Android :: Using Permissions Need To Set Four Levels

I'm currently reading the specs about Android's Security system and something is not clear on my mind... Can somebody explain me ? About the Permissions, it is possible to set four levels (Normal, Dangerous, Signature and SignatureOrSystem) The documentation is here : http://developer.android.com/reference/android/R.styleable.html#Andro...About the "Dangerous" level, it's written : "For example, any dangerous permissions requested by an application may be displayed to the user and require confirmation before proceeding, or some other approach may be taken to avoid the user automatically allowing the use of such facilities." What does "Some other approach may be taken..." means ? How does that work ? Is there any example?