What is "unns"

The United Nations Naval Service is a futuristic fictional military organisation created by David Feintuch in his Seafort Saga series of novels. The organisation is heavily based on the Napoleonic-era Royal Navy, including the presence of teenage officers serving aboard major ships, largely illiterate lower-deck crewmembers, and draconian discipline. The command structure is extremely simplified compared with modern military organisations, with 'line' officers proceeding from Cadet to Midshipman (often abbreviated to 'Middy'), Lieutenant (the lowest commissioned rank), Commander, Captain, Admiral, and Fleet Admiral. The UNNS operates FTL interstellar vessels on multi-year voyages between Earth and several colonies. The series follows the career of a UNNS officer, Nicholas Seafort.