title: s4s-elt-schema-ns: The namespace of element 'schema' must be from the schema namespace, 'http://www.w3.org/2001/XMLSchema'
body: <p>I have a more or less simple task to build a XSD schema of but I'm not sure if my idea here is right. Especially for the element <code>comment</code>.</p>
  <p>Customers can make <strong>purchase orders</strong>. A purchase order includes at least one <strong>order position</strong> (product name, quantity, and price are obligatory; comment and shipping date are
  optional).</p>
  <p>A purchase order has a <strong>date</strong> (order date) and an optional <strong>comment</strong>.
  Customers can specify different <strong>addresses</strong> (billing and
  shipping). Only the shipping address is required.</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  
  &lt;xs:schema xmlns:xs=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;&gt;
      &lt;xs:element name=&quot;purchase-order&quot;&gt;
          &lt;xs:element name=&quot;order-position&quot; type=&quot;order-position-type&quot; minOccurs=&quot;1&quot;&gt;
              &lt;xs:complexType name=&quot;order-position-type&quot;&gt;
                  &lt;xs:sequence&gt;
                      &lt;xs:element name=&quot;product-name&quot; type=&quot;xs:string&quot;&gt;&lt;/xs:element&gt;
                      &lt;xs:element name=&quot;quantity&quot; type=&quot;xs:integer&quot;&gt;&lt;/xs:element&gt;
                      &lt;xs:element name=&quot;price&quot; type=&quot;xs:decimal&quot;&gt;&lt;/xs:element&gt;
                      &lt;xs:element name=&quot;comment&quot; type=&quot;xs:string&quot; minOccurs=&quot;0&quot; maxOccurs=&quot;2&quot;&gt;&lt;/xs:element&gt;
                      &lt;xs:element name=&quot;shipping-date&quot; type=&quot;xs:date&quot; minOccurs=&quot;0&quot;&gt;&lt;/xs:element&gt;
                  &lt;/xs:sequence&gt;
              &lt;/xs:complexType&gt;
          &lt;/xs:element&gt;
          &lt;xs:element name=&quot;order-date&quot; type=&quot;xs:date&quot; minOccurs=&quot;0&quot;&gt;&lt;/xs:element&gt;
          &lt;xs:element name=&quot;billing-address&quot; type=&quot;xs:string&quot;&gt;&lt;/xs:element&gt;
          &lt;xs:element name=&quot;shipping-address&quot; type=&quot;xs:string&quot; minOccurs=&quot;1&quot;&gt;&lt;/xs:element&gt;
      &lt;/xs:element&gt;
  &lt;/xs:schema&gt;
  </code></pre>
  <p>So does the same element, here <code>comment</code>, appear multiple times? Now I have min and maxOccurs for <code>comment</code> but in the sequence so it's probably wrong.</p>
  <p>Where else are errors you maybe see? Or can I make it even easier? The point <code>at least one order position</code> let me create an element before the complexType to tell that the minOccurs value is 1.</p>