Another optimistic development is expanding research into what are being called product-service systems (or PSS). Researchers and policy-makers, mainly in Europe, are exploring the practical possibilities for eco-service production, which was first raised by Swiss industrial ecologist Walter Stahel in the eighties and early nineties. As described earlier, the service economy notion arises from a recognition that the real needs of consumers are mainly for services: clean clothes rather than detergents; mobility or access rather than cars; music, rather than CDs. The PSS perspective recognizes that to meet these needs, products and materials often have a role. (But as a means to satisfy the service-need, not as a goal of open-ended production). Many needs must be satisfied by some combination of a product and a service, and the product-service ratio can vary, in terms of either function fulfilment or economic value. A product-service system has been defined as a marketable set of products and services capable of jointly fulfilling a users need (Goedkoop, te Riele, & Rommens, 1999). System organization commonly typically tries to facilitate sale of the use of product (rather than the product itself); operational leasing, rather than ownership by consumers repair rather than throwaway relationships Almost by definition, a PSS involves many stakeholders, and usually requires their participation early in the design process. Because of its spirit of stewardship, it can entails major changes in property rights that radically affect the behaviour of both producers and consumers. This is quite obvious in the case of the leasing rather than the selling of durables. The implementation of PSSs involves changes for manufacturing companies (who must add a service component), for service companies (who add a