Dialog for editing QSO is displayed from QSOs window by pressing <ENTER> key on selected QSO. There is no check of written items in this dialogue.
If you change one or booth locators and not change mode, the QSO mode is updated from reports. In other case this dialog is dumb, it makes no validity control.
Option Error signs QSO as bad QSO and Tucnak counts zero points for this QSO. It is possible to turn QSO back as valid.