The relationship shown depends on the type of symbol. You can specify what relationship is shown for different symbol types in the Relation Window Properties dialog box. For example, you could set the relationship viewed for functions to “Calls”, and the relationship viewed for classes to “Inheritance”.
Each time the Relation Window expands a symbol to show a new level, the relationship represented by the expansion is based on the type of symbol being expanded. That means each Relation Window can potentially show multiple relationships. See also “Relation Window Properties”.