Protected Function OnReadValue( _
   ByVal context As ISystemContext, _
   ByVal node As NodeState, _
   ByVal indexRange As NumericRange, _
   ByVal dataEncoding As QualifiedName, _
   ByRef value As Object, _
   ByRef statusCode As StatusCode, _
   ByRef timestamp As Date _
) As ServiceResult

protected ServiceResult OnReadValue( 
   ISystemContext context,
   NodeState node,
   NumericRange indexRange,
   QualifiedName dataEncoding,
   ref object value,
   ref StatusCode statusCode,
   ref DateTime timestamp
)