Dispositor
A planet's dispositor is the ruler of the sign it sits in, so a Mars in Cancer is disposited by the Moon, and following that chain is one of the oldest ways of reading a chart's structure.
Follow each planet to its dispositor and the chain either arrives at a planet in its own sign, which then disposits itself, or it closes into a loop. A planet that ends the chain is called the final dispositor and carries unusual weight, because everything else reports to it.
Two planets each in the other's sign make a mutual reception, which is a two-link loop and is read as cooperation rather than dominance.
Frequently asked
What is a final dispositor?
A planet in its own sign that ends the chain, so every other planet ultimately answers to it. Not every chart has one.
What happens if the chain forms a loop?
It is read as a closed circuit with no single authority, which classical practice treats as a chart that negotiates rather than obeys.