Check Out to Edit
If you have add a tasklist to ToDoList's built-in source control (see below), this command locks the active tasklist so that only you may edit it while you have it checked out.

Check In
When you have finished editing, this removes the lock and enables others to check-out the the tasklist for editing.

Add Tasklist to Source Control
Enabling source control on a tasklist enables multiple users (over a LAN) to access and edit the tasklist without the risk of overwriting each other's changes.

Remove Tasklist from Source Control
If you find that you no longer need source control for a tasklist or it was enabled in error then you can remove the feature with this command.

See also: Multi-User Preferences.