The IsNull() function is now deprecated in the 5.0 parser engine (versions 5.0 and later) and has been replaced with the GetState() function. However, for backward compatibility reasons, the IsNull() function will still be available and supported.

The GetState function allows you to easily get the state of a field (i.e. whether the field is valid, invalid, empty or present but null). To learn how to set the state of a value, see Distinguishing Between Null, Zero, Empty and Invalid in Fields.