During the current year, USACo (a domestic corporation) sold equipment to FrenchCo, a foreign corporation, for $350,000, with title passing to the buyer in France. USACo purchased the equipment several years ago for $100,000 and took $80,000 of depreciation deductions on the equipment, all of which were allocated to U.S.-source income. USACos adjusted basis in the equipment is $20,000 on the date of sale. What is the source of the $330,000 gain on the sale of this equipment? Explain your answer.