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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-09.txt&nbsp;</th><th> </th><th>&nbsp;draft-ietf-httpbis-p6-cache-10.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                                              Day Software</td><td> </td><td class="right">Internet-Draft                                              Day Software</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><a name="diff0001" /></td></tr>
44      <tr><td class="lineno" valign="top"></td><td class="lblock">Intended status: Standards Track                    <span class="delete">One Laptop per Child</span></td><td> </td><td class="rblock">Intended status: Standards Track                          <span class="insert">Alcatel-Lucent</span></td><td class="lineno" valign="top"></td></tr>
45      <tr><td class="lineno" valign="top"></td><td class="lblock">Expires: <span class="delete">September 9, 2010</span>                                      J. Mogul</td><td> </td><td class="rblock">Expires: <span class="insert">January 13, 2011</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 Systems</td><td> </td><td class="right">                                                           Adobe Systems</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 class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
59      <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>
60      <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>
61      <tr><td><a name="diff0002" /></td></tr>
62      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                           <span class="delete">March 8</span>, 2010</td><td> </td><td class="rblock">                                                           <span class="insert">July 12</span>, 2010</td><td class="lineno" valign="top"></td></tr>
63      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
64      <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>
65      <tr><td><a name="diff0003" /></td></tr>
66      <tr><td class="lineno" valign="top"></td><td class="lblock">                     draft-ietf-httpbis-p6-cache-<span class="delete">09</span></td><td> </td><td class="rblock">                     draft-ietf-httpbis-p6-cache-<span class="insert">10</span></td><td class="lineno" valign="top"></td></tr>
67      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
68      <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>
69      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
70      <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>
71      <tr><td class="lineno" valign="top"></td><td class="left">   protocol for distributed, collaborative, hypermedia information</td><td> </td><td class="right">   protocol for distributed, collaborative, hypermedia information</td><td class="lineno" valign="top"></td></tr>
72      <tr><td class="lineno" valign="top"></td><td class="left">   systems.  This document is Part 6 of the seven-part specification</td><td> </td><td class="right">   systems.  This document is Part 6 of the seven-part specification</td><td class="lineno" valign="top"></td></tr>
73      <tr><td class="lineno" valign="top"></td><td class="left">   that defines the protocol referred to as "HTTP/1.1" and, taken</td><td> </td><td class="right">   that defines the protocol referred to as "HTTP/1.1" and, taken</td><td class="lineno" valign="top"></td></tr>
74      <tr><td class="lineno" valign="top"></td><td class="left">   together, obsoletes RFC 2616.  Part 6 defines requirements on HTTP</td><td> </td><td class="right">   together, obsoletes RFC 2616.  Part 6 defines requirements on HTTP</td><td class="lineno" valign="top"></td></tr>
75      <tr><td class="lineno" valign="top"></td><td class="left">   caches and the associated header fields that control cache behavior</td><td> </td><td class="right">   caches and the associated header fields that control cache behavior</td><td class="lineno" valign="top"></td></tr>
76      <tr><td class="lineno" valign="top"></td><td class="left">   or indicate cacheable response messages.</td><td> </td><td class="right">   or indicate cacheable response messages.</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" valign="top"></td><td class="left">Editorial Note (To be removed by RFC Editor)</td><td> </td><td class="right">Editorial Note (To be removed by RFC Editor)</td><td class="lineno" valign="top"></td></tr>
79      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
80      <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>
81      <tr><td class="lineno" valign="top"></td><td class="left">   group mailing list (ietf-http-wg@w3.org).  The current issues list is</td><td> </td><td class="right">   group mailing list (ietf-http-wg@w3.org).  The current issues list is</td><td class="lineno" valign="top"></td></tr>
82      <tr><td class="lineno" valign="top"></td><td class="left">   at &lt;http://tools.ietf.org/wg/httpbis/trac/report/11&gt; and related</td><td> </td><td class="right">   at &lt;http://tools.ietf.org/wg/httpbis/trac/report/11&gt; and related</td><td class="lineno" valign="top"></td></tr>
83      <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>
84      <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>
85      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
86      <tr><td><a name="diff0004" /></td></tr>
87      <tr><td class="lineno" valign="top"></td><td class="lblock">   The changes in this draft are summarized in Appendix C.1<span class="delete">0</span>.</td><td> </td><td class="rblock">   The changes in this draft are summarized in Appendix C.1<span class="insert">1</span>.</td><td class="lineno" valign="top"></td></tr>
88      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
89      <tr><td><a name="diff0005" /></td></tr>
90      <tr><td class="lineno" valign="top"></td><td class="lblock">Status of <span class="delete">this</span> Memo</td><td> </td><td class="rblock">Status of <span class="insert">This</span> Memo</td><td class="lineno" valign="top"></td></tr>
91      <tr><td class="lineno" valign="top"></td><td class="lblock">   This Internet-Draft is submitted <span class="delete">to IETF</span> in full conformance with the</td><td> </td><td class="rblock">   This Internet-Draft is submitted in full conformance with the</td><td class="lineno" valign="top"></td></tr>
92      <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>
93      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
94      <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>
95      <tr><td><a name="diff0006" /></td></tr>
96      <tr><td class="lineno" valign="top"></td><td class="lblock">   Task Force <span class="delete">(IETF), its areas, and its working groups.</span>  Note that</td><td> </td><td class="rblock">   Task Force <span class="insert">(IETF).</span>  Note that other groups may also distribute</td><td class="lineno" valign="top"></td></tr>
97      <tr><td class="lineno" valign="top"></td><td class="lblock">   other groups may also distribute working documents as Internet-</td><td> </td><td class="rblock">   working documents as <span class="insert">Internet-Drafts.  The list of current</span> Internet-</td><td class="lineno" valign="top"></td></tr>
98      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">Drafts.</span></td><td> </td><td class="rblock">   <span class="insert">Drafts is at http://datatracker.ietf.org/drafts/current/.</span></td><td class="lineno" valign="top"></td></tr>
99      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
100      <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>
101      <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>
102      <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>
103      <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>
104      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
105      <tr><td><a name="diff0007" /></td></tr>
106      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">The list of current Internet-Drafts can be accessed at</span></td><td> </td><td class="rblock">   This Internet-Draft will expire on <span class="insert">January 13, 2011.</span></td><td class="lineno" valign="top"></td></tr>
107      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   http://www.ietf.org/ietf/1id-abstracts.txt.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
108      <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>
109      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   The list of Internet-Draft Shadow Directories can be accessed at</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
110      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   http://www.ietf.org/shadow.html.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
111      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                                         </td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
112      <tr><td class="lineno" valign="top"></td><td class="lblock">   This Internet-Draft will expire on <span class="delete">September 9, 2010.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
113      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
114      <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>
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>
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119      <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>
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121      <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>
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124      <tr><td class="lineno" valign="top"></td><td class="left">   to this document.  Code Components extracted from this document must</td><td> </td><td class="right">   to this document.  Code Components extracted from this document must</td><td class="lineno" valign="top"></td></tr>
125      <tr><td class="lineno" valign="top"></td><td class="left">   include Simplified BSD License text as described in Section 4.e of</td><td> </td><td class="right">   include Simplified BSD License text as described in Section 4.e of</td><td class="lineno" valign="top"></td></tr>
126      <tr><td class="lineno" valign="top"></td><td class="left">   the Trust Legal Provisions and are provided without warranty as</td><td> </td><td class="right">   the Trust Legal Provisions and are provided without warranty as</td><td class="lineno" valign="top"></td></tr>
127      <tr><td><a name="diff0008" /></td></tr>
128      <tr><td class="lineno" valign="top"></td><td class="lblock">   described in the BSD License.</td><td> </td><td class="rblock">   described in the <span class="insert">Simplified </span>BSD License.</td><td class="lineno" valign="top"></td></tr>
129      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
130      <tr><td class="lineno" valign="top"></td><td class="left">   This document may contain material from IETF Documents or IETF</td><td> </td><td class="right">   This document may contain material from IETF Documents or IETF</td><td class="lineno" valign="top"></td></tr>
131      <tr><td class="lineno" valign="top"></td><td class="left">   Contributions published or made publicly available before November</td><td> </td><td class="right">   Contributions published or made publicly available before November</td><td class="lineno" valign="top"></td></tr>
132      <tr><td class="lineno" valign="top"></td><td class="left">   10, 2008.  The person(s) controlling the copyright in some of this</td><td> </td><td class="right">   10, 2008.  The person(s) controlling the copyright in some of this</td><td class="lineno" valign="top"></td></tr>
133      <tr><td class="lineno" valign="top"></td><td class="left">   material may not have granted the IETF Trust the right to allow</td><td> </td><td class="right">   material may not have granted the IETF Trust the right to allow</td><td class="lineno" valign="top"></td></tr>
134      <tr><td class="lineno" valign="top"></td><td class="left">   modifications of such material outside the IETF Standards Process.</td><td> </td><td class="right">   modifications of such material outside the IETF Standards Process.</td><td class="lineno" valign="top"></td></tr>
135      <tr><td class="lineno" valign="top"></td><td class="left">   Without obtaining an adequate license from the person(s) controlling</td><td> </td><td class="right">   Without obtaining an adequate license from the person(s) controlling</td><td class="lineno" valign="top"></td></tr>
136      <tr><td class="lineno" valign="top"></td><td class="left">   the copyright in such materials, this document may not be modified</td><td> </td><td class="right">   the copyright in such materials, this document may not be modified</td><td class="lineno" valign="top"></td></tr>
137      <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>
138      <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>
139      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
140      <tr bgcolor="gray" ><td></td><th><a name="part-l2" /><small>skipping to change at</small><em> page 3, line 25</em></th><th> </th><th><a name="part-r2" /><small>skipping to change at</small><em> page 3, line 18</em></th><td></td></tr>
141      <tr><td class="lineno" valign="top"></td><td class="left">   2.  Cache Operation  . . . . . . . . . . . . . . . . . . . . . . .  7</td><td> </td><td class="right">   2.  Cache Operation  . . . . . . . . . . . . . . . . . . . . . . .  7</td><td class="lineno" valign="top"></td></tr>
142      <tr><td class="lineno" valign="top"></td><td class="left">     2.1.  Response Cacheability  . . . . . . . . . . . . . . . . . .  7</td><td> </td><td class="right">     2.1.  Response Cacheability  . . . . . . . . . . . . . . . . . .  7</td><td class="lineno" valign="top"></td></tr>
143      <tr><td class="lineno" valign="top"></td><td class="left">       2.1.1.  Storing Partial and Incomplete Responses . . . . . . .  8</td><td> </td><td class="right">       2.1.1.  Storing Partial and Incomplete Responses . . . . . . .  8</td><td class="lineno" valign="top"></td></tr>
144      <tr><td class="lineno" valign="top"></td><td class="left">     2.2.  Constructing Responses from Caches . . . . . . . . . . . .  9</td><td> </td><td class="right">     2.2.  Constructing Responses from Caches . . . . . . . . . . . .  9</td><td class="lineno" valign="top"></td></tr>
145      <tr><td class="lineno" valign="top"></td><td class="left">     2.3.  Freshness Model  . . . . . . . . . . . . . . . . . . . . . 10</td><td> </td><td class="right">     2.3.  Freshness Model  . . . . . . . . . . . . . . . . . . . . . 10</td><td class="lineno" valign="top"></td></tr>
146      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.1.  Calculating Freshness Lifetime . . . . . . . . . . . . 11</td><td> </td><td class="right">       2.3.1.  Calculating Freshness Lifetime . . . . . . . . . . . . 11</td><td class="lineno" valign="top"></td></tr>
147      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.2.  Calculating Age  . . . . . . . . . . . . . . . . . . . 12</td><td> </td><td class="right">       2.3.2.  Calculating Age  . . . . . . . . . . . . . . . . . . . 12</td><td class="lineno" valign="top"></td></tr>
148      <tr><td class="lineno" valign="top"></td><td class="left">       2.3.3.  Serving Stale Responses  . . . . . . . . . . . . . . . 13</td><td> </td><td class="right">       2.3.3.  Serving Stale Responses  . . . . . . . . . . . . . . . 13</td><td class="lineno" valign="top"></td></tr>
149      <tr><td class="lineno" valign="top"></td><td class="left">     2.4.  Validation Model . . . . . . . . . . . . . . . . . . . . . 14</td><td> </td><td class="right">     2.4.  Validation Model . . . . . . . . . . . . . . . . . . . . . 14</td><td class="lineno" valign="top"></td></tr>
150      <tr><td class="lineno" valign="top"></td><td class="left">     2.5.  Request Methods that Invalidate  . . . . . . . . . . . . . 14</td><td> </td><td class="right">     2.5.  Request Methods that Invalidate  . . . . . . . . . . . . . 14</td><td class="lineno" valign="top"></td></tr>
151      <tr><td><a name="diff0009" /></td></tr>
152      <tr><td class="lineno" valign="top"></td><td class="lblock">     2.6.  Caching Negotiated Responses . . . . . . . . . . . . . . . <span class="delete">15</span></td><td> </td><td class="rblock">     2.6.  <span class="insert">Shared Caching of Authenticated Responses  . . . . . . . . 15</span></td><td class="lineno" valign="top"></td></tr>
153      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">     2.7.</span>  Combining Responses  . . . . . . . . . . . . . . . . . . . 16</td><td> </td><td class="rblock"><span class="insert">     2.7.</span>  Caching Negotiated Responses . . . . . . . . . . . . . . . <span class="insert">16</span></td><td class="lineno" valign="top"></td></tr>
154      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">     2.8.</span>  Combining Responses  . . . . . . . . . . . . . . . . . . . 16</td><td class="lineno" valign="top"></td></tr>
155      <tr><td class="lineno" valign="top"></td><td class="left">   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . . 17</td><td> </td><td class="right">   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . . 17</td><td class="lineno" valign="top"></td></tr>
156      <tr><td class="lineno" valign="top"></td><td class="left">     3.1.  Age  . . . . . . . . . . . . . . . . . . . . . . . . . . . 17</td><td> </td><td class="right">     3.1.  Age  . . . . . . . . . . . . . . . . . . . . . . . . . . . 17</td><td class="lineno" valign="top"></td></tr>
157      <tr><td class="lineno" valign="top"></td><td class="left">     3.2.  Cache-Control  . . . . . . . . . . . . . . . . . . . . . . 18</td><td> </td><td class="right">     3.2.  Cache-Control  . . . . . . . . . . . . . . . . . . . . . . 18</td><td class="lineno" valign="top"></td></tr>
158      <tr><td><a name="diff0010" /></td></tr>
159      <tr><td class="lineno" valign="top"></td><td class="lblock">       3.2.1.  Request Cache-Control Directives . . . . . . . . . . . 1<span class="delete">8</span></td><td> </td><td class="rblock">       3.2.1.  Request Cache-Control Directives . . . . . . . . . . . 1<span class="insert">9</span></td><td class="lineno" valign="top"></td></tr>
160      <tr><td class="lineno" valign="top"></td><td class="left">       3.2.2.  Response Cache-Control Directives  . . . . . . . . . . 20</td><td> </td><td class="right">       3.2.2.  Response Cache-Control Directives  . . . . . . . . . . 20</td><td class="lineno" valign="top"></td></tr>
161      <tr><td><a name="diff0011" /></td></tr>
162      <tr><td class="lineno" valign="top"></td><td class="lblock">       3.2.3.  Cache Control Extensions . . . . . . . . . . . . . . . <span class="delete">22</span></td><td> </td><td class="rblock">       3.2.3.  Cache Control Extensions . . . . . . . . . . . . . . . <span class="insert">23</span></td><td class="lineno" valign="top"></td></tr>
163      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.3.  Expires  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">23</span></td><td> </td><td class="rblock">     3.3.  Expires  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">24</span></td><td class="lineno" valign="top"></td></tr>
164      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.4.  Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">24</span></td><td> </td><td class="rblock">     3.4.  Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">25</span></td><td class="lineno" valign="top"></td></tr>
165      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.5.  Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">24</span></td><td> </td><td class="rblock">     3.5.  Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">25</span></td><td class="lineno" valign="top"></td></tr>
166      <tr><td class="lineno" valign="top"></td><td class="lblock">     3.6.  Warning  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">25</span></td><td> </td><td class="rblock">     3.6.  Warning  . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">26</span></td><td class="lineno" valign="top"></td></tr>
167      <tr><td class="lineno" valign="top"></td><td class="lblock">   4.  History Lists  . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">28</span></td><td> </td><td class="rblock">   4.  History Lists  . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">29</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">28</span></td><td> </td><td class="rblock">   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . <span class="insert">29</span></td><td class="lineno" valign="top"></td></tr>
169      <tr><td class="lineno" valign="top"></td><td class="lblock">     5.1.  Message Header Registration  . . . . . . . . . . . . . . . <span class="delete">28</span></td><td> </td><td class="rblock">     5.1.  <span class="insert">Cache Directive Registry . . . . . . . . . . . . . . . . . 29</span></td><td class="lineno" valign="top"></td></tr>
170      <tr><td class="lineno" valign="top"></td><td class="lblock">   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . <span class="delete">28</span></td><td> </td><td class="rblock"><span class="insert">     5.2.</span>  Message Header Registration  . . . . . . . . . . . . . . . <span class="insert">30</span></td><td class="lineno" valign="top"></td></tr>
171      <tr><td class="lineno" valign="top"></td><td class="lblock">   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">29</span></td><td> </td><td class="rblock">   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . <span class="insert">30</span></td><td class="lineno" valign="top"></td></tr>
172      <tr><td class="lineno" valign="top"></td><td class="lblock">   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="delete">29</span></td><td> </td><td class="rblock">   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">30</span></td><td class="lineno" valign="top"></td></tr>
173      <tr><td class="lineno" valign="top"></td><td class="lblock">     8.1.  Normative References . . . . . . . . . . . . . . . . . . . <span class="delete">29</span></td><td> </td><td class="rblock">   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . <span class="insert">30</span></td><td class="lineno" valign="top"></td></tr>
174      <tr><td class="lineno" valign="top"></td><td class="lblock">     8.2.  Informative References . . . . . . . . . . . . . . . . . . <span class="delete">30</span></td><td> </td><td class="rblock">     8.1.  Normative References . . . . . . . . . . . . . . . . . . . <span class="insert">30</span></td><td class="lineno" valign="top"></td></tr>
175      <tr><td class="lineno" valign="top"></td><td class="lblock">   Appendix A.  Compatibility with Previous Versions  . . . . . . . . <span class="delete">30</span></td><td> </td><td class="rblock">     8.2.  Informative References . . . . . . . . . . . . . . . . . . <span class="insert">31</span></td><td class="lineno" valign="top"></td></tr>
176      <tr><td class="lineno" valign="top"></td><td class="lblock">     A.1.  Changes from RFC 2068  . . . . . . . . . . . . . . . . . . <span class="delete">30</span></td><td> </td><td class="rblock">   Appendix A.  Compatibility with Previous Versions  . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
177      <tr><td class="lineno" valign="top"></td><td class="lblock">     A.2.  Changes from RFC 2616  . . . . . . . . . . . . . . . . . . <span class="delete">30</span></td><td> </td><td class="rblock">     A.1.  Changes from RFC 2068  . . . . . . . . . . . . . . . . . . <span class="insert">32</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">31</span></td><td> </td><td class="rblock">     A.2.  Changes from RFC 2616  . . . . . . . . . . . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
179      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   Appendix B.  Collected ABNF  . . . . . . . . . . . . . . . . . . . <span class="insert">32</span></td><td class="lineno" valign="top"></td></tr>
180      <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>
181      <tr><td><a name="diff0012" /></td></tr>
182      <tr><td class="lineno" valign="top"></td><td class="lblock">                publication)  . . . . . . . . . . . . . . . . . . . . <span class="delete">32</span></td><td> </td><td class="rblock">                publication)  . . . . . . . . . . . . . . . . . . . . <span class="insert">34</span></td><td class="lineno" valign="top"></td></tr>
183      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.1.  Since RFC2616  . . . . . . . . . . . . . . . . . . . . . . <span class="delete">32</span></td><td> </td><td class="rblock">     C.1.  Since RFC2616  . . . . . . . . . . . . . . . . . . . . . . <span class="insert">34</span></td><td class="lineno" valign="top"></td></tr>
184      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.2.  Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . <span class="delete">32</span></td><td> </td><td class="rblock">     C.2.  Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . <span class="insert">34</span></td><td class="lineno" valign="top"></td></tr>
185      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.3.  Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . <span class="delete">33</span></td><td> </td><td class="rblock">     C.3.  Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . <span class="insert">35</span></td><td class="lineno" valign="top"></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">33</span></td><td> </td><td class="rblock">     C.4.  Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . <span class="insert">35</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">34</span></td><td> </td><td class="rblock">     C.5.  Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . <span class="insert">35</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">34</span></td><td> </td><td class="rblock">     C.6.  Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . <span class="insert">35</span></td><td class="lineno" valign="top"></td></tr>
189      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.7.  Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . <span class="delete">34</span></td><td> </td><td class="rblock">     C.7.  Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . <span class="insert">36</span></td><td class="lineno" valign="top"></td></tr>
190      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.8.  Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . <span class="delete">35</span></td><td> </td><td class="rblock">     C.8.  Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . <span class="insert">36</span></td><td class="lineno" valign="top"></td></tr>
191      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.9.  Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . <span class="delete">35</span></td><td> </td><td class="rblock">     C.9.  Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . <span class="insert">36</span></td><td class="lineno" valign="top"></td></tr>
192      <tr><td class="lineno" valign="top"></td><td class="lblock">     C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . <span class="delete">35</span></td><td> </td><td class="rblock">     C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . <span class="insert">37</span></td><td class="lineno" valign="top"></td></tr>
193      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   Index  . . . . . . . . . . . . .</span> . . . . . . . . . . . . . . . . . <span class="delete">36</span></td><td> </td><td class="rblock"><span class="insert">     C.11. Since draft-ietf-httpbis-p6-cache-09</span> . . . . . . . . . . . <span class="insert">37</span></td><td class="lineno" valign="top"></td></tr>
194      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   Authors' Addresses</span> . . . . . . . . . . . . . . . . . . . . . . . . 38</td><td> </td><td class="rblock"><span class="insert">   Index</span>  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38</td><td class="lineno" valign="top"></td></tr>
195      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
196      <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>
197      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
198      <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>
199      <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>
200      <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>
201      <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>
202      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
203      <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>
204      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
205      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
206      <tr bgcolor="gray" ><td></td><th><a name="part-l3" /><small>skipping to change at</small><em> page 8, line 17</em></th><th> </th><th><a name="part-r3" /><small>skipping to change at</small><em> page 8, line 14</em></th><td></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">   o  the response status code is understood by the cache, and</td><td> </td><td class="right">   o  the response status code is understood by the cache, and</td><td class="lineno" valign="top"></td></tr>
209      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
210      <tr><td class="lineno" valign="top"></td><td class="left">   o  the "no-store" cache directive (see Section 3.2) does not appear</td><td> </td><td class="right">   o  the "no-store" cache directive (see Section 3.2) does not appear</td><td class="lineno" valign="top"></td></tr>
211      <tr><td class="lineno" valign="top"></td><td class="left">      in request or response headers, and</td><td> </td><td class="right">      in request or response headers, and</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">   o  the "private" cache response directive (see Section 3.2.2 does not</td><td> </td><td class="right">   o  the "private" cache response directive (see Section 3.2.2 does not</td><td class="lineno" valign="top"></td></tr>
214      <tr><td class="lineno" valign="top"></td><td class="left">      appear in the response, if the cache is shared, and</td><td> </td><td class="right">      appear in the response, if the cache is shared, and</td><td class="lineno" valign="top"></td></tr>
215      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
216      <tr><td class="lineno" valign="top"></td><td class="left">   o  the "Authorization" header (see Section 3.1 of [Part7]) does not</td><td> </td><td class="right">   o  the "Authorization" header (see Section 3.1 of [Part7]) does not</td><td class="lineno" valign="top"></td></tr>
217      <tr><td><a name="diff0013" /></td></tr>
218      <tr><td class="lineno" valign="top"></td><td class="lblock">      appear in the request, if the cache is <span class="delete">shared (unless</span> the <span class="delete">"public"</span></td><td> </td><td class="rblock">      appear in the request, if the cache is <span class="insert">shared, unless</span> the <span class="insert">response</span></td><td class="lineno" valign="top"></td></tr>
219      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      directive is present; see</span> Section <span class="delete">3.2),</span> and</td><td> </td><td class="rblock"><span class="insert">      explicitly allows it (see</span> Section <span class="insert">2.6),</span> and</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">   o  the response either:</td><td> </td><td class="right">   o  the response either:</td><td class="lineno" valign="top"></td></tr>
222      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
223      <tr><td class="lineno" valign="top"></td><td class="left">      *  contains an Expires header (see Section 3.3), or</td><td> </td><td class="right">      *  contains an Expires header (see Section 3.3), or</td><td class="lineno" valign="top"></td></tr>
224      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
225      <tr><td class="lineno" valign="top"></td><td class="left">      *  contains a max-age response cache directive (see</td><td> </td><td class="right">      *  contains a max-age response cache directive (see</td><td class="lineno" valign="top"></td></tr>
226      <tr><td class="lineno" valign="top"></td><td class="left">         Section 3.2.2), or</td><td> </td><td class="right">         Section 3.2.2), or</td><td class="lineno" valign="top"></td></tr>
227      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
228      <tr><td class="lineno" valign="top"></td><td class="left">      *  contains a s-maxage response cache directive and the cache is</td><td> </td><td class="right">      *  contains a s-maxage response cache directive and the cache is</td><td class="lineno" valign="top"></td></tr>
229      <tr><td class="lineno" valign="top"></td><td class="left">         shared, or</td><td> </td><td class="right">         shared, or</td><td class="lineno" valign="top"></td></tr>
230      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
231      <tr bgcolor="gray" ><td></td><th><a name="part-l4" /><small>skipping to change at</small><em> page 9, line 18</em></th><th> </th><th><a name="part-r4" /><small>skipping to change at</small><em> page 9, line 14</em></th><td></td></tr>
232      <tr><td class="lineno" valign="top"></td><td class="left">   status code.</td><td> </td><td class="right">   status code.</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 class="lineno" valign="top"></td><td class="left">   A cache that does not support the Range and Content-Range headers</td><td> </td><td class="right">   A cache that does not support the Range and Content-Range headers</td><td class="lineno" valign="top"></td></tr>
235      <tr><td class="lineno" valign="top"></td><td class="left">   MUST NOT store incomplete or partial responses.</td><td> </td><td class="right">   MUST NOT store incomplete or partial responses.</td><td class="lineno" valign="top"></td></tr>
236      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
237      <tr><td class="lineno" valign="top"></td><td class="left">2.2.  Constructing Responses from Caches</td><td> </td><td class="right">2.2.  Constructing Responses from Caches</td><td class="lineno" valign="top"></td></tr>
238      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
239      <tr><td class="lineno" valign="top"></td><td class="left">   For a presented request, a cache MUST NOT return a stored response,</td><td> </td><td class="right">   For a presented request, a cache MUST NOT return a stored response,</td><td class="lineno" valign="top"></td></tr>
240      <tr><td class="lineno" valign="top"></td><td class="left">   unless:</td><td> </td><td class="right">   unless:</td><td class="lineno" valign="top"></td></tr>
241      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
242      <tr><td><a name="diff0014" /></td></tr>
243      <tr><td class="lineno" valign="top"></td><td class="lblock">   o  The presented <span class="delete">Request-URI</span> and that of the stored response <span class="delete">match</span></td><td> </td><td class="rblock">   o  The presented <span class="insert">Effective Request URI (Section 4.3 of [Part1])</span> and</td><td class="lineno" valign="top"></td></tr>
244      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      ([[TODO-Request-URI: Need to find a new term for this, as Part 1</span></td><td> </td><td class="rblock">      that of the stored response <span class="insert">match,</span> and</td><td class="lineno" valign="top"></td></tr>
245      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      doesn't define Request-URI anymore; the new term request-target</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
246      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      does not work for this. (see</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
247      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      &lt;http://tools.ietf.org/wg/httpbis/trac/ticket/196&gt;)]]),</span> and</td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
248      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
249      <tr><td class="lineno" valign="top"></td><td class="left">   o  the request method associated with the stored response allows it</td><td> </td><td class="right">   o  the request method associated with the stored response allows it</td><td class="lineno" valign="top"></td></tr>
250      <tr><td class="lineno" valign="top"></td><td class="left">      to be used for the presented request, and</td><td> </td><td class="right">      to be used for the presented request, and</td><td class="lineno" valign="top"></td></tr>
251      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
252      <tr><td class="lineno" valign="top"></td><td class="left">   o  selecting request-headers nominated by the stored response (if</td><td> </td><td class="right">   o  selecting request-headers nominated by the stored response (if</td><td class="lineno" valign="top"></td></tr>
253      <tr><td><a name="diff0015" /></td></tr>
254      <tr><td class="lineno" valign="top"></td><td class="lblock">      any) match those presented (see Section 2.<span class="delete">6</span>), and</td><td> </td><td class="rblock">      any) match those presented (see Section 2.<span class="insert">7</span>), and</td><td class="lineno" valign="top"></td></tr>
255      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
256      <tr><td class="lineno" valign="top"></td><td class="left">   o  the presented request and stored response are free from directives</td><td> </td><td class="right">   o  the presented request and stored response are free from directives</td><td class="lineno" valign="top"></td></tr>
257      <tr><td class="lineno" valign="top"></td><td class="left">      that would prevent its use (see Section 3.2 and Section 3.4), and</td><td> </td><td class="right">      that would prevent its use (see Section 3.2 and Section 3.4), and</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">   o  the stored response is either:</td><td> </td><td class="right">   o  the stored response is either:</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">      *  fresh (see Section 2.3), or</td><td> </td><td class="right">      *  fresh (see Section 2.3), or</td><td class="lineno" valign="top"></td></tr>
262      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
263      <tr><td class="lineno" valign="top"></td><td class="left">      *  allowed to be served stale (see Section 2.3.3), or</td><td> </td><td class="right">      *  allowed to be served stale (see Section 2.3.3), or</td><td class="lineno" valign="top"></td></tr>
264      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
265      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
266      <tr bgcolor="gray" ><td></td><th><a name="part-l5" /><small>skipping to change at</small><em> page 10, line 14</em></th><th> </th><th><a name="part-r5" /><small>skipping to change at</small><em> page 10, line 8</em></th><td></td></tr>
267      <tr><td class="lineno" valign="top"></td><td class="left">   having received a corresponding response.</td><td> </td><td class="right">   having received a corresponding response.</td><td class="lineno" valign="top"></td></tr>
268      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
269      <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>
270      <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>
271      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
272      <tr><td class="lineno" valign="top"></td><td class="left">   Caches MUST use the most recent response (as determined by the Date</td><td> </td><td class="right">   Caches MUST use the most recent response (as determined by the Date</td><td class="lineno" valign="top"></td></tr>
273      <tr><td class="lineno" valign="top"></td><td class="left">   header) when more than one suitable response is stored.  They can</td><td> </td><td class="right">   header) when more than one suitable response is stored.  They can</td><td class="lineno" valign="top"></td></tr>
274      <tr><td class="lineno" valign="top"></td><td class="left">   also forward a request with "Cache-Control: max-age=0" or "Cache-</td><td> </td><td class="right">   also forward a request with "Cache-Control: max-age=0" or "Cache-</td><td class="lineno" valign="top"></td></tr>
275      <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>
276      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
277      <tr><td><a name="diff0016" /></td></tr>
278      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">[[TODO-header-properties: end-to-end and hop-by-hop headers, non-</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
279      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   modifiable headers removed; re-spec in p1]]</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
280      <tr><td class="lineno" valign="top"></td><td class="lblock">                                                                         </td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
281      <tr><td class="lineno" valign="top"></td><td class="left">2.3.  Freshness Model</td><td> </td><td class="right">2.3.  Freshness Model</td><td class="lineno" valign="top"></td></tr>
282      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
283      <tr><td class="lineno" valign="top"></td><td class="left">   When a response is "fresh" in the cache, it can be used to satisfy</td><td> </td><td class="right">   When a response is "fresh" in the cache, it can be used to satisfy</td><td class="lineno" valign="top"></td></tr>
284      <tr><td class="lineno" valign="top"></td><td class="left">   subsequent requests without contacting the origin server, thereby</td><td> </td><td class="right">   subsequent requests without contacting the origin server, thereby</td><td class="lineno" valign="top"></td></tr>
285      <tr><td class="lineno" valign="top"></td><td class="left">   improving efficiency.</td><td> </td><td class="right">   improving efficiency.</td><td class="lineno" valign="top"></td></tr>
286      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
287      <tr><td class="lineno" valign="top"></td><td class="left">   The primary mechanism for determining freshness is for an origin</td><td> </td><td class="right">   The primary mechanism for determining freshness is for an origin</td><td class="lineno" valign="top"></td></tr>
288      <tr><td class="lineno" valign="top"></td><td class="left">   server to provide an explicit expiration time in the future, using</td><td> </td><td class="right">   server to provide an explicit expiration time in the future, using</td><td class="lineno" valign="top"></td></tr>
289      <tr><td class="lineno" valign="top"></td><td class="left">   either the Expires header (Section 3.3) or the max-age response cache</td><td> </td><td class="right">   either the Expires header (Section 3.3) or the max-age response cache</td><td class="lineno" valign="top"></td></tr>
290      <tr><td class="lineno" valign="top"></td><td class="left">   directive (Section 3.2.2).  Generally, origin servers will assign</td><td> </td><td class="right">   directive (Section 3.2.2).  Generally, origin servers will assign</td><td class="lineno" valign="top"></td></tr>
291      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
292      <tr bgcolor="gray" ><td></td><th><a name="part-l6" /><small>skipping to change at</small><em> page 11, line 32</em></th><th> </th><th><a name="part-r6" /><small>skipping to change at</small><em> page 11, line 22</em></th><td></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">   o  If the cache is shared and the s-maxage response cache directive</td><td> </td><td class="right">   o  If the cache is shared and the s-maxage response cache directive</td><td class="lineno" valign="top"></td></tr>
295      <tr><td class="lineno" valign="top"></td><td class="left">      (Section 3.2.2) is present, use its value, or</td><td> </td><td class="right">      (Section 3.2.2) is present, use its value, or</td><td class="lineno" valign="top"></td></tr>
296      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
297      <tr><td class="lineno" valign="top"></td><td class="left">   o  If the max-age response cache directive (Section 3.2.2) is</td><td> </td><td class="right">   o  If the max-age response cache directive (Section 3.2.2) is</td><td class="lineno" valign="top"></td></tr>
298      <tr><td class="lineno" valign="top"></td><td class="left">      present, use its value, or</td><td> </td><td class="right">      present, use its value, or</td><td class="lineno" valign="top"></td></tr>
299      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
300      <tr><td class="lineno" valign="top"></td><td class="left">   o  If the Expires response header (Section 3.3) is present, use its</td><td> </td><td class="right">   o  If the Expires response header (Section 3.3) is present, use its</td><td class="lineno" valign="top"></td></tr>
301      <tr><td class="lineno" valign="top"></td><td class="left">      value minus the value of the Date response header, or</td><td> </td><td class="right">      value minus the value of the Date response header, or</td><td class="lineno" valign="top"></td></tr>
302      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
303      <tr><td><a name="diff0017" /></td></tr>
304      <tr><td class="lineno" valign="top"></td><td class="lblock">   o  Otherwise, no explicit expiration time is present in the <span class="delete">response,</span></td><td> </td><td class="rblock">   o  Otherwise, no explicit expiration time is present in the <span class="insert">response.</span></td><td class="lineno" valign="top"></td></tr>
305      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">      but a</span> heuristic <span class="delete">may</span> be <span class="delete">used;</span> see Section 2.3.1.1.</td><td> </td><td class="rblock"><span class="insert">      A</span> heuristic <span class="insert">freshness lifetime might</span> be <span class="insert">applicable;</span> see</td><td class="lineno" valign="top"></td></tr>
306      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      Section 2.3.1.1.</td><td class="lineno" valign="top"></td></tr>
307      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
308      <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>
309      <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>
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">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>
312      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
313      <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>
314      <tr><td class="lineno" valign="top"></td><td class="left">   has a status code of 200, 203, 206, 300, 301 or 410, a heuristic</td><td> </td><td class="right">   has a status code of 200, 203, 206, 300, 301 or 410, a heuristic</td><td class="lineno" valign="top"></td></tr>
315      <tr><td class="lineno" valign="top"></td><td class="left">   expiration time can be calculated.  Heuristics MUST NOT be used for</td><td> </td><td class="right">   expiration time can be calculated.  Heuristics MUST NOT be used for</td><td class="lineno" valign="top"></td></tr>
316      <tr><td class="lineno" valign="top"></td><td class="left">   other response status codes.</td><td> </td><td class="right">   other response status codes.</td><td class="lineno" valign="top"></td></tr>
317      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
318      <tr bgcolor="gray" ><td></td><th><a name="part-l7" /><small>skipping to change at</small><em> page 12, line 6</em></th><th> </th><th><a name="part-r7" /><small>skipping to change at</small><em> page 11, line 46</em></th><td></td></tr>
319      <tr><td class="lineno" valign="top"></td><td class="left">   When a heuristic is used to calculate freshness lifetime, the cache</td><td> </td><td class="right">   When a heuristic is used to calculate freshness lifetime, the cache</td><td class="lineno" valign="top"></td></tr>
320      <tr><td class="lineno" valign="top"></td><td class="left">   SHOULD attach a Warning header with a 113 warn-code to the response</td><td> </td><td class="right">   SHOULD attach a Warning header with a 113 warn-code to the response</td><td class="lineno" valign="top"></td></tr>
321      <tr><td class="lineno" valign="top"></td><td class="left">   if its current_age is more than 24 hours and such a warning is not</td><td> </td><td class="right">   if its current_age is more than 24 hours and such a warning is not</td><td class="lineno" valign="top"></td></tr>
322      <tr><td class="lineno" valign="top"></td><td class="left">   already present.</td><td> </td><td class="right">   already present.</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">   Also, if the response has a Last-Modified header (Section 6.6 of</td><td> </td><td class="right">   Also, if the response has a Last-Modified header (Section 6.6 of</td><td class="lineno" valign="top"></td></tr>
325      <tr><td class="lineno" valign="top"></td><td class="left">   [Part4]), the heuristic expiration value SHOULD be no more than some</td><td> </td><td class="right">   [Part4]), the heuristic expiration value SHOULD be no more than some</td><td class="lineno" valign="top"></td></tr>
326      <tr><td class="lineno" valign="top"></td><td class="left">   fraction of the interval since that time.  A typical setting of this</td><td> </td><td class="right">   fraction of the interval since that time.  A typical setting of this</td><td class="lineno" valign="top"></td></tr>
327      <tr><td class="lineno" valign="top"></td><td class="left">   fraction might be 10%.</td><td> </td><td class="right">   fraction might be 10%.</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><a name="diff0018" /></td></tr>
330      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">[[REVIEW-query-string-heuristics: took away HTTP/1.0 query string</span></td><td> </td><td class="rblock">      <span class="insert">Note: RFC 2616 ([RFC2616], Section 13.9) required that caches do</span></td><td class="lineno" valign="top"></td></tr>
331      <tr><td class="lineno" valign="top"></td><td class="lblock">   heuristic <span class="delete">uncacheability.]]</span></td><td> </td><td class="rblock"><span class="insert">      not calculate</span> heuristic <span class="insert">freshness for URLs with query components</span></td><td class="lineno" valign="top"></td></tr>
332      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      (i.e., those containing '?').  In practice, this has not been</span></td><td class="lineno" valign="top"></td></tr>
333      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      widely implemented.  Therefore, servers are encouraged to send</span></td><td class="lineno" valign="top"></td></tr>
334      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      explicit directives (e.g., Cache-Control: no-cache) if they wish</span></td><td class="lineno" valign="top"></td></tr>
335      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      to preclude caching.</span></td><td class="lineno" valign="top"></td></tr>
336      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
337      <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>
338      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
339      <tr><td class="lineno" valign="top"></td><td class="left">   HTTP/1.1 uses the Age response-header to convey the estimated age of</td><td> </td><td class="right">   HTTP/1.1 uses the Age response-header to convey the estimated age of</td><td class="lineno" valign="top"></td></tr>
340      <tr><td class="lineno" valign="top"></td><td class="left">   the response message when obtained from a cache.  The Age field value</td><td> </td><td class="right">   the response message when obtained from a cache.  The Age field value</td><td class="lineno" valign="top"></td></tr>
341      <tr><td class="lineno" valign="top"></td><td class="left">   is the cache's estimate of the amount of time since the response was</td><td> </td><td class="right">   is the cache's estimate of the amount of time since the response was</td><td class="lineno" valign="top"></td></tr>
342      <tr><td class="lineno" valign="top"></td><td class="left">   generated or validated by the origin server.  In essence, the Age</td><td> </td><td class="right">   generated or validated by the origin server.  In essence, the Age</td><td class="lineno" valign="top"></td></tr>
343      <tr><td class="lineno" valign="top"></td><td class="left">   value is the sum of the time that the response has been resident in</td><td> </td><td class="right">   value is the sum of the time that the response has been resident in</td><td class="lineno" valign="top"></td></tr>
344      <tr><td class="lineno" valign="top"></td><td class="left">   each of the caches along the path from the origin server, plus the</td><td> </td><td class="right">   each of the caches along the path from the origin server, plus the</td><td class="lineno" valign="top"></td></tr>
345      <tr><td class="lineno" valign="top"></td><td class="left">   amount of time it has been in transit along network paths.</td><td> </td><td class="right">   amount of time it has been in transit along network paths.</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><a name="diff0019" /></td></tr>
348      <tr><td class="lineno" valign="top"></td><td class="lblock">   The <span class="delete">term "age_value" denotes the value of the Age header, in a form</span></td><td> </td><td class="rblock">   The <span class="insert">following data is used</span> for <span class="insert">the age calculation:</span></td><td class="lineno" valign="top"></td></tr>
349      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   appropriate</span> for <span class="delete">arithmetic operations.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
350      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
351      <tr><td><a name="diff0020" /></td></tr>
352      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">HTTP/1.1 requires origin servers to send a Date header, if possible,</span></td><td> </td><td class="rblock">   <span class="insert">age_value</span></td><td class="lineno" valign="top"></td></tr>
353      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   with every response, giving the time at which the response was</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
354      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   generated (see Section 9.3 of [Part1]).  The term "date_value"</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
355      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   denotes the value of the Date header, in a form appropriate for</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
356      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   arithmetic operations.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
357      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
358      <tr><td><a name="diff0021" /></td></tr>
359      <tr><td class="lineno" valign="top"></td><td class="lblock">   The term <span class="delete">"now" means "the current</span> value of the <span class="delete">clock at the host</span></td><td> </td><td class="rblock">      The term <span class="insert">"age_value" denotes the</span> value of the <span class="insert">Age header</span></td><td class="lineno" valign="top"></td></tr>
360      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   performing the calculation."  Hosts that use HTTP, but especially</span></td><td> </td><td class="rblock"><span class="insert">      (Section 3.1), in</span> a <span class="insert">form appropriate for arithmetic operation; or</span></td><td class="lineno" valign="top"></td></tr>
361      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   hosts running origin servers and caches, SHOULD use NTP [RFC1305] or</span></td><td> </td><td class="rblock"><span class="insert">      0, if not available.</span></td><td class="lineno" valign="top"></td></tr>
362      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   some similar protocol to synchronize their clocks to</span> a <span class="delete">globally</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
363      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   accurate time standard.</span></td><td> </td><td class="rblock"></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><a name="diff0022" /></td></tr>
366      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">A response's age can be calculated in two entirely independent ways:</span></td><td> </td><td class="rblock">   <span class="insert">date_value</span></td><td class="lineno" valign="top"></td></tr>
367      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
368      <tr><td><a name="diff0023" /></td></tr>
369      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">1.  now minus date_value,</span> if the <span class="delete">local clock is reasonably well</span></td><td> </td><td class="rblock">      <span class="insert">HTTP/1.1 requires origin servers to send a Date header,</span> if</td><td class="lineno" valign="top"></td></tr>
370      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">       synchronized to</span> the <span class="delete">origin server's clock.  If the result is</span></td><td> </td><td class="rblock">      <span class="insert">possible, with every response, giving</span> the <span class="insert">time at which</span> the</td><td class="lineno" valign="top"></td></tr>
371      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">       negative, the result is replaced by zero.</span></td><td> </td><td class="rblock">      <span class="insert">response was generated.  The term "date_value" denotes the value</span></td><td class="lineno" valign="top"></td></tr>
372      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      of the Date header, in a form appropriate for arithmetic</span></td><td class="lineno" valign="top"></td></tr>
373      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      operations.  See Section 9.3 of [Part1] for the definition of the</span></td><td class="lineno" valign="top"></td></tr>
374      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      Date header, and for requirements regarding responses without a</span></td><td class="lineno" valign="top"></td></tr>
375      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      Date response header.</span></td><td class="lineno" valign="top"></td></tr>
376      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
377      <tr><td><a name="diff0024" /></td></tr>
378      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">2.  age_value, if all of the caches along the response path implement</span></td><td> </td><td class="rblock">   <span class="insert">now</span></td><td class="lineno" valign="top"></td></tr>
379      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">       HTTP/1.1.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
380      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
381      <tr><td><a name="diff0025" /></td></tr>
382      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">These are combined as</span></td><td> </td><td class="rblock">      <span class="insert">The term "now" means "the current value of the clock at the host</span></td><td class="lineno" valign="top"></td></tr>
383      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      performing the calculation".  Hosts that use HTTP, but especially</span></td><td class="lineno" valign="top"></td></tr>
384      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      hosts running origin servers and caches, SHOULD use NTP</span></td><td class="lineno" valign="top"></td></tr>
385      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      ([RFC1305]) or some similar protocol to synchronize their clocks</span></td><td class="lineno" valign="top"></td></tr>
386      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      to a globally accurate time standard.</span></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><a name="diff0026" /></td></tr>
389      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">    corrected_received_age = max(now - date_value, age_value)</span></td><td> </td><td class="rblock">   <span class="insert">request_time</span></td><td class="lineno" valign="top"></td></tr>
390      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
391      <tr><td><a name="diff0027" /></td></tr>
392      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">When an Age</span> value <span class="delete">is received, it MUST be interpreted relative to</span> the</td><td> </td><td class="rblock">      <span class="insert">The current</span> value <span class="insert">of</span> the <span class="insert">clock at</span> the <span class="insert">host at</span> the time the <span class="insert">request</span></td><td class="lineno" valign="top"></td></tr>
393      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">time</span> the <span class="delete">request was initiated, not</span> the time <span class="delete">that</span> the response was</td><td> </td><td class="rblock"><span class="insert">      resulting in the stored</span> response was <span class="insert">made.</span></td><td class="lineno" valign="top"></td></tr>
394      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">received.</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
395      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
396      <tr><td><a name="diff0028" /></td></tr>
397      <tr><td class="lineno" valign="top"></td><td class="lblock">      <span class="delete">corrected_initial_age = corrected_received_age</span></td><td> </td><td class="rblock">   <span class="insert">response_time</span></td><td class="lineno" valign="top"></td></tr>
398      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">                            + (now - request_time)</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
399      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
400      <tr><td><a name="diff0029" /></td></tr>
401      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">where "request_time" is</span> the <span class="delete">time (according to</span> the <span class="delete">local clock) when</span></td><td> </td><td class="rblock">      <span class="insert">The current value of</span> the <span class="insert">clock at the host at</span> the <span class="insert">time</span> the</td><td class="lineno" valign="top"></td></tr>
402      <tr><td class="lineno" valign="top"></td><td class="lblock">   the <span class="delete">request that elicited this</span> response was <span class="delete">sent.</span></td><td> </td><td class="rblock">      response was <span class="insert">received.</span></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><a name="diff0030" /></td></tr>
405      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">The current_age of a stored response</span> can <span class="delete">then</span> be calculated <span class="delete">by adding</span></td><td> </td><td class="rblock">   <span class="insert">A response's age</span> can be calculated <span class="insert">in two entirely independent ways:</span></td><td class="lineno" valign="top"></td></tr>
406      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   the amount of time (in seconds) since the stored response was last</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
407      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   validated by the origin server to the corrected_initial_age.</span></td><td> </td><td class="rblock"></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><a name="diff0031" /></td></tr>
410      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">In summary:</span></td><td> </td><td class="rblock">   <span class="insert">1.  the "apparent_age": response_time minus date_value, if the local</span></td><td class="lineno" valign="top"></td></tr>
411      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">       clock is reasonably well synchronized to the origin server's</span></td><td class="lineno" valign="top"></td></tr>
412      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">       clock.  If the result is negative, the result is replaced by</span></td><td class="lineno" valign="top"></td></tr>
413      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">       zero.</span></td><td class="lineno" valign="top"></td></tr>
414      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
415      <tr><td><a name="diff0032" /></td></tr>
416      <tr><td class="lineno" valign="top"></td><td class="lblock">     <span class="delete">age_value     - Age header field-value received with</span> the <span class="delete">response</span></td><td> </td><td class="rblock">   <span class="insert">2.</span>  the <span class="insert">"corrected_age_value", if all of the caches along</span> the</td><td class="lineno" valign="top"></td></tr>
417      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">     date_value    - Date header field-value received with</span> the response</td><td> </td><td class="rblock">       response <span class="insert">path implement HTTP/1.1; note this value MUST be</span></td><td class="lineno" valign="top"></td></tr>
418      <tr><td class="lineno" valign="top"></td><td class="lblock">     <span class="delete">request_time  - local time when</span> the <span class="delete">cache made</span> the request</td><td> </td><td class="rblock"><span class="insert">       interpreted relative to</span> the <span class="insert">time</span> the request <span class="insert">was initiated, not</span></td><td class="lineno" valign="top"></td></tr>
419      <tr><td class="lineno" valign="top"></td><td class="lblock">                    <span class="delete">resulting in</span> the <span class="delete">stored response</span></td><td> </td><td class="rblock">       the time <span class="insert">that</span> the response <span class="insert">was received.</span></td><td class="lineno" valign="top"></td></tr>
420      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">     response_time - local</span> time <span class="delete">when the cache received</span> the response</td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
421      <tr><td class="lineno" valign="top"></td><td class="lblock">     <span class="delete">now           - current local time</span></td><td> </td><td class="rblock"></td><td class="lineno" valign="top"></td></tr>
422      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
423      <tr><td class="lineno" valign="top"></td><td class="left">     apparent_age = max(0, response_time - date_value);</td><td> </td><td class="right">     apparent_age = max(0, response_time - date_value);</td><td class="lineno" valign="top"></td></tr>
424      <tr><td><a name="diff0033" /></td></tr>
425      <tr><td class="lineno" valign="top"></td><td class="lblock">     <span class="delete">corrected_received_age = max(apparent_age, age_value);</span></td><td> </td><td class="rblock">     <span class="insert">                                                                    </span></td><td class="lineno" valign="top"></td></tr>
426      <tr><td class="lineno" valign="top"></td><td class="left">     response_delay = response_time - request_time;</td><td> </td><td class="right">     response_delay = response_time - request_time;</td><td class="lineno" valign="top"></td></tr>
427      <tr><td><a name="diff0034" /></td></tr>
428      <tr><td class="lineno" valign="top"></td><td class="lblock">     <span class="delete">corrected_initial_age</span> = <span class="delete">corrected_received_age</span> + response_delay;</td><td> </td><td class="rblock">     <span class="insert">corrected_age_value</span> = <span class="insert">age_value</span> + response_delay;</td><td class="lineno" valign="top"></td></tr>
429      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
430      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   <span class="insert">These are combined as</span></td><td class="lineno" valign="top"></td></tr>
431      <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>
432      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">     corrected_initial_age = max(apparent_age, corrected_age_value);</span></td><td class="lineno" valign="top"></td></tr>
433      <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>
434      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   The current_age of a stored response can then be calculated by adding</span></td><td class="lineno" valign="top"></td></tr>
435      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   the amount of time (in seconds) since the stored response was last</span></td><td class="lineno" valign="top"></td></tr>
436      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   validated by the origin server to the corrected_initial_age.</span></td><td class="lineno" valign="top"></td></tr>
437      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
438      <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>
439      <tr><td><a name="diff0035" /></td></tr>
440      <tr><td class="lineno" valign="top"></td><td class="lblock">     current_age <span class="delete">  </span>= corrected_initial_age + resident_time;</td><td> </td><td class="rblock">     current_age = corrected_initial_age + resident_time;</td><td class="lineno" valign="top"></td></tr>
441      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
442      <tr><td class="lineno" valign="top"></td><td class="left">2.3.3.  Serving Stale Responses</td><td> </td><td class="right">2.3.3.  Serving Stale Responses</td><td class="lineno" valign="top"></td></tr>
443      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
444      <tr><td><a name="diff0036" /></td></tr>
445      <tr><td class="lineno" valign="top"></td><td class="lblock">   A "stale" response is one that either has explicit expiry</td><td> </td><td class="rblock">   A "stale" response is one that either has explicit expiry <span class="insert">information</span></td><td class="lineno" valign="top"></td></tr>
446      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">information,</span> or is allowed to have heuristic expiry calculated, but</td><td> </td><td class="rblock">   or is allowed to have heuristic expiry calculated, but is not fresh</td><td class="lineno" valign="top"></td></tr>
447      <tr><td class="lineno" valign="top"></td><td class="lblock">   is not fresh according to the calculations in Section 2.3.</td><td> </td><td class="rblock">   according to the calculations in Section 2.3.</td><td class="lineno" valign="top"></td></tr>
448      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
449      <tr><td class="lineno" valign="top"></td><td class="left">   Caches MUST NOT return a stale response if it is prohibited by an</td><td> </td><td class="right">   Caches MUST NOT return a stale response if it is prohibited by an</td><td class="lineno" valign="top"></td></tr>
450      <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>
451      <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>
452      <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>
453      <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>
454      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
455      <tr><td class="lineno" valign="top"></td><td class="left">   Caches SHOULD NOT return stale responses unless they are disconnected</td><td> </td><td class="right">   Caches SHOULD NOT return stale responses unless they are disconnected</td><td class="lineno" valign="top"></td></tr>
456      <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>
457      <tr><td class="lineno" valign="top"></td><td class="left">   forward path) or otherwise explicitly allowed (e.g., the max-stale</td><td> </td><td class="right">   forward path) or otherwise explicitly allowed (e.g., the max-stale</td><td class="lineno" valign="top"></td></tr>
458      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
459      <tr bgcolor="gray" ><td></td><th><a name="part-l8" /><small>skipping to change at</small><em> page 14, line 14</em></th><th> </th><th><a name="part-r8" /><small>skipping to change at</small><em> page 14, line 17</em></th><td></td></tr>
460      <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>
461      <tr><td class="lineno" valign="top"></td><td class="left">   the cache SHOULD forward it to the requesting client without adding a</td><td> </td><td class="right">   the cache SHOULD forward it to the requesting client without adding a</td><td class="lineno" valign="top"></td></tr>
462      <tr><td class="lineno" valign="top"></td><td class="left">   new Warning (but without removing any existing Warning headers).  A</td><td> </td><td class="right">   new Warning (but without removing any existing Warning headers).  A</td><td class="lineno" valign="top"></td></tr>
463      <tr><td class="lineno" valign="top"></td><td class="left">   cache SHOULD NOT attempt to validate a response simply because that</td><td> </td><td class="right">   cache SHOULD NOT attempt to validate a response simply because that</td><td class="lineno" valign="top"></td></tr>
464      <tr><td class="lineno" valign="top"></td><td class="left">   response became stale in transit.</td><td> </td><td class="right">   response became stale in transit.</td><td class="lineno" valign="top"></td></tr>
465      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
466      <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>
467      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
468      <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>
469      <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>
470      <tr><td><a name="diff0037" /></td></tr>
471      <tr><td class="lineno" valign="top"></td><td class="lblock">   one cannot be selected; see Section 2.<span class="delete">6</span>), it can use the conditional</td><td> </td><td class="rblock">   one cannot be selected; see Section 2.<span class="insert">7</span>), it can use the conditional</td><td class="lineno" valign="top"></td></tr>
472      <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>
473      <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>
474      <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>
475      <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>
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 class="lineno" valign="top"></td><td class="left">   When sending such a conditional request, the cache SHOULD add an If-</td><td> </td><td class="right">   When sending such a conditional request, the cache SHOULD add an If-</td><td class="lineno" valign="top"></td></tr>
478      <tr><td class="lineno" valign="top"></td><td class="left">   Modified-Since header whose value is that of the Last-Modified header</td><td> </td><td class="right">   Modified-Since header whose value is that of the Last-Modified header</td><td class="lineno" valign="top"></td></tr>
479      <tr><td><a name="diff0038" /></td></tr>
480      <tr><td class="lineno" valign="top"></td><td class="lblock">   from the selected (see Section 2.<span class="delete">6</span>) stored response, if available.</td><td> </td><td class="rblock">   from the selected (see Section 2.<span class="insert">7</span>) stored response, if available.</td><td class="lineno" valign="top"></td></tr>
481      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
482      <tr><td class="lineno" valign="top"></td><td class="left">   Additionally, the cache SHOULD add an If-None-Match header whose</td><td> </td><td class="right">   Additionally, the cache SHOULD add an If-None-Match header whose</td><td class="lineno" valign="top"></td></tr>
483      <tr><td class="lineno" valign="top"></td><td class="left">   value is that of the ETag header(s) from all responses stored for the</td><td> </td><td class="right">   value is that of the ETag header(s) from all responses stored for the</td><td class="lineno" valign="top"></td></tr>
484      <tr><td class="lineno" valign="top"></td><td class="left">   requested URI, if present.  However, if any of the stored responses</td><td> </td><td class="right">   requested URI, if present.  However, if any of the stored responses</td><td class="lineno" valign="top"></td></tr>
485      <tr><td class="lineno" valign="top"></td><td class="left">   contains only partial content, its entity-tag SHOULD NOT be included</td><td> </td><td class="right">   contains only partial content, its entity-tag SHOULD NOT be included</td><td class="lineno" valign="top"></td></tr>
486      <tr><td class="lineno" valign="top"></td><td class="left">   in the If-None-Match header field unless the request is for a range</td><td> </td><td class="right">   in the If-None-Match header field unless the request is for a range</td><td class="lineno" valign="top"></td></tr>
487      <tr><td class="lineno" valign="top"></td><td class="left">   that would be fully satisfied by that stored response.</td><td> </td><td class="right">   that would be fully satisfied by that stored response.</td><td class="lineno" valign="top"></td></tr>
488      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
489      <tr><td class="lineno" valign="top"></td><td class="left">   A 304 (Not Modified) response status code indicates that the stored</td><td> </td><td class="right">   A 304 (Not Modified) response status code indicates that the stored</td><td class="lineno" valign="top"></td></tr>
490      <tr><td><a name="diff0039" /></td></tr>
491      <tr><td class="lineno" valign="top"></td><td class="lblock">   response can be updated and reused; see Section 2.<span class="delete">7</span>.</td><td> </td><td class="rblock">   response can be updated and reused; see Section 2.<span class="insert">8</span>.</td><td class="lineno" valign="top"></td></tr>
492      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
493      <tr><td class="lineno" valign="top"></td><td class="left">   A full response (i.e., one with a response body) indicates that none</td><td> </td><td class="right">   A full response (i.e., one with a response body) indicates that none</td><td class="lineno" valign="top"></td></tr>
494      <tr><td class="lineno" valign="top"></td><td class="left">   of the stored responses nominated in the conditional request is</td><td> </td><td class="right">   of the stored responses nominated in the conditional request is</td><td class="lineno" valign="top"></td></tr>
495      <tr><td class="lineno" valign="top"></td><td class="left">   suitable.  Instead, the full response is used both to satisfy the</td><td> </td><td class="right">   suitable.  Instead, the full response is used both to satisfy the</td><td class="lineno" valign="top"></td></tr>
496      <tr><td class="lineno" valign="top"></td><td class="left">   request and replace the stored response.  [[TODO-req-missing: Should</td><td> </td><td class="right">   request and replace the stored response.  [[TODO-req-missing: Should</td><td class="lineno" valign="top"></td></tr>
497      <tr><td class="lineno" valign="top"></td><td class="left">   there be a requirement here?]]</td><td> </td><td class="right">   there be a requirement here?]]</td><td class="lineno" valign="top"></td></tr>
498      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
499      <tr><td class="lineno" valign="top"></td><td class="left">   If a cache receives a 5xx response while attempting to validate a</td><td> </td><td class="right">   If a cache receives a 5xx response while attempting to validate a</td><td class="lineno" valign="top"></td></tr>
500      <tr><td class="lineno" valign="top"></td><td class="left">   response, it MAY either forward this response to the requesting</td><td> </td><td class="right">   response, it MAY either forward this response to the requesting</td><td class="lineno" valign="top"></td></tr>
501      <tr><td class="lineno" valign="top"></td><td class="left">   client, or act as if the server failed to respond.  In the latter</td><td> </td><td class="right">   client, or act as if the server failed to respond.  In the latter</td><td class="lineno" valign="top"></td></tr>
502      <tr><td class="lineno" valign="top"></td><td class="left">   case, it MAY return a previously stored response (see Section 2.3.3).</td><td> </td><td class="right">   case, it MAY return a previously stored response (see Section 2.3.3).</td><td class="lineno" valign="top"></td></tr>
503      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
504      <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>
505      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
506      <tr><td class="lineno" valign="top"></td><td class="left">   Because unsafe methods (Section 7.1.1 of [Part2]) have the potential</td><td> </td><td class="right">   Because unsafe methods (Section 7.1.1 of [Part2]) have the potential</td><td class="lineno" valign="top"></td></tr>
507      <tr><td class="lineno" valign="top"></td><td class="left">   for changing state on the origin server, intervening caches can use</td><td> </td><td class="right">   for changing state on the origin server, intervening caches can use</td><td class="lineno" valign="top"></td></tr>
508      <tr><td class="lineno" valign="top"></td><td class="left">   them to keep their contents up-to-date.</td><td> </td><td class="right">   them to keep their contents up-to-date.</td><td class="lineno" valign="top"></td></tr>
509      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
510      <tr><td class="lineno" valign="top"></td><td class="left">   The following HTTP methods MUST cause a cache to invalidate the</td><td> </td><td class="right">   The following HTTP methods MUST cause a cache to invalidate the</td><td class="lineno" valign="top"></td></tr>
511      <tr><td><a name="diff0040" /></td></tr>
512      <tr><td class="lineno" valign="top"></td><td class="lblock">   <span class="delete">Request-URI</span> as well as the URI(s) in the Location and <span class="delete">Content-</span></td><td> </td><td class="rblock">   <span class="insert">Effective Request URI (Section 4.3 of [Part1])</span> as well as the URI(s)</td><td class="lineno" valign="top"></td></tr>
513      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   Location</span> headers (if present):</td><td> </td><td class="rblock">   in the Location and <span class="insert">Content-Location</span> headers (if present):</td><td class="lineno" valign="top"></td></tr>
514      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
515      <tr><td class="lineno" valign="top"></td><td class="left">   o  PUT</td><td> </td><td class="right">   o  PUT</td><td class="lineno" valign="top"></td></tr>
516      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
517      <tr><td class="lineno" valign="top"></td><td class="left">   o  DELETE</td><td> </td><td class="right">   o  DELETE</td><td class="lineno" valign="top"></td></tr>
518      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
519      <tr><td class="lineno" valign="top"></td><td class="left">   o  POST</td><td> </td><td class="right">   o  POST</td><td class="lineno" valign="top"></td></tr>
520      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
521      <tr><td class="lineno" valign="top"></td><td class="left">   An invalidation based on a URI from a Location or Content-Location</td><td> </td><td class="right">   An invalidation based on a URI from a Location or Content-Location</td><td class="lineno" valign="top"></td></tr>
522      <tr><td class="lineno" valign="top"></td><td class="left">   header MUST NOT be performed if the host part of that URI differs</td><td> </td><td class="right">   header MUST NOT be performed if the host part of that URI differs</td><td class="lineno" valign="top"></td></tr>
523      <tr><td><a name="diff0041" /></td></tr>
524      <tr><td class="lineno" valign="top"></td><td class="lblock">   from the host part in the <span class="delete">Request-URI.</span>  This helps prevent denial of</td><td> </td><td class="rblock">   from the host part in the <span class="insert">Effective Request URI (Section 4.3 of</span></td><td class="lineno" valign="top"></td></tr>
525      <tr><td class="lineno" valign="top"></td><td class="lblock">   service attacks.</td><td> </td><td class="rblock"><span class="insert">   [Part1]).</span>  This helps prevent denial of service attacks.</td><td class="lineno" valign="top"></td></tr>
526      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
527      <tr><td class="lineno" valign="top"></td><td class="left">   [[TODO-def-host-part: "host part" needs to be specified better.]]</td><td> </td><td class="right">   [[TODO-def-host-part: "host part" needs to be specified better.]]</td><td class="lineno" valign="top"></td></tr>
528      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
529      <tr><td class="lineno" valign="top"></td><td class="left">   A cache that passes through requests for methods it does not</td><td> </td><td class="right">   A cache that passes through requests for methods it does not</td><td class="lineno" valign="top"></td></tr>
530      <tr><td><a name="diff0042" /></td></tr>
531      <tr><td class="lineno" valign="top"></td><td class="lblock">   understand SHOULD invalidate the <span class="delete">Request-URI.</span></td><td> </td><td class="rblock">   understand SHOULD invalidate the <span class="insert">Effective Request URI (Section 4.3</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">   of [Part1]).</span></td><td class="lineno" valign="top"></td></tr>
533      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
534      <tr><td class="lineno" valign="top"></td><td class="left">   Here, "invalidate" means that the cache will either remove all stored</td><td> </td><td class="right">   Here, "invalidate" means that the cache will either remove all stored</td><td class="lineno" valign="top"></td></tr>
535      <tr><td><a name="diff0043" /></td></tr>
536      <tr><td class="lineno" valign="top"></td><td class="lblock">   responses related to the <span class="delete">Request-URI,</span> or will mark these as "invalid"</td><td> </td><td class="rblock">   responses related to the <span class="insert">Effective Request URI,</span> or will mark these as</td><td class="lineno" valign="top"></td></tr>
537      <tr><td class="lineno" valign="top"></td><td class="lblock">   and in need of a mandatory validation before they can be returned in</td><td> </td><td class="rblock">   "invalid" and in need of a mandatory validation before they can be</td><td class="lineno" valign="top"></td></tr>
538      <tr><td class="lineno" valign="top"></td><td class="lblock">   response to a subsequent request.</td><td> </td><td class="rblock">   returned in response to a subsequent request.</td><td class="lineno" valign="top"></td></tr>
539      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
540      <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>
541      <tr><td class="lineno" valign="top"></td><td class="left">   invalidated.  For example, the request that caused the change at the</td><td> </td><td class="right">   invalidated.  For example, the request that caused the change at the</td><td class="lineno" valign="top"></td></tr>
542      <tr><td class="lineno" valign="top"></td><td class="left">   origin server might not have gone through the cache where a response</td><td> </td><td class="right">   origin server might not have gone through the cache where a response</td><td class="lineno" valign="top"></td></tr>
543      <tr><td class="lineno" valign="top"></td><td class="left">   is stored.</td><td> </td><td class="right">   is stored.</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 class="lineno" valign="top"></td><td class="left">   [[TODO-spec-success-invalidate: specify that only successful (2xx,</td><td> </td><td class="right">   [[TODO-spec-success-invalidate: specify that only successful (2xx,</td><td class="lineno" valign="top"></td></tr>
546      <tr><td class="lineno" valign="top"></td><td class="left">   3xx?) responses invalidate.]]</td><td> </td><td class="right">   3xx?) responses invalidate.]]</td><td class="lineno" valign="top"></td></tr>
547      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
548      <tr><td><a name="diff0044" /></td></tr>
549      <tr><td class="lineno" valign="top"></td><td class="lblock">2.6.  Caching Negotiated Responses</td><td> </td><td class="rblock">2.6.  <span class="insert">Shared Caching of Authenticated Responses</span></td><td class="lineno" valign="top"></td></tr>
550      <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>
551      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Shared caches MUST NOT use a cached response to a request with an</span></td><td class="lineno" valign="top"></td></tr>
552      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Authorization header (Section 3.1 of [Part7]) to satisfy any</span></td><td class="lineno" valign="top"></td></tr>
553      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   subsequent request unless a cache directive that allows such</span></td><td class="lineno" valign="top"></td></tr>
554      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   responses to be stored is present in the response.</span></td><td class="lineno" valign="top"></td></tr>
555      <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>
556      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   In this specification, the following Cache-Control response</span></td><td class="lineno" valign="top"></td></tr>
557      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   directives (Section 3.2.2) have such an effect: must-revalidate,</span></td><td class="lineno" valign="top"></td></tr>
558      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   public, s-maxage.</span></td><td class="lineno" valign="top"></td></tr>
559      <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>
560      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Note that cached responses that contain the "must-revalidate" and/or</span></td><td class="lineno" valign="top"></td></tr>
561      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   "s-maxage" response directives are not allowed to be served stale</span></td><td class="lineno" valign="top"></td></tr>
562      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   (Section 2.3.3) by shared caches.  In particular, a response with</span></td><td class="lineno" valign="top"></td></tr>
563      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   either "max-age=0, must-revalidate" or "s-maxage=0" cannot be used to</span></td><td class="lineno" valign="top"></td></tr>
564      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   satisfy a subsequent request without revalidating it on the origin</span></td><td class="lineno" valign="top"></td></tr>
565      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   server.</span></td><td class="lineno" valign="top"></td></tr>
566      <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>
567      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">2.7.</span>  Caching Negotiated Responses</td><td class="lineno" valign="top"></td></tr>
568      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
569      <tr><td class="lineno" valign="top"></td><td class="left">   When a cache receives a request that can be satisfied by a stored</td><td> </td><td class="right">   When a cache receives a request that can be satisfied by a stored</td><td class="lineno" valign="top"></td></tr>
570      <tr><td class="lineno" valign="top"></td><td class="left">   response that has a Vary header field (Section 3.5), it MUST NOT use</td><td> </td><td class="right">   response that has a Vary header field (Section 3.5), it MUST NOT use</td><td class="lineno" valign="top"></td></tr>
571      <tr><td class="lineno" valign="top"></td><td class="left">   that response unless all of the selecting request-headers nominated</td><td> </td><td class="right">   that response unless all of the selecting request-headers nominated</td><td class="lineno" valign="top"></td></tr>
572      <tr><td class="lineno" valign="top"></td><td class="left">   by the Vary header match in both the original request (i.e., that</td><td> </td><td class="right">   by the Vary header match in both the original request (i.e., that</td><td class="lineno" valign="top"></td></tr>
573      <tr><td class="lineno" valign="top"></td><td class="left">   associated with the stored response), and the presented request.</td><td> </td><td class="right">   associated with the stored response), and the presented request.</td><td class="lineno" valign="top"></td></tr>
574      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
575      <tr><td class="lineno" valign="top"></td><td class="left">   The selecting request-headers from two requests are defined to match</td><td> </td><td class="right">   The selecting request-headers from two requests are defined to match</td><td class="lineno" valign="top"></td></tr>
576      <tr><td class="lineno" valign="top"></td><td class="left">   if and only if those in the first request can be transformed to those</td><td> </td><td class="right">   if and only if those in the first request can be transformed to those</td><td class="lineno" valign="top"></td></tr>
577      <tr><td class="lineno" valign="top"></td><td class="left">   in the second request by applying any of the following:</td><td> </td><td class="right">   in the second request by applying any of the following:</td><td class="lineno" valign="top"></td></tr>
578      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
579      <tr bgcolor="gray" ><td></td><th><a name="part-l9" /><small>skipping to change at</small><em> page 16, line 29</em></th><th> </th><th><a name="part-r9" /><small>skipping to change at</small><em> page 16, line 47</em></th><td></td></tr>
580      <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>
581      <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>
582      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
583      <tr><td class="lineno" valign="top"></td><td class="left">   The stored response with matching selecting request-headers is known</td><td> </td><td class="right">   The stored response with matching selecting request-headers is known</td><td class="lineno" valign="top"></td></tr>
584      <tr><td class="lineno" valign="top"></td><td class="left">   as the selected response.</td><td> </td><td class="right">   as the selected response.</td><td class="lineno" valign="top"></td></tr>
585      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
586      <tr><td class="lineno" valign="top"></td><td class="left">   If no selected response is available, the cache MAY forward the</td><td> </td><td class="right">   If no selected response is available, the cache MAY 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><a name="diff0045" /></td></tr>
591      <tr><td class="lineno" valign="top"></td><td class="lblock">2.<span class="delete">7</span>.  Combining Responses</td><td> </td><td class="rblock">2.<span class="insert">8</span>.  Combining Responses</td><td class="lineno" valign="top"></td></tr>
592      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
593      <tr><td class="lineno" valign="top"></td><td class="left">   When a cache receives a 304 (Not Modified) response or a 206 (Partial</td><td> </td><td class="right">   When a cache receives a 304 (Not Modified) response or a 206 (Partial</td><td class="lineno" valign="top"></td></tr>
594      <tr><td class="lineno" valign="top"></td><td class="left">   Content) response (in this section, the "new" response"), it needs to</td><td> </td><td class="right">   Content) response (in this section, the "new" response"), it needs to</td><td class="lineno" valign="top"></td></tr>
595      <tr><td class="lineno" valign="top"></td><td class="left">   created an updated response by combining the stored response with the</td><td> </td><td class="right">   created an updated response by combining the stored response with the</td><td class="lineno" valign="top"></td></tr>
596      <tr><td class="lineno" valign="top"></td><td class="left">   new one, so that the updated response can be used to satisfy the</td><td> </td><td class="right">   new one, so that the updated response can be used to satisfy the</td><td class="lineno" valign="top"></td></tr>
597      <tr><td class="lineno" valign="top"></td><td class="left">   request.</td><td> </td><td class="right">   request.</td><td class="lineno" valign="top"></td></tr>
598      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
599      <tr><td class="lineno" valign="top"></td><td class="left">   If the new response contains an ETag, it identifies the stored</td><td> </td><td class="right">   If the new response contains an ETag, it identifies the stored</td><td class="lineno" valign="top"></td></tr>
600      <tr><td class="lineno" valign="top"></td><td class="left">   response to use.  [[TODO-mention-CL: may need language about Content-</td><td> </td><td class="right">   response to use.  [[TODO-mention-CL: may need language about Content-</td><td class="lineno" valign="top"></td></tr>
601      <tr><td class="lineno" valign="top"></td><td class="left">   Location here]][[TODO-inm-mult-etags: cover case where INM with</td><td> </td><td class="right">   Location here]][[TODO-inm-mult-etags: cover case where INM with</td><td class="lineno" valign="top"></td></tr>
602      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
603      <tr bgcolor="gray" ><td></td><th><a name="part-l10" /><small>skipping to change at</small><em> page 18, line 9</em></th><th> </th><th><a name="part-r10" /><small>skipping to change at</small><em> page 18, line 27</em></th><td></td></tr>
604      <tr><td class="lineno" valign="top"></td><td class="left">   MUST transmit an Age header with a field-value of 2147483648 (2^31).</td><td> </td><td class="right">   MUST transmit an Age header with a field-value of 2147483648 (2^31).</td><td class="lineno" valign="top"></td></tr>
605      <tr><td class="lineno" valign="top"></td><td class="left">   Caches SHOULD use an arithmetic type of at least 31 bits of range.</td><td> </td><td class="right">   Caches SHOULD use an arithmetic type of at least 31 bits of range.</td><td class="lineno" valign="top"></td></tr>
606      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
607      <tr><td class="lineno" valign="top"></td><td class="left">   The presence of an Age header field in a response implies that a</td><td> </td><td class="right">   The presence of an Age header field in a response implies that a</td><td class="lineno" valign="top"></td></tr>
608      <tr><td class="lineno" valign="top"></td><td class="left">   response is not first-hand.  However, the converse is not true, since</td><td> </td><td class="right">   response is not first-hand.  However, the converse is not true, since</td><td class="lineno" valign="top"></td></tr>
609      <tr><td class="lineno" valign="top"></td><td class="left">   HTTP/1.0 caches may not implement the Age header field.</td><td> </td><td class="right">   HTTP/1.0 caches may not implement the Age header field.</td><td class="lineno" valign="top"></td></tr>
610      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
611      <tr><td class="lineno" valign="top"></td><td class="left">3.2.  Cache-Control</td><td> </td><td class="right">3.2.  Cache-Control</td><td class="lineno" valign="top"></td></tr>
612      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
613      <tr><td class="lineno" valign="top"></td><td class="left">   The "Cache-Control" general-header field is used to specify</td><td> </td><td class="right">   The "Cache-Control" general-header field is used to specify</td><td class="lineno" valign="top"></td></tr>
614      <tr><td><a name="diff0046" /></td></tr>
615      <tr><td class="lineno" valign="top"></td><td class="lblock">   directives <span class="delete">that MUST be obeyed by all</span> caches along the <span class="delete">request/</span></td><td> </td><td class="rblock">   directives <span class="insert">for</span> caches along the <span class="insert">request/response</span> chain.  Such cache</td><td class="lineno" valign="top"></td></tr>
616      <tr><td class="lineno" valign="top"></td><td class="lblock"><span class="delete">   response</span> chain.  Such cache directives are unidirectional in that the</td><td> </td><td class="rblock">   directives are unidirectional in that the presence of a directive in</td><td class="lineno" valign="top"></td></tr>
617      <tr><td class="lineno" valign="top"></td><td class="lblock">   presence of a directive in a request does not imply that the same</td><td> </td><td class="rblock">   a request does not imply that the same directive is to be given in</td><td class="lineno" valign="top"></td></tr>
618      <tr><td class="lineno" valign="top"></td><td class="lblock">   directive is to be given in the response.</td><td> </td><td class="rblock">   the response.</td><td class="lineno" valign="top"></td></tr>
619      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
620      <tr><td><a name="diff0047" /></td></tr>
621      <tr><td class="lineno" valign="top"></td><td class="lblock">      <span class="delete">Note that</span> HTTP/1.0 caches might not implement Cache-Control and</td><td> </td><td class="rblock">   <span class="insert">HTTP/1.1 caches MUST obey the requirements of the Cache-Control</span></td><td class="lineno" valign="top"></td></tr>
622      <tr><td class="lineno" valign="top"></td><td class="lblock">      might only implement Pragma: no-cache (see Section 3.4).</td><td> </td><td class="rblock"><span class="insert">   directives defined in this section.  See Section 3.2.3 for</span></td><td class="lineno" valign="top"></td></tr>
623      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   information about how Cache-Control directives defined elsewhere are</span></td><td class="lineno" valign="top"></td></tr>
624      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   handled.</span></td><td class="lineno" valign="top"></td></tr>
625      <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>
626      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">      Note:</span> HTTP/1.0 caches might not implement Cache-Control and might</td><td class="lineno" valign="top"></td></tr>
627      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">      only implement Pragma: no-cache (see Section 3.4).</td><td class="lineno" valign="top"></td></tr>
628      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
629      <tr><td class="lineno" valign="top"></td><td class="left">   Cache directives MUST be passed through by a proxy or gateway</td><td> </td><td class="right">   Cache directives MUST be passed through by a proxy or gateway</td><td class="lineno" valign="top"></td></tr>
630      <tr><td class="lineno" valign="top"></td><td class="left">   application, regardless of their significance to that application,</td><td> </td><td class="right">   application, regardless of their significance to that application,</td><td class="lineno" valign="top"></td></tr>
631      <tr><td class="lineno" valign="top"></td><td class="left">   since the directives might be applicable to all recipients along the</td><td> </td><td class="right">   since the directives might be applicable to all recipients along the</td><td class="lineno" valign="top"></td></tr>
632      <tr><td class="lineno" valign="top"></td><td class="left">   request/response chain.  It is not possible to target a directive to</td><td> </td><td class="right">   request/response chain.  It is not possible to target a directive to</td><td class="lineno" valign="top"></td></tr>
633      <tr><td class="lineno" valign="top"></td><td class="left">   a specific cache.</td><td> </td><td class="right">   a specific cache.</td><td class="lineno" valign="top"></td></tr>
634      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
635      <tr><td class="lineno" valign="top"></td><td class="left">     Cache-Control   = "Cache-Control" ":" OWS Cache-Control-v</td><td> </td><td class="right">     Cache-Control   = "Cache-Control" ":" OWS Cache-Control-v</td><td class="lineno" valign="top"></td></tr>
636      <tr><td class="lineno" valign="top"></td><td class="left">     Cache-Control-v = 1#cache-directive</td><td> </td><td class="right">     Cache-Control-v = 1#cache-directive</td><td class="lineno" valign="top"></td></tr>
637      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
638      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
639      <tr bgcolor="gray" ><td></td><th><a name="part-l11" /><small>skipping to change at</small><em> page 19, line 21</em></th><th> </th><th><a name="part-r11" /><small>skipping to change at</small><em> page 19, line 44</em></th><td></td></tr>
640      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
641      <tr><td class="lineno" valign="top"></td><td class="left">      This directive is NOT a reliable or sufficient mechanism for</td><td> </td><td class="right">      This directive is NOT a reliable or sufficient mechanism for</td><td class="lineno" valign="top"></td></tr>
642      <tr><td class="lineno" valign="top"></td><td class="left">      ensuring privacy.  In particular, malicious or compromised caches</td><td> </td><td class="right">      ensuring privacy.  In particular, malicious or compromised caches</td><td class="lineno" valign="top"></td></tr>
643      <tr><td class="lineno" valign="top"></td><td class="left">      might not recognize or obey this directive, and communications</td><td> </td><td class="right">      might not recognize or obey this directive, and communications</td><td class="lineno" valign="top"></td></tr>
644      <tr><td class="lineno" valign="top"></td><td class="left">      networks may be vulnerable to eavesdropping.</td><td> </td><td class="right">      networks may be vulnerable to eavesdropping.</td><td class="lineno" valign="top"></td></tr>
645      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
646      <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>
647      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
648      <tr><td class="lineno" valign="top"></td><td class="left">      The max-age request directive indicates that the client is willing</td><td> </td><td class="right">      The max-age request directive indicates that the client is willing</td><td class="lineno" valign="top"></td></tr>
649      <tr><td class="lineno" valign="top"></td><td class="left">      to accept a response whose age is no greater than the specified</td><td> </td><td class="right">      to accept a response whose age is no greater than the specified</td><td class="lineno" valign="top"></td></tr>
650      <tr><td><a name="diff0048" /></td></tr>
651      <tr><td class="lineno" valign="top"></td><td class="lblock">      time in seconds.  Unless max-stale directive is also <span class="delete">included,</span> the</td><td> </td><td class="rblock">      time in seconds.  Unless <span class="insert">the</span> max-stale <span class="insert">request</span> directive is also</td><td class="lineno" valign="top"></td></tr>
652      <tr><td class="lineno" valign="top"></td><td class="lblock">      client is not willing to accept a stale response.</td><td> </td><td class="rblock">      <span class="insert">present,</span> the client is not willing to accept a stale response.</td><td class="lineno" valign="top"></td></tr>
653      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
654      <tr><td class="lineno" valign="top"></td><td class="left">   max-stale</td><td> </td><td class="right">   max-stale</td><td class="lineno" valign="top"></td></tr>
655      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
656      <tr><td class="lineno" valign="top"></td><td class="left">      The max-stale request directive indicates that the client is</td><td> </td><td class="right">      The max-stale request directive indicates that the client is</td><td class="lineno" valign="top"></td></tr>
657      <tr><td class="lineno" valign="top"></td><td class="left">      willing to accept a response that has exceeded its expiration</td><td> </td><td class="right">      willing to accept a response that has exceeded its expiration</td><td class="lineno" valign="top"></td></tr>
658      <tr><td class="lineno" valign="top"></td><td class="left">      time.  If max-stale is assigned a value, then the client is</td><td> </td><td class="right">      time.  If max-stale is assigned a value, then the client is</td><td class="lineno" valign="top"></td></tr>
659      <tr><td class="lineno" valign="top"></td><td class="left">      willing to accept a response that has exceeded its expiration time</td><td> </td><td class="right">      willing to accept a response that has exceeded its expiration time</td><td class="lineno" valign="top"></td></tr>
660      <tr><td class="lineno" valign="top"></td><td class="left">      by no more than the specified number of seconds.  If no value is</td><td> </td><td class="right">      by no more than the specified number of seconds.  If no value is</td><td class="lineno" valign="top"></td></tr>
661      <tr><td class="lineno" valign="top"></td><td class="left">      assigned to max-stale, then the client is willing to accept a</td><td> </td><td class="right">      assigned to max-stale, then the client is willing to accept a</td><td class="lineno" valign="top"></td></tr>
662      <tr><td class="lineno" valign="top"></td><td class="left">      stale response of any age.  [[TODO-staleness: of any staleness?</td><td> </td><td class="right">      stale response of any age.  [[TODO-staleness: of any staleness?</td><td class="lineno" valign="top"></td></tr>
663      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
664      <tr bgcolor="gray" ><td></td><th><a name="part-l12" /><small>skipping to change at</small><em> page 23, line 31</em></th><th> </th><th><a name="part-r12" /><small>skipping to change at</small><em> page 24, line 8</em></th><td></td></tr>
665      <tr><td class="lineno" valign="top"></td><td class="left">   does not understand the community cache-extension, since it will also</td><td> </td><td class="right">   does not understand the community cache-extension, since it will also</td><td class="lineno" valign="top"></td></tr>
666      <tr><td class="lineno" valign="top"></td><td class="left">   see and understand the private directive and thus default to the safe</td><td> </td><td class="right">   see and understand the private directive and thus default to the safe</td><td class="lineno" valign="top"></td></tr>
667      <tr><td class="lineno" valign="top"></td><td class="left">   behavior.</td><td> </td><td class="right">   behavior.</td><td class="lineno" valign="top"></td></tr>
668      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
669      <tr><td class="lineno" valign="top"></td><td class="left">   Unrecognized cache directives MUST be ignored; it is assumed that any</td><td> </td><td class="right">   Unrecognized cache directives MUST be ignored; it is assumed that any</td><td class="lineno" valign="top"></td></tr>
670      <tr><td class="lineno" valign="top"></td><td class="left">   cache directive likely to be unrecognized by an HTTP/1.1 cache will</td><td> </td><td class="right">   cache directive likely to be unrecognized by an HTTP/1.1 cache will</td><td class="lineno" valign="top"></td></tr>
671      <tr><td class="lineno" valign="top"></td><td class="left">   be combined with standard directives (or the response's default</td><td> </td><td class="right">   be combined with standard directives (or the response's default</td><td class="lineno" valign="top"></td></tr>
672      <tr><td class="lineno" valign="top"></td><td class="left">   cacheability) such that the cache behavior will remain minimally</td><td> </td><td class="right">   cacheability) such that the cache behavior will remain minimally</td><td class="lineno" valign="top"></td></tr>
673      <tr><td class="lineno" valign="top"></td><td class="left">   correct even if the cache does not understand the extension(s).</td><td> </td><td class="right">   correct even if the cache does not understand the extension(s).</td><td class="lineno" valign="top"></td></tr>
674      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
675      <tr><td><a name="diff0049" /></td></tr>
676      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">   <span class="insert">The HTTP Cache Directive Registry defines the name space for the</span></td><td class="lineno" valign="top"></td></tr>
677      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   cache directives.</span></td><td class="lineno" valign="top"></td></tr>
678      <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>
679      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Registrations MUST include the following fields:</span></td><td class="lineno" valign="top"></td></tr>
680      <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>
681      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  Cache Directive Name</span></td><td class="lineno" valign="top"></td></tr>
682      <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>
683      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   o  Pointer to specification text</span></td><td class="lineno" valign="top"></td></tr>
684      <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>
685      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   Values to be added to this name space are subject to IETF review</span></td><td class="lineno" valign="top"></td></tr>
686      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   ([RFC5226], Section 4.1).</span></td><td class="lineno" valign="top"></td></tr>
687      <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>
688      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   The registry itself is maintained at</span></td><td class="lineno" valign="top"></td></tr>
689      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock"><span class="insert">   &lt;http://www.iana.org/assignments/http-cache-directives&gt;.</span></td><td class="lineno" valign="top"></td></tr>
690      <tr><td class="lineno" valign="top"></td><td class="lblock"></td><td> </td><td class="rblock">                                                                         </td><td class="lineno" valign="top"></td></tr>
691      <tr><td class="lineno" valign="top"></td><td class="left">3.3.  Expires</td><td> </td><td class="right">3.3.  Expires</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 class="lineno" valign="top"></td><td class="left">   The "Expires" entity-header field gives the date/time after which the</td><td> </td><td class="right">   The "Expires" entity-header field gives the date/time after which the</td><td class="lineno" valign="top"></td></tr>
694      <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>
695      <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>
696      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
697      <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>
698      <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>
699      <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>
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"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
702      <tr bgcolor="gray" ><td></td><th><a name="part-l13" /><small>skipping to change at</small><em> page 25, line 4</em></th><th> </th><th><a name="part-r13" /><small>skipping to change at</small><em> page 25, line 43</em></th><td></td></tr>
703      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
704      <tr><td class="lineno" valign="top"></td><td class="left">   This mechanism is deprecated; no new Pragma directives will be</td><td> </td><td class="right">   This mechanism is deprecated; no new Pragma directives will be</td><td class="lineno" valign="top"></td></tr>
705      <tr><td class="lineno" valign="top"></td><td class="left">   defined in HTTP.</td><td> </td><td class="right">   defined in HTTP.</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">3.5.  Vary</td><td> </td><td class="right">3.5.  Vary</td><td class="lineno" valign="top"></td></tr>
708      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
709      <tr><td class="lineno" valign="top"></td><td class="left">   The "Vary" response-header field conveys the set of request-header</td><td> </td><td class="right">   The "Vary" response-header field conveys the set of request-header</td><td class="lineno" valign="top"></td></tr>
710      <tr><td class="lineno" valign="top"></td><td class="left">   fields that were used to select the representation.</td><td> </td><td class="right">   fields that were used to select the representation.</td><td class="lineno" valign="top"></td></tr>
711      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
712      <tr><td class="lineno" valign="top"></td><td class="left">   Caches use this information, in part, to determine whether a stored</td><td> </td><td class="right">   Caches use this information, in part, to determine whether a stored</td><td class="lineno" valign="top"></td></tr>
713      <tr><td><a name="diff0050" /></td></tr>
714      <tr><td class="lineno" valign="top"></td><td class="lblock">   response can be used to satisfy a given request; see Section 2.<span class="delete">6</span>.</td><td> </td><td class="rblock">   response can be used to satisfy a given request; see Section 2.<span class="insert">7</span>.</td><td class="lineno" valign="top"></td></tr>
715      <tr><td class="lineno" valign="top"></td><td class="left">   determines, while the response is fresh, whether a cache is permitted</td><td> </td><td class="right">   determines, while the response is fresh, whether a cache is permitted</td><td class="lineno" valign="top"></td></tr>
716      <tr><td class="lineno" valign="top"></td><td class="left">   to use the response to reply to a subsequent request without</td><td> </td><td class="right">   to use the response to reply to a subsequent request without</td><td class="lineno" valign="top"></td></tr>
717      <tr><td><a name="diff0051" /></td></tr>
718      <tr><td class="lineno" valign="top"></td><td class="lblock">   validation; see Section 2.<span class="delete">6</span>.</td><td> </td><td class="rblock">   validation; see Section 2.<span class="insert">7</span>.</td><td class="lineno" valign="top"></td></tr>
719      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
720      <tr><td class="lineno" valign="top"></td><td class="left">   In uncacheable or stale responses, the Vary field value advises the</td><td> </td><td class="right">   In uncacheable or stale responses, the Vary field value advises the</td><td class="lineno" valign="top"></td></tr>
721      <tr><td class="lineno" valign="top"></td><td class="left">   user agent about the criteria that were used to select the</td><td> </td><td class="right">   user agent about the criteria that were used to select the</td><td class="lineno" valign="top"></td></tr>
722      <tr><td class="lineno" valign="top"></td><td class="left">   representation.</td><td> </td><td class="right">   representation.</td><td class="lineno" valign="top"></td></tr>
723      <tr><td class="lineno" valign="top"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno" valign="top"></td></tr>
724      <tr><td class="lineno" valign="top"></td><td class="left">     Vary   = "Vary" ":" OWS Vary-v</td><td> </td><td class="right">     Vary   = "Vary" ":" OWS Vary-v</td><td class="lineno" valign="top"></td></tr>
725      <tr><td class="lineno" valign="top"></td><td class="left">     Vary-v = "*" / 1#field-name</td><td> </td><td class="right">     Vary-v = "*" / 1#field-name</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">   The set of header fields named by the Vary field value is known as</td><td> </td><td class="right">   The set of header fields named by the Vary field value is known as</td><td class="lineno" valign="top"></td></tr>
728      <tr><td class="lineno" valign="top"></td><td class="left">   the selecting request-headers.</td><td> </td><td class="right">   the selecting request-headers.</td><td class="lineno" valign="top"></td></tr>
729      <tr><td class="lineno"></td><td class="left"></td><td> </td><td class="right"></td><td class="lineno"></td></tr>
730      <tr bgcolor="gray" ><td></td><th><a name="part-l14" /><small>skipping to change at</small><em> page 28, line 27</em></th><th> </th><th><a name="part-r14" /><small>skipping to change at</small><em> page 29, line 22</em></th><td></td></tr>
731      <tr><td class="lineno" valign="top"></td><td class="left">   The freshness model (Section 2.3) does not necessarily apply to</td><td> </td><td class="right">   The freshness model (Section 2.3) does not necessarily apply to</td><td class="lineno" valign="top"></td></tr>
732      <tr><td class="lineno" valign="top"></td><td class="left">   history mechanisms.  I.e., a history mechanism can display a previous</td><td> </td