1) the three roots, [guru, yidam, dakini [+ dharmapala]. 2) the three channels, {ro ma} / {la la na}, {rkyang ma} / {ra sa na}, {dbu ma} / {kun 'dar ma} / avadhuti]
roots, three Guru, yidam, and dharmapala. These three are objects of refuge in the Vajrayana in addition to the Three Jewels