title: InvalidRegex: Pattern value '(?:Y|N)' is not a valid regular expression.
body: <p>I have used regular expression for yes no type. but compiler throwing exception like this.</p>
  
  <pre><code>&lt;xsd:simpleType name="YesNoType"&gt;
          &lt;xsd:annotation&gt;
              &lt;xsd:documentation&gt;
                  Type for yes and no inputs.
              &lt;/xsd:documentation&gt;
          &lt;/xsd:annotation&gt;
          &lt;xsd:restriction base="xsd:string"&gt;
                  &lt;xsd:pattern value="(?:Y|N)"/&gt;
          &lt;/xsd:restriction&gt;
  &lt;/xsd:simpleType&gt;
  </code></pre>
  
  <p>InvalidRegex: Pattern value '(?:Y|N)' is not a valid regular expression. The reported error was: 'This expression is not supported in the current option setting.'.</p>
  
  <p>Please help me regarding this.</p>