Compatibility
Reading two charts side by side to see where they support each other and where they rub.
In one sentence
Reading two charts side by side to see where they support each other and where they rub.
How it is used
The strongest single signal is a combination between the two Day Masters; after that a reading looks at how the day branches meet, whether one chart supplies the element the other is short of, and where the clashes fall. Year animals on their own are the weakest version of this and the one most often sold as the whole answer. A score summarises those relations; it does not predict a relationship, and two people who read as difficult on paper are not being told to walk away.