US FAA requires A321XLR fire resistance in vicinity of rear fuel tank

https://www.flightglobal.com/safety/us-faa-requires-a321xlr-fire-resistance-in-vicinity-of-rear-fuel-tank/151274.article 

US regulators have laid out formal requirements for the Airbus A321XLR's lower fuselage, in the vicinity of the rear centre fuel tank, to be resistant to fire penetration