four vajra drops
Four attainments of the union of clear light and illusory body, they are: the posture of the drop, retaining the drops while in union without emission; the posture of the wind, using the wind to block the channel by use of a syllable; the posture of the channel, the meeting of channels of the father and mother; and the posture of the body, the syllables that adorn the secret places at the time of unification.