The SelectedValuePath property specifies the path to the property that is used to determine the value of the SelectedValue property. For example, assume that a TreeView is bound to a collection of objects of type Employee, which has two properties called EmployeeName and EnployeeNumber. You can use a HierarchicalDataTemplate to display the value of EmployeeName in the TreeView and set SelectedValuePath to "EmployeeNumber" to have SelectedValue return the value of EmployeeNumber.
The SelectedValue property is a read-only property. To change the value of a selected item in a TreeView, use the SelectedItem property to access the TreeViewItem.
The following example shows a TreeView that uses a HierarchicalDataTemplate to display the EmployeeName and EmployeeWorkDay properties of an Employee and sets the SelectedValue property to the EmployeeNumber. When you select an EmployeeName in the TreeView, the SelectedValue is set to the EmployeeNumber.