title: XML Schema Definition (XSD) for XML files
body: <p>How can I check whether a XML file uses a XML Schema Definition (XSD)? For example, if you decompress a signed odt file (LibreOffice or OpenOffice text document), in the directory META-INF is the signaturefile <em>documentsignatures.xml</em>.
  In this file the attribute <code>xmlns</code> defines a default namespace for the elements <code>&lt;Signature&gt;</code> and <code>&lt;document-signatures&gt;</code>. There is neither a reference by the attribute <code>xmlns:xsi</code> to the XML Schema Instance (XSI) namespace <code>"http://www.w3.org/2001/XMLSchema-instance"</code> nor a reference by the attribute <code>xsi:schemaLocation</code> to the XML schema file <code>xmldsig-core-schema.xsd</code>. As a result, the entire content of the documentsignatures.xml file should not be validated under any scheme. Is that correct?</p>
  
  <p>Here are the first lines of the correspnding XML document <em>documentsignatures.xml</em>:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;document-signatures xmlns="urn:oasis:names:tc:opendocument:xmlns:digitalsignature:1.0"&gt;
      &lt;Signature xmlns="http://www.w3.org/2000/09/xmldsig#" Id="ID_006900630020002d0084000e004a008b009b00a6006f004b007c007b002d007f"&gt;
          &lt;SignedInfo&gt;...
  </code></pre>
  
  <p>Greetings</p>
  
  <p>Kaleun</p>