The topic of the ownership of rights suffers with an excessively theoretical approach whereby all patrimonial rights are either considered to be property, or denied that quality. Positive law, however, leaves room for treating only some rights as property. In order to understand why some rights – only some of them – are property, and not mere obligational ties, it is necessary to distinguish between titularity and ownership. Titularity is a concept devoid of any specific legal content, whereas ownership is a technique which allows for the reservation of a right against usurpation by outsiders. This distinction also underlines the difference between the opposability of rights and the exclusivity conferred by ownership. A right is said to be opposable when a successor to the debtor’s interests has real or presumed knowledge of it. On the other hand, the exclusivity of ownership is unconditional and applies to all outsiders to the legal relation.