title: how to add validation in xsd for blank spaces
body: <p>i have created basic xsd successfully however I want to add restriction for the element that it should be present and contains atleast one character. it also has 4 attributes. i am facing problem in adding restriction since I can not use simple type as the element has attributes. </p>
  
  <p>Please suggest something</p>
  
  <p>thanks in advance</p>
  
  <p><strong>Added XSD data posted by OP in comments (sic)</strong></p>
  
  <pre><code>&lt;xs:element name="Engines"&gt;
    &lt;xs:complexType&gt;
      &lt;xs:sequence&gt;
        &lt;xs:element maxOccurs="unbounded" ref="Engine" /&gt;
      &lt;/xs:sequence&gt;
      &lt;xs:attribute name="Count" use="required" type="xs:integer" /&gt;
    &lt;/xs:complexType&gt;
  &lt;/xs:element&gt;
  &lt;xs:element name="Engine"&gt;
    &lt;xs:complexType&gt;
      &lt;xs:sequence&gt;
        &lt;xs:element name="Model" type="Model"/&gt;
        &lt;xs:element ref="SerialNumber" /&gt;
      &lt;/xs:sequence&gt;
    &lt;/xs:complexType&gt;
  &lt;/element&gt;
  
  &lt;xs:simpleType name="trimValueType"&gt;
    &lt;xs:restriction base="xs:string"&gt;
      &lt;xs:minLength value="1"&gt;&lt;/xs:minLength&gt;
      &lt;xs:whiteSpace value="collapse"&gt;&lt;/xs:whiteSpace&gt;
    &lt;/xs:restriction&gt;
  &lt;/xs:simpleType&gt;
  &lt;xs:complexTyp‌​e name="Model"&gt;
    &lt;xs:simpleContent&gt;
      &lt;xs:extension base="trimValueType"&gt;
        &lt;xs:attribute name="ATTRIBUTE" use="required" /&gt;
      &lt;/xs:extension&gt;
    &lt;/xs:simpleContent&gt;
  &lt;/xs:complexType&gt;
  
  
  &lt;Engines count = 1&gt; &lt;Engine&gt; &lt;Model ATTRIBUTE = "r\w"&gt; &lt;/Model&gt; &lt;SerialNumber ATTRIBUTE = "r/w"&gt;1234567&lt;/SerialNumber&gt; &lt;Engine&gt; &lt;Engines&gt;
  </code></pre>