Ignore:
Timestamp:
26/02/11 10:54:51 (10 years ago)
Author:
julian.reschke@…
Message:

add sender advice appendix, remove fallback bug note from earlier part of the spec

Location:
draft-ietf-httpbis-content-disp/latest
Files:
2 edited

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  • draft-ietf-httpbis-content-disp/latest/draft-ietf-httpbis-content-disp.html

    r1141 r1142  
    400400      <link rel="Appendix" title="B Differences compared to RFC 2183" href="#rfc.section.B">
    401401      <link rel="Appendix" title="C Alternative Approaches to Internationalization" href="#rfc.section.C">
    402       <link rel="Appendix" title="D Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.D">
     402      <link rel="Appendix" title="D Advice on Generating Content-Disposition Header Fields" href="#rfc.section.D">
     403      <link rel="Appendix" title="E Change Log (to be removed by RFC Editor before publication)" href="#rfc.section.E">
    403404      <meta name="generator" content="http://greenbytes.de/tech/webdav/rfc2629.xslt, Revision 1.540, 2011-01-10 09:27:20, XSLT vendor: SAXON 8.9 from Saxonica http://www.saxonica.com/">
    404405      <link rel="schema.dct" href="http://purl.org/dc/terms/">
    … …  
    448449         list is at &lt;<a href="http://trac.tools.ietf.org/wg/httpbis/trac/query?component=content-disp">http://trac.tools.ietf.org/wg/httpbis/trac/query?component=content-disp</a>&gt; and related documents (including fancy diffs) can be found at &lt;<a href="http://tools.ietf.org/wg/httpbis/">http://tools.ietf.org/wg/httpbis/</a>&gt;.
    449450      </p> 
    450       <p>The changes in this draft are summarized in <a href="#changes.since.05" title="Since draft-ietf-httpbis-content-disp-05">Appendix&nbsp;D.10</a>.
     451      <p>The changes in this draft are summarized in <a href="#changes.since.05" title="Since draft-ietf-httpbis-content-disp-05">Appendix&nbsp;E.10</a>.
    451452      </p>
    452453      <h1><a id="rfc.status" href="#rfc.status">Status of This Memo</a></h1>
    … …  
    505506            </ul>
    506507         </li>
    507          <li>D.&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
    508                <li>D.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.1">Since draft-reschke-rfc2183-in-http-00</a></li>
    509                <li>D.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.2">Since draft-reschke-rfc2183-in-http-01</a></li>
    510                <li>D.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.3">Since draft-reschke-rfc2183-in-http-02</a></li>
    511                <li>D.4&nbsp;&nbsp;&nbsp;<a href="#rfc.section.D.4">Since draft-reschke-rfc2183-in-http-03</a></li>
    512                <li>D.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></li>
    513                <li>D.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></li>
    514                <li>D.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></li>
    515                <li>D.8&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></li>
    516                <li>D.9&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></li>
    517                <li>D.10&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-content-disp-05</a></li>
     508         <li>D.&nbsp;&nbsp;&nbsp;<a href="#advice.generating">Advice on Generating Content-Disposition Header Fields</a></li>
     509         <li>E.&nbsp;&nbsp;&nbsp;<a href="#change.log">Change Log (to be removed by RFC Editor before publication)</a><ul>
     510               <li>E.1&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.1">Since draft-reschke-rfc2183-in-http-00</a></li>
     511               <li>E.2&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.2">Since draft-reschke-rfc2183-in-http-01</a></li>
     512               <li>E.3&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.3">Since draft-reschke-rfc2183-in-http-02</a></li>
     513               <li>E.4&nbsp;&nbsp;&nbsp;<a href="#rfc.section.E.4">Since draft-reschke-rfc2183-in-http-03</a></li>
     514               <li>E.5&nbsp;&nbsp;&nbsp;<a href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></li>
     515               <li>E.6&nbsp;&nbsp;&nbsp;<a href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></li>
     516               <li>E.7&nbsp;&nbsp;&nbsp;<a href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></li>
     517               <li>E.8&nbsp;&nbsp;&nbsp;<a href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></li>
     518               <li>E.9&nbsp;&nbsp;&nbsp;<a href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></li>
     519               <li>E.10&nbsp;&nbsp;&nbsp;<a href="#changes.since.05">Since draft-ietf-httpbis-content-disp-05</a></li>
    518520            </ul>
    519521         </li>
    … …  
    673675                     filename="EURO rates";
    674676                     filename*=utf-8''<b>%e2%82%ac</b>%20rates
    675 </pre>  <p>Note: as of February 2011, those user agents that do not support the RFC 5987 encoding ignore "filename*" when it occurs after
    676          "filename". Unfortunately, one user agent that does support RFC 5987 picks the "filename" rather than the "filename*" parameter
    677          when it occurs first; it is expected that this situation is going to improve soon.
    678       </p>
     677</pre>  <p>Note: those user agents that do not support the RFC 5987 encoding ignore "filename*" when it occurs after "filename".</p>
    679678      <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a>&nbsp;<a id="i18n" href="#i18n">Internationalization Considerations</a></h1>
    680679      <p id="rfc.section.6.p.1">The "filename*" parameter (<a href="#disposition.parameter.filename" title="Disposition Parameter: 'Filename'">Section&nbsp;4.3</a>), using the encoding defined in <a href="#RFC5987" id="rfc.xref.RFC5987.5"><cite title="Character Set and Language Encoding for Hypertext Transfer Protocol (HTTP) Header Field Parameters">[RFC5987]</cite></a>, allows the server to transmit characters outside the ISO-8859-1 character set, and also to optionally specify the language
    … …  
    905904      </p>
    906905      <p id="rfc.section.C.4.p.4">(**) Starting with IE9RC, but only implements UTF-8.</p>
    907       <h1 id="rfc.section.D"><a href="#rfc.section.D">D.</a>&nbsp;<a id="change.log" href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
    908       <p id="rfc.section.D.p.1">Note: the issues names in the change log entries for draft-reschke-rfc2183-in-http refer to &lt;<a href="http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html">http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html</a>&gt;.
    909       </p>
    910       <h2 id="rfc.section.D.1"><a href="#rfc.section.D.1">D.1</a>&nbsp;Since draft-reschke-rfc2183-in-http-00
     906      <h1 id="rfc.section.D"><a href="#rfc.section.D">D.</a>&nbsp;<a id="advice.generating" href="#advice.generating">Advice on Generating Content-Disposition Header Fields</a></h1>
     907      <p id="rfc.section.D.p.1">To successfully interoperate with existing and future user agents, senders of the Content-Disposition header field are advised
     908         to:
     909      </p>
     910      <p id="rfc.section.D.p.2"> </p>
     911      <ul>
     912         <li>Include a 'filename' parameter when US-ASCII is sufficiently expressive.</li>
     913         <li>Use the 'token' form of the filename parameter only when it does not contain disallowed characters (e.g., spaces); in such
     914            cases, the quoted-string form should be used.
     915         </li>
     916         <li>Avoid including the percent character followed by two hexadecimal characters (e.g., %A9) in the filename parameter, since
     917            some existing implementations consider it to be an escape character, while others will pass it through unchanged.
     918         </li>
     919         <li>Avoid including the "\" character in the quoted-string form of the filename parameter, as escaping is not implemented by some
     920            user agents, and can be considered as an illegal path character.
     921         </li>
     922         <li>Avoid using non-ASCII characters in the filename parameter. Although most existing implementations will decode them as ISO-8859-1,
     923            some will apply heuristics to detect UTF-8, and thus might fail on certain names.
     924         </li>
     925         <li>Include a 'filename*' parameter where the desired filename cannot be expressed faithfully using the 'filename' form. Note
     926            that legacy user agents will not process this, and will fall back to using the 'filename' parameter's content.
     927         </li>
     928         <li>When a 'filename*' parameter is sent, to also generate a 'filename' parameter as a fallback for user agents that do not support
     929            the 'filename*' form, if possible. This can be done by substituting characters with US-ASCII sequences (e.g., Unicode character
     930            point U+00E4 (LATIN SMALL LETTER A WITH DIARESIS) by "ae"). Note that this may not be possible in some locales.
     931         </li>
     932         <li>When a 'filename' parameter is included as a fallback (as per above), 'filename' should occur first, due to parsing problems
     933            in some existing implementations. <span class="comment" id="fallbackbug">[<a href="#fallbackbug" class="smpl">fallbackbug</a>: Firefox is known to pick the wrong parameter; a bug fix is scheduled for Firefox 5. --jre]</span>
     934         </li>
     935         <li>Use UTF-8 as the encoding of the 'filename*' parameter, when present, because at least one existing implementation only implements
     936            that encoding.
     937         </li>
     938      </ul>
     939      <p id="rfc.section.D.p.3">Note that this advice is based upon UA behaviour at the time of writing, and might be superseded. &lt;<a href="http://purl.org/NET/http/content-disposition-tests">http://purl.org/NET/http/content-disposition-tests</a>&gt; provides an overview of current levels of support in various implementations.
     940      </p>
     941      <h1 id="rfc.section.E"><a href="#rfc.section.E">E.</a>&nbsp;<a id="change.log" href="#change.log">Change Log (to be removed by RFC Editor before publication)</a></h1>
     942      <p id="rfc.section.E.p.1">Note: the issues names in the change log entries for draft-reschke-rfc2183-in-http refer to &lt;<a href="http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html">http://greenbytes.de/tech/webdav/draft-reschke-rfc2183-in-http-issues.html</a>&gt;.
     943      </p>
     944      <h2 id="rfc.section.E.1"><a href="#rfc.section.E.1">E.1</a>&nbsp;Since draft-reschke-rfc2183-in-http-00
    911945      </h2>
    912       <p id="rfc.section.D.1.p.1">Adjust terminology ("header" -&gt; "header field"). Update rfc2231-in-http reference.</p>
    913       <h2 id="rfc.section.D.2"><a href="#rfc.section.D.2">D.2</a>&nbsp;Since draft-reschke-rfc2183-in-http-01
     946      <p id="rfc.section.E.1.p.1">Adjust terminology ("header" -&gt; "header field"). Update rfc2231-in-http reference.</p>
     947      <h2 id="rfc.section.E.2"><a href="#rfc.section.E.2">E.2</a>&nbsp;Since draft-reschke-rfc2183-in-http-01
    914948      </h2>
    915       <p id="rfc.section.D.2.p.1">Update rfc2231-in-http reference. Actually define the "filename" parameter. Add internationalization considerations. Add examples
     949      <p id="rfc.section.E.2.p.1">Update rfc2231-in-http reference. Actually define the "filename" parameter. Add internationalization considerations. Add examples
    916950         using the RFC 5987 encoding. Add overview over other approaches, plus a table reporting implementation status. Add and resolve
    917951         issue "nodep2183". Add issues "asciivsiso", "deplboth", "quoted", and "registry".
    918952      </p>
    919       <h2 id="rfc.section.D.3"><a href="#rfc.section.D.3">D.3</a>&nbsp;Since draft-reschke-rfc2183-in-http-02
     953      <h2 id="rfc.section.E.3"><a href="#rfc.section.E.3">E.3</a>&nbsp;Since draft-reschke-rfc2183-in-http-02
    920954      </h2>
    921       <p id="rfc.section.D.3.p.1">Add and close issue "docfallback". Close issues "asciivsiso", "deplboth", "quoted", and "registry".</p>
    922       <h2 id="rfc.section.D.4"><a href="#rfc.section.D.4">D.4</a>&nbsp;Since draft-reschke-rfc2183-in-http-03
     955      <p id="rfc.section.E.3.p.1">Add and close issue "docfallback". Close issues "asciivsiso", "deplboth", "quoted", and "registry".</p>
     956      <h2 id="rfc.section.E.4"><a href="#rfc.section.E.4">E.4</a>&nbsp;Since draft-reschke-rfc2183-in-http-03
    923957      </h2>
    924       <p id="rfc.section.D.4.p.1">Updated to be a Working Draft of the IETF HTTPbis Working Group.</p>
    925       <h2 id="rfc.section.D.5"><a href="#rfc.section.D.5">D.5</a>&nbsp;<a id="changes.since.00" href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></h2>
    926       <p id="rfc.section.D.5.p.1">Closed issues: </p>
     958      <p id="rfc.section.E.4.p.1">Updated to be a Working Draft of the IETF HTTPbis Working Group.</p>
     959      <h2 id="rfc.section.E.5"><a href="#rfc.section.E.5">E.5</a>&nbsp;<a id="changes.since.00" href="#changes.since.00">Since draft-ietf-httpbis-content-disp-00</a></h2>
     960      <p id="rfc.section.E.5.p.1">Closed issues: </p>
    927961      <ul>
    928962         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/242">http://tools.ietf.org/wg/httpbis/trac/ticket/242</a>&gt;: "handling of unknown disposition types"
    929963         </li>
    930964      </ul>
    931       <p id="rfc.section.D.5.p.2">Slightly updated the notes about the proposed fallback behavior.</p>
    932       <h2 id="rfc.section.D.6"><a href="#rfc.section.D.6">D.6</a>&nbsp;<a id="changes.since.01" href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></h2>
    933       <p id="rfc.section.D.6.p.1">Various editorial improvements.</p>
    934       <h2 id="rfc.section.D.7"><a href="#rfc.section.D.7">D.7</a>&nbsp;<a id="changes.since.02" href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></h2>
    935       <p id="rfc.section.D.7.p.1">Closed issues: </p>
     965      <p id="rfc.section.E.5.p.2">Slightly updated the notes about the proposed fallback behavior.</p>
     966      <h2 id="rfc.section.E.6"><a href="#rfc.section.E.6">E.6</a>&nbsp;<a id="changes.since.01" href="#changes.since.01">Since draft-ietf-httpbis-content-disp-01</a></h2>
     967      <p id="rfc.section.E.6.p.1">Various editorial improvements.</p>
     968      <h2 id="rfc.section.E.7"><a href="#rfc.section.E.7">E.7</a>&nbsp;<a id="changes.since.02" href="#changes.since.02">Since draft-ietf-httpbis-content-disp-02</a></h2>
     969      <p id="rfc.section.E.7.p.1">Closed issues: </p>
    936970      <ul>
    937971         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/244">http://tools.ietf.org/wg/httpbis/trac/ticket/244</a>&gt;: "state that repeating parameters are invalid"
    … …  
    942976         </li>
    943977      </ul>
    944       <p id="rfc.section.D.7.p.2">Update <a href="#alternatives.implementations" title="Implementations (to be removed by RFC Editor before publication)">Appendix&nbsp;C.4</a>; Opera 10.63 RC implements the recommended fallback behavior.
    945       </p>
    946       <h2 id="rfc.section.D.8"><a href="#rfc.section.D.8">D.8</a>&nbsp;<a id="changes.since.03" href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></h2>
    947       <p id="rfc.section.D.8.p.1">Closed issues: </p>
     978      <p id="rfc.section.E.7.p.2">Update <a href="#alternatives.implementations" title="Implementations (to be removed by RFC Editor before publication)">Appendix&nbsp;C.4</a>; Opera 10.63 RC implements the recommended fallback behavior.
     979      </p>
     980      <h2 id="rfc.section.E.8"><a href="#rfc.section.E.8">E.8</a>&nbsp;<a id="changes.since.03" href="#changes.since.03">Since draft-ietf-httpbis-content-disp-03</a></h2>
     981      <p id="rfc.section.E.8.p.1">Closed issues: </p>
    948982      <ul>
    949983         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/252">http://tools.ietf.org/wg/httpbis/trac/ticket/252</a>&gt;: "'modification-date' *is* implemented in Konq 4.5"
    … …  
    960994         </li>
    961995      </ul>
    962       <h2 id="rfc.section.D.9"><a href="#rfc.section.D.9">D.9</a>&nbsp;<a id="changes.since.04" href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></h2>
    963       <p id="rfc.section.D.9.p.1">Updated implementation information (Chrome 9 implements RFC 5987, IE 9 RC implements it for UTF-8 only).</p>
    964       <p id="rfc.section.D.9.p.2">Clarify who requirements are on, add a section discussing conformance and handling of invalid field values in general.</p>
    965       <p id="rfc.section.D.9.p.3">Closed issues: </p>
     996      <h2 id="rfc.section.E.9"><a href="#rfc.section.E.9">E.9</a>&nbsp;<a id="changes.since.04" href="#changes.since.04">Since draft-ietf-httpbis-content-disp-04</a></h2>
     997      <p id="rfc.section.E.9.p.1">Updated implementation information (Chrome 9 implements RFC 5987, IE 9 RC implements it for UTF-8 only).</p>
     998      <p id="rfc.section.E.9.p.2">Clarify who requirements are on, add a section discussing conformance and handling of invalid field values in general.</p>
     999      <p id="rfc.section.E.9.p.3">Closed issues: </p>
    9661000      <ul>
    9671001         <li> &lt;<a href="http://trac.tools.ietf.org/wg/httpbis/trac/ticket/243">http://trac.tools.ietf.org/wg/httpbis/trac/ticket/243</a>&gt;: "avoid stating ISO-8859-1 default for header param" (the default is still mentioned, but it was clarified what it applies
    … …  
    9711005         </li>
    9721006      </ul>
    973       <h2 id="rfc.section.D.10"><a href="#rfc.section.D.10">D.10</a>&nbsp;<a id="changes.since.05" href="#changes.since.05">Since draft-ietf-httpbis-content-disp-05</a></h2>
    974       <p id="rfc.section.D.10.p.1">Editorial changes: Fixed two typos where the new Conformance section said "Content-Location" instead of "Content-Disposition".
     1007      <h2 id="rfc.section.E.10"><a href="#rfc.section.E.10">E.10</a>&nbsp;<a id="changes.since.05" href="#changes.since.05">Since draft-ietf-httpbis-content-disp-05</a></h2>
     1008      <p id="rfc.section.E.10.p.1">Editorial changes: Fixed two typos where the new Conformance section said "Content-Location" instead of "Content-Disposition".
    9751009         Cleaned up terminology ("user agent", "recipient", "sender", "message body", ...). Stated what the escape character for quoted-string
    9761010         is. Explained a use case for "inline" disposition type. Updated implementation notes with respect to the fallback behavior.
    9771011      </p>
     1012      <p id="rfc.section.E.10.p.2">Added appendix "Advice on Generating Content-Disposition Header Fields".</p>
    9781013      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
    9791014      <p class="noprint"><a href="#rfc.index.C">C</a> <a href="#rfc.index.H">H</a> <a href="#rfc.index.I">I</a> <a href="#rfc.index.R">R</a>

  • draft-ietf-httpbis-content-disp/latest/draft-ietf-httpbis-content-disp.xml

    r1141 r1142  
    353353</artwork>
    354354<postamble>
    355   Note: as of February 2011, those user agents that do not support the RFC 5987
    356   encoding ignore "filename*" when it occurs after "filename". Unfortunately,
    357   one user agent that does support RFC 5987 picks the "filename" rather
    358   than the "filename*" parameter when it occurs first; it is expected that
    359   this situation is going to improve soon.
     355  Note: those user agents that do not support the RFC 5987 encoding ignore
     356  "filename*" when it occurs after "filename".
    360357</postamble>
    361358</figure>
    … …  
    832829</section>
    833830
     831<section title="Advice on Generating Content-Disposition Header Fields" anchor="advice.generating">
     832<t>
     833  To successfully interoperate with existing and future user agents, senders of
     834  the Content-Disposition header field are advised to:
     835</t>
     836<t>
     837  <list style="symbols">
     838    <t>Include a 'filename' parameter when US-ASCII is sufficiently
     839    expressive.</t>
     840    <t>Use the 'token' form of the filename parameter only when it does not
     841    contain disallowed characters (e.g., spaces); in such cases, the
     842    quoted-string form should be used.</t>
     843    <t>Avoid including the percent character followed by two hexadecimal
     844    characters (e.g., %A9) in the filename parameter, since some existing
     845    implementations consider it to be an escape character, while others will
     846    pass it through unchanged.</t>
     847    <t>Avoid including the "\" character in the quoted-string form of the
     848    filename parameter, as escaping is not implemented by some user agents,
     849    and can be considered as an illegal path character.</t>
     850    <t>Avoid using non-ASCII characters in the filename parameter. Although
     851    most existing implementations will decode them as ISO-8859-1, some
     852    will apply heuristics to detect UTF-8, and thus might fail on certain names.</t>
     853    <t>Include a 'filename*' parameter where the desired filename cannot be
     854    expressed faithfully using the 'filename' form. Note that legacy user
     855    agents will not process this, and will fall back to using the 'filename'
     856    parameter's content.
     857    </t>
     858    <t>When a 'filename*' parameter is sent, to also generate a 'filename'
     859    parameter as a fallback for user agents that do not support the 'filename*'
     860    form, if possible. This can be done by substituting characters with
     861    US-ASCII sequences (e.g., Unicode character point U+00E4 (LATIN SMALL
     862    LETTER A WITH DIARESIS) by "ae"). Note that this may not be possible in
     863    some locales.
     864    </t>
     865    <t>When a 'filename' parameter is included as a fallback (as per above),
     866    'filename' should occur first, due to parsing problems in some existing
     867    implementations.
     868    <cref anchor="fallbackbug" source="jre">
     869    Firefox is known to pick the wrong parameter; a bug fix is scheduled for
     870    Firefox 5.</cref>
     871    </t>
     872    <t>Use UTF-8 as the encoding of the 'filename*' parameter, when present,
     873    because at least one existing implementation only implements that encoding.</t>
     874  </list>
     875</t>
     876<t>
     877  Note that this advice is based upon UA behaviour at the time of writing, and
     878  might be superseded.
     879  <eref target="http://purl.org/NET/http/content-disposition-tests"/> provides
     880  an overview of current levels of support in various implementations.
     881</t>
     882</section>
    834883
    835884<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
    … …  
    9841033  notes with respect to the fallback behavior.
    9851034</t>
     1035<t>
     1036  Added appendix "Advice on Generating Content-Disposition Header Fields".
     1037</t>
    9861038</section>
    9871039
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