There's one particular kind of relationship that's particularly important in a business network, and that's the concept of ownership. Ownership is an associative relationship such as the insurance policy document we discussed earlier. Let's think about a specific example—a person owns a car. Is the owner an attribute of the car? Is the car an attribute of the person? After a little thinking, we might realize that neither statement captures what it means to own something. Ownership is a mapping between the person and the car. Ownership is a concept that's quite separate to the car and its owner.
It's important to understand this way of thinking about ownership, because in many cases we model the ownership relationship via the car, or via the owner, and that's sufficient for many purposes. But, the nature of an ownership relationship is an associative one, and it's important to realize this—because blockchains are often used to record ownership and transfer of ownership in a business network. For example, governments often hold ownership records—for land or vehicles. In these cases, the primary assets under consideration are ownership relationships. When a vehicle or land is transferred between participants, it's this ownership record that changes rather than the assets. That's important because we're often interested in the the history of a vehicle or piece of land, and while the vehicle or land itself may not change, it's ownership most definitely does. It's important, therefore, to be clear whether we're talking about the history of the asset, or the history of ownership. These kinds of history are often called provenance—they tell us who has owned an asset, and how it has changed over time. Both aspects are important because knowing the provenance of an asset increases our confidence in it.