As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AROUND 45 MIN INTO CRUISE FLIGHT WE NOTICED THE GREEN HYD REVISOR QUANTITY DECREASING. SHORTLY AFTER WE RECEIVED AN ECAM - GREEN RSVR LO LEVEL. COMPLIED WITH ECAM AND ASSOCIATED PROC S. LANDING GEAR WAS MANUALLY EXTENDED. UNEVENTFUL LANDING KMEM 36C. EMERGENCY DECLARED. REMOVED AND REPLACED GREEN RESERVOIR HYDRAULIC QUANTITY TRANSMITTER.