Nullable Integer type
IntegerNullable = record;
Clear
Sets the IsNull property to True 
HasValue
The property returns False if the value is Null; otherwise, the property returns True. 
IsNull
The property returns True if the value is Null; otherwise, the property returns False. 
ToString
The method converts a value to string representation, so that it is suitable for display. 
Value
The property returns a value if it is not Null.