Type Alias EquipSlotValue

The relationship between an item and a slot has three states:

1. The item cannot be equipped in the slot, e.g. cannot equip a head item in the leg slot.
2. The item can be equipped in the slot, e.g. a ring can be equipped to left right or right ring slot.
3. The item cannot be equipped in the slot, but if equipped into its correct slot, will block this slot. e.g. Vermilion Cloak.