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  * xmlindex.html
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  *
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  *      Authors: Jivka Bojilova
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  *    Copyright: 2000 Regents of the University of California and the
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  *               National Center for Ecological Analysis and Synthesis
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  *  For Details: http://www.nceas.ucsb.edu/
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  *      Created: 2000 April 5
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  *      Version: 0.01
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  *    File Info: '$Id: xmlindex.html 878 2001-12-18 18:11:42Z berkley $'
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  * 
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  * October Meeting SDSC, 2000
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<HTML>
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<TITLE>Metacat</TITLE>
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</HEAD> 
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<BODY>
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  <table width="100%">
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    <tr>
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      <td class="tablehead" colspan="2"><p class="label">Indexing for Performance</p></td>
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      <td class="tablehead" colspan="2" align="right">
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        <a href="./saxparser.html">Back</a> | <a href="./metacattour.html">Home</a> | 
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        <a href="./acontrol.html">Next</a>
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      </td>
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    </tr>
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  </table>
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  <P>Metacat DB stores indeces for the current version of all documents in <i>xml_index</i> 
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  table. All relative and absolute paths to any node in a document are stored in 
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  this table. These paths are used for structured query searches to a specified 
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  location in an XML tree. Path expressions specified in the 
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  <a href="./metacatquery.html">pathquery</a> document are queried from this 
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  table.</p>
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  <p>Indeces become necessary because relational databases are not efficient
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  at querying tree structures.  By slightly denormalizing the database and listing
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  the tree structure in a flat table, the relational database engine can more
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  effectively handle large path queries.</p>
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  <p>Example: </p>
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  <pre>
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    &lt;?xml version="1.0"?&gt;
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    &lt;!DOCTYPE employee&gt;
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    &lt;employee&gt;
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      &lt;name&gt;
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        &lt;first&gt;Chad&lt;/first&gt;
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        &lt;last&gt;Berkley&lt;/last&gt;
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      &lt;/name&gt;
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      &lt;address&gt;
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        &lt;street&gt;735 State St. Ste. 303&lt;/street&gt;
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        &lt;city&gt;Santa Barbara&lt;/city&gt;
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        &lt;state&gt;California&lt;/state&gt; 
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        &lt;zip&gt;93101&lt;/zip&gt;
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      &lt;/address&gt;
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      &lt;occupation&gt;
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        &lt;title&gt;Metadata Systems Developer&lt;/title&gt;
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        &lt;location&gt;
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          &lt;type&gt;
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            &lt;grant&gt;
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              &lt;name&gt;DBA&lt;/name&gt;
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              &lt;grantor&gt;NSF&lt;/grantor&gt;
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              &lt;PI&gt;Jim Reichman&lt;/PI&gt;
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              &lt;PI&gt;Matt Jones&lt;/PI&gt;
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              &lt;PI&gt;Mark Schildhauer&lt;/PI&gt;
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            &lt;/grant&gt;
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          &lt;/type&gt;
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          &lt;system&gt;UC&lt;/system&gt;
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          &lt;location&gt;Santa Barbara&lt;/location&gt;
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        &lt;/location&gt;
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      &lt;/occupation&gt;
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    &lt;/employee&gt;
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  </pre>
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  <p>The XML document above is logically deconstructed into all possible paths
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  through the document.  Each path (relative and absolute) is entered as a record
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  in xml_index along with the nodeid of the deepest node.  In this way, any path
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  can be quickly queried.  It's contents can be assertained from cross linking
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  the nodeid back to the <a href="#xml_nodes">xml_nodes</a> table.  
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  <table border="1">
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    <tr>
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      <td><b>PATH</b></td><td><b>NODEID</b></td><td><b>PARENTNODEID</b></td>
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    </tr>
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    <tr><td>occupation/location/type/grant/grantor</td><td>200150</td><td>200145<td></tr>
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    <tr><td>location/type/grant/grantor</td><td>200150</td><td>200145<td></tr>
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    <tr><td>grantor</td><td>200150</td><td>200145<td></tr>
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    <tr><td>location/type/grant/PI</td><td>200153</td><td>200145<td></tr>
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    <tr><td>grant/PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>/employee/occupation/location/type/grant/PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>employee/occupation/location/type/grant/PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>occupation/location/type/grant/PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>type/grant/PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>PI</td><td>200153</td><td>	  200145<td></tr>
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    <tr><td>location/type/grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>/employee/occupation/location/type/grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>employee/occupation/location/type/grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>occupation/location/type/grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>type/grant/PI</td><td>200156</td><td>	  200145<td></tr>
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    <tr><td>PI</td><td>	200156</td><td>	  200145<td></tr>
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    <tr><td>location/type/grant/PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>grant/PI</td><td>200159</td><td>	  200145
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    <tr><td>/employee/occupation/location/type/grant/PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>employee/occupation/location/type/grant/PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>occupation/location/type/grant/PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>type/grant/PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>PI</td><td>200159</td><td>	  200145<td></tr>
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    <tr><td>occupation/location/system</td><td>200164</td><td>	  200141<td></tr>
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    <tr><td>system</td><td>200164</td><td>	  200141<td></tr>
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    <tr><td>employee/occupation/location/system</td><td>200164</td><td>	  200141<td></tr>
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    <tr><td>location/system</td><td>200164</td><td>	  200141<td></tr>
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    <tr><td>/employee/occupation/location/system</td><td>200164</td><td>	  200141<td></tr>
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    <tr><td>/employee/occupation/location/location</td><td>200167</td><td>	  200141<td></tr>
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    <tr><td>employee/occupation/location/location</td><td>200167</td><td>	  200141<td></tr>
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    <tr><td>occupation/location/location</td><td>200167</td><td>	  200141<td></tr>
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    <tr><td>location</td><td>200167</td><td>	  200141<td></tr>
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    <tr><td>location/location</td><td>200167</td><td>	  200141<td></tr>
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    <tr><td>/employee/name</td><td>200112</td><td>	  200110<td></tr>
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    <tr><td>name</td><td>200112</td><td>	  200110<td></tr>
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    <tr><td>employee/name</td><td>200112</td><td>	  200110<td></tr>
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    <tr><td>/employee/name/first</td><td>200114</td><td>	  200112<td></tr>
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    <tr><td>name/first</td><td>200114</td><td>	  200112<td></tr>
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    <tr><td>/employee</td><td>200110</td><td>	  200109<td></tr>
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    <tr><td>employee</td><td>200110</td><td>	  200109<td></tr>
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    <tr><td>employee/name/first</td><td>200114</td><td>	  200112<td></tr>
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    <tr><td>first</td><td>200114</td><td>	  200112<td></tr>
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    <tr><td>name/last</td><td>200117</td><td>	  200112<td></tr>
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    <tr><td>/employee/name/last</td><td>200117</td><td>	  200112<td></tr>
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    <tr><td>employee/name/last</td><td>200117</td><td>	  200112<td></tr>
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    <tr><td>last</td><td>200117</td><td>	  200112<td></tr>
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    <tr><td>employee/address</td><td>200121</td><td>	  200110<td></tr>
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    <tr><td>address</td><td>200121</td><td>	  200110<td></tr>
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    <tr><td>/employee/address</td><td>200121</td><td>	  200110<td></tr>
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    <tr><td>/employee/address/street</td><td>200123</td><td>	  200121<td></tr>
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    <tr><td>employee/address/street</td><td>200123</td><td>	  200121<td></tr>
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    <tr><td>address/street</td><td>200123</td><td>	  200121<td></tr>
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    <tr><td>street</td><td>200123</td><td>	  200121<td></tr>
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    <tr><td>employee/address/city</td><td>200126</td><td>	  200121<td></tr>
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    <tr><td>address/city</td><td>200126</td><td>	  200121<td></tr>
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    <tr><td>/employee/address/city</td><td>200126</td><td>	  200121<td></tr>
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    <tr><td>city</td><td>200126</td><td>	  200121<td></tr>
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    <tr><td>address/state</td><td>200129</td><td>	  200121<td></tr>
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    <tr><td>/employee/address/state</td><td>200129</td><td>	  200121<td></tr>
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    <tr><td>employee/address/state</td><td>200129</td><td>	  200121<td></tr>
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    <tr><td>state</td><td>200129</td><td>	  200121<td></tr>
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    <tr><td>employee/address/zip</td><td>200132</td><td>	  200121<td></tr>
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    <tr><td>zip</td><td>200132</td><td>	  200121<td></tr>
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    <tr><td>/employee/address/zip</td><td>200132</td><td>	  200121<td></tr>
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    <tr><td>address/zip</td><td>200132</td><td>	  200121<td></tr>
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    <tr><td>employee/occupation</td><td>200136</td><td>	  200110<td></tr>
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    <tr><td>/employee/occupation</td><td>200136</td><td>	  200110<td></tr>
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    <tr><td>occupation</td><td>200136</td><td>	  200110<td></tr>
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    <tr><td>/employee/occupation/title</td><td>200138</td><td>	  200136<td></tr>
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    <tr><td>employee/occupation/title</td><td>200138</td><td>	  200136<td></tr>
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    <tr><td>occupation/title</td><td>200138</td><td>  200136<td></tr>
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    <tr><td>title</td><td>200138</td><td>	  200136<td></tr>
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    <tr><td>location</td><td>200141</td><td>	  200136<td></tr>
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    <tr><td>employee/occupation/location</td><td>200141</td><td>	  200136<td></tr>
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    <tr><td>/employee/occupation/location</td><td>200141</td><td>	  200136<td></tr>
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    <tr><td>occupation/location</td><td>200141</td><td>	  200136<td></tr>
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    <tr><td>occupation/location/type</td><td>200143</td><td>	  200141<td></tr>
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    <tr><td>type</td><td>200143</td><td>	  200141<td></tr>
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    <tr><td>/employee/occupation/location/type</td><td>200143</td><td>	  200141<td></tr>
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    <tr><td>location/type</td><td>200143</td><td>	  200141<td></tr>
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    <tr><td>employee/occupation/location/type</td><td>200143</td><td>	  200141<td></tr>
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    <tr><td>type/grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>occupation/location/type/grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>location/type/grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>/employee/occupation/location/type/grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>employee/occupation/location/type/grant</td><td>200145</td><td>	  200143<td></tr>
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    <tr><td>grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>/employee/occupation/location/type/grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>occupation/location/type/grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>type/grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>location/type/grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>employee/occupation/location/type/grant/name</td><td>200147</td><td>	  200145<td></tr>
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    <tr><td>/employee/occupation/location/type/grant/grantor</td><td>200150</td><td>	  200145<td></tr>
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    <tr><td>type/grant/grantor</td><td>200150</td><td>	  200145<td></tr>
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    <tr><td>grant/grantor</td><td>200150</td><td>	  200145<td></tr>
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    <tr><td>employee/occupation/location/type/grant/grantor</td><td>200150</td><td>	  200145<td></tr>
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  </table>
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  <br>
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  <a name="xml_nodes"></a>
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  <p>The following is the document in xml_nodes.</p>
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  <br>
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  <table border="1">
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    <tr>
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      <td><b>nodeid</b></td><td><b>nodetype</b></td><td><b>nodename</b></td>
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      <td><b>nodedata</b></td><td><b>rootnodeid</b></td><td><b>parentnodeid</b></td>
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    </tr>
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    <tr><td>200164</td> <td>ELEMENT </td> <td>system</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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    <tr><td>200165</td> <td>TEXT </td> <td>&nbsp;</td><td>UC</td><td>200109</td><td>200164</td> </tr>
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    <tr><td>200166</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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    <tr><td>200167</td> <td>ELEMENT </td> <td> location</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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    <tr><td>200168</td> <td>TEXT </td> <td>&nbsp;</td><td>Santa Barbara</td><td>200109</td><td>200167</td> </tr>
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    <tr><td>200169</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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    <tr><td>200170</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200136</td> </tr>
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    <tr><td>200171</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
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    <tr><td>200109</td> <td>DOCUMENT </td> <td> employee</td><td>&nbsp;</td><td>200109</td><td>&nbsp;</td> </tr>
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    <tr><td>200110</td> <td>ELEMENT </td> <td> employee</td><td>&nbsp;</td><td>200109</td><td>200109</td> </tr>
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    <tr><td>200111</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
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    <tr><td>200112</td> <td>ELEMENT </td> <td> name</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
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    <tr><td>200113</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200112</td> </tr>
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    <tr><td>200114</td> <td>ELEMENT </td> <td> first</td><td>&nbsp;</td><td>200109</td><td>200112</td> </tr>
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    <tr><td>200115</td> <td>TEXT </td> <td>&nbsp;</td><td>Chad</td><td>200109</td><td>200114</td> </tr>
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    <tr><td>200116</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200112</td> </tr>
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    <tr><td>200117</td> <td>ELEMENT </td> <td> last</td><td>&nbsp;</td><td>200109</td><td>200112</td> </tr>
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    <tr><td>200118</td> <td>TEXT </td> <td>&nbsp;</td><td>Berkley</td><td>200109</td><td>200117</td> </tr>
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    <tr><td>200119</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200112</td> </tr>
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    <tr><td>200120</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
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    <tr><td>200121</td> <td>ELEMENT </td> <td> address</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
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    <tr><td>200122</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
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    <tr><td>200123</td> <td>ELEMENT </td> <td> street</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
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    <tr><td>200124</td> <td>TEXT </td> <td>&nbsp;</td><td>735 State St. Ste. 303</td><td>200109</td><td>200123</td> </tr>
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    <tr><td>200125</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
216
    <tr><td>200126</td> <td>ELEMENT </td> <td> city</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
217
    <tr><td>200127</td> <td>TEXT </td> <td>&nbsp;</td><td>Santa Barbara</td><td>200109</td><td>200126</td> </tr>
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    <tr><td>200128</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
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    <tr><td>200129</td> <td>ELEMENT </td> <td> state</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
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    <tr><td>200130</td> <td>TEXT </td> <td>&nbsp;</td><td>California</td><td>200109</td><td>200129</td> </tr>
221
    <tr><td>200131</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
222
    <tr><td>200132</td> <td>ELEMENT </td> <td> zip</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
223
    <tr><td>200133</td> <td>TEXT </td> <td>&nbsp;</td><td>93101</td><td>200109</td><td>200132</td> </tr>
224
    <tr><td>200134</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200121</td> </tr>
225
    <tr><td>200135</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
226
    <tr><td>200136</td> <td>ELEMENT </td> <td> occupation</td><td>&nbsp;</td><td>200109</td><td>200110</td> </tr>
227
    <tr><td>200137</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200136</td> </tr>
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    <tr><td>200138</td> <td>ELEMENT </td> <td> title</td><td>&nbsp;</td><td>200109</td><td>200136</td> </tr>
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    <tr><td>200139</td> <td>TEXT </td> <td>&nbsp;</td><td>Metadata Systems Developer</td><td>200109</td><td>200138</td> </tr>
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    <tr><td>200140</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200136</td> </tr>
231
    <tr><td>200141</td> <td>ELEMENT </td> <td> location</td><td>&nbsp;</td><td>200109</td><td>200136</td> </tr>
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    <tr><td>200142</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
233
    <tr><td>200143</td> <td>ELEMENT </td> <td> type</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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    <tr><td>200144</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200143</td> </tr>
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    <tr><td>200145</td> <td>ELEMENT </td> <td> grant</td><td>&nbsp;</td><td>200109</td><td>200143</td> </tr>
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    <tr><td>200146</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200147</td> <td>ELEMENT </td> <td> name</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200148</td> <td>TEXT </td> <td>&nbsp;</td><td>DBA</td><td>200109</td><td>200147</td> </tr>
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    <tr><td>200149</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200150</td> <td>ELEMENT </td> <td> grantor</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200151</td> <td>TEXT </td> <td>&nbsp;</td><td>NSF</td><td>200109</td><td>200150</td> </tr>
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    <tr><td>200152</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200153</td> <td>ELEMENT </td> <td> PI</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200154</td> <td>TEXT </td> <td>&nbsp;</td><td>Jim Reichman</td><td>200109</td><td>200153</td> </tr>
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    <tr><td>200155</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200156</td> <td>ELEMENT </td> <td> PI</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200157</td> <td>TEXT </td> <td>&nbsp;</td><td>Matt Jones</td><td>200109</td><td>200156</td> </tr>
248
    <tr><td>200158</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr
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    <tr><td>200159</td> <td>ELEMENT </td> <td> PI</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200160</td> <td>TEXT </td> <td>&nbsp;</td><td>Mark Schilhauer</td><td>200109</td><td>200159</td> </tr>
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    <tr><td>200161</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200145</td> </tr>
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    <tr><td>200162</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200143</td> </tr>
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    <tr><td>200163</td> <td>TEXT </td> <td>&nbsp;</td><td>&nbsp;</td><td>200109</td><td>200141</td> </tr>
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  </table>
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