.45">D</a>, <a href="#rfc.xref.Part1.46">D</a>, <a href="#rfc.xref.Part1.47">D</a></li> 5138 5123 <li><em>Section 3.2.4</em> <a href="#rfc.xref.Part1.32">9.3.1</a>, <a href="#rfc.xref.Part1.50">D</a>, <a href="#rfc.xref.Part1.53">D</a>, <a href="#rfc.xref.Part1.54">D</a>, <a href="#rfc.xref.Part1.55">D</a></li> 5139 <li><em>Section 3.3.1</em> <a href="#rfc.xref.Part1.9">3. 4.1</a></li>5124 <li><em>Section 3.3.1</em> <a href="#rfc.xref.Part1.9">3.3.1</a></li> 5140 5125 <li><em>Section 3.3</em> <a href="#rfc.xref.Part1.20">6.3.6</a>, <a href="#rfc.xref.Part1.29">9.1.2</a></li> 5141 <li><em>Section 3.3.2</em> <a href="#rfc.xref.Part1.8">3. 4.1</a></li>5126 <li><em>Section 3.3.2</em> <a href="#rfc.xref.Part1.8">3.3.1</a></li> 5142 5127 <li><em>Section 4</em> <a href="#rfc.xref.Part1.37">9.4.1</a></li> 5143 5128 <li><em>Section 4.1</em> <a href="#rfc.xref.Part1.35">9.3.1</a></li> … … 5149 5134 <li><em>Section 5.3</em> <a href="#rfc.xref.Part1.5">2</a>, <a href="#rfc.xref.Part1.11">4.3.6</a>, <a href="#rfc.xref.Part1.12">4.3.7</a></li> 5150 5135 <li><em>Section 5.4</em> <a href="#rfc.xref.Part1.15">5.1</a></li> 5151 <li><em>Section 5.5</em> <a href="#rfc.xref.Part1.6">2</a>, <a href="#rfc.xref.Part1.7">3.1.4</a>, <a href="#rfc.xref.Part1.10">3. 4.2</a>, <a href="#rfc.xref.Part1.23">7</a></li>5136 <li><em>Section 5.5</em> <a href="#rfc.xref.Part1.6">2</a>, <a href="#rfc.xref.Part1.7">3.1.4</a>, <a href="#rfc.xref.Part1.10">3.3.2</a>, <a href="#rfc.xref.Part1.23">7</a></li> 5152 5137 <li><em>Section 5.7</em> <a href="#rfc.xref.Part1.13">4.3.8</a>, <a href="#rfc.xref.Part1.25">7.4.2</a>, <a href="#rfc.xref.Part1.43">C</a></li> 5153 5138 <li><em>Section 6.1</em> <a href="#rfc.xref.Part1.34">9.3.1</a></li> … … 5158 5143 </ul> 5159 5144 </li> 5160 <li><em>Part4</em> <a href="#rfc.xref.Part4.1"> 3.2</a>, <a href="#rfc.xref.Part4.2">3.2</a>, <a href="#rfc.xref.Part4.3">4.3.1</a>, <a href="#rfc.xref.Part4.4">5.2</a>, <a href="#rfc.xref.Part4.5">5.2</a>, <a href="#rfc.xref.Part4.6">5.2</a>, <a href="#rfc.xref.Part4.7">5.2</a>, <a href="#rfc.xref.Part4.8">5.2</a>, <a href="#rfc.xref.Part4.9">6.1</a>, <a href="#rfc.xref.Part4.10">6.1</a>, <a href="#rfc.xref.Part4.11">6.1</a>, <a href="#rfc.xref.Part4.12">6.3.2</a>, <a href="#rfc.xref.Part4.13">6.4</a>, <a href="#Part4"><b>12.1</b></a>, <a href="#rfc.xref.Part4.14">F.2</a><ul>5161 <li><em>Section 2.2</em> <a href="#rfc.xref.Part4. 2">3.2</a></li>5162 <li><em>Section 2.3</em> <a href="#rfc.xref.Part4.1 ">3.2</a>, <a href="#rfc.xref.Part4.12">6.3.2</a></li>5163 <li><em>Section 3.1</em> <a href="#rfc.xref.Part4. 5">5.2</a></li>5164 <li><em>Section 3.2</em> <a href="#rfc.xref.Part4. 6">5.2</a></li>5165 <li><em>Section 3.3</em> <a href="#rfc.xref.Part4. 7">5.2</a></li>5166 <li><em>Section 3.4</em> <a href="#rfc.xref.Part4. 8">5.2</a></li>5167 <li><em>Section 4</em> <a href="#rfc.xref.Part4. 9">6.1</a></li>5168 <li><em>Section 4.1</em> <a href="#rfc.xref.Part4. 10">6.1</a>, <a href="#rfc.xref.Part4.13">6.4</a></li>5169 <li><em>Section 4.2</em> <a href="#rfc.xref.Part4. 11">6.1</a></li>5145 <li><em>Part4</em> <a href="#rfc.xref.Part4.1">4.3.1</a>, <a href="#rfc.xref.Part4.2">5.2</a>, <a href="#rfc.xref.Part4.3">5.2</a>, <a href="#rfc.xref.Part4.4">5.2</a>, <a href="#rfc.xref.Part4.5">5.2</a>, <a href="#rfc.xref.Part4.6">5.2</a>, <a href="#rfc.xref.Part4.7">6.1</a>, <a href="#rfc.xref.Part4.8">6.1</a>, <a href="#rfc.xref.Part4.9">6.1</a>, <a href="#rfc.xref.Part4.10">6.3.2</a>, <a href="#rfc.xref.Part4.11">6.4</a>, <a href="#rfc.xref.Part4.12">7.2</a>, <a href="#rfc.xref.Part4.13">7.2</a>, <a href="#Part4"><b>12.1</b></a>, <a href="#rfc.xref.Part4.14">F.2</a><ul> 5146 <li><em>Section 2.2</em> <a href="#rfc.xref.Part4.13">7.2</a></li> 5147 <li><em>Section 2.3</em> <a href="#rfc.xref.Part4.10">6.3.2</a>, <a href="#rfc.xref.Part4.12">7.2</a></li> 5148 <li><em>Section 3.1</em> <a href="#rfc.xref.Part4.3">5.2</a></li> 5149 <li><em>Section 3.2</em> <a href="#rfc.xref.Part4.4">5.2</a></li> 5150 <li><em>Section 3.3</em> <a href="#rfc.xref.Part4.5">5.2</a></li> 5151 <li><em>Section 3.4</em> <a href="#rfc.xref.Part4.6">5.2</a></li> 5152 <li><em>Section 4</em> <a href="#rfc.xref.Part4.7">6.1</a></li> 5153 <li><em>Section 4.1</em> <a href="#rfc.xref.Part4.8">6.1</a>, <a href="#rfc.xref.Part4.11">6.4</a></li> 5154 <li><em>Section 4.2</em> <a href="#rfc.xref.Part4.9">6.1</a></li> 5170 5155 </ul> 5171 5156 </li> 5172 <li><em>Part5</em> <a href="#rfc.xref.Part5.1">3. 4.1</a>, <a href="#rfc.xref.Part5.2">4.3.1</a>, <a href="#rfc.xref.Part5.3">4.3.1</a>, <a href="#rfc.xref.Part5.4">4.3.4</a>, <a href="#rfc.xref.Part5.5">5.1</a>, <a href="#rfc.xref.Part5.6">5.2</a>, <a href="#rfc.xref.Part5.7">6.1</a>, <a href="#rfc.xref.Part5.8">6.1</a>, <a href="#rfc.xref.Part5.9">6.1</a>, <a href="#rfc.xref.Part5.10">7.4</a>, <a href="#Part5"><b>12.1</b></a><ul>5157 <li><em>Part5</em> <a href="#rfc.xref.Part5.1">3.3.1</a>, <a href="#rfc.xref.Part5.2">4.3.1</a>, <a href="#rfc.xref.Part5.3">4.3.1</a>, <a href="#rfc.xref.Part5.4">4.3.4</a>, <a href="#rfc.xref.Part5.5">5.1</a>, <a href="#rfc.xref.Part5.6">5.2</a>, <a href="#rfc.xref.Part5.7">6.1</a>, <a href="#rfc.xref.Part5.8">6.1</a>, <a href="#rfc.xref.Part5.9">6.1</a>, <a href="#rfc.xref.Part5.10">7.4</a>, <a href="#Part5"><b>12.1</b></a><ul> 5173 5158 <li><em>Section 3</em> <a href="#rfc.xref.Part5.7">6.1</a></li> 5174 5159 <li><em>Section 3.1</em> <a href="#rfc.xref.Part5.8">6.1</a></li> 5175 5160 <li><em>Section 3.2</em> <a href="#rfc.xref.Part5.9">6.1</a></li> 5176 5161 <li><em>Section 5.1</em> <a href="#rfc.xref.Part5.10">7.4</a></li> 5177 <li><em>Section 5.2</em> <a href="#rfc.xref.Part5.1">3. 4.1</a>, <a href="#rfc.xref.Part5.4">4.3.4</a></li>5162 <li><em>Section 5.2</em> <a href="#rfc.xref.Part5.1">3.3.1</a>, <a href="#rfc.xref.Part5.4">4.3.4</a></li> 5178 5163 <li><em>Section 5.3</em> <a href="#rfc.xref.Part5.6">5.2</a></li> 5179 5164 <li><em>Section 5.4</em> <a href="#rfc.xref.Part5.3">4.3.1</a>, <a href="#rfc.xref.Part5.5">5.1</a></li> 5180 5165 </ul> 5181 5166 </li> 5182 <li><em>Part6</em> <a href="#rfc.xref.Part6.1">3.1</a>, <a href="#rfc.xref.Part6.2">4.2.3</a>, <a href="#rfc.xref.Part6.3">4.3.1</a>, <a href="#rfc.xref.Part6.4">4.3.2</a>, <a href="#rfc.xref.Part6.5">4.3.3</a>, <a href="#rfc.xref.Part6.6">4.3.4</a>, <a href="#rfc.xref.Part6.7">4.3.5</a>, <a href="#rfc.xref.Part6.8">6.3.1</a>, <a href="#rfc.xref.Part6.9">6.3.4</a>, <a href="#rfc.xref.Part6.10">6.3.4</a>, <a href="#rfc.xref.Part6.11">6.3.4</a>, <a href="#rfc.xref.Part6.12">6.4.1</a>, <a href="#rfc.xref.Part6.13">6.4.2</a>, <a href="#rfc.xref.Part6.14">6.5.9</a>, <a href="#rfc.xref.Part6.15">7. 2</a>, <a href="#rfc.xref.Part6.16">7.2.2</a>, <a href="#rfc.xref.Part6.17">9.2.2</a>, <a href="#rfc.xref.Part6.18">9.3.1</a>, <a href="#Part6"><b>12.1</b></a><ul>5167 <li><em>Part6</em> <a href="#rfc.xref.Part6.1">3.1</a>, <a href="#rfc.xref.Part6.2">4.2.3</a>, <a href="#rfc.xref.Part6.3">4.3.1</a>, <a href="#rfc.xref.Part6.4">4.3.2</a>, <a href="#rfc.xref.Part6.5">4.3.3</a>, <a href="#rfc.xref.Part6.6">4.3.4</a>, <a href="#rfc.xref.Part6.7">4.3.5</a>, <a href="#rfc.xref.Part6.8">6.3.1</a>, <a href="#rfc.xref.Part6.9">6.3.4</a>, <a href="#rfc.xref.Part6.10">6.3.4</a>, <a href="#rfc.xref.Part6.11">6.3.4</a>, <a href="#rfc.xref.Part6.12">6.4.1</a>, <a href="#rfc.xref.Part6.13">6.4.2</a>, <a href="#rfc.xref.Part6.14">6.5.9</a>, <a href="#rfc.xref.Part6.15">7.1</a>, <a href="#rfc.xref.Part6.16">7.2.1</a>, <a href="#rfc.xref.Part6.17">9.2.2</a>, <a href="#rfc.xref.Part6.18">9.3.1</a>, <a href="#Part6"><b>12.1</b></a><ul> 5183 5168 <li><em>Section 4.1.1</em> <a href="#rfc.xref.Part6.5">4.3.3</a></li> 5184 5169 <li><em>Section 4.1.2</em> <a href="#rfc.xref.Part6.8">6.3.1</a>, <a href="#rfc.xref.Part6.11">6.3.4</a>, <a href="#rfc.xref.Part6.12">6.4.1</a>, <a href="#rfc.xref.Part6.13">6.4.2</a>, <a href="#rfc.xref.Part6.14">6.5.9</a></li> 5185 <li><em>Section 4.3</em> <a href="#rfc.xref.Part6.16">7.2. 2</a></li>5170 <li><em>Section 4.3</em> <a href="#rfc.xref.Part6.16">7.2.1</a></li> 5186 5171 <li><em>Section 5</em> <a href="#rfc.xref.Part6.4">4.3.2</a></li> 5187 5172 <li><em>Section 6</em> <a href="#rfc.xref.Part6.6">4.3.4</a>, <a href="#rfc.xref.Part6.7">4.3.5</a></li> 5188 <li><em>Section 7.1</em> <a href="#rfc.xref.Part6.15">7. 2</a></li>5173 <li><em>Section 7.1</em> <a href="#rfc.xref.Part6.15">7.1</a></li> 5189 5174 <li><em>Section 7.2</em> <a href="#rfc.xref.Part6.9">6.3.4</a></li> 5190 5175 <li><em>Section 7.3</em> <a href="#rfc.xref.Part6.1">3.1</a></li> … … 5202 5187 </ul> 5203 5188 </li> 5204 <li>payload <a href="#rfc.iref.p.1">3. 4</a></li>5205 <li>POST method <a href="#rfc.xref.POST.1">3. 4</a>, <a href="#rfc.xref.POST.2">4.1</a>, <a href="#rfc.iref.p.2"><b>4.3.3</b></a>, <a href="#rfc.xref.POST.3">9.1.3</a>, <a href="#rfc.xref.POST.4">C</a></li>5206 <li>PUT method <a href="#rfc.xref.PUT.1">3. 4</a>, <a href="#rfc.xref.PUT.2">4.1</a>, <a href="#rfc.iref.p.3"><b>4.3.4</b></a>, <a href="#rfc.xref.PUT.3">9.1.3</a>, <a href="#rfc.xref.PUT.4">C</a></li>5189 <li>payload <a href="#rfc.iref.p.1">3.3</a></li> 5190 <li>POST method <a href="#rfc.xref.POST.1">3.3</a>, <a href="#rfc.xref.POST.2">4.1</a>, <a href="#rfc.iref.p.2"><b>4.3.3</b></a>, <a href="#rfc.xref.POST.3">9.1.3</a>, <a href="#rfc.xref.POST.4">C</a></li> 5191 <li>PUT method <a href="#rfc.xref.PUT.1">3.3</a>, <a href="#rfc.xref.PUT.2">4.1</a>, <a href="#rfc.iref.p.3"><b>4.3.4</b></a>, <a href="#rfc.xref.PUT.3">9.1.3</a>, <a href="#rfc.xref.PUT.4">C</a></li> 5207 5192 </ul> 5208 5193 </li> … … 5211 5196 <li>representation <a href="#rfc.iref.r.1">3</a></li> 5212 5197 <li><em>REST</em> <a href="#rfc.xref.REST.1">3</a>, <a href="#rfc.xref.REST.2">4.1</a>, <a href="#REST"><b>12.2</b></a></li> 5213 <li>Retry-After header field <a href="#rfc.xref.header.retry-after.1">6.6.4</a>, <a href="#rfc.xref.header.retry-after.2">7.1</a>, <a href="#rfc.iref.r.3"><b>7.1. 2</b></a>, <a href="#rfc.xref.header.retry-after.3">9.3.2</a></li>5198 <li>Retry-After header field <a href="#rfc.xref.header.retry-after.1">6.6.4</a>, <a href="#rfc.xref.header.retry-after.2">7.1</a>, <a href="#rfc.iref.r.3"><b>7.1.3</b></a>, <a href="#rfc.xref.header.retry-after.3">9.3.2</a></li> 5214 5199 <li><em>RFC1123</em> <a href="#rfc.xref.RFC1123.1">8.1</a>, <a href="#rfc.xref.RFC1123.2">8.1</a>, <a href="#RFC1123"><b>12.2</b></a><ul> 5215 5200 <li><em>Section 5.2.14</em> <a href="#rfc.xref.RFC1123.2">8.1</a></li> … … 5224 5209 <li><em>RFC1952</em> <a href="#rfc.xref.RFC1952.1">9.4.2</a>, <a href="#RFC1952"><b>12.1</b></a></li> 5225 5210 <li><em>RFC2045</em> <a href="#RFC2045"><b>12.1</b></a>, <a href="#rfc.xref.RFC2045.1">A</a>, <a href="#rfc.xref.RFC2045.2">A.1</a></li> 5226 <li><em>RFC2046</em> <a href="#rfc.xref.RFC2046.1">3. 3</a>, <a href="#rfc.xref.RFC2046.2">8.5</a>, <a href="#rfc.xref.RFC2046.3">8.5.2</a>, <a href="#RFC2046"><b>12.1</b></a>, <a href="#rfc.xref.RFC2046.4">A.2</a><ul>5227 <li><em>Section 4.5.1</em> <a href="#rfc.xref.RFC2046.1">3. 3</a></li>5211 <li><em>RFC2046</em> <a href="#rfc.xref.RFC2046.1">3.2</a>, <a href="#rfc.xref.RFC2046.2">8.5</a>, <a href="#rfc.xref.RFC2046.3">8.5.2</a>, <a href="#RFC2046"><b>12.1</b></a>, <a href="#rfc.xref.RFC2046.4">A.2</a><ul> 5212 <li><em>Section 4.5.1</em> <a href="#rfc.xref.RFC2046.1">3.2</a></li> 5228 5213 <li><em>Section 5.1.1</em> <a href="#rfc.xref.RFC2046.3">8.5.2</a></li> 5229 5214 </ul> … … 5241 5226 <li><em>RFC2119</em> <a href="#rfc.xref.RFC2119.1">1.1</a>, <a href="#RFC2119"><b>12.1</b></a></li> 5242 5227 <li><em>RFC2277</em> <a href="#rfc.xref.RFC2277.1">8.3</a>, <a href="#RFC2277"><b>12.2</b></a></li> 5243 <li><em>RFC2295</em> <a href="#rfc.xref.RFC2295.1">3. 5</a>, <a href="#RFC2295"><b>12.2</b></a></li>5228 <li><em>RFC2295</em> <a href="#rfc.xref.RFC2295.1">3.4</a>, <a href="#RFC2295"><b>12.2</b></a></li> 5244 5229 <li><em>RFC2388</em> <a href="#rfc.xref.RFC2388.1">8.5.2</a>, <a href="#RFC2388"><b>12.2</b></a></li> 5245 5230 <li><em>RFC2557</em> <a href="#rfc.xref.RFC2557.1">3.1.4</a>, <a href="#RFC2557"><b>12.2</b></a>, <a href="#rfc.xref.RFC2557.2">A.6</a><ul> … … 5261 5246 </ul> 5262 5247 </li> 5263 <li><em>RFC3986</em> <a href="#rfc.xref.RFC3986.1">7.1. 1</a>, <a href="#rfc.xref.RFC3986.2">7.1.1</a>, <a href="#RFC3986"><b>12.1</b></a><ul>5264 <li><em>Section 4.2</em> <a href="#rfc.xref.RFC3986.1">7.1. 1</a></li>5265 <li><em>Section 5</em> <a href="#rfc.xref.RFC3986.2">7.1. 1</a></li>5248 <li><em>RFC3986</em> <a href="#rfc.xref.RFC3986.1">7.1.2</a>, <a href="#rfc.xref.RFC3986.2">7.1.2</a>, <a href="#RFC3986"><b>12.1</b></a><ul> 5249 <li><em>Section 4.2</em> <a href="#rfc.xref.RFC3986.1">7.1.2</a></li> 5250 <li><em>Section 5</em> <a href="#rfc.xref.RFC3986.2">7.1.2</a></li> 5266 5251 </ul> 5267 5252 </li> … … 5282 5267 </ul> 5283 5268 </li> 5284 <li><em>RFC5322</em> <a href="#rfc.xref.RFC5322.1">5.5.1</a>, <a href="#rfc.xref.RFC5322.2">5.5.1</a>, <a href="#rfc.xref.RFC5322.3">7. 2.1</a>, <a href="#rfc.xref.RFC5322.4">8.1</a>, <a href="#RFC5322"><b>12.2</b></a>, <a href="#rfc.xref.RFC5322.5">A</a><ul>5269 <li><em>RFC5322</em> <a href="#rfc.xref.RFC5322.1">5.5.1</a>, <a href="#rfc.xref.RFC5322.2">5.5.1</a>, <a href="#rfc.xref.RFC5322.3">7.1.1</a>, <a href="#rfc.xref.RFC5322.4">8.1</a>, <a href="#RFC5322"><b>12.2</b></a>, <a href="#rfc.xref.RFC5322.5">A</a><ul> 5285 5270 <li><em>Section 3.3</em> <a href="#rfc.xref.RFC5322.4">8.1</a></li> 5286 5271 <li><em>Section 3.4</em> <a href="#rfc.xref.RFC5322.1">5.5.1</a>, <a href="#rfc.xref.RFC5322.2">5.5.1</a></li> 5287 <li><em>Section 3.6.1</em> <a href="#rfc.xref.RFC5322.3">7. 2.1</a></li>5272 <li><em>Section 3.6.1</em> <a href="#rfc.xref.RFC5322.3">7.1.1</a></li> 5288 5273 </ul> 5289 5274 </li> … … 5299 5284 </li> 5300 5285 <li><a id="rfc.index.S" href="#rfc.index.S"><b>S</b></a><ul> 5301 <li>safe <a href="#rfc.iref.s. 2"><b>4.2.1</b></a></li>5302 <li>selected representation <a href="#rfc.iref.s. 1"><b>3.2</b></a></li>5286 <li>safe <a href="#rfc.iref.s.1"><b>4.2.1</b></a></li> 5287 <li>selected representation <a href="#rfc.iref.s.7"><b>7.2</b></a></li> 5303 5288 <li>Server header field <a href="#rfc.xref.header.server.1">7.4</a>, <a href="#rfc.iref.s.8"><b>7.4.2</b></a>, <a href="#rfc.xref.header.server.2">9.3.2</a>, <a href="#rfc.xref.header.server.3">10.1</a>, <a href="#rfc.xref.header.server.4">C</a></li> 5304 5289 <li>Status Codes Classes 5305 5290 <ul> 5306 <li>1xx Informational <a href="#rfc.iref.s. 3"><b>6.2</b></a></li>5307 <li>2xx Successful <a href="#rfc.iref.s. 4"><b>6.3</b></a></li>5308 <li>3xx Redirection <a href="#rfc.iref.s. 5"><b>6.4</b></a>, <a href="#rfc.xref.status.3xx.1">C</a></li>5309 <li>4xx Client Error <a href="#rfc.iref.s. 6"><b>6.5</b></a></li>5310 <li>5xx Server Error <a href="#rfc.iref.s. 7"><b>6.6</b></a></li>5291 <li>1xx Informational <a href="#rfc.iref.s.2"><b>6.2</b></a></li> 5292 <li>2xx Successful <a href="#rfc.iref.s.3"><b>6.3</b></a></li> 5293 <li>3xx Redirection <a href="#rfc.iref.s.4"><b>6.4</b></a>, <a href="#rfc.xref.status.3xx.1">C</a></li> 5294 <li>4xx Client Error <a href="#rfc.iref.s.5"><b>6.5</b></a></li> 5295 <li>5xx Server Error <a href="#rfc.iref.s.6"><b>6.6</b></a></li> 5311 5296 </ul> 5312 5297 </li> … … 5319 5304 </li> 5320 5305 <li><a id="rfc.index.U" href="#rfc.index.U"><b>U</b></a><ul> 5321 <li>User-Agent header field <a href="#rfc.xref.header.user-agent.1">3. 5.1</a>, <a href="#rfc.xref.header.user-agent.2">5.5</a>, <a href="#rfc.iref.u.1"><b>5.5.3</b></a>, <a href="#rfc.xref.header.user-agent.3">9.3.2</a>, <a href="#rfc.xref.header.user-agent.4">10.1</a></li>5306 <li>User-Agent header field <a href="#rfc.xref.header.user-agent.1">3.4.1</a>, <a href="#rfc.xref.header.user-agent.2">5.5</a>, <a href="#rfc.iref.u.1"><b>5.5.3</b></a>, <a href="#rfc.xref.header.user-agent.3">9.3.2</a>, <a href="#rfc.xref.header.user-agent.4">10.1</a></li> 5322 5307 </ul> 5323 5308 </li> 5324 5309 <li><a id="rfc.index.V" href="#rfc.index.V"><b>V</b></a><ul> 5325 <li>Vary header field <a href="#rfc.xref.header.vary.1">3. 5.1</a>, <a href="#rfc.xref.header.vary.2">7.2</a>, <a href="#rfc.iref.v.1"><b>7.2.2</b></a>, <a href="#rfc.xref.header.vary.3">9.3.2</a></li>5310 <li>Vary header field <a href="#rfc.xref.header.vary.1">3.4.1</a>, <a href="#rfc.xref.header.vary.2">7.2</a>, <a href="#rfc.iref.v.1"><b>7.2.1</b></a>, <a href="#rfc.xref.header.vary.3">9.3.2</a></li> 5326 5311 </ul> 5327 5312 </li> -
draft-ietf-httpbis/latest/p2-semantics.xml
r1918 r1920 529 529 </section> 530 530 531 <section title="Selected Representation Header Fields" anchor="selected.representation">532 <t><iref primary="true" item="selected representation"/>533 We use the term "<x:dfn>selected representation</x:dfn>" to refer to the534 the current representation of a target resource that would have been535 selected in a successful response if the same request had used the536 method GET and excluded any conditional request header fields.537 </t>538 <t>539 Additional header fields define metadata about the selected540 representation, which might differ from the representation included541 in the message for responses to some state-changing methods.542 The following header fields are defined as selected representation543 metadata:544 </t>545 <texttable align="left">546 <ttcol>Header Field Name</ttcol>547 <ttcol>Defined in...</ttcol>548 549 <c>ETag</c> <c>&header-etag;</c>550 <c>Last-Modified</c> <c>&header-last-modified;</c>551 </texttable>552 </section>553 554 531 <section title="Representation Data" anchor="representation.data"> 555 532 <x:anchor-alias value="representation-data"/> … … 3261 3238 <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol> 3262 3239 3240 <c>Age</c> <c>&header-age;</c> 3241 <c>Date</c> <c><xref target="header.date"/></c> 3263 3242 <c>Location</c> <c><xref target="header.location"/></c> 3264 3243 <c>Retry-After</c> <c><xref target="header.retry-after"/></c> 3265 3244 </texttable> 3245 3246 <section title="Date" anchor="header.date"> 3247 <iref primary="true" item="Date header field" x:for-anchor=""/> 3248 <x:anchor-alias value="Date"/> 3249 <t> 3250 The "Date" header field represents the date and time at which 3251 the message was originated, having the same semantics as the Origination 3252 Date Field (orig-date) defined in <xref target="RFC5322" x:fmt="of" x:sec="3.6.1"/>. 3253 The field value is an HTTP-date, as defined in <xref target="http.date"/>; 3254 it &MUST; be sent in rfc1123-date format. 3255 </t> 3256 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Date"/> 3257 <x:ref>Date</x:ref> = <x:ref>HTTP-date</x:ref> 3258 </artwork></figure> 3259 <t> 3260 An example is 3261 </t> 3262 <figure><artwork type="example"> 3263 Date: Tue, 15 Nov 1994 08:12:31 GMT 3264 </artwork></figure> 3265 <t> 3266 Origin servers &MUST; include a Date header field in all responses, 3267 except in these cases: 3268 <list style="numbers"> 3269 <t>If the response status code is <x:ref>100 (Continue)</x:ref> or 3270 <x:ref>101 (Switching Protocols)</x:ref>, the response &MAY; include a 3271 Date header field, at the server's option.</t> 3272 3273 <t>If the response status code conveys a server error, e.g., <x:ref>500 3274 (Internal Server Error)</x:ref> or <x:ref>503 (Service Unavailable)</x:ref>, 3275 and it is inconvenient or impossible to generate a valid Date.</t> 3276 3277 <t>If the server does not have a clock that can provide a 3278 reasonable approximation of the current time, its responses 3279 &MUST-NOT; include a Date header field.</t> 3280 </list> 3281 </t> 3282 <t> 3283 A received message that does not have a Date header field &MUST; be 3284 assigned one by the recipient if the message will be cached by that 3285 recipient. 3286 </t> 3287 <t> 3288 Clients can use the Date header field as well; in order to keep request 3289 messages small, they are advised not to include it when it doesn't convey 3290 any useful information (as is usually the case for requests that do not 3291 contain a payload). 3292 </t> 3293 <t> 3294 The HTTP-date sent in a Date header field &SHOULD-NOT; represent a date and 3295 time subsequent to the generation of the message. It &SHOULD; represent 3296 the best available approximation of the date and time of message 3297 generation, unless the implementation has no means of generating a 3298 reasonably accurate date and time. In theory, the date ought to 3299 represent the moment just before the payload is generated. In 3300 practice, the date can be generated at any time during the message 3301 origination without affecting its semantic value. 3302 </t> 3303 </section> 3266 3304 3267 3305 <section title="Location" anchor="header.location"> … … 3367 3405 </section> 3368 3406 3369 <section title="Cache-related" anchor="response.cache.related"> 3370 <t> 3371 Cache-related response header fields provide metadata about the message 3372 in order to assist downstream caches. 3407 <section title="Selected Representation Header Fields" anchor="selected.representation"> 3408 <t><iref primary="true" item="selected representation"/> 3409 We use the term "<x:dfn>selected representation</x:dfn>" to refer to the 3410 the current representation of a target resource that would have been 3411 selected in a successful response if the same request had used the 3412 method GET and excluded any conditional request header fields. 3413 </t> 3414 <t> 3415 Additional header fields define metadata about the selected 3416 representation, which might differ from the representation included 3417 in the message for responses to some state-changing methods. 3418 The following header fields are defined as selected representation 3419 metadata: 3373 3420 </t> 3374 3421 <texttable align="left"> 3375 <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol> 3376 3377 <c>Age</c> <c>&header-age;</c> 3378 <c>Date</c> <c><xref target="header.date"/></c> 3422 <ttcol>Header Field Name</ttcol> 3423 <ttcol>Defined in...</ttcol> 3424 3425 <c>ETag</c> <c>&header-etag;</c> 3426 <c>Last-Modified</c> <c>&header-last-modified;</c> 3379 3427 <c>Vary</c> <c><xref target="header.vary"/></c> 3380 3428 </texttable> 3381 3382 <section title="Date" anchor="header.date">3383 <iref primary="true" item="Date header field" x:for-anchor=""/>3384 <x:anchor-alias value="Date"/>3385 <t>3386 The "Date" header field represents the date and time at which3387 the message was originated, having the same semantics as the Origination3388 Date Field (orig-date) defined in <xref target="RFC5322" x:fmt="of" x:sec="3.6.1"/>.3389 The field value is an HTTP-date, as defined in <xref target="http.date"/>;3390 it &MUST; be sent in rfc1123-date format.3391 </t>3392 <figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Date"/>3393 <x:ref>Date</x:ref> = <x:ref>HTTP-date</x:ref>3394 </artwork></figure>3395 <t>3396 An example is3397 </t>3398 <figure><artwork type="example">3399 Date: Tue, 15 Nov 1994 08:12:31 GMT3400 </artwork></figure>3401 <t>3402 Origin servers &MUST; include a Date header field in all responses,3403 except in these cases:3404 <list style="numbers">3405 <t>If the response status code is <x:ref>100 (Continue)</x:ref> or3406 <x:ref>101 (Switching Protocols)</x:ref>, the response &MAY; include a3407 Date header field, at the server's option.</t>3408 3409 <t>If the response status code conveys a server error, e.g., <x:ref>5003410 (Internal Server Error)</x:ref> or <x:ref>503 (Service Unavailable)</x:ref>,3411 and it is inconvenient or impossible to generate a valid Date.</t>3412 3413 <t>If the server does not have a clock that can provide a3414 reasonable approximation of the current time, its responses3415 &MUST-NOT; include a Date header field.</t>3416 </list>3417 </t>3418 <t>3419 A received message that does not have a Date header field &MUST; be3420 assigned one by the recipient if the message will be cached by that3421 recipient.3422 </t>3423 <t>3424 Clients can use the Date header field as well; in order to keep request3425 messages small, they are advised not to include it when it doesn't convey3426 any useful information (as is usually the case for requests that do not3427 contain a payload).3428 </t>3429 <t>3430 The HTTP-date sent in a Date header field &SHOULD-NOT; represent a date and3431 time subsequent to the generation of the message. It &SHOULD; represent3432 the best available approximation of the date and time of message3433 generation, unless the implementation has no means of generating a3434 reasonably accurate date and time. In theory, the date ought to3435 represent the moment just before the payload is generated. In3436 practice, the date can be generated at any time during the message3437 origination without affecting its semantic value.3438 </t>3439 </section>3440 3429 3441 3430 <section anchor="header.vary" title="Vary">
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