The additional property item property is a descriptive property added in patch 1.69. It has no intrinsic use; rather, it was provided for custom content to make use of (without requiring a hak pak to define new item properties). There are two types of this property, called "unknown" and "cursed". (Technically, these are considered cost parameters.) The latter may be used to tell a player that an item is considered cursed, but does not intrinsically have the functionality of the cursed flag.