That is what I understand.
From University of Georgia...
Grand Frost™ lemon, which also originates from a Chinese cultivar, produces large, juicy fruit and has been grown by backyard citrus growers since the 1930s. Grand Frost™ has significantly fewer seeds than the Chinese cultivar, and also is able to survive cold winters in South Georgia.
From Growing Produce...
‘Sweet Frost’ is an irradiated Changsha mandarin with two to three seeds per fruit. It has a Brix range of 11-12, it is very easy peel, well-colored, and matures (in GA) in November or December.
TFN