The LM log editor provides an option to roll the last changes on the QSO data back; a so called Undo feature. The Undo list is being activated automatically when opening or creating a log and will be deleted not before closing the log.
Every change on the QSO data will be saved on top of the Undo list and will be taken from there if the user runs the "Undo" action to roll the changes back. The length of the Undo list is practically unlimited.
Changes which affect data of multiple QSOs (e.g. actions with selected QSOs or several tools) will be straight undone the same way when running the Undo action.
Some LM functions are a kind of collective actions, they run several actions automatically in a row. For example, the action Compile calls further sub-actions like removing QSOs with empty calls and sorting chronologically. Such actions will be undone one by one when running the Undo action. That means, the Undo action has to be launched perhaps several times to get the QSO data back to their original state.
Note, that Undo relates to editable QSO data only. Dynamically determined data like points and multipliers can be re-calculated at any time using the "Compile" action.
The following actions will empty the Undo list:
Edit header data
Menu: Edit | Undo
Menu and toolbar icon:
The log editor