Structure Rules
When you have created a structure, you can write conditional rules that take your company's hierarchy into consideration. For example, suppose you want to restrict HR11 (EMPLOYEE) data only to users who are at a certain level in your organization. You could create a rule that says, "If the current user is at level Manager or higher [in the structure], he or she can view EMPLOYEE data." There are other ways to achieve this same result through roles, but, depending on your needs, you might want to make use of these kinds of rules.
To refine this example further, you could say that only managers who report to a particular VP, can view EMPLOYEE data. In this case, the rule would take not just the manager's rank but also which node (person) he or she reports to.