title: What does the acronym EE mean in the .NET reference source?
body: <p>In the .NET reference source for the <code>String</code> class, there are various comments referencing something called the <code>EE</code>.</p>
  
  <p><a href="http://referencesource.microsoft.com/#mscorlib/system/string.cs#54" rel="noreferrer">The first is on <code>m_stringLength</code></a>:</p>
  
  <blockquote>
  <pre><code>//NOTE NOTE NOTE NOTE
  //These fields map directly onto the fields in an EE StringObject.  See object.h for the layout.
  //
  [NonSerialized]private int  m_stringLength;
  </code></pre>
  </blockquote>
  
  <p><a href="http://referencesource.microsoft.com/#mscorlib/system/string.cs#72" rel="noreferrer">It's found again again for <code>.Empty</code></a>:</p>
  
  <blockquote>
  <pre><code>// The Empty constant holds the empty string value. It is initialized by the EE during startup.
  // It is treated as intrinsic by the JIT as so the static constructor would never run.
  // Leaving it uninitialized would confuse debuggers.
  //
  //We need to call the String constructor so that the compiler doesn't mark this as a literal.
  //Marking this as a literal would mean that it doesn't show up as a field which we can access 
  //from native.
  public static readonly String Empty;
  </code></pre>
  </blockquote>
  
  <p>It's also on <a href="http://referencesource.microsoft.com/#mscorlib/system/string.cs#924" rel="noreferrer"><code>Length</code></a>:</p>
  
  <blockquote>
  <pre><code>// Gets the length of this string
  //
  /// This is a EE implemented function so that the JIT can recognise is specially
  /// and eliminate checks on character fetchs in a loop like:
  ///        for(int I = 0; I &lt; str.Length; i++) str[i]
  /// The actually code generated for this will be one instruction and will be inlined.
  </code></pre>
  </blockquote>
  
  <p>I would venture that it might have something to do with an <b>E</b>ngine or is <b>E</b>xternal, but I'd like an actual reference defining what it is.</p>
  
  <p>What does the <code>EE</code> mean?</p>