A String expression that defines the path of selected items, using the Key
column in each view.
The view's Select property selects items within the view
and its descendents. The Key property indicates the
column that defines the key of the view. Based on the key, and the current
selection the next view is created. The Select property can select items using
wild characters such as * or ?, if the view's SingleSel
property is False. The Key property can be
specified also through Key field of the control's DataSource
property.