The Yod is a rare astrological aspect that involves any three planets or points in the chart that form an isosceles triangle, and Yods can be formed within several Harmonics, such as the Biquintile Yod or the Quindecile Yod, but these thoughts are about the 6th/12th Harmonic geometrical structure, the classic Yod formed by two Quincunxes connected through a Sextile.
- All Yods are Boomerangs; I'm not sure the term Boomerang is the best term for this structure, but I see a Yod is being made of four planets/points, because there is always a 4th release point, which is cumulated in a transit or there is almost always something there in the chart, in the release point, such as an important asteroid. No Yod would miss a 4th leg, its release point.
- It's a highly fated structure, pointing to a special mission in this life, perhaps the cumulus of several lifetimes. The preparation continues in this life and there is a "gestation" period. The Yod cannot be triggered before its time.