title: Make an xsd element mandatory
body: <p>I have an xml file that I am trying to validate against an xsd file. Works fine. I want to modify the xsd to make an element value mandatory. How do I do this so when I validate the xml file I want it to fail if the element <code>FirstName</code> is blank  (<code>&lt;FirstName&gt;&lt;/FirstName&gt;</code>)</p>
  
  <p><strong>xml File</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
  &lt;Patient&gt;
     &lt;FirstName&gt;Patient First&lt;/FirstName&gt;
     &lt;LastName&gt;Patient Last&lt;/LastName&gt;
  &lt;/Patient&gt;
  </code></pre>
  
  <p><strong>xsd File</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"&gt;
    &lt;xs:element name="Patient"&gt;
      &lt;xs:complexType&gt;
        &lt;xs:sequence&gt;
          &lt;xs:element name="FirstName" type="xs:string" /&gt;
          &lt;xs:element name="LastName" type="xs:string" /&gt;
        &lt;/xs:sequence&gt;
      &lt;/xs:complexType&gt;
    &lt;/xs:element&gt;
  &lt;/xs:schema&gt;
  </code></pre>