Every checklist has a name and string representation.
Next to the "Import" and "Export" buttons there are two input fields.
With "Import" you load and store locally the checklist with the given name and string representation (if there is already one with that name, it is overridden).
With "Export", the name and string representation of the currently opened checklist is put into those two fields (and is stored locally, export also functions as a save button).
Sharing your checklists is done by exporting the current checklist and sharing the string representation, no collaborative support is implemented or planned.
From the drop-down menu below, you can select any one of your locally stored checklists, and either load them with "Open" or remove them with "Delete".
Below that is the name of the currently opened checklist.
Renaming a checklist is done by opening it, changing the name, exporting it and deleting the old named one.
With "+" you add an item to the bottom of a checklist.
With "-" you remove it.
With "Lock" you disable all editing.
"U" and "C" uncheck and check all items on the checklist or sub-items of an item.