Eric,
There is. The simplest and perhaps most common example would be a text field. You could add the following script on the exit event to test for null.
if (this.formattedValue.length == 0 && this.editValue.length == 0) {
xfa.host.messageBox("This field is null.")
}
Note that I am not testing for (this.rawValue == ""). For empty fields, rawValue is represented as a null object. A test for "" will not successfully detect an empty field since null != "".
Steve
