Selecting

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Click on an item to select it (this will unselect the previous selection).
A selected item is surrounded with a border and the color of its dots are reversed (as illustrated above).
To add a child item to it (and begin editing the child), tap the Space key.
To duplicate an item (and begin editing the duplicate), tap the D key.
To delete it, tap the Delete key.
To move it, hold the Option key down and tap an arrow key.
To add a line, tap the Hyphen key.
To select a second item, hold down the Shift key when you click on it.
To unselect an item, hold the Shift key down when you click on it.