For instance, installing The Elder Scrolls IV: Knights of the Nine onto a computer with Oblivion sets XX to "01". If Vile Lair was installed second, XX becomes "02" and so on indefinitely. As another example, if one owns all of the add-ons (as part of the Legendary Edition) for The Elder Scrolls V: Skyrim, items added by The Elder Scrolls V: Dawnguard will, by default, have "02" as their first two digits, while items added by The Elder Scrolls V: Dragonborn will normally have "04".