When Yod aspect pattern has a 4th planet in opposition to the Yod's apex planet, it is called a Yod Kite. This puts extra stress and significance on the apex planet.
The Yod Kite is sometimes called a Boomerang or Focused Yod.
The Yod Kite operates similar to the Yod, but the planets in opposition can either add clarity (you know where the problem is and what needs to be done) or extra stress (needing to manage a concrete solution to problems that are more easily dealt with through abstract or philosophical contemplation).
The planet at the apex may signify the focus of the problem, challenge, distraction or dilemma. In a sense, the planet in opposition to the apex has the "last word" in the conversation between the Yod planets.
In Huber psychological astrology, this configuration is called a Striving Figure. See Bruno and Louise Huber's book Aspect Pattern Astrology for excellent information about this and other aspect patterns.
