Empty and Null are special in that they do not have a corresponding specific Visual Basic data type. In fact, it is a bit of misnomer to call these subtypes, because they are actually special values that a Variant variable can hold. When the subtype of a variable is Empty or Null, its value is also either Empty or Null. This is different then the other subtypes, which only describe the type of value that the variable holds, not the value itself. For example, when the subtype of a variable is Long, the value of the variable can be 0, or 15, or 2,876,456, or one of about 4.3 billion numbers (-2,147,483,648 to 2,147,483,647). However, when the subtype of a variable is Empty, it's value is also always a special value called Empty. In the same fashion, when the subtype of a variable is Null, the value is always a special value called Null.
Empty
Null