ServiceUUID is an identifier of a service that is unique in the context of the network, but not linked to one service provider.
A Machtigingenregister (MR) (entitlements registry) MUST register entitlements to the ServiceUUID rather than the ServiceID. This way, service providers can share ServiceUUID's for generic services, such as "Apply for a parking permit". Once a user is entitled for this service, he will be entitled for the same service for all service providers that offer it.
There are also ServiceUUID's registered in the ServiceCatalog under ServiceDefinition, but the interface specifications refer to the ServiceUUID under ServiceInstance.