US National Aeronautical Space Agency (NASA) and Aeronautics Research Institute (NARI) have released an initial concept of operations and associated operational requirements for cooperative air traffic management in High Altitude Airspace (Upper E) Traffic Management (ETM).
Full story: https://www.unmannedairspace.info/emerging-regulations/nasa-releases-initial-concept-operations-for-high-altitude-airspace-traffic-management/