You can reference component names, custom object and field names, class names, and so on in your Lightning components markup. When they change—for example, if you change the name of a custom component—code that references the changed item also needs to change. In some cases—for example, changing the name of a custom object—these changes are made automatically and happen behind the scenes. In other instances, you need to make code changes manually. In those cases, you receive a compilation error when you try to save the incompatible change.
Referential integrity checking is expanded to include explicit dependency references using <aura:dependency> and references that extend through an inheritance hierarchy. References to custom fields are also validated and updated more thoroughly.