title: What Internal Property In ECMAScript is defined for?
body: <p>What the <a href="http://es5.github.com/#x8.6">Internal Property</a> in ECMAScript is defined for ? What does the spec mean by </p>
  
  <blockquote>
    <p>This specification uses various internal properties to define the
    semantics of object  values.These internal properties are not part of
    the ECMAScript language. They are defined by    this specification
    purely for expository purposes.</p>
  </blockquote>
  
  <p>Does it mean that <strong>Internal properties defined by ECMAScript are not available for programming. They are used in the implementation of the javascript engine</strong> ? </p>