Ius in re, or jus in re, under civil law, more commonly referred to as a real right or right in rem, is a right in property, known as an interest under common law. A real right vests in a person with respect to property, inherent in his relation to it, and is good against the world (erga omnes). The primary real right is ownership (dominium) (freehold, leasehold, commonhold). Whether possession (possessio) is recognized as a real right, or merely as a source of certain powers and actions, depends on the legal system at hand. Subordinate or limited real rights generally refer to encumbrances, rights of use and security interests. The term right in rem is derived from the action given to its holder, an actio in rem. In Latin grammar the action against the thing demands a fourth case. The und