Recognized service directory. A registry stores information about services in an SOA. At a minimum, the registry includes information that other participants can look up to find out the location of the service and what it does (the UDDI specification defines a web services standard for this functionality). A registry may also include information about policies that are applied to the service, such as security requirements, quality of service commitments and billing. Some registries are extended with document repositories, providing more detailed information about the operation and constraints of the service that may be useful to developers, administrators or users.