As a result, agents' control over the uses of their commodities can be imperfect, because the system of rights which defines that control is incomplete. Typically, this falls into two generalized rights – "excludability" and "transferability". Excludability deals with the ability of agents to control who uses their commodity, and for how long – and the related costs associated with doing so. Transferability reflects the right of agents to transfer the rights of use from one agent to another, for instance by selling or leasing a commodity, and the costs associated with doing so. If a given system of rights does not fully guarantee these at minimal (or no) cost, then the resulting distribution can be inefficient. Considerations such as these form an important part of the work of institutional economics. Nonetheless, views still differ on whether something displaying these attributes is meaningful without the information provided by the market price system.