source: draft-ietf-httpbis/diffs/draft-ietf-httpbis-p6-cache-17-from-16.diff.html @ 1697

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36<body > 
37  <table border="0" cellpadding="0" cellspacing="0"> 
38  <tr bgcolor="orange"><th></th><th>&nbsp;draft-ietf-httpbis-p6-cache-16.txt&nbsp;</th><th> </th><th>&nbsp;draft-ietf-httpbis-p6-cache-17.txt&nbsp;</th><th></th></tr> 
39      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
40      <tr><td class="lineno" valign="top"></td><td class="left">HTTPbis Working Group                                   R. Fielding, Ed.</td><td> </td><td class="right">HTTPbis Working Group                                   R. Fielding, Ed.</td><td class="lineno" valign="top"></td></tr>
41      <tr><td class="lineno" valign="top"></td><td class="left">Internet-Draft                                                     Adobe</td><td> </td><td class="right">Internet-Draft                                                     Adobe</td><td class="lineno" valign="top"></td></tr>
42      <tr><td class="lineno" valign="top"></td><td class="left">Obsoletes: 2616 (if approved)                                  J. Gettys</td><td> </td><td class="right">Obsoletes: 2616 (if approved)                                  J. Gettys</td><td class="lineno" valign="top"></td></tr>
43      <tr><td class="lineno" valign="top"></td><td class="left">Intended status: Standards Track                          Alcatel-Lucent</td><td> </td><td class="right">Intended status: Standards Track                          Alcatel-Lucent</td><td class="lineno" valign="top"></td></tr>
44      <tr><td><a name="diff0001" /></td></tr>
45      <tr><td class="lineno" valign="top"></td><td class="lblock">Expires: <span class="delete">February 25, 2012</span>                                      J. Mogul</td><td> </td><td class="rblock">Expires: <span class="insert">May 3, 2012      </span>                                      J. Mogul</td><td class="lineno" valign="top"></td></tr>
46      <tr><td class="lineno" valign="top"></td><td class="left">                                                                      HP</td><td> </td><td class="right">                                                                      HP</td><td class="lineno" valign="top"></td></tr>
47      <tr><td class="lineno" valign="top"></td><td class="left">                                                              H. Frystyk</td><td> </td><td class="right">                                                              H. Frystyk</td><td class="lineno" valign="top"></td></tr>
48      <tr><td class="lineno" valign="top"></td><td class="left">                                                               Microsoft</td><td> </td><td class="right">                                                               Microsoft</td><td class="lineno" valign="top"></td></tr>
49      <tr><td class="lineno" valign="top"></td><td class="left">                                                             L. Masinter</td><td> </td><td class="right">                                                             L. Masinter</td><td class="lineno" valign="top"></td></tr>
50      <tr><td class="lineno" valign="top"></td><td class="left">                                                                   Adobe</td><td> </td><td class="right">                                                                   Adobe</td><td class="lineno" valign="top"></td></tr>
51      <tr><td class="lineno" valign="top"></td><td class="left">                                                                P. Leach</td><td> </td><td class="right">                                                                P. Leach</td><td class="lineno" valign="top"></td></tr>
52      <tr><td class="lineno" valign="top"></td><td class="left">                                                               Microsoft</td><td> </td><td class="right">                                                               Microsoft</td><td class="lineno" valign="top"></td></tr>
53      <tr><td class="lineno" valign="top"></td><td class="left">                                                          T. Berners-Lee</td><td> </td><td class="right">                                                          T. Berners-Lee</td><td class="lineno" valign="top"></td></tr>
54      <tr><td class="lineno" valign="top"></td><td class="left">                                                                 W3C/MIT</td><td> </td><td class="right">                                                                 W3C/MIT</td><td class="lineno" valign="top"></td></tr>
55      <tr><td class="lineno" valign="top"></td><td class="left">                                                           Y. Lafon, Ed.</td><td> </td><td class="right">                                                           Y. Lafon, Ed.</td><td class="lineno" valign="top"></td></tr>
56      <tr><td class="lineno" valign="top"></td><td class="left">                                                                     W3C</td><td> </td><td class="right">                                                                     W3C</td><td class="lineno" valign="top"></td></tr>
57      <tr><td class="lineno" valign="top"></td><td class="left">                                                      M. Nottingham, Ed.</td><td> </td><td class="right">                                                      M. Nottingham, Ed.</td><td class="lineno" valign="top"></td></tr>
58      <tr><td><a name="diff0002" /></td></tr>
59      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                               <span class="delete">          </span></td><td> </td><td class="rblock">                                                               <span class="insert">Rackspace</span></td><td class="lineno" valign="top"></td></tr>
60      <tr><td class="lineno" valign="top"></td><td class="left">                                                         J. Reschke, Ed.</td><td> </td><td class="right">                                                         J. Reschke, Ed.</td><td class="lineno" valign="top"></td></tr>
61      <tr><td class="lineno" valign="top"></td><td class="left">                                                              greenbytes</td><td> </td><td class="right">                                                              greenbytes</td><td class="lineno" valign="top"></td></tr>
62      <tr><td><a name="diff0003" /></td></tr>
63      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                        <span class="delete"> August 24</span>, 2011</td><td> </td><td class="rblock">                                                        <span class="insert">October 31</span>, 2011</td><td class="lineno" valign="top"></td></tr>
64      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
65      <tr><td class="lineno" valign="top"></td><td class="left">                       HTTP/1.1, part 6: Caching</td><td> </td><td class="right">                       HTTP/1.1, part 6: Caching</td><td class="lineno" valign="top"></td></tr>
66      <tr><td><a name="diff0004" /></td></tr>
67      <tr><td class="lineno" valign="top"></td><td class="lblock">                     draft-ietf-httpbis-p6-cache-1<span class="delete">6</span></td><td> </td><td class="rblock">                     draft-ietf-httpbis-p6-cache-1<span class="insert">7</span></td><td class="lineno" valign="top"></td></tr>
68      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
69      <tr><td class="lineno" valign="top"></td><td class="left">Abstract</td><td> </td><td class="right">Abstract</td><td class="lineno" valign="top"></td></tr>
70      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
71      <tr><td class="lineno" valign="top"></td><td class="left">   The Hypertext Transfer Protocol (HTTP) is an application-level</td><td> </td><td class="right">   The Hypertext Transfer Protocol (HTTP) is an application-level</td><td class="lineno" valign="top"></td></tr>
72      <tr><td class="lineno" valign="top"></td><td class="left">   protocol for distributed, collaborative, hypertext information</td><td> </td><td class="right">   protocol for distributed, collaborative, hypertext information</td><td class="lineno" valign="top"></td></tr>
73      <tr><td class="lineno" valign="top"></td><td class="left">   systems.  HTTP has been in use by the World Wide Web global</td><td> </td><td class="right">   systems.  HTTP has been in use by the World Wide Web global</td><td class="lineno" valign="top"></td></tr>
74      <tr><td class="lineno" valign="top"></td><td class="left">   information initiative since 1990.  This document is Part 6 of the</td><td> </td><td class="right">   information initiative since 1990.  This document is Part 6 of the</td><td class="lineno" valign="top"></td></tr>
75      <tr><td class="lineno" valign="top"></td><td class="left">   seven-part specification that defines the protocol referred to as</td><td> </td><td class="right">   seven-part specification that defines the protocol referred to as</td><td class="lineno" valign="top"></td></tr>
76      <tr><td class="lineno" valign="top"></td><td class="left">   "HTTP/1.1" and, taken together, obsoletes RFC 2616.</td><td> </td><td class="right">   "HTTP/1.1" and, taken together, obsoletes RFC 2616.</td><td class="lineno" valign="top"></td></tr>
77      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
78      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
79      <tr bgcolor="gray" ><td></td><th><a name="part-l2" /><small>skipping to change at</small><em> page 2, line 6</em></th><th> </th><th><a name="part-r2" /><small>skipping to change at</small><em> page 2, line 6</em></th><td></td></tr>
80      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
81      <tr><td class="lineno" valign="top"></td><td class="left">   Discussion of this draft should take place on the HTTPBIS working</td><td> </td><td class="right">   Discussion of this draft should take place on the HTTPBIS working</td><td class="lineno" valign="top"></td></tr>
82      <tr><td class="lineno" valign="top"></td><td class="left">   group mailing list (ietf-http-wg@w3.org), which is archived at</td><td> </td><td class="right">   group mailing list (ietf-http-wg@w3.org), which is archived at</td><td class="lineno" valign="top"></td></tr>
83      <tr><td class="lineno" valign="top"></td><td class="left">   &lt;http://lists.w3.org/Archives/Public/ietf-http-wg/&gt;.</td><td> </td><td class="right">   &lt;http://lists.w3.org/Archives/Public/ietf-http-wg/&gt;.</td><td class="lineno" valign="top"></td></tr>
84      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
85      <tr><td class="lineno" valign="top"></td><td class="left">   The current issues list is at</td><td> </td><td class="right">   The current issues list is at</td><td class="lineno" valign="top"></td></tr>
86      <tr><td class="lineno" valign="top"></td><td class="left">   &lt;http://tools.ietf.org/wg/httpbis/trac/report/3&gt; and related</td><td> </td><td class="right">   &lt;http://tools.ietf.org/wg/httpbis/trac/report/3&gt; and related</td><td class="lineno" valign="top"></td></tr>
87      <tr><td class="lineno" valign="top"></td><td class="left">   documents (including fancy diffs) can be found at</td><td> </td><td class="right">   documents (including fancy diffs) can be found at</td><td class="lineno" valign="top"></td></tr>
88      <tr><td class="lineno" valign="top"></td><td class="left">   &lt;http://tools.ietf.org/wg/httpbis/&gt;.</td><td> </td><td class="right">   &lt;http://tools.ietf.org/wg/httpbis/&gt;.</td><td class="lineno" valign="top"></td></tr>
89      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
90      <tr><td><a name="diff0005" /></td></tr>
91      <tr><td class="lineno" valign="top"></td><td class="lblock">   The changes in this draft are summarized in Appendix C.1<span class="delete">7</span>.</td><td> </td><td class="rblock">   The changes in this draft are summarized in Appendix C.1<span class="insert">8</span>.</td><td class="lineno" valign="top"></td></tr>
92      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
93      <tr><td class="lineno" valign="top"></td><td class="left">Status of This Memo</td><td> </td><td class="right">Status of This Memo</td><td class="lineno" valign="top"></td></tr>
94      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
95      <tr><td class="lineno" valign="top"></td><td class="left">   This Internet-Draft is submitted in full conformance with the</td><td> </td><td class="right">   This Internet-Draft is submitted in full conformance with the</td><td class="lineno" valign="top"></td></tr>
96      <tr><td class="lineno" valign="top"></td><td class="left">   provisions of BCP 78 and BCP 79.</td><td> </td><td class="right">   provisions of BCP 78 and BCP 79.</td><td class="lineno" valign="top"></td></tr>
97      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
98      <tr><td class="lineno" valign="top"></td><td class="left">   Internet-Drafts are working documents of the Internet Engineering</td><td> </td><td class="right">   Internet-Drafts are working documents of the Internet Engineering</td><td class="lineno" valign="top"></td></tr>
99      <tr><td class="lineno" valign="top"></td><td class="left">   Task Force (IETF).  Note that other groups may also distribute</td><td> </td><td class="right">   Task Force (IETF).  Note that other groups may also distribute</td><td class="lineno" valign="top"></td></tr>
100      <tr><td class="lineno" valign="top"></td><td class="left">   working documents as Internet-Drafts.  The list of current Internet-</td><td> </td><td class="right">   working documents as Internet-Drafts.  The list of current Internet-</td><td class="lineno" valign="top"></td></tr>
101      <tr><td class="lineno" valign="top"></td><td class="left">   Drafts is at http://datatracker.ietf.org/drafts/current/.</td><td> </td><td class="right">   Drafts is at http://datatracker.ietf.org/drafts/current/.</td><td class="lineno" valign="top"></td></tr>
102      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
103      <tr><td class="lineno" valign="top"></td><td class="left">   Internet-Drafts are draft documents valid for a maximum of six months</td><td> </td><td class="right">   Internet-Drafts are draft documents valid for a maximum of six months</td><td class="lineno" valign="top"></td></tr>
104      <tr><td class="lineno" valign="top"></td><td class="left">   and may be updated, replaced, or obsoleted by other documents at any</td><td> </td><td class="right">   and may be updated, replaced, or obsoleted by other documents at any</td><td class="lineno" valign="top"></td></tr>
105      <tr><td class="lineno" valign="top"></td><td class="left">   time.  It is inappropriate to use Internet-Drafts as reference</td><td> </td><td class="right">   time.  It is inappropriate to use Internet-Drafts as reference</td><td class="lineno" valign="top"></td></tr>
106      <tr><td class="lineno" valign="top"></td><td class="left">   material or to cite them other than as "work in progress."</td><td> </td><td class="right">   material or to cite them other than as "work in progress."</td><td class="lineno" valign="top"></td></tr>
107      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
108      <tr><td><a name="diff0006" /></td></tr>
109      <tr><td class="lineno" valign="top"></td><td class="lblock">   This Internet-Draft will expire on <span class="delete">February 25</span>, 2012.</td><td> </td><td class="rblock">   This Internet-Draft will expire on <span class="insert">May 3</span>, 2012.</td><td class="lineno" valign="top"></td></tr>
110      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
111      <tr><td class="lineno" valign="top"></td><td class="left">Copyright Notice</td><td> </td><td class="right">Copyright Notice</td><td class="lineno" valign="top"></td></tr>
112      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
113      <tr><td class="lineno" valign="top"></td><td class="left">   Copyright (c) 2011 IETF Trust and the persons identified as the</td><td> </td><td class="right">   Copyright (c) 2011 IETF Trust and the persons identified as the</td><td class="lineno" valign="top"></td></tr>
114      <tr><td class="lineno" valign="top"></td><td class="left">   document authors.  All rights reserved.</td><td> </td><td class="right">   document authors.  All rights reserved.</td><td class="lineno" valign="top"></td></tr>
115      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
116      <tr><td class="lineno" valign="top"></td><td class="left">   This document is subject to BCP 78 and the IETF Trust's Legal</td><td> </td><td class="right">   This document is subject to BCP 78 and the IETF Trust's Legal</td><td class="lineno" valign="top"></td></tr>
117      <tr><td class="lineno" valign="top"></td><td class="left">   Provisions Relating to IETF Documents</td><td> </td><td class="right">   Provisions Relating to IETF Documents</td><td class="lineno" valign="top"></td></tr>
118      <tr><td class="lineno" valign="top"></td><td class="left">   (http://trustee.ietf.org/license-info) in effect on the date of</td><td> </td><td class="right">   (http://trustee.ietf.org/license-info) in effect on the date of</td><td class="lineno" valign="top"></td></tr>
119      <tr><td class="lineno" valign="top"></td><td class="left">   publication of this document.  Please review these documents</td><td> </td><td class="right">   publication of this document.  Please review these documents</td><td class="lineno" valign="top"></td></tr>
120      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
121      <tr bgcolor="gray" ><td></td><th><a name="part-l3" /><small>skipping to change at</small><em> page 3, line 10</em></th><th> </th><th><a name="part-r3" /><small>skipping to change at</small><em> page 3, line 10</em></th><td></td></tr>
122      <tr><td class="lineno" valign="top"></td><td class="left">   outside the IETF Standards Process, and derivative works of it may</td><td> </td><td class="right">   outside the IETF Standards Process, and derivative works of it may</td><td class="lineno" valign="top"></td></tr>
123      <tr><td class="lineno" valign="top"></td><td class="left">   not be created outside the IETF Standards Process, except to format</td><td> </td><td class="right">   not be created outside the IETF Standards Process, except to format</td><td class="lineno" valign="top"></td></tr>
124      <tr><td class="lineno" valign="top"></td><td class="left">   it for publication as an RFC or to translate it into languages other</td><td> </td><td class="right">   it for publication as an RFC or to translate it into languages other</td><td class="lineno" valign="top"></td></tr>
125      <tr><td class="lineno" valign="top"></td><td class="left">   than English.</td><td> </td><td class="right">   than English.</td><td class="lineno" valign="top"></td></tr>
126      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
127      <tr><td class="lineno" valign="top"></td><td class="left">Table of Contents</td><td> </td><td class="right">Table of Contents</td><td class="lineno" valign="top"></td></tr>
128      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
129      <tr><td class="lineno" valign="top"></td><td class="left">   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5</td><td> </td><td class="right">   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5</td><td class="lineno" valign="top"></td></tr>
130      <tr><td class="lineno" valign="top"></td><td class="left">     1.1.  Purpose  . . . . . . . . . . . . . . . . . . . . . . . . .  5</td><td> </td><td class="right">     1.1.  Purpose  . . . . . . . . . . . . . . . . . . . . . . . . .  5</td><td class="lineno" valign="top"></td></tr>
131      <tr><td class="lineno" valign="top"></td><td class="left">     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5</td><td> </td><td class="right">     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  5</td><td class="lineno" valign="top"></td></tr>
132      <tr><td><a name="diff0007" /></td></tr>
133      <tr><td class="lineno" valign="top"></td><td class="lblock">     1.3.  <span class="delete">Requirements . . . . . . . . .</span> . . . . . . . . . . . . . .  7</td><td> </td><td class="rblock">     1.3.  <span class="insert">Conformance and Error Handling</span> . . . . . . . . . . . . . .  7</td><td class="lineno" valign="top"></td></tr>
134      <tr><td class="lineno" valign="top"></td><td class="left">     1.4.  Syntax Notation  . . . . . . . . . . . . . . . . . . . . .  7</td><td> </td><td class="right">     1.4.  Syntax Notation  . . . . . . . . . . . . . . . . . . . . .  7</td><td class="lineno" valign="top"></td></tr>
135      <tr><td><a name="diff0008" /></td></tr>
136      <tr><td class="lineno" valign="top"></td><td class="lblock">       1.4.1.  Core Rules . . . . . . . . . . . . . . . . . . . . . .  <span class="delete">7</span></td><td> </td><td class="rblock">       1.4.1.  Core Rules . . . . . . . . . . . . . . . . . . . . . .  <span class="insert">8</span></td><td class="lineno" valign="top"></td></tr>
137      <tr><td class="lineno" valign="top"></td><td class="left">       1.4.2.  ABNF Rules defined in other Parts of the</td><td> </td><td class="right">       1.4.2.  ABNF Rules defined in other Parts of the</td><td class="lineno" valign="top"></td></tr>
138      <tr><td class="lineno" valign="top"></td><td class="left">               Specification  . . . . . . . . . . . . . . . . . . . .  8</td><td> </td><td class="right">               Specification  . . . . . . . . . . . . . . . . . . . .  8</td><td class="lineno" valign="top"></td></tr>
139      <tr><td class="lineno" valign="top"></td><td class="left">     1.5.  Delta Seconds  . . . . . . . . . . . . . . . . . . . . . .  8</td><td> </td><td class="right">     1.5.  Delta Seconds  . . . . . . . . . . . . . . . . . . . . . .  8</td><td class="lineno" valign="top"></td></tr>
140      <tr><td class="lineno" valign="top"></td><td class="left">   2.  Cache Operation  . . . . . . . . . . . . . . . . . . . . . . .  8</td><td> </td><td class="right">   2.  Cache Operation  . . . . . . . . . . . . . . . . . . . . . . .  8</td><td class="lineno" valign="top"></td></tr>
141      <tr><td class="lineno" valign="top"></td><td class="left">     2.1.  Response Cacheability  . . . . . . . . . . . . . . . . . .  9</td><td> </td><td class="right">     2.1.  Response Cacheability  . . . . . . . . . . . . . . . . . .  9</td><td class="lineno" valign="top"></td></tr>
142      <tr><td class="lineno" valign="top"></td><td class="left">     2.2.  Constructing Responses from Caches . . . . . . . . . . . . 10</td><td> </td><td class="right">     2.2.  Constructing Responses from Caches . . . . . . . . . . . . 10</td><td class="lineno" valign="top"></td></tr>
143      <tr><td class="lineno" valign="top"></td><td class="left">     2.3.  Freshness Model  . . . . . . . . . . . . . . . . . . . . . 11</td><td> </td><td class="right">     2.3.  Freshness Model  . . . . . . . . . . . . . . . . . . . . . 11</td><td class="lineno" valign="top"></td></tr>
144      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.1.  Calculating Freshness Lifetime . . . . . . . . . . . . 12</td><td> </td><td class="right">       2.3.1.  Calculating Freshness Lifetime . . . . . . . . . . . . 12</td><td class="lineno" valign="top"></td></tr>
145      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.2.  Calculating Age  . . . . . . . . . . . . . . . . . . . 13</td><td> </td><td class="right">       2.3.2.  Calculating Age  . . . . . . . . . . . . . . . . . . . 13</td><td class="lineno" valign="top"></td></tr>
146      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.3.  Serving Stale Responses  . . . . . . . . . . . . . . . 15</td><td> </td><td class="right">       2.3.3.  Serving Stale Responses  . . . . . . . . . . . . . . . 15</td><td class="lineno" valign="top"></td></tr>
147      <tr><td class="lineno" valign="top"></td><td class="left">     2.4.  Validation Model . . . . . . . . . . . . . . . . . . . . . 16</td><td> </td><td class="right">     2.4.  Validation Model . . . . . . . . . . . . . . . . . . . . . 16</td><td class="lineno" valign="top"></td></tr>
148      <tr><td><a name="diff0009" /></td></tr>
149      <tr><td class="lineno" valign="top"></td><td class="lblock">     2.5.  Request Methods that Invalidate  . . . . . . . . . . . . . <span class="delete">16</span></td><td> </td><td class="rblock">       <span class="insert">2.4.1.  Freshening Responses . . . . . . . . . . . . . . . . . 17</span></td><td class="lineno" valign="top"></td></tr>
150      <tr><td class="lineno" valign="top"></td><td class="lblock">     2.6.  Shared Caching of Authenticated Responses  . . . . . . . . <span class="delete">17</span></td><td> </td><td class="rblock">     2.5.  Request Methods that Invalidate  . . . . . . . . . . . . . <span class="insert">18</span></td><td class="lineno" valign="top"></td></tr>
151      <tr><td class="lineno" valign="top"></td><td class="lblock">     2.7.  Caching Negotiated Responses . . . . . . . . . . . . . . . <span class="delete">18</span></td><td> </td><td class="rblock">     2.6.  Shared Caching of Authenticated Responses  . . . . . . . . <span class="insert">18</span></td><td class="lineno" valign="top"></td></tr>
152      <tr><td class="lineno" valign="top"></td><td class="lblock">     2.8.  Combining Partial Content  . . . . . . . . . . . . . . . . <span class="delete">18</span></td><td> </td><td class="rblock">     2.7.  Caching Negotiated Responses . . . . . . . . . . . . . . . <span class="insert">19</span></td><td class="lineno" valign="top"></td></tr>
153      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">     2.9.  Freshening Responses . . . . . . . . . . . . . . . . . . . 19</span></td><td> </td><td class="rblock">     2.8.  Combining Partial Content  . . . . . . . . . . . . . . . . <span class="insert">20</span></td><td class="lineno" valign="top"></td></tr>
154      <tr><td class="lineno" valign="top"></td><td class="left">   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . . 20</td><td> </td><td class="right">   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . . 20</td><td class="lineno" valign="top"></td></tr>
155      <tr><td class="lineno" valign="top"></td><td class="left">     3.1.  Age  . . . . . . . . . . . . . . . . . . . . . . . . . . . 20</td><td> </td><td class="right">     3.1.  Age  . . . . . . . . . . . . . . . . . . . . . . . . . . . 20</td><td class="lineno" valign="top"></td></tr>
156      <tr><td><a name="diff0010" /></td></tr>
157      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.2.  Cache-Control  . . . . . . . . . . . . . . . . . . . . . . 2<span class="delete">0</span></td><td> </td><td class="rblock">     3.2.  Cache-Control  . . . . . . . . . . . . . . . . . . . . . . 2<span class="insert">1</span></td><td class="lineno" valign="top"></td></tr>
158      <tr><td class="lineno" valign="top"></td><td class="left">       3.2.1.  Request Cache-Control Directives . . . . . . . . . . . 21</td><td> </td><td class="right">       3.2.1.  Request Cache-Control Directives . . . . . . . . . . . 21</td><td class="lineno" valign="top"></td></tr>
159      <tr><td class="lineno" valign="top"></td><td class="left">       3.2.2.  Response Cache-Control Directives  . . . . . . . . . . 23</td><td> </td><td class="right">       3.2.2.  Response Cache-Control Directives  . . . . . . . . . . 23</td><td class="lineno" valign="top"></td></tr>
160      <tr><td><a name="diff0011" /></td></tr>
161      <tr><td class="lineno" valign="top"></td><td class="lblock">       3.2.3.  Cache Control Extensions . . . . . . . . . . . . . . . <span class="delete">25</span></td><td> </td><td class="rblock">       3.2.3.  Cache Control Extensions . . . . . . . . . . . . . . . <span class="insert">26</span></td><td class="lineno" valign="top"></td></tr>
162      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.3.  Expires  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">26</span></td><td> </td><td class="rblock">     3.3.  Expires  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">27</span></td><td class="lineno" valign="top"></td></tr>
163      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.4.  Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">27</span></td><td> </td><td class="rblock">     3.4.  Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">28</span></td><td class="lineno" valign="top"></td></tr>
164      <tr><td class="lineno" valign="top"></td><td class="left">     3.5.  Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 28</td><td> </td><td class="right">     3.5.  Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 28</td><td class="lineno" valign="top"></td></tr>
165      <tr><td class="lineno" valign="top"></td><td class="left">     3.6.  Warning  . . . . . . . . . . . . . . . . . . . . . . . . . 29</td><td> </td><td class="right">     3.6.  Warning  . . . . . . . . . . . . . . . . . . . . . . . . . 29</td><td class="lineno" valign="top"></td></tr>
166      <tr><td><a name="diff0012" /></td></tr>
167      <tr><td class="lineno" valign="top"></td><td class="lblock">   4.  History Lists  . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">31</span></td><td> </td><td class="rblock">   4.  History Lists  . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
168      <tr><td class="lineno" valign="top"></td><td class="lblock">   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . <span class="delete">31</span></td><td> </td><td class="rblock">   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
169      <tr><td class="lineno" valign="top"></td><td class="lblock">     5.1.  Cache Directive Registry . . . . . . . . . . . . . . . . . <span class="delete">31</span></td><td> </td><td class="rblock">     5.1.  Cache Directive Registry . . . . . . . . . . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
170      <tr><td class="lineno" valign="top"></td><td class="lblock">     5.2.  Header Field Registration  . . . . . . . . . . . . . . . . <span class="delete">32</span></td><td> </td><td class="rblock">     5.2.  Header Field Registration  . . . . . . . . . . . . . . . . <span class="insert">33</span></td><td class="lineno" valign="top"></td></tr>
171      <tr><td class="lineno" valign="top"></td><td class="lblock">   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . <span class="delete">32</span></td><td> </td><td class="rblock">   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . <span class="insert">33</span></td><td class="lineno" valign="top"></td></tr>
172      <tr><td class="lineno" valign="top"></td><td class="left">   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 33</td><td> </td><td class="right">   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 33</td><td class="lineno" valign="top"></td></tr>
173      <tr><td class="lineno" valign="top"></td><td class="left">   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 33</td><td> </td><td class="right">   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 33</td><td class="lineno" valign="top"></td></tr>
174      <tr><td class="lineno" valign="top"></td><td class="left">     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 33</td><td> </td><td class="right">     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 33</td><td class="lineno" valign="top"></td></tr>
175      <tr><td><a name="diff0013" /></td></tr>
176      <tr><td class="lineno" valign="top"></td><td class="lblock">     8.2.  Informative References . . . . . . . . . . . . . . . . . . <span class="delete">33</span></td><td> </td><td class="rblock">     8.2.  Informative References . . . . . . . . . . . . . . . . . . <span class="insert">34</span></td><td class="lineno" valign="top"></td></tr>
177      <tr><td class="lineno" valign="top"></td><td class="lblock">   Appendix A.  Changes from RFC 2616 . . . . . . . . . . . . . . . . <span class="delete">34</span></td><td> </td><td class="rblock">   Appendix A.  Changes from RFC 2616 . . . . . . . . . . . . . . . . <span class="insert">35</span></td><td class="lineno" valign="top"></td></tr>
178      <tr><td class="lineno" valign="top"></td><td class="lblock">   Appendix B.  Collected ABNF  . . . . . . . . . . . . . . . . . . . <span class="delete">34</span></td><td> </td><td class="rblock">   Appendix B.  Collected ABNF  . . . . . . . . . . . . . . . . . . . <span class="insert">35</span></td><td class="lineno" valign="top"></td></tr>
179      <tr><td class="lineno" valign="top"></td><td class="left">   Appendix C.  Change Log (to be removed by RFC Editor before</td><td> </td><td class="right">   Appendix C.  Change Log (to be removed by RFC Editor before</td><td class="lineno" valign="top"></td></tr>
180      <tr><td class="lineno" valign="top"></td><td class="left">                publication)  . . . . . . . . . . . . . . . . . . . . 36</td><td> </td><td class="right">                publication)  . . . . . . . . . . . . . . . . . . . . 36</td><td class="lineno" valign="top"></td></tr>
181      <tr><td class="lineno" valign="top"></td><td class="left">     C.1.  Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 36</td><td> </td><td class="right">     C.1.  Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 36</td><td class="lineno" valign="top"></td></tr>
182      <tr><td><a name="diff0014" /></td></tr>
183      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.2.  Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 3<span class="delete">6</span></td><td> </td><td class="rblock">     C.2.  Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 3<span class="insert">7</span></td><td class="lineno" valign="top"></td></tr>
184      <tr><td class="lineno" valign="top"></td><td class="left">     C.3.  Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 37</td><td> </td><td class="right">     C.3.  Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 37</td><td class="lineno" valign="top"></td></tr>
185      <tr><td><a name="diff0015" /></td></tr>
186      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.4.  Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . <span class="delete">37</span></td><td> </td><td class="rblock">     C.4.  Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . <span class="insert">38</span></td><td class="lineno" valign="top"></td></tr>
187      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.5.  Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . <span class="delete">37</span></td><td> </td><td class="rblock">     C.5.  Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . <span class="insert">38</span></td><td class="lineno" valign="top"></td></tr>
188      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.6.  Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . <span class="delete">37</span></td><td> </td><td class="rblock">     C.6.  Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . <span class="insert">38</span></td><td class="lineno" valign="top"></td></tr>
189      <tr><td class="lineno" valign="top"></td><td class="left">     C.7.  Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 38</td><td> </td><td class="right">     C.7.  Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 38</td><td class="lineno" valign="top"></td></tr>
190      <tr><td><a name="diff0016" /></td></tr>
191      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.8.  Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . <span class="delete">38</span></td><td> </td><td class="rblock">     C.8.  Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . <span class="insert">39</span></td><td class="lineno" valign="top"></td></tr>
192      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.9.  Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . <span class="delete">38</span></td><td> </td><td class="rblock">     C.9.  Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . <span class="insert">39</span></td><td class="lineno" valign="top"></td></tr>
193      <tr><td class="lineno" valign="top"></td><td class="left">     C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . 39</td><td> </td><td class="right">     C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . 39</td><td class="lineno" valign="top"></td></tr>
194      <tr><td><a name="diff0017" /></td></tr>
195      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.11. Since draft-ietf-httpbis-p6-cache-09 . . . . . . . . . . . <span class="delete">39</span></td><td> </td><td class="rblock">     C.11. Since draft-ietf-httpbis-p6-cache-09 . . . . . . . . . . . <span class="insert">40</span></td><td class="lineno" valign="top"></td></tr>
196      <tr><td class="lineno" valign="top"></td><td class="left">     C.12. Since draft-ietf-httpbis-p6-cache-10 . . . . . . . . . . . 40</td><td> </td><td class="right">     C.12. Since draft-ietf-httpbis-p6-cache-10 . . . . . . . . . . . 40</td><td class="lineno" valign="top"></td></tr>
197      <tr><td><a name="diff0018" /></td></tr>
198      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.13. Since draft-ietf-httpbis-p6-cache-11 . . . . . . . . . . . <span class="delete">40</span></td><td> </td><td class="rblock">     C.13. Since draft-ietf-httpbis-p6-cache-11 . . . . . . . . . . . <span class="insert">41</span></td><td class="lineno" valign="top"></td></tr>
199      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.14. Since draft-ietf-httpbis-p6-cache-12 . . . . . . . . . . . <span class="delete">40</span></td><td> </td><td class="rblock">     C.14. Since draft-ietf-httpbis-p6-cache-12 . . . . . . . . . . . <span class="insert">41</span></td><td class="lineno" valign="top"></td></tr>
200      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.15. Since draft-ietf-httpbis-p6-cache-13 . . . . . . . . . . . <span class="delete">40</span></td><td> </td><td class="rblock">     C.15. Since draft-ietf-httpbis-p6-cache-13 . . . . . . . . . . . <span class="insert">41</span></td><td class="lineno" valign="top"></td></tr>
201      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.16. Since draft-ietf-httpbis-p6-cache-14 . . . . . . . . . . . <span class="delete">40</span></td><td> </td><td class="rblock">     C.16. Since draft-ietf-httpbis-p6-cache-14 . . . . . . . . . . . <span class="insert">41</span></td><td class="lineno" valign="top"></td></tr>
202      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.17. Since draft-ietf-httpbis-p6-cache-15 . . . . . . . . . . . <span class="delete">41</span></td><td> </td><td class="rblock">     C.17. Since draft-ietf-httpbis-p6-cache-15 . . . . . . . . . . . <span class="insert">42</span></td><td class="lineno" valign="top"></td></tr>
203      <tr><td class="lineno" valign="top"></td><td class="lblock">   Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">41</span></td><td> </td><td class="rblock"><span class="insert">     C.18. Since draft-ietf-httpbis-p6-cache-16 . . . . . . . . . . . 42</span></td><td class="lineno" valign="top"></td></tr>
204      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">42</span></td><td class="lineno" valign="top"></td></tr>
205      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
206      <tr><td class="lineno" valign="top"></td><td class="left">1.  Introduction</td><td> </td><td class="right">1.  Introduction</td><td class="lineno" valign="top"></td></tr>
207      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
208      <tr><td class="lineno" valign="top"></td><td class="left">   HTTP is typically used for distributed information systems, where</td><td> </td><td class="right">   HTTP is typically used for distributed information systems, where</td><td class="lineno" valign="top"></td></tr>
209      <tr><td class="lineno" valign="top"></td><td class="left">   performance can be improved by the use of response caches.  This</td><td> </td><td class="right">   performance can be improved by the use of response caches.  This</td><td class="lineno" valign="top"></td></tr>
210      <tr><td class="lineno" valign="top"></td><td class="left">   document defines aspects of HTTP/1.1 related to caching and reusing</td><td> </td><td class="right">   document defines aspects of HTTP/1.1 related to caching and reusing</td><td class="lineno" valign="top"></td></tr>
211      <tr><td class="lineno" valign="top"></td><td class="left">   response messages.</td><td> </td><td class="right">   response messages.</td><td class="lineno" valign="top"></td></tr>
212      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
213      <tr><td class="lineno" valign="top"></td><td class="left">1.1.  Purpose</td><td> </td><td class="right">1.1.  Purpose</td><td class="lineno" valign="top"></td></tr>
214      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
215      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
216      <tr bgcolor="gray" ><td></td><th><a name="part-l4" /><small>skipping to change at</small><em> page 7, line 13</em></th><th> </th><th><a name="part-r4" /><small>skipping to change at</small><em> page 7, line 13</em></th><td></td></tr>
217      <tr><td class="lineno" valign="top"></td><td class="left">      equivalent copy of a representation.  See Section 2.1 of [Part4].</td><td> </td><td class="right">      equivalent copy of a representation.  See Section 2.1 of [Part4].</td><td class="lineno" valign="top"></td></tr>
218      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
219      <tr><td class="lineno" valign="top"></td><td class="left">   strong validator</td><td> </td><td class="right">   strong validator</td><td class="lineno" valign="top"></td></tr>
220      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
221      <tr><td class="lineno" valign="top"></td><td class="left">      A validator that is defined by the origin server such that its</td><td> </td><td class="right">      A validator that is defined by the origin server such that its</td><td class="lineno" valign="top"></td></tr>
222      <tr><td class="lineno" valign="top"></td><td class="left">      current value will change if the representation body changes;</td><td> </td><td class="right">      current value will change if the representation body changes;</td><td class="lineno" valign="top"></td></tr>
223      <tr><td class="lineno" valign="top"></td><td class="left">      i.e., an entity-tag that is not marked as weak (Section 2.3 of</td><td> </td><td class="right">      i.e., an entity-tag that is not marked as weak (Section 2.3 of</td><td class="lineno" valign="top"></td></tr>
224      <tr><td class="lineno" valign="top"></td><td class="left">      [Part4]) or, if no entity-tag is provided, a Last-Modified value</td><td> </td><td class="right">      [Part4]) or, if no entity-tag is provided, a Last-Modified value</td><td class="lineno" valign="top"></td></tr>
225      <tr><td class="lineno" valign="top"></td><td class="left">      that is strong in the sense defined by Section 2.2.2 of [Part4].</td><td> </td><td class="right">      that is strong in the sense defined by Section 2.2.2 of [Part4].</td><td class="lineno" valign="top"></td></tr>
226      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
227      <tr><td><a name="diff0019" /></td></tr>
228      <tr><td class="lineno" valign="top"></td><td class="lblock">1.3.  <span class="delete">Requirements</span></td><td> </td><td class="rblock">1.3.  <span class="insert">Conformance and Error Handling</span></td><td class="lineno" valign="top"></td></tr>
229      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
230      <tr><td class="lineno" valign="top"></td><td class="left">   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",</td><td> </td><td class="right">   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",</td><td class="lineno" valign="top"></td></tr>
231      <tr><td class="lineno" valign="top"></td><td class="left">   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this</td><td> </td><td class="right">   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this</td><td class="lineno" valign="top"></td></tr>
232      <tr><td class="lineno" valign="top"></td><td class="left">   document are to be interpreted as described in [RFC2119].</td><td> </td><td class="right">   document are to be interpreted as described in [RFC2119].</td><td class="lineno" valign="top"></td></tr>
233      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
234      <tr><td><a name="diff0020" /></td></tr>
235      <tr><td class="lineno" valign="top"></td><td class="lblock">   An implementation is <span class="delete">not compliant</span> if it <span class="delete">fails to satisfy one or more</span></td><td> </td><td class="rblock">   <span class="insert">This document defines conformance criteria for several roles in HTTP</span></td><td class="lineno" valign="top"></td></tr>
236      <tr><td class="lineno" valign="top"></td><td class="lblock">   of the <span class="delete">"MUST" or "REQUIRED" level</span> requirements <span class="delete">for the protocols it</span></td><td> </td><td class="rblock"><span class="insert">   communication, including Senders, Recipients, Clients, Servers, User-</span></td><td class="lineno" valign="top"></td></tr>
237      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   implements.  An implementation</span> that <span class="delete">satisfies all the "MUST" or</span></td><td> </td><td class="rblock"><span class="insert">   Agents, Origin Servers, Intermediaries, Proxies and Gateways.  See</span></td><td class="lineno" valign="top"></td></tr>
238      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   "REQUIRED" level and all the "SHOULD" level</span> requirements <span class="delete">for its</span></td><td> </td><td class="rblock"><span class="insert">   Section 2 of [Part1] for definitions of these terms.</span></td><td class="lineno" valign="top"></td></tr>
239      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   protocols</span> is <span class="delete">said</span> to <span class="delete">be "unconditionally compliant"; one that</span></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
240      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   satisfies all</span> the <span class="delete">"MUST" level</span> requirements <span class="delete">but</span> not <span class="delete">all</span> the <span class="delete">"SHOULD"</span></td><td> </td><td class="rblock">   An implementation is <span class="insert">considered conformant</span> if it <span class="insert">complies with all</span> of</td><td class="lineno" valign="top"></td></tr>
241      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   level requirements</span> for <span class="delete">its protocols is said</span> to <span class="delete">be "conditionally</span></td><td> </td><td class="rblock">   the requirements <span class="insert">associated with its role(s).  Note</span> that <span class="insert">SHOULD-level</span></td><td class="lineno" valign="top"></td></tr>
242      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   compliant".</span></td><td> </td><td class="rblock">   requirements <span class="insert">are relevant here, unless one of the documented</span></td><td class="lineno" valign="top"></td></tr>
243      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   exceptions</span> is <span class="insert">applicable.</span></td><td class="lineno" valign="top"></td></tr>
244      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
245      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   This document also uses ABNF to define valid protocol elements</span></td><td class="lineno" valign="top"></td></tr>
246      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   (Section 1.4).  In addition</span> to the <span class="insert">prose</span> requirements <span class="insert">placed upon</span></td><td class="lineno" valign="top"></td></tr>
247      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   them, Senders MUST NOT generate protocol elements that are invalid.</span></td><td class="lineno" valign="top"></td></tr>
248      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
249      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Unless noted otherwise, Recipients MAY take steps to recover a usable</span></td><td class="lineno" valign="top"></td></tr>
250      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   protocol element from an invalid construct.  However, HTTP does</span> not</td><td class="lineno" valign="top"></td></tr>
251      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   <span class="insert">define specific error handling mechanisms, except in cases where it</span></td><td class="lineno" valign="top"></td></tr>
252      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   has direct impact on security.  This is because different uses of</span> the</td><td class="lineno" valign="top"></td></tr>
253      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   <span class="insert">protocol require different error handling strategies;</span> for <span class="insert">example, a</span></td><td class="lineno" valign="top"></td></tr>
254      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Web browser may wish to transparently recover from a response where</span></td><td class="lineno" valign="top"></td></tr>
255      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   the Location header field doesn't parse according to the ABNF,</span></td><td class="lineno" valign="top"></td></tr>
256      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   whereby in a systems control protocol using HTTP, this type of error</span></td><td class="lineno" valign="top"></td></tr>
257      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   recovery could lead</span> to <span class="insert">dangerous consequences.</span></td><td class="lineno" valign="top"></td></tr>
258      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
259      <tr><td class="lineno" valign="top"></td><td class="left">1.4.  Syntax Notation</td><td> </td><td class="right">1.4.  Syntax Notation</td><td class="lineno" valign="top"></td></tr>
260      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
261      <tr><td class="lineno" valign="top"></td><td class="left">   This specification uses the ABNF syntax defined in Section 1.2 of</td><td> </td><td class="right">   This specification uses the ABNF syntax defined in Section 1.2 of</td><td class="lineno" valign="top"></td></tr>
262      <tr><td class="lineno" valign="top"></td><td class="left">   [Part1] (which extends the syntax defined in [RFC5234] with a list</td><td> </td><td class="right">   [Part1] (which extends the syntax defined in [RFC5234] with a list</td><td class="lineno" valign="top"></td></tr>
263      <tr><td class="lineno" valign="top"></td><td class="left">   rule).  Appendix B shows the collected ABNF, with the list rule</td><td> </td><td class="right">   rule).  Appendix B shows the collected ABNF, with the list rule</td><td class="lineno" valign="top"></td></tr>
264      <tr><td class="lineno" valign="top"></td><td class="left">   expanded.</td><td> </td><td class="right">   expanded.</td><td class="lineno" valign="top"></td></tr>
265      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
266      <tr><td class="lineno" valign="top"></td><td class="left">   The following core rules are included by reference, as defined in</td><td> </td><td class="right">   The following core rules are included by reference, as defined in</td><td class="lineno" valign="top"></td></tr>
267      <tr><td class="lineno" valign="top"></td><td class="left">   [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF</td><td> </td><td class="right">   [RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF</td><td class="lineno" valign="top"></td></tr>
268      <tr><td class="lineno" valign="top"></td><td class="left">   (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),</td><td> </td><td class="right">   (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),</td><td class="lineno" valign="top"></td></tr>
269      <tr><td class="lineno" valign="top"></td><td class="left">   HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit</td><td> </td><td class="right">   HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit</td><td class="lineno" valign="top"></td></tr>
270      <tr><td><a name="diff0021" /></td></tr>
271      <tr><td class="lineno" valign="top"></td><td class="lblock">   sequence of data), SP (space), VCHAR (any visible <span class="delete">USASCII character),</span></td><td> </td><td class="rblock">   sequence of data), SP (space), <span class="insert">and</span> VCHAR (any visible <span class="insert">US-ASCII</span></td><td class="lineno" valign="top"></td></tr>
272      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   and WSP (whitespace).</span></td><td> </td><td class="rblock"><span class="insert">   character).</span></td><td class="lineno" valign="top"></td></tr>
273      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
274      <tr><td class="lineno" valign="top"></td><td class="left">1.4.1.  Core Rules</td><td> </td><td class="right">1.4.1.  Core Rules</td><td class="lineno" valign="top"></td></tr>
275      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
276      <tr><td class="lineno" valign="top"></td><td class="left">   The core rules below are defined in [Part1]:</td><td> </td><td class="right">   The core rules below are defined in [Part1]:</td><td class="lineno" valign="top"></td></tr>
277      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
278      <tr><td class="lineno" valign="top"></td><td class="left">     OWS           = &lt;OWS, defined in [Part1], Section 1.2.2&gt;</td><td> </td><td class="right">     OWS           = &lt;OWS, defined in [Part1], Section 1.2.2&gt;</td><td class="lineno" valign="top"></td></tr>
279      <tr><td class="lineno" valign="top"></td><td class="left">     quoted-string = &lt;quoted-string, defined in [Part1], Section 3.2.3&gt;</td><td> </td><td class="right">     quoted-string = &lt;quoted-string, defined in [Part1], Section 3.2.3&gt;</td><td class="lineno" valign="top"></td></tr>
280      <tr><td class="lineno" valign="top"></td><td class="left">     token         = &lt;token, defined in [Part1], Section 3.2.3&gt;</td><td> </td><td class="right">     token         = &lt;token, defined in [Part1], Section 3.2.3&gt;</td><td class="lineno" valign="top"></td></tr>
281      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
282      <tr><td class="lineno" valign="top"></td><td class="left">1.4.2.  ABNF Rules defined in other Parts of the Specification</td><td> </td><td class="right">1.4.2.  ABNF Rules defined in other Parts of the Specification</td><td class="lineno" valign="top"></td></tr>
283      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
284      <tr><td class="lineno" valign="top"></td><td class="left">   The ABNF rules below are defined in other parts:</td><td> </td><td class="right">   The ABNF rules below are defined in other parts:</td><td class="lineno" valign="top"></td></tr>
285      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
286      <tr><td class="lineno" valign="top"></td><td class="left">     field-name    = &lt;field-name, defined in [Part1], Section 3.2&gt;</td><td> </td><td class="right">     field-name    = &lt;field-name, defined in [Part1], Section 3.2&gt;</td><td class="lineno" valign="top"></td></tr>
287      <tr><td><a name="diff0022" /></td></tr>
288      <tr><td class="lineno" valign="top"></td><td class="lblock">     HTTP-date     = &lt;HTTP-date, defined in [Part<span class="delete">1], Section 6.1</span>&gt;</td><td> </td><td class="rblock">     HTTP-date     = &lt;HTTP-date, defined in [Part<span class="insert">2], Section 8</span>&gt;</td><td class="lineno" valign="top"></td></tr>
289      <tr><td class="lineno" valign="top"></td><td class="left">     port          = &lt;port, defined in [Part1], Section 2.7&gt;</td><td> </td><td class="right">     port          = &lt;port, defined in [Part1], Section 2.7&gt;</td><td class="lineno" valign="top"></td></tr>
290      <tr><td><a name="diff0023" /></td></tr>
291      <tr><td class="lineno" valign="top"></td><td class="lblock">     pseudonym     = &lt;pseudonym, defined in [Part1], Section <span class="delete">9.9</span>&gt;</td><td> </td><td class="rblock">     pseudonym     = &lt;pseudonym, defined in [Part1], Section <span class="insert">8.8</span>&gt;</td><td class="lineno" valign="top"></td></tr>
292      <tr><td class="lineno" valign="top"></td><td class="left">     uri-host      = &lt;uri-host, defined in [Part1], Section 2.7&gt;</td><td> </td><td class="right">     uri-host      = &lt;uri-host, defined in [Part1], Section 2.7&gt;</td><td class="lineno" valign="top"></td></tr>
293      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
294      <tr><td class="lineno" valign="top"></td><td class="left">1.5.  Delta Seconds</td><td> </td><td class="right">1.5.  Delta Seconds</td><td class="lineno" valign="top"></td></tr>
295      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
296      <tr><td class="lineno" valign="top"></td><td class="left">   The delta-seconds rule specifies a non-negative integer, representing</td><td> </td><td class="right">   The delta-seconds rule specifies a non-negative integer, representing</td><td class="lineno" valign="top"></td></tr>
297      <tr><td class="lineno" valign="top"></td><td class="left">   time in seconds.</td><td> </td><td class="right">   time in seconds.</td><td class="lineno" valign="top"></td></tr>
298      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
299      <tr><td class="lineno" valign="top"></td><td class="left">     delta-seconds  = 1*DIGIT</td><td> </td><td class="right">     delta-seconds  = 1*DIGIT</td><td class="lineno" valign="top"></td></tr>
300      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
301      <tr><td class="lineno" valign="top"></td><td class="left">   If an implementation receives a delta-seconds value larger than the</td><td> </td><td class="right">   If an implementation receives a delta-seconds value larger than the</td><td class="lineno" valign="top"></td></tr>
302      <tr><td class="lineno" valign="top"></td><td class="left">   largest positive integer it can represent, or if any of its</td><td> </td><td class="right">   largest positive integer it can represent, or if any of its</td><td class="lineno" valign="top"></td></tr>
303      <tr><td class="lineno" valign="top"></td><td class="left">   subsequent calculations overflows, it MUST consider the value to be</td><td> </td><td class="right">   subsequent calculations overflows, it MUST consider the value to be</td><td class="lineno" valign="top"></td></tr>
304      <tr><td><a name="diff0024" /></td></tr>
305      <tr><td class="lineno" valign="top"></td><td class="lblock">   2147483648 (2^31).  Recipients parsing a delta-seconds value <span class="delete">SHOULD</span></td><td> </td><td class="rblock">   2147483648 (2^31).  Recipients parsing a delta-seconds value <span class="insert">MUST</span> use</td><td class="lineno" valign="top"></td></tr>
306      <tr><td class="lineno" valign="top"></td><td class="lblock">   use an arithmetic type of at least 31 bits of range, and senders MUST</td><td> </td><td class="rblock">   an arithmetic type of at least 31 bits of range, and senders MUST NOT</td><td class="lineno" valign="top"></td></tr>
307      <tr><td class="lineno" valign="top"></td><td class="lblock">   NOT send delta-seconds with a value greater than 2147483648.</td><td> </td><td class="rblock">   send delta-seconds with a value greater than 2147483648.</td><td class="lineno" valign="top"></td></tr>
308      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
309      <tr><td class="lineno" valign="top"></td><td class="left">2.  Cache Operation</td><td> </td><td class="right">2.  Cache Operation</td><td class="lineno" valign="top"></td></tr>
310      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
311      <tr><td class="lineno" valign="top"></td><td class="left">   Proper cache operation preserves the semantics of HTTP transfers</td><td> </td><td class="right">   Proper cache operation preserves the semantics of HTTP transfers</td><td class="lineno" valign="top"></td></tr>
312      <tr><td class="lineno" valign="top"></td><td class="left">   ([Part2]) while eliminating the transfer of information already held</td><td> </td><td class="right">   ([Part2]) while eliminating the transfer of information already held</td><td class="lineno" valign="top"></td></tr>
313      <tr><td class="lineno" valign="top"></td><td class="left">   in the cache.  Although caching is an entirely OPTIONAL feature of</td><td> </td><td class="right">   in the cache.  Although caching is an entirely OPTIONAL feature of</td><td class="lineno" valign="top"></td></tr>
314      <tr><td class="lineno" valign="top"></td><td class="left">   HTTP, we assume that reusing the cached response is desirable and</td><td> </td><td class="right">   HTTP, we assume that reusing the cached response is desirable and</td><td class="lineno" valign="top"></td></tr>
315      <tr><td class="lineno" valign="top"></td><td class="left">   that such reuse is the default behavior when no requirement or</td><td> </td><td class="right">   that such reuse is the default behavior when no requirement or</td><td class="lineno" valign="top"></td></tr>
316      <tr><td class="lineno" valign="top"></td><td class="left">   locally-desired configuration prevents it.  Therefore, HTTP cache</td><td> </td><td class="right">   locally-desired configuration prevents it.  Therefore, HTTP cache</td><td class="lineno" valign="top"></td></tr>
317      <tr><td class="lineno" valign="top"></td><td class="left">   requirements are focused on preventing a cache from either storing a</td><td> </td><td class="right">   requirements are focused on preventing a cache from either storing a</td><td class="lineno" valign="top"></td></tr>
318      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
319      <tr bgcolor="gray" ><td></td><th><a name="part-l5" /><small>skipping to change at</small><em> page 11, line 17</em></th><th> </th><th><a name="part-r5" /><small>skipping to change at</small><em> page 11, line 31</em></th><td></td></tr>
320      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
321      <tr><td class="lineno" valign="top"></td><td class="left">   Note that any of the requirements listed above can be overridden by a</td><td> </td><td class="right">   Note that any of the requirements listed above can be overridden by a</td><td class="lineno" valign="top"></td></tr>
322      <tr><td class="lineno" valign="top"></td><td class="left">   cache-control extension; see Section 3.2.3.</td><td> </td><td class="right">   cache-control extension; see Section 3.2.3.</td><td class="lineno" valign="top"></td></tr>
323      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
324      <tr><td class="lineno" valign="top"></td><td class="left">   When a stored response is used to satisfy a request without</td><td> </td><td class="right">   When a stored response is used to satisfy a request without</td><td class="lineno" valign="top"></td></tr>
325      <tr><td class="lineno" valign="top"></td><td class="left">   validation, a cache MUST include a single Age header field</td><td> </td><td class="right">   validation, a cache MUST include a single Age header field</td><td class="lineno" valign="top"></td></tr>
326      <tr><td class="lineno" valign="top"></td><td class="left">   (Section 3.1) in the response with a value equal to the stored</td><td> </td><td class="right">   (Section 3.1) in the response with a value equal to the stored</td><td class="lineno" valign="top"></td></tr>
327      <tr><td class="lineno" valign="top"></td><td class="left">   response's current_age; see Section 2.3.2.</td><td> </td><td class="right">   response's current_age; see Section 2.3.2.</td><td class="lineno" valign="top"></td></tr>
328      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
329      <tr><td class="lineno" valign="top"></td><td class="left">   A cache MUST write through requests with methods that are unsafe</td><td> </td><td class="right">   A cache MUST write through requests with methods that are unsafe</td><td class="lineno" valign="top"></td></tr>
330      <tr><td><a name="diff0025" /></td></tr>
331      <tr><td class="lineno" valign="top"></td><td class="lblock">   (Section <span class="delete">7</span>.1.1 of [Part2]) to the origin server; i.e., a cache must</td><td> </td><td class="rblock">   (Section <span class="insert">6</span>.1.1 of [Part2]) to the origin server; i.e., a cache must</td><td class="lineno" valign="top"></td></tr>
332      <tr><td class="lineno" valign="top"></td><td class="left">   not generate a reply to such a request before having forwarded the</td><td> </td><td class="right">   not generate a reply to such a request before having forwarded the</td><td class="lineno" valign="top"></td></tr>
333      <tr><td class="lineno" valign="top"></td><td class="left">   request and having received a corresponding response.</td><td> </td><td class="right">   request and having received a corresponding response.</td><td class="lineno" valign="top"></td></tr>
334      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
335      <tr><td class="lineno" valign="top"></td><td class="left">   Also, note that unsafe requests might invalidate already stored</td><td> </td><td class="right">   Also, note that unsafe requests might invalidate already stored</td><td class="lineno" valign="top"></td></tr>
336      <tr><td class="lineno" valign="top"></td><td class="left">   responses; see Section 2.5.</td><td> </td><td class="right">   responses; see Section 2.5.</td><td class="lineno" valign="top"></td></tr>
337      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
338      <tr><td class="lineno" valign="top"></td><td class="left">   When more than one suitable response is stored, a cache MUST use the</td><td> </td><td class="right">   When more than one suitable response is stored, a cache MUST use the</td><td class="lineno" valign="top"></td></tr>
339      <tr><td class="lineno" valign="top"></td><td class="left">   most recent response (as determined by the Date header field).  It</td><td> </td><td class="right">   most recent response (as determined by the Date header field).  It</td><td class="lineno" valign="top"></td></tr>
340      <tr><td class="lineno" valign="top"></td><td class="left">   can also forward a request with "Cache-Control: max-age=0" or "Cache-</td><td> </td><td class="right">   can also forward a request with "Cache-Control: max-age=0" or "Cache-</td><td class="lineno" valign="top"></td></tr>
341      <tr><td class="lineno" valign="top"></td><td class="left">   Control: no-cache" to disambiguate which response to use.</td><td> </td><td class="right">   Control: no-cache" to disambiguate which response to use.</td><td class="lineno" valign="top"></td></tr>
342      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
343      <tr bgcolor="gray" ><td></td><th><a name="part-l6" /><small>skipping to change at</small><em> page 13, line 9</em></th><th> </th><th><a name="part-r6" /><small>skipping to change at</small><em> page 13, line 22</em></th><td></td></tr>
344      <tr><td class="lineno" valign="top"></td><td class="left">      A heuristic freshness lifetime might be applicable; see</td><td> </td><td class="right">      A heuristic freshness lifetime might be applicable; see</td><td class="lineno" valign="top"></td></tr>
345      <tr><td class="lineno" valign="top"></td><td class="left">      Section 2.3.1.1.</td><td> </td><td class="right">      Section 2.3.1.1.</td><td class="lineno" valign="top"></td></tr>
346      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
347      <tr><td class="lineno" valign="top"></td><td class="left">   Note that this calculation is not vulnerable to clock skew, since all</td><td> </td><td class="right">   Note that this calculation is not vulnerable to clock skew, since all</td><td class="lineno" valign="top"></td></tr>
348      <tr><td class="lineno" valign="top"></td><td class="left">   of the information comes from the origin server.</td><td> </td><td class="right">   of the information comes from the origin server.</td><td class="lineno" valign="top"></td></tr>
349      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
350      <tr><td class="lineno" valign="top"></td><td class="left">2.3.1.1.  Calculating Heuristic Freshness</td><td> </td><td class="right">2.3.1.1.  Calculating Heuristic Freshness</td><td class="lineno" valign="top"></td></tr>
351      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
352      <tr><td class="lineno" valign="top"></td><td class="left">   If no explicit expiration time is present in a stored response that</td><td> </td><td class="right">   If no explicit expiration time is present in a stored response that</td><td class="lineno" valign="top"></td></tr>
353      <tr><td class="lineno" valign="top"></td><td class="left">   has a status code whose definition allows heuristic freshness to be</td><td> </td><td class="right">   has a status code whose definition allows heuristic freshness to be</td><td class="lineno" valign="top"></td></tr>
354      <tr><td><a name="diff0026" /></td></tr>
355      <tr><td class="lineno" valign="top"></td><td class="lblock">   used (including the following in Section <span class="delete">8</span> of [Part2]: 200, 203, 206,</td><td> </td><td class="rblock">   used (including the following in Section <span class="insert">7</span> of [Part2]: 200, 203, 206,</td><td class="lineno" valign="top"></td></tr>
356      <tr><td class="lineno" valign="top"></td><td class="left">   300, 301 and 410), a cache MAY calculate a heuristic expiration time.</td><td> </td><td class="right">   300, 301 and 410), a cache MAY calculate a heuristic expiration time.</td><td class="lineno" valign="top"></td></tr>
357      <tr><td class="lineno" valign="top"></td><td class="left">   A cache MUST NOT use heuristics to determine freshness for responses</td><td> </td><td class="right">   A cache MUST NOT use heuristics to determine freshness for responses</td><td class="lineno" valign="top"></td></tr>
358      <tr><td class="lineno" valign="top"></td><td class="left">   with status codes that do not explicitly allow it.</td><td> </td><td class="right">   with status codes that do not explicitly allow it.</td><td class="lineno" valign="top"></td></tr>
359      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
360      <tr><td class="lineno" valign="top"></td><td class="left">   When a heuristic is used to calculate freshness lifetime, a cache</td><td> </td><td class="right">   When a heuristic is used to calculate freshness lifetime, a cache</td><td class="lineno" valign="top"></td></tr>
361      <tr><td class="lineno" valign="top"></td><td class="left">   SHOULD attach a Warning header field with a 113 warn-code to the</td><td> </td><td class="right">   SHOULD attach a Warning header field with a 113 warn-code to the</td><td class="lineno" valign="top"></td></tr>
362      <tr><td class="lineno" valign="top"></td><td class="left">   response if its current_age is more than 24 hours and such a warning</td><td> </td><td class="right">   response if its current_age is more than 24 hours and such a warning</td><td class="lineno" valign="top"></td></tr>
363      <tr><td class="lineno" valign="top"></td><td class="left">   is not already present.</td><td> </td><td class="right">   is not already present.</td><td class="lineno" valign="top"></td></tr>
364      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
365      <tr><td class="lineno" valign="top"></td><td class="left">   Also, if the response has a Last-Modified header field (Section 2.2</td><td> </td><td class="right">   Also, if the response has a Last-Modified header field (Section 2.2</td><td class="lineno" valign="top"></td></tr>
366      <tr><td><a name="diff0027" /></td></tr>
367      <tr><td class="lineno" valign="top"></td><td class="lblock">   of [Part4]), <span class="delete">a cache SHOULD NOT</span> use a heuristic expiration value that</td><td> </td><td class="rblock">   of [Part4]), <span class="insert">caches are encouraged to</span> use a heuristic expiration</td><td class="lineno" valign="top"></td></tr>
368      <tr><td class="lineno" valign="top"></td><td class="lblock">   is more than some fraction of the interval since that time.  A</td><td> </td><td class="rblock">   value that is <span class="insert">no</span> more than some fraction of the interval since that</td><td class="lineno" valign="top"></td></tr>
369      <tr><td class="lineno" valign="top"></td><td class="lblock">   typical setting of this fraction might be 10%.</td><td> </td><td class="rblock">   time.  A typical setting of this fraction might be 10%.</td><td class="lineno" valign="top"></td></tr>
370      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
371      <tr><td class="lineno" valign="top"></td><td class="left">      Note: RFC 2616 ([RFC2616], Section 13.9) required that caches do</td><td> </td><td class="right">      Note: RFC 2616 ([RFC2616], Section 13.9) required that caches do</td><td class="lineno" valign="top"></td></tr>
372      <tr><td class="lineno" valign="top"></td><td class="left">      not calculate heuristic freshness for URIs with query components</td><td> </td><td class="right">      not calculate heuristic freshness for URIs with query components</td><td class="lineno" valign="top"></td></tr>
373      <tr><td class="lineno" valign="top"></td><td class="left">      (i.e., those containing '?').  In practice, this has not been</td><td> </td><td class="right">      (i.e., those containing '?').  In practice, this has not been</td><td class="lineno" valign="top"></td></tr>
374      <tr><td class="lineno" valign="top"></td><td class="left">      widely implemented.  Therefore, servers are encouraged to send</td><td> </td><td class="right">      widely implemented.  Therefore, servers are encouraged to send</td><td class="lineno" valign="top"></td></tr>
375      <tr><td class="lineno" valign="top"></td><td class="left">      explicit directives (e.g., Cache-Control: no-cache) if they wish</td><td> </td><td class="right">      explicit directives (e.g., Cache-Control: no-cache) if they wish</td><td class="lineno" valign="top"></td></tr>
376      <tr><td class="lineno" valign="top"></td><td class="left">      to preclude caching.</td><td> </td><td class="right">      to preclude caching.</td><td class="lineno" valign="top"></td></tr>
377      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
378      <tr><td class="lineno" valign="top"></td><td class="left">2.3.2.  Calculating Age</td><td> </td><td class="right">2.3.2.  Calculating Age</td><td class="lineno" valign="top"></td></tr>
379      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
380      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
381      <tr bgcolor="gray" ><td></td><th><a name="part-l7" /><small>skipping to change at</small><em> page 14, line 6</em></th><th> </th><th><a name="part-r7" /><small>skipping to change at</small><em> page 14, line 19</em></th><td></td></tr>
382      <tr><td class="lineno" valign="top"></td><td class="left">      The term "age_value" denotes the value of the Age header field</td><td> </td><td class="right">      The term "age_value" denotes the value of the Age header field</td><td class="lineno" valign="top"></td></tr>
383      <tr><td class="lineno" valign="top"></td><td class="left">      (Section 3.1), in a form appropriate for arithmetic operation; or</td><td> </td><td class="right">      (Section 3.1), in a form appropriate for arithmetic operation; or</td><td class="lineno" valign="top"></td></tr>
384      <tr><td class="lineno" valign="top"></td><td class="left">      0, if not available.</td><td> </td><td class="right">      0, if not available.</td><td class="lineno" valign="top"></td></tr>
385      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
386      <tr><td class="lineno" valign="top"></td><td class="left">   date_value</td><td> </td><td class="right">   date_value</td><td class="lineno" valign="top"></td></tr>
387      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
388      <tr><td class="lineno" valign="top"></td><td class="left">      HTTP/1.1 requires origin servers to send a Date header field, if</td><td> </td><td class="right">      HTTP/1.1 requires origin servers to send a Date header field, if</td><td class="lineno" valign="top"></td></tr>
389      <tr><td class="lineno" valign="top"></td><td class="left">      possible, with every response, giving the time at which the</td><td> </td><td class="right">      possible, with every response, giving the time at which the</td><td class="lineno" valign="top"></td></tr>
390      <tr><td class="lineno" valign="top"></td><td class="left">      response was generated.  The term "date_value" denotes the value</td><td> </td><td class="right">      response was generated.  The term "date_value" denotes the value</td><td class="lineno" valign="top"></td></tr>
391      <tr><td class="lineno" valign="top"></td><td class="left">      of the Date header field, in a form appropriate for arithmetic</td><td> </td><td class="right">      of the Date header field, in a form appropriate for arithmetic</td><td class="lineno" valign="top"></td></tr>
392      <tr><td><a name="diff0028" /></td></tr>
393      <tr><td class="lineno" valign="top"></td><td class="lblock">      operations.  See Section 9.<span class="delete">3 of [Part1</span>] for the definition of the</td><td> </td><td class="rblock">      operations.  See Section 9.<span class="insert">2 of [Part2</span>] for the definition of the</td><td class="lineno" valign="top"></td></tr>
394      <tr><td class="lineno" valign="top"></td><td class="left">      Date header field, and for requirements regarding responses</td><td> </td><td class="right">      Date header field, and for requirements regarding responses</td><td class="lineno" valign="top"></td></tr>
395      <tr><td class="lineno" valign="top"></td><td class="left">      without it.</td><td> </td><td class="right">      without it.</td><td class="lineno" valign="top"></td></tr>
396      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
397      <tr><td class="lineno" valign="top"></td><td class="left">   now</td><td> </td><td class="right">   now</td><td class="lineno" valign="top"></td></tr>
398      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
399      <tr><td class="lineno" valign="top"></td><td class="left">      The term "now" means "the current value of the clock at the host</td><td> </td><td class="right">      The term "now" means "the current value of the clock at the host</td><td class="lineno" valign="top"></td></tr>
400      <tr><td class="lineno" valign="top"></td><td class="left">      performing the calculation".  A cache SHOULD use NTP ([RFC1305])</td><td> </td><td class="right">      performing the calculation".  A cache SHOULD use NTP ([RFC1305])</td><td class="lineno" valign="top"></td></tr>
401      <tr><td class="lineno" valign="top"></td><td class="left">      or some similar protocol to synchronize its clocks to a globally</td><td> </td><td class="right">      or some similar protocol to synchronize its clocks to a globally</td><td class="lineno" valign="top"></td></tr>
402      <tr><td class="lineno" valign="top"></td><td class="left">      accurate time standard.</td><td> </td><td class="right">      accurate time standard.</td><td class="lineno" valign="top"></td></tr>
403      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
404      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
405      <tr bgcolor="gray" ><td></td><th><a name="part-l8" /><small>skipping to change at</small><em> page 15, line 8</em></th><th> </th><th><a name="part-r8" /><small>skipping to change at</small><em> page 15, line 21</em></th><td></td></tr>
406      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
407      <tr><td class="lineno" valign="top"></td><td class="left">     corrected_initial_age = max(apparent_age, corrected_age_value);</td><td> </td><td class="right">     corrected_initial_age = max(apparent_age, corrected_age_value);</td><td class="lineno" valign="top"></td></tr>
408      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
409      <tr><td class="lineno" valign="top"></td><td class="left">   The current_age of a stored response can then be calculated by adding</td><td> </td><td class="right">   The current_age of a stored response can then be calculated by adding</td><td class="lineno" valign="top"></td></tr>
410      <tr><td class="lineno" valign="top"></td><td class="left">   the amount of time (in seconds) since the stored response was last</td><td> </td><td class="right">   the amount of time (in seconds) since the stored response was last</td><td class="lineno" valign="top"></td></tr>
411      <tr><td class="lineno" valign="top"></td><td class="left">   validated by the origin server to the corrected_initial_age.</td><td> </td><td class="right">   validated by the origin server to the corrected_initial_age.</td><td class="lineno" valign="top"></td></tr>
412      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
413      <tr><td class="lineno" valign="top"></td><td class="left">     resident_time = now - response_time;</td><td> </td><td class="right">     resident_time = now - response_time;</td><td class="lineno" valign="top"></td></tr>
414      <tr><td class="lineno" valign="top"></td><td class="left">     current_age = corrected_initial_age + resident_time;</td><td> </td><td class="right">     current_age = corrected_initial_age + resident_time;</td><td class="lineno" valign="top"></td></tr>
415      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
416      <tr><td><a name="diff0029" /></td></tr>
417      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">Additional rules for requirements on parsing and encoding of dates</span></td><td> </td><td class="rblock">   <span class="insert">Additionally, to avoid common</span> problems <span class="insert">in</span> date <span class="insert">parsing:</span></td><td class="lineno" valign="top"></td></tr>
418      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   and other potential</span> problems <span class="delete">with</span> date <span class="delete">encodings include:</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
419      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
420      <tr><td class="lineno" valign="top"></td><td class="left">   o  HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date</td><td> </td><td class="right">   o  HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date</td><td class="lineno" valign="top"></td></tr>
421      <tr><td class="lineno" valign="top"></td><td class="left">      which appears to be more than 50 years in the future is in fact in</td><td> </td><td class="right">      which appears to be more than 50 years in the future is in fact in</td><td class="lineno" valign="top"></td></tr>
422      <tr><td class="lineno" valign="top"></td><td class="left">      the past (this helps solve the "year 2000" problem).</td><td> </td><td class="right">      the past (this helps solve the "year 2000" problem).</td><td class="lineno" valign="top"></td></tr>
423      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
424      <tr><td class="lineno" valign="top"></td><td class="left">   o  Although all date formats are specified to be case-sensitive,</td><td> </td><td class="right">   o  Although all date formats are specified to be case-sensitive,</td><td class="lineno" valign="top"></td></tr>
425      <tr><td class="lineno" valign="top"></td><td class="left">      recipients SHOULD match day, week and timezone names case-</td><td> </td><td class="right">      recipients SHOULD match day, week and timezone names case-</td><td class="lineno" valign="top"></td></tr>
426      <tr><td class="lineno" valign="top"></td><td class="left">      insensitively.</td><td> </td><td class="right">      insensitively.</td><td class="lineno" valign="top"></td></tr>
427      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
428      <tr><td class="lineno" valign="top"></td><td class="left">   o  An HTTP/1.1 implementation MAY internally represent a parsed</td><td> </td><td class="right">   o  An HTTP/1.1 implementation MAY internally represent a parsed</td><td class="lineno" valign="top"></td></tr>
429      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
430      <tr bgcolor="gray" ><td></td><th><a name="part-l9" /><small>skipping to change at</small><em> page 15, line 44</em></th><th> </th><th><a name="part-r9" /><small>skipping to change at</small><em> page 16, line 7</em></th><td></td></tr>
431      <tr><td class="lineno" valign="top"></td><td class="left">   A "stale" response is one that either has explicit expiry information</td><td> </td><td class="right">   A "stale" response is one that either has explicit expiry information</td><td class="lineno" valign="top"></td></tr>
432      <tr><td class="lineno" valign="top"></td><td class="left">   or is allowed to have heuristic expiry calculated, but is not fresh</td><td> </td><td class="right">   or is allowed to have heuristic expiry calculated, but is not fresh</td><td class="lineno" valign="top"></td></tr>
433      <tr><td class="lineno" valign="top"></td><td class="left">   according to the calculations in Section 2.3.</td><td> </td><td class="right">   according to the calculations in Section 2.3.</td><td class="lineno" valign="top"></td></tr>
434      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
435      <tr><td class="lineno" valign="top"></td><td class="left">   A cache MUST NOT return a stale response if it is prohibited by an</td><td> </td><td class="right">   A cache MUST NOT return a stale response if it is prohibited by an</td><td class="lineno" valign="top"></td></tr>
436      <tr><td class="lineno" valign="top"></td><td class="left">   explicit in-protocol directive (e.g., by a "no-store" or "no-cache"</td><td> </td><td class="right">   explicit in-protocol directive (e.g., by a "no-store" or "no-cache"</td><td class="lineno" valign="top"></td></tr>
437      <tr><td class="lineno" valign="top"></td><td class="left">   cache directive, a "must-revalidate" cache-response-directive, or an</td><td> </td><td class="right">   cache directive, a "must-revalidate" cache-response-directive, or an</td><td class="lineno" valign="top"></td></tr>
438      <tr><td class="lineno" valign="top"></td><td class="left">   applicable "s-maxage" or "proxy-revalidate" cache-response-directive;</td><td> </td><td class="right">   applicable "s-maxage" or "proxy-revalidate" cache-response-directive;</td><td class="lineno" valign="top"></td></tr>
439      <tr><td class="lineno" valign="top"></td><td class="left">   see Section 3.2.2).</td><td> </td><td class="right">   see Section 3.2.2).</td><td class="lineno" valign="top"></td></tr>
440      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
441      <tr><td><a name="diff0030" /></td></tr>
442      <tr><td class="lineno" valign="top"></td><td class="lblock">   A cache <span class="delete">SHOULD</span> NOT return stale responses unless it is disconnected</td><td> </td><td class="rblock">   A cache <span class="insert">MUST</span> NOT return stale responses unless it is disconnected</td><td class="lineno" valign="top"></td></tr>
443      <tr><td class="lineno" valign="top"></td><td class="left">   (i.e., it cannot contact the origin server or otherwise find a</td><td> </td><td class="right">   (i.e., it cannot contact the origin server or otherwise find a</td><td class="lineno" valign="top"></td></tr>
444      <tr><td class="lineno" valign="top"></td><td class="left">   forward path) or doing so is explicitly allowed (e.g., by the max-</td><td> </td><td class="right">   forward path) or doing so is explicitly allowed (e.g., by the max-</td><td class="lineno" valign="top"></td></tr>
445      <tr><td class="lineno" valign="top"></td><td class="left">   stale request directive; see Section 3.2.1).</td><td> </td><td class="right">   stale request directive; see Section 3.2.1).</td><td class="lineno" valign="top"></td></tr>
446      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
447      <tr><td class="lineno" valign="top"></td><td class="left">   A cache SHOULD append a Warning header field with the 110 warn-code</td><td> </td><td class="right">   A cache SHOULD append a Warning header field with the 110 warn-code</td><td class="lineno" valign="top"></td></tr>
448      <tr><td class="lineno" valign="top"></td><td class="left">   (see Section 3.6) to stale responses.  Likewise, a cache SHOULD add</td><td> </td><td class="right">   (see Section 3.6) to stale responses.  Likewise, a cache SHOULD add</td><td class="lineno" valign="top"></td></tr>
449      <tr><td class="lineno" valign="top"></td><td class="left">   the 112 warn-code to stale responses if the cache is disconnected.</td><td> </td><td class="right">   the 112 warn-code to stale responses if the cache is disconnected.</td><td class="lineno" valign="top"></td></tr>
450      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
451      <tr><td class="lineno" valign="top"></td><td class="left">   If a cache receives a first-hand response (either an entire response,</td><td> </td><td class="right">   If a cache receives a first-hand response (either an entire response,</td><td class="lineno" valign="top"></td></tr>
452      <tr><td class="lineno" valign="top"></td><td class="left">   or a 304 (Not Modified) response) that it would normally forward to</td><td> </td><td class="right">   or a 304 (Not Modified) response) that it would normally forward to</td><td class="lineno" valign="top"></td></tr>
453      <tr><td class="lineno" valign="top"></td><td class="left">   the requesting client, and the received response is no longer fresh,</td><td> </td><td class="right">   the requesting client, and the received response is no longer fresh,</td><td class="lineno" valign="top"></td></tr>
454      <tr><td><a name="diff0031" /></td></tr>
455      <tr><td class="lineno" valign="top"></td><td class="lblock">   the cache <span class="delete">SHOULD</span> forward it to the requesting client without adding a</td><td> </td><td class="rblock">   the cache <span class="insert">can</span> forward it to the requesting client without adding a</td><td class="lineno" valign="top"></td></tr>
456      <tr><td class="lineno" valign="top"></td><td class="left">   new Warning (but without removing any existing Warning header</td><td> </td><td class="right">   new Warning (but without removing any existing Warning header</td><td class="lineno" valign="top"></td></tr>
457      <tr><td><a name="diff0032" /></td></tr>
458      <tr><td class="lineno" valign="top"></td><td class="lblock">   fields).  A cache <span class="delete">SHOULD NOT</span> attempt to validate a response simply</td><td> </td><td class="rblock">   fields).  A cache <span class="insert">shouldn't</span> attempt to validate a response simply</td><td class="lineno" valign="top"></td></tr>
459      <tr><td class="lineno" valign="top"></td><td class="left">   because that response became stale in transit.</td><td> </td><td class="right">   because that response became stale in transit.</td><td class="lineno" valign="top"></td></tr>
460      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
461      <tr><td class="lineno" valign="top"></td><td class="left">2.4.  Validation Model</td><td> </td><td class="right">2.4.  Validation Model</td><td class="lineno" valign="top"></td></tr>
462      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
463      <tr><td class="lineno" valign="top"></td><td class="left">   When a cache has one or more stored responses for a requested URI,</td><td> </td><td class="right">   When a cache has one or more stored responses for a requested URI,</td><td class="lineno" valign="top"></td></tr>
464      <tr><td class="lineno" valign="top"></td><td class="left">   but cannot serve any of them (e.g., because they are not fresh, or</td><td> </td><td class="right">   but cannot serve any of them (e.g., because they are not fresh, or</td><td class="lineno" valign="top"></td></tr>
465      <tr><td class="lineno" valign="top"></td><td class="left">   one cannot be selected; see Section 2.7), it can use the conditional</td><td> </td><td class="right">   one cannot be selected; see Section 2.7), it can use the conditional</td><td class="lineno" valign="top"></td></tr>
466      <tr><td class="lineno" valign="top"></td><td class="left">   request mechanism [Part4] in the forwarded request to give the origin</td><td> </td><td class="right">   request mechanism [Part4] in the forwarded request to give the origin</td><td class="lineno" valign="top"></td></tr>
467      <tr><td class="lineno" valign="top"></td><td class="left">   server an opportunity to both select a valid stored response to be</td><td> </td><td class="right">   server an opportunity to both select a valid stored response to be</td><td class="lineno" valign="top"></td></tr>
468      <tr><td class="lineno" valign="top"></td><td class="left">   used, and to update it.  This process is known as "validating" or</td><td> </td><td class="right">   used, and to update it.  This process is known as "validating" or</td><td class="lineno" valign="top"></td></tr>
469      <tr><td class="lineno" valign="top"></td><td class="left">   "revalidating" the stored response.</td><td> </td><td class="right">   "revalidating" the stored response.</td><td class="lineno" valign="top"></td></tr>
470      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
471      <tr><td><a name="diff0033" /></td></tr>
472      <tr><td class="lineno" valign="top"></td><td class="lblock">   When sending such a conditional request, a cache <span class="delete">SHOULD add</span> an <span class="delete">If-</span></td><td> </td><td class="rblock">   When sending such a conditional request, a cache <span class="insert">adds</span> an <span class="insert">If-Modified-</span></td><td class="lineno" valign="top"></td></tr>
473      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   Modified-Since</span> header field whose value is that of the Last-Modified</td><td> </td><td class="rblock"><span class="insert">   Since</span> header field whose value is that of the Last-Modified header</td><td class="lineno" valign="top"></td></tr>
474      <tr><td class="lineno" valign="top"></td><td class="lblock">   header field from the selected (see Section 2.7) stored response, if</td><td> </td><td class="rblock">   field from the selected (see Section 2.7) stored response, if</td><td class="lineno" valign="top"></td></tr>
475      <tr><td class="lineno" valign="top"></td><td class="left">   available.</td><td> </td><td class="right">   available.</td><td class="lineno" valign="top"></td></tr>
476      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
477      <tr><td><a name="diff0034" /></td></tr>
478      <tr><td class="lineno" valign="top"></td><td class="lblock">   Additionally, a cache <span class="delete">SHOULD</span> add an If-None-Match header field whose</td><td> </td><td class="rblock">   Additionally, a cache <span class="insert">can</span> add an If-None-Match header field whose</td><td class="lineno" valign="top"></td></tr>
479      <tr><td class="lineno" valign="top"></td><td class="left">   value is that of the ETag header field(s) from all responses stored</td><td> </td><td class="right">   value is that of the ETag header field(s) from all responses stored</td><td class="lineno" valign="top"></td></tr>
480      <tr><td class="lineno" valign="top"></td><td class="left">   for the requested URI, if present.  However, if any of the stored</td><td> </td><td class="right">   for the requested URI, if present.  However, if any of the stored</td><td class="lineno" valign="top"></td></tr>
481      <tr><td><a name="diff0035" /></td></tr>
482      <tr><td class="lineno" valign="top"></td><td class="lblock">   responses contains only partial content, the cache <span class="delete">SHOULD NOT</span> include</td><td> </td><td class="rblock">   responses contains only partial content, the cache <span class="insert">shouldn't</span> include</td><td class="lineno" valign="top"></td></tr>
483      <tr><td class="lineno" valign="top"></td><td class="left">   its entity-tag in the If-None-Match header field unless the request</td><td> </td><td class="right">   its entity-tag in the If-None-Match header field unless the request</td><td class="lineno" valign="top"></td></tr>
484      <tr><td class="lineno" valign="top"></td><td class="left">   is for a range that would be fully satisfied by that stored response.</td><td> </td><td class="right">   is for a range that would be fully satisfied by that stored response.</td><td class="lineno" valign="top"></td></tr>
485      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
486      <tr><td><a name="diff0036" /></td></tr>
487      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">A 304 (Not Modified)</span> response status <span class="delete">code indicates that the stored</span></td><td> </td><td class="rblock">   <span class="insert">Cache handling of a</span> response <span class="insert">to a conditional request is dependent</span></td><td class="lineno" valign="top"></td></tr>
488      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   response can be updated and reused; see Section 2.9.</span></td><td> </td><td class="rblock"><span class="insert">   upon its</span> status <span class="insert">code:</span></td><td class="lineno" valign="top"></td></tr>
489      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
490      <tr><td><a name="diff0037" /></td></tr>
491      <tr><td class="lineno" valign="top"></td><td class="lblock">   A <span class="delete">full</span> response <span class="delete">(i.e., one with a response body)</span> indicates that <span class="delete">none</span></td><td> </td><td class="rblock">   <span class="insert">o</span>  A <span class="insert">304 (Not Modified)</span> response <span class="insert">status code</span> indicates that the</td><td class="lineno" valign="top"></td></tr>
492      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   of</span> the stored <span class="delete">responses nominated in the conditional request is</span></td><td> </td><td class="rblock">      stored response <span class="insert">can be updated</span> and <span class="insert">reused; see Section 2.4.1.</span></td><td class="lineno" valign="top"></td></tr>
493      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   suitable.  Instead, a cache SHOULD use the full</span> response <span class="delete">to satisfy</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
494      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   the request</span> and <span class="delete">MAY replace the stored response(s).</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
495      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
496      <tr><td><a name="diff0038" /></td></tr>
497      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">If</span> a cache receives a 5xx response while attempting to validate a</td><td> </td><td class="rblock">   <span class="insert">o  A full response (i.e., one with a response body) indicates that</span></td><td class="lineno" valign="top"></td></tr>
498      <tr><td class="lineno" valign="top"></td><td class="lblock">   response, it <span class="delete">MAY</span> either forward this response to the requesting</td><td> </td><td class="rblock"><span class="insert">      none of the stored responses nominated in the conditional request</span></td><td class="lineno" valign="top"></td></tr>
499      <tr><td class="lineno" valign="top"></td><td class="lblock">   client, or act as if the server failed to respond.  In the latter</td><td> </td><td class="rblock"><span class="insert">      is suitable.  Instead, the cache can use the full response to</span></td><td class="lineno" valign="top"></td></tr>
500      <tr><td class="lineno" valign="top"></td><td class="lblock">   case, it <span class="delete">MAY</span> return a previously stored response (see Section 2.3.3).</td><td> </td><td class="rblock"><span class="insert">      satisfy the request and MAY replace the stored response(s).</span></td><td class="lineno" valign="top"></td></tr>
501      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
502      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  However, if</span> a cache receives a 5xx response while attempting to</td><td class="lineno" valign="top"></td></tr>
503      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      validate a response, it <span class="insert">can</span> either forward this response to the</td><td class="lineno" valign="top"></td></tr>
504      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      requesting client, or act as if the server failed to respond.  In</td><td class="lineno" valign="top"></td></tr>
505      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      the latter case, it <span class="insert">can</span> return a previously stored response (see</td><td class="lineno" valign="top"></td></tr>
506      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      Section 2.3.3).</td><td class="lineno" valign="top"></td></tr>
507      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
508      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">2.4.1.  Freshening Responses</span></td><td class="lineno" valign="top"></td></tr>
509      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
510      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   When a cache receives a 304 (Not Modified) response and already has</span></td><td class="lineno" valign="top"></td></tr>
511      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   one or more stored 200 (OK) responses for the same cache key, the</span></td><td class="lineno" valign="top"></td></tr>
512      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   cache needs to identify which of the stored responses are updated by</span></td><td class="lineno" valign="top"></td></tr>
513      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   this new response and then update the stored response(s) with the new</span></td><td class="lineno" valign="top"></td></tr>
514      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   information provided in the 304 response.</span></td><td class="lineno" valign="top"></td></tr>
515      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
516      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  If the new response contains a strong validator, then that strong</span></td><td class="lineno" valign="top"></td></tr>
517      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      validator identifies the selected representation.  All of the</span></td><td class="lineno" valign="top"></td></tr>
518      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      stored responses with the same strong validator are selected.  If</span></td><td class="lineno" valign="top"></td></tr>
519      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      none of the stored responses contain the same strong validator,</span></td><td class="lineno" valign="top"></td></tr>
520      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      then this new response corresponds to a new selected</span></td><td class="lineno" valign="top"></td></tr>
521      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      representation and MUST NOT update the existing stored responses.</span></td><td class="lineno" valign="top"></td></tr>
522      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
523      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  If the new response contains a weak validator and that validator</span></td><td class="lineno" valign="top"></td></tr>
524      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      corresponds to one of the cache's stored responses, then the most</span></td><td class="lineno" valign="top"></td></tr>
525      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      recent of those matching stored responses is selected.</span></td><td class="lineno" valign="top"></td></tr>
526      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
527      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  If the new response does not include any form of validator, there</span></td><td class="lineno" valign="top"></td></tr>
528      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      is only one stored response, and that stored response also lacks a</span></td><td class="lineno" valign="top"></td></tr>
529      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      validator, then that stored response is selected.</span></td><td class="lineno" valign="top"></td></tr>
530      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
531      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   If a stored response is selected for update, the cache MUST:</span></td><td class="lineno" valign="top"></td></tr>
532      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
533      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  delete any Warning header fields in the stored response with warn-</span></td><td class="lineno" valign="top"></td></tr>
534      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      code 1xx (see Section 3.6);</span></td><td class="lineno" valign="top"></td></tr>
535      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
536      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  retain any Warning header fields in the stored response with warn-</span></td><td class="lineno" valign="top"></td></tr>
537      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      code 2xx; and,</span></td><td class="lineno" valign="top"></td></tr>
538      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert"></span></td><td class="lineno" valign="top"></td></tr>
539      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  use other header fields provided in the 304 response to replace</span></td><td class="lineno" valign="top"></td></tr>
540      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      all instances of the corresponding header fields in the stored</span></td><td class="lineno" valign="top"></td></tr>
541      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      response.</span></td><td class="lineno" valign="top"></td></tr>
542      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
543      <tr><td class="lineno" valign="top"></td><td class="left">2.5.  Request Methods that Invalidate</td><td> </td><td class="right">2.5.  Request Methods that Invalidate</td><td class="lineno" valign="top"></td></tr>
544      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
545      <tr><td><a name="diff0039" /></td></tr>
546      <tr><td class="lineno" valign="top"></td><td class="lblock">   Because unsafe request methods (Section <span class="delete">7</span>.1.1 of [Part2]) such as</td><td> </td><td class="rblock">   Because unsafe request methods (Section <span class="insert">6</span>.1.1 of [Part2]) such as</td><td class="lineno" valign="top"></td></tr>
547      <tr><td class="lineno" valign="top"></td><td class="left">   PUT, POST or DELETE have the potential for changing state on the</td><td> </td><td class="right">   PUT, POST or DELETE have the potential for changing state on the</td><td class="lineno" valign="top"></td></tr>
548      <tr><td class="lineno" valign="top"></td><td class="left">   origin server, intervening caches can use them to keep their contents</td><td> </td><td class="right">   origin server, intervening caches can use them to keep their contents</td><td class="lineno" valign="top"></td></tr>
549      <tr><td class="lineno" valign="top"></td><td class="left">   up-to-date.</td><td> </td><td class="right">   up-to-date.</td><td class="lineno" valign="top"></td></tr>
550      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
551      <tr><td class="lineno" valign="top"></td><td class="left">   A cache MUST invalidate the effective Request URI (Section 4.3 of</td><td> </td><td class="right">   A cache MUST invalidate the effective Request URI (Section 4.3 of</td><td class="lineno" valign="top"></td></tr>
552      <tr><td class="lineno" valign="top"></td><td class="left">   [Part1]) as well as the URI(s) in the Location and Content-Location</td><td> </td><td class="right">   [Part1]) as well as the URI(s) in the Location and Content-Location</td><td class="lineno" valign="top"></td></tr>
553      <tr><td class="lineno" valign="top"></td><td class="left">   header fields (if present) when a non-error response to a request</td><td> </td><td class="right">   header fields (if present) when a non-error response to a request</td><td class="lineno" valign="top"></td></tr>
554      <tr><td class="lineno" valign="top"></td><td class="left">   with an unsafe method is received.</td><td> </td><td class="right">   with an unsafe method is received.</td><td class="lineno" valign="top"></td></tr>
555      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
556      <tr><td class="lineno" valign="top"></td><td class="left">   However, a cache MUST NOT invalidate a URI from a Location or</td><td> </td><td class="right">   However, a cache MUST NOT invalidate a URI from a Location or</td><td class="lineno" valign="top"></td></tr>
557      <tr><td class="lineno" valign="top"></td><td class="left">   Content-Location header field if the host part of that URI differs</td><td> </td><td class="right">   Content-Location header field if the host part of that URI differs</td><td class="lineno" valign="top"></td></tr>
558      <tr><td class="lineno" valign="top"></td><td class="left">   from the host part in the effective request URI (Section 4.3 of</td><td> </td><td class="right">   from the host part in the effective request URI (Section 4.3 of</td><td class="lineno" valign="top"></td></tr>
559      <tr><td class="lineno" valign="top"></td><td class="left">   [Part1]).  This helps prevent denial of service attacks.</td><td> </td><td class="right">   [Part1]).  This helps prevent denial of service attacks.</td><td class="lineno" valign="top"></td></tr>
560      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
561      <tr><td><a name="diff0040" /></td></tr>
562      <tr><td class="lineno" valign="top"></td><td class="lblock">   A cache <span class="delete">SHOULD</span> invalidate the effective request URI (Section 4.3 of</td><td> </td><td class="rblock">   A cache <span class="insert">MUST</span> invalidate the effective request URI (Section 4.3 of</td><td class="lineno" valign="top"></td></tr>
563      <tr><td class="lineno" valign="top"></td><td class="left">   [Part1]) when it receives a non-error response to a request with a</td><td> </td><td class="right">   [Part1]) when it receives a non-error response to a request with a</td><td class="lineno" valign="top"></td></tr>
564      <tr><td class="lineno" valign="top"></td><td class="left">   method whose safety is unknown.</td><td> </td><td class="right">   method whose safety is unknown.</td><td class="lineno" valign="top"></td></tr>
565      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
566      <tr><td class="lineno" valign="top"></td><td class="left">   Here, a "non-error response" is one with a 2xx or 3xx status code.</td><td> </td><td class="right">   Here, a "non-error response" is one with a 2xx or 3xx status code.</td><td class="lineno" valign="top"></td></tr>
567      <tr><td class="lineno" valign="top"></td><td class="left">   "Invalidate" means that the cache will either remove all stored</td><td> </td><td class="right">   "Invalidate" means that the cache will either remove all stored</td><td class="lineno" valign="top"></td></tr>
568      <tr><td class="lineno" valign="top"></td><td class="left">   responses related to the effective request URI, or will mark these as</td><td> </td><td class="right">   responses related to the effective request URI, or will mark these as</td><td class="lineno" valign="top"></td></tr>
569      <tr><td class="lineno" valign="top"></td><td class="left">   "invalid" and in need of a mandatory validation before they can be</td><td> </td><td class="right">   "invalid" and in need of a mandatory validation before they can be</td><td class="lineno" valign="top"></td></tr>
570      <tr><td class="lineno" valign="top"></td><td class="left">   returned in response to a subsequent request.</td><td> </td><td class="right">   returned in response to a subsequent request.</td><td class="lineno" valign="top"></td></tr>
571      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
572      <tr><td class="lineno" valign="top"></td><td class="left">   Note that this does not guarantee that all appropriate responses are</td><td> </td><td class="right">   Note that this does not guarantee that all appropriate responses are</td><td class="lineno" valign="top"></td></tr>
573      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
574      <tr bgcolor="gray" ><td></td><th><a name="part-l10" /><small>skipping to change at</small><em> page 18, line 44</em></th><th> </th><th><a name="part-r10" /><small>skipping to change at</small><em> page 19, line 45</em></th><td></td></tr>
575      <tr><td class="lineno" valign="top"></td><td class="left">   subsequent requests to that resource can only be properly interpreted</td><td> </td><td class="right">   subsequent requests to that resource can only be properly interpreted</td><td class="lineno" valign="top"></td></tr>
576      <tr><td class="lineno" valign="top"></td><td class="left">   by the origin server.</td><td> </td><td class="right">   by the origin server.</td><td class="lineno" valign="top"></td></tr>
577      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
578      <tr><td class="lineno" valign="top"></td><td class="left">   The stored response with matching selecting header fields is known as</td><td> </td><td class="right">   The stored response with matching selecting header fields is known as</td><td class="lineno" valign="top"></td></tr>
579      <tr><td class="lineno" valign="top"></td><td class="left">   the selected response.</td><td> </td><td class="right">   the selected response.</td><td class="lineno" valign="top"></td></tr>
580      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
581      <tr><td class="lineno" valign="top"></td><td class="left">   If multiple selected responses are available, the most recent</td><td> </td><td class="right">   If multiple selected responses are available, the most recent</td><td class="lineno" valign="top"></td></tr>
582      <tr><td class="lineno" valign="top"></td><td class="left">   response (as determined by the Date header field) is used; see</td><td> </td><td class="right">   response (as determined by the Date header field) is used; see</td><td class="lineno" valign="top"></td></tr>
583      <tr><td class="lineno" valign="top"></td><td class="left">   Section 2.2.</td><td> </td><td class="right">   Section 2.2.</td><td class="lineno" valign="top"></td></tr>
584      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
585      <tr><td><a name="diff0041" /></td></tr>
586      <tr><td class="lineno" valign="top"></td><td class="lblock">   If no selected response is available, the cache <span class="delete">MAY</span> forward the</td><td> </td><td class="rblock">   If no selected response is available, the cache <span class="insert">can</span> forward the</td><td class="lineno" valign="top"></td></tr>
587      <tr><td class="lineno" valign="top"></td><td class="left">   presented request to the origin server in a conditional request; see</td><td> </td><td class="right">   presented request to the origin server in a conditional request; see</td><td class="lineno" valign="top"></td></tr>
588      <tr><td class="lineno" valign="top"></td><td class="left">   Section 2.4.</td><td> </td><td class="right">   Section 2.4.</td><td class="lineno" valign="top"></td></tr>
589      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
590      <tr><td class="lineno" valign="top"></td><td class="left">2.8.  Combining Partial Content</td><td> </td><td class="right">2.8.  Combining Partial Content</td><td class="lineno" valign="top"></td></tr>
591      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
592      <tr><td class="lineno" valign="top"></td><td class="left">   A response might transfer only a partial representation if the</td><td> </td><td class="right">   A response might transfer only a partial representation if the</td><td class="lineno" valign="top"></td></tr>
593      <tr><td class="lineno" valign="top"></td><td class="left">   connection closed prematurely or if the request used one or more</td><td> </td><td class="right">   connection closed prematurely or if the request used one or more</td><td class="lineno" valign="top"></td></tr>
594      <tr><td class="lineno" valign="top"></td><td class="left">   Range specifiers ([Part5]).  After several such transfers, a cache</td><td> </td><td class="right">   Range specifiers ([Part5]).  After several such transfers, a cache</td><td class="lineno" valign="top"></td></tr>
595      <tr><td class="lineno" valign="top"></td><td class="left">   might have received several ranges of the same representation.  A</td><td> </td><td class="right">   might have received several ranges of the same representation.  A</td><td class="lineno" valign="top"></td></tr>
596      <tr><td class="lineno" valign="top"></td><td class="left">   cache MAY combine these ranges into a single stored response, and</td><td> </td><td class="right">   cache MAY combine these ranges into a single stored response, and</td><td class="lineno" valign="top"></td></tr>
597      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
598      <tr bgcolor="gray" ><td></td><th><a name="part-l11" /><small>skipping to change at</small><em> page 19, line 23</em></th><th> </th><th><a name="part-r11" /><small>skipping to change at</small><em> page 20, line 29</em></th><td></td></tr>
599      <tr><td class="lineno" valign="top"></td><td class="left">   o  delete any Warning header fields in the stored response with warn-</td><td> </td><td class="right">   o  delete any Warning header fields in the stored response with warn-</td><td class="lineno" valign="top"></td></tr>
600      <tr><td class="lineno" valign="top"></td><td class="left">      code 1xx (see Section 3.6);</td><td> </td><td class="right">      code 1xx (see Section 3.6);</td><td class="lineno" valign="top"></td></tr>
601      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
602      <tr><td class="lineno" valign="top"></td><td class="left">   o  retain any Warning header fields in the stored response with warn-</td><td> </td><td class="right">   o  retain any Warning header fields in the stored response with warn-</td><td class="lineno" valign="top"></td></tr>
603      <tr><td class="lineno" valign="top"></td><td class="left">      code 2xx; and,</td><td> </td><td class="right">      code 2xx; and,</td><td class="lineno" valign="top"></td></tr>
604      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
605      <tr><td class="lineno" valign="top"></td><td class="left">   o  use other header fields provided in the new response, aside from</td><td> </td><td class="right">   o  use other header fields provided in the new response, aside from</td><td class="lineno" valign="top"></td></tr>
606      <tr><td class="lineno" valign="top"></td><td class="left">      Content-Range, to replace all instances of the corresponding</td><td> </td><td class="right">      Content-Range, to replace all instances of the corresponding</td><td class="lineno" valign="top"></td></tr>
607      <tr><td class="lineno" valign="top"></td><td class="left">      header fields in the stored response.</td><td> </td><td class="right">      header fields in the stored response.</td><td class="lineno" valign="top"></td></tr>
608      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
609      <tr><td><a name="diff0042" /></td></tr>
610      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">2.9.  Freshening Responses</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
611      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
612      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   When a cache receives a 304 (Not Modified) response and already has</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
613      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   one or more stored 200 (OK) responses for the same cache key, the</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
614      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   cache needs to identify which of the stored responses are updated by</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
615      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   this new response and then update the stored response(s) with the new</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
616      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   information provided in the 304 response.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
617      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
618      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  If the new response contains a strong validator, then that strong</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
619      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      validator identifies the selected representation.  All of the</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
620      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      stored responses with the same strong validator are selected.  If</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
621      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      none of the stored responses contain the same strong validator,</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
622      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      then this new response corresponds to a new selected</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
623      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      representation and MUST NOT update the existing stored responses.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
624      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
625      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  If the new response contains a weak validator and that validator</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
626      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      corresponds to one of the cache's stored responses, then the most</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
627      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      recent of those matching stored responses is selected.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
628      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
629      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  If the new response does not include any form of validator, there</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
630      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      is only one stored response, and that stored response also lacks a</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
631      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      validator, then that stored response is selected.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
632      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
633      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   If a stored response is selected for update, the cache MUST:</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
634      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
635      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  delete any Warning header fields in the stored response with warn-</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
636      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      code 1xx (see Section 3.6);</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
637      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
638      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  retain any Warning header fields in the stored response with warn-</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
639      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      code 2xx; and,</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
640      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete"></span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
641      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   o  use other header fields provided in the 304 response to replace</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
642      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      all instances of the corresponding header fields in the stored</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
643      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      response.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
644      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                                         </td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
645      <tr><td class="lineno" valign="top"></td><td class="left">3.  Header Field Definitions</td><td> </td><td class="right">3.  Header Field Definitions</td><td class="lineno" valign="top"></td></tr>
646      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
647      <tr><td class="lineno" valign="top"></td><td class="left">   This section defines the syntax and semantics of HTTP/1.1 header</td><td> </td><td class="right">   This section defines the syntax and semantics of HTTP/1.1 header</td><td class="lineno" valign="top"></td></tr>
648      <tr><td class="lineno" valign="top"></td><td class="left">   fields related to caching.</td><td> </td><td class="right">   fields related to caching.</td><td class="lineno" valign="top"></td></tr>
649      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
650      <tr><td class="lineno" valign="top"></td><td class="left">3.1.  Age</td><td> </td><td class="right">3.1.  Age</td><td class="lineno" valign="top"></td></tr>
651      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
652      <tr><td class="lineno" valign="top"></td><td class="left">   The "Age" header field conveys the sender's estimate of the amount of</td><td> </td><td class="right">   The "Age" header field conveys the sender's estimate of the amount of</td><td class="lineno" valign="top"></td></tr>
653      <tr><td class="lineno" valign="top"></td><td class="left">   time since the response was generated or successfully validated at</td><td> </td><td class="right">   time since the response was generated or successfully validated at</td><td class="lineno" valign="top"></td></tr>
654      <tr><td class="lineno" valign="top"></td><td class="left">   the origin server.  Age values are calculated as specified in</td><td> </td><td class="right">   the origin server.  Age values are calculated as specified in</td><td class="lineno" valign="top"></td></tr>
655      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
656      <tr bgcolor="gray" ><td></td><th><a name="part-l12" /><small>skipping to change at</small><em> page 21, line 5</em></th><th> </th><th><a name="part-r12" /><small>skipping to change at</small><em> page 21, line 25</em></th><td></td></tr>
657      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
658      <tr><td class="lineno" valign="top"></td><td class="left">      Note: HTTP/1.0 caches might not implement Cache-Control and might</td><td> </td><td class="right">      Note: HTTP/1.0 caches might not implement Cache-Control and might</td><td class="lineno" valign="top"></td></tr>
659      <tr><td class="lineno" valign="top"></td><td class="left">      only implement Pragma: no-cache (see Section 3.4).</td><td> </td><td class="right">      only implement Pragma: no-cache (see Section 3.4).</td><td class="lineno" valign="top"></td></tr>
660      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
661      <tr><td class="lineno" valign="top"></td><td class="left">   A proxy, whether or not it implements a cache, MUST pass cache</td><td> </td><td class="right">   A proxy, whether or not it implements a cache, MUST pass cache</td><td class="lineno" valign="top"></td></tr>
662      <tr><td class="lineno" valign="top"></td><td class="left">   directives through in forwarded messages, regardless of their</td><td> </td><td class="right">   directives through in forwarded messages, regardless of their</td><td class="lineno" valign="top"></td></tr>
663      <tr><td class="lineno" valign="top"></td><td class="left">   significance to that application, since the directives might be</td><td> </td><td class="right">   significance to that application, since the directives might be</td><td class="lineno" valign="top"></td></tr>
664      <tr><td class="lineno" valign="top"></td><td class="left">   applicable to all recipients along the request/response chain.  It is</td><td> </td><td class="right">   applicable to all recipients along the request/response chain.  It is</td><td class="lineno" valign="top"></td></tr>
665      <tr><td class="lineno" valign="top"></td><td class="left">   not possible to target a directive to a specific cache.</td><td> </td><td class="right">   not possible to target a directive to a specific cache.</td><td class="lineno" valign="top"></td></tr>
666      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
667      <tr><td><a name="diff0043" /></td></tr>
668      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   <span class="insert">Cache directives are identified by a token, to be compared case-</span></td><td class="lineno" valign="top"></td></tr>
669      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   insensitively, and have an optional argument.</span></td><td class="lineno" valign="top"></td></tr>
670      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
671      <tr><td class="lineno" valign="top"></td><td class="left">     Cache-Control   = 1#cache-directive</td><td> </td><td class="right">     Cache-Control   = 1#cache-directive</td><td class="lineno" valign="top"></td></tr>
672      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
673      <tr><td class="lineno" valign="top"></td><td class="left">     cache-directive = cache-request-directive</td><td> </td><td class="right">     cache-directive = cache-request-directive</td><td class="lineno" valign="top"></td></tr>
674      <tr><td class="lineno" valign="top"></td><td class="left">        / cache-response-directive</td><td> </td><td class="right">        / cache-response-directive</td><td class="lineno" valign="top"></td></tr>
675      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
676      <tr><td class="lineno" valign="top"></td><td class="left">     cache-extension = token [ "=" ( token / quoted-string ) ]</td><td> </td><td class="right">     cache-extension = token [ "=" ( token / quoted-string ) ]</td><td class="lineno" valign="top"></td></tr>
677      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
678      <tr><td class="lineno" valign="top"></td><td class="left">3.2.1.  Request Cache-Control Directives</td><td> </td><td class="right">3.2.1.  Request Cache-Control Directives</td><td class="lineno" valign="top"></td></tr>
679      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
680      <tr><td class="lineno" valign="top"></td><td class="left">     cache-request-directive =</td><td> </td><td class="right">     cache-request-directive =</td><td class="lineno" valign="top"></td></tr>
681      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
682      <tr bgcolor="gray" ><td></td><th><a name="part-l13" /><small>skipping to change at</small><em> page 24, line 48</em></th><th> </th><th><a name="part-r13" /><small>skipping to change at</small><em> page 25, line 18</em></th><td></td></tr>
683      <tr><td class="lineno" valign="top"></td><td class="left">      become stale, a cache MUST NOT use the response to satisfy</td><td> </td><td class="right">      become stale, a cache MUST NOT use the response to satisfy</td><td class="lineno" valign="top"></td></tr>
684      <tr><td class="lineno" valign="top"></td><td class="left">      subsequent requests without successful validation on the origin</td><td> </td><td class="right">      subsequent requests without successful validation on the origin</td><td class="lineno" valign="top"></td></tr>
685      <tr><td class="lineno" valign="top"></td><td class="left">      server.</td><td> </td><td class="right">      server.</td><td class="lineno" valign="top"></td></tr>
686      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
687      <tr><td class="lineno" valign="top"></td><td class="left">      The must-revalidate directive is necessary to support reliable</td><td> </td><td class="right">      The must-revalidate directive is necessary to support reliable</td><td class="lineno" valign="top"></td></tr>
688      <tr><td class="lineno" valign="top"></td><td class="left">      operation for certain protocol features.  In all circumstances a</td><td> </td><td class="right">      operation for certain protocol features.  In all circumstances a</td><td class="lineno" valign="top"></td></tr>
689      <tr><td class="lineno" valign="top"></td><td class="left">      cache MUST obey the must-revalidate directive; in particular, if a</td><td> </td><td class="right">      cache MUST obey the must-revalidate directive; in particular, if a</td><td class="lineno" valign="top"></td></tr>
690      <tr><td class="lineno" valign="top"></td><td class="left">      cache cannot reach the origin server for any reason, it MUST</td><td> </td><td class="right">      cache cannot reach the origin server for any reason, it MUST</td><td class="lineno" valign="top"></td></tr>
691      <tr><td class="lineno" valign="top"></td><td class="left">      generate a 504 (Gateway Timeout) response.</td><td> </td><td class="right">      generate a 504 (Gateway Timeout) response.</td><td class="lineno" valign="top"></td></tr>
692      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
693      <tr><td><a name="diff0044" /></td></tr>
694      <tr><td class="lineno" valign="top"></td><td class="lblock">      <span class="delete">A server SHOULD send the</span> must-revalidate directive if and only if</td><td> </td><td class="rblock">      <span class="insert">The</span> must-revalidate directive <span class="insert">ought to be used by servers</span> if and</td><td class="lineno" valign="top"></td></tr>
695      <tr><td class="lineno" valign="top"></td><td class="lblock">      failure to validate a request on the representation could result</td><td> </td><td class="rblock">      only if failure to validate a request on the representation could</td><td class="lineno" valign="top"></td></tr>
696      <tr><td class="lineno" valign="top"></td><td class="lblock">      in incorrect operation, such as a silently unexecuted financial</td><td> </td><td class="rblock">      result in incorrect operation, such as a silently unexecuted</td><td class="lineno" valign="top"></td></tr>
697      <tr><td class="lineno" valign="top"></td><td class="lblock">      transaction.</td><td> </td><td class="rblock">      financial transaction.</td><td class="lineno" valign="top"></td></tr>
698      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
699      <tr><td class="lineno" valign="top"></td><td class="left">   proxy-revalidate</td><td> </td><td class="right">   proxy-revalidate</td><td class="lineno" valign="top"></td></tr>
700      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
701      <tr><td class="lineno" valign="top"></td><td class="left">      The proxy-revalidate response directive has the same meaning as</td><td> </td><td class="right">      The proxy-revalidate response directive has the same meaning as</td><td class="lineno" valign="top"></td></tr>
702      <tr><td class="lineno" valign="top"></td><td class="left">      the must-revalidate response directive, except that it does not</td><td> </td><td class="right">      the must-revalidate response directive, except that it does not</td><td class="lineno" valign="top"></td></tr>
703      <tr><td class="lineno" valign="top"></td><td class="left">      apply to private caches.</td><td> </td><td class="right">      apply to private caches.</td><td class="lineno" valign="top"></td></tr>
704      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
705      <tr><td class="lineno" valign="top"></td><td class="left">   max-age</td><td> </td><td class="right">   max-age</td><td class="lineno" valign="top"></td></tr>
706      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
707      <tr><td class="lineno" valign="top"></td><td class="left">      The max-age response directive indicates that the response is to</td><td> </td><td class="right">      The max-age response directive indicates that the response is to</td><td class="lineno" valign="top"></td></tr>
708      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
709      <tr bgcolor="gray" ><td></td><th><a name="part-l14" /><small>skipping to change at</small><em> page 26, line 52</em></th><th> </th><th><a name="part-r14" /><small>skipping to change at</small><em> page 27, line 26</em></th><td></td></tr>
710      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
711      <tr><td class="lineno" valign="top"></td><td class="left">   The "Expires" header field gives the date/time after which the</td><td> </td><td class="right">   The "Expires" header field gives the date/time after which the</td><td class="lineno" valign="top"></td></tr>
712      <tr><td class="lineno" valign="top"></td><td class="left">   response is considered stale.  See Section 2.3 for further discussion</td><td> </td><td class="right">   response is considered stale.  See Section 2.3 for further discussion</td><td class="lineno" valign="top"></td></tr>
713      <tr><td class="lineno" valign="top"></td><td class="left">   of the freshness model.</td><td> </td><td class="right">   of the freshness model.</td><td class="lineno" valign="top"></td></tr>
714      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
715      <tr><td class="lineno" valign="top"></td><td class="left">   The presence of an Expires field does not imply that the original</td><td> </td><td class="right">   The presence of an Expires field does not imply that the original</td><td class="lineno" valign="top"></td></tr>
716      <tr><td class="lineno" valign="top"></td><td class="left">   resource will change or cease to exist at, before, or after that</td><td> </td><td class="right">   resource will change or cease to exist at, before, or after that</td><td class="lineno" valign="top"></td></tr>
717      <tr><td class="lineno" valign="top"></td><td class="left">   time.</td><td> </td><td class="right">   time.</td><td class="lineno" valign="top"></td></tr>
718      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
719      <tr><td class="lineno" valign="top"></td><td class="left">   The field-value is an absolute date and time as defined by HTTP-date</td><td> </td><td class="right">   The field-value is an absolute date and time as defined by HTTP-date</td><td class="lineno" valign="top"></td></tr>
720      <tr><td><a name="diff0045" /></td></tr>
721      <tr><td class="lineno" valign="top"></td><td class="lblock">   in Section <span class="delete">6.1 of [Part1</span>]; a sender MUST use the rfc1123-date format.</td><td> </td><td class="rblock">   in Section <span class="insert">8 of [Part2</span>]; a sender MUST use the rfc1123-date format.</td><td class="lineno" valign="top"></td></tr>
722      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
723      <tr><td class="lineno" valign="top"></td><td class="left">     Expires = HTTP-date</td><td> </td><td class="right">     Expires = HTTP-date</td><td class="lineno" valign="top"></td></tr>
724      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
725      <tr><td class="lineno" valign="top"></td><td class="left">   For example</td><td> </td><td class="right">   For example</td><td class="lineno" valign="top"></td></tr>
726      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
727      <tr><td class="lineno" valign="top"></td><td class="left">     Expires: Thu, 01 Dec 1994 16:00:00 GMT</td><td> </td><td class="right">     Expires: Thu, 01 Dec 1994 16:00:00 GMT</td><td class="lineno" valign="top"></td></tr>
728      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
729      <tr><td class="lineno" valign="top"></td><td class="left">   A cache MUST treat other invalid date formats, especially including</td><td> </td><td class="right">   A cache MUST treat other invalid date formats, especially including</td><td class="lineno" valign="top"></td></tr>
730      <tr><td class="lineno" valign="top"></td><td class="left">   the value "0", as in the past (i.e., "already expired").</td><td> </td><td class="right">   the value "0", as in the past (i.e., "already expired").</td><td class="lineno" valign="top"></td></tr>
731      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
732      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
733      <tr bgcolor="gray" ><td></td><th><a name="part-l15" /><small>skipping to change at</small><em> page 27, line 26</em></th><th> </th><th><a name="part-r15" /><small>skipping to change at</small><em> page 27, line 49</em></th><td></td></tr>
734      <tr><td class="lineno" valign="top"></td><td class="left">      Expires field.  Likewise, the s-maxage directive overrides Expires</td><td> &l