QSqlRecord::field documentation is inconsise

The documentation for QSqlRecord::field states:
"Returns the field at position index. If the position is out of range, an empty field is returned."

The QSqlField class however, does not seem to have a concept of being "empty". If it would have, it should have an isEmpty() method, just like other classes that can be empty. Instead, QSqlField can be Null and can be valid or invalid, but it is not clear from the documentation of QSqlRecord which one will be returned for an out of range position.