The relation view that appears when you select a symbol depends on the type of symbol. You have control over this in the Relation Window Options. For example, you can specify that if you select a function in your source code, the Relation Window will show references to that function. And, if you select a class name, the Relation Window will show the classes derived from it.
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: Relation Window Options.
The relationships fall into these general categories, listed from computationally the fastest to slowest:
Contains – show the contents of the current symbol. For example, the members of a struct.
Calls – show what other symbols are referred to by the current symbol. For example, functions that are called by the current function.
Calls and Callers - show a split graph; one side are the functions called by the current function, the other side is the functions that call the current function.
References – show what other symbols refer to the current symbol. For example, functions that call the current function.