They are intermodulation products. The first part (2T, 3T) represents the number of transmitters and the second (3O, 5O, 7O), the order of the intermodulation. For 2 transmitters transmitting at respectively f1 and f2, the 2T3O products are equal to 2*f1 – f2 and 2*f2 – f1. The 2T5O products are equal to 3*f1 – 2*f2 and 3*f2 – 2*f1... The smaller the order, the stronger the intermodulation is. You should absolutely avoid 2T3O intermodulations products. The 3T3O can be strong but the likeliness of having 3 transmitters close enough to create 3T3O intermodulations is depending upon your setup.