Registries can create measurementSets and add them to any submission object. In practice, this means that with your organization API key, you are authorized to send POST requests to these two endpoints: https://qpp.cms.gov/api/submissions/measurement-sets and https://qpp.cms.gov/api/submissions/measurements. You can learn more about these permissions in the Google Developer Group here: https://groups.google.com/d/msg/qpp-apis/mZTborxePxE/HaqvQvVLAwAJ