Function: IsNull()
Purpose: The IsNull function returns a value of true if the referenced variable contains a null value. Otherwise, it returns false.
Usage: IsNull(variable_name)
Where variable_name is the name of the variable you wish to test.
Returns: True if the referenced variable contains the null value; False otherwise.
Example
Dim TestEmpty
Dim TestQuote
Dim TestNull
TestQuote = ""
TestNull = Null
IsNull(TestEmpty) returns False
IsDate(TestQuote) returns False
IsDate(TestNull) returns True