The Substitutes subkey stores the codes of alternative keyboard layouts preferred by the user. The system checks the user's Substitutes subkey when loading the keyboard layout, and if a substitute is specified, the corresponding layout is substituted for the default layout. The Substitutes key has no entries unless the user has selected a substitute keyboard layout.
To change the keyboard layout, double-click Keyboard in Control Panel. Click the Input Locales tab, and then click the Add button in the Installed input locales box.