=== 6.2.5.1 Java Card RE Context ===

The Java Card RE context does not have an AID. If an applet calls the **getPreviousContextAID** method when the context of the applet was entered directly from the Java Card RE context, this method returns null. 

If the applet calls **getPreviousContextAID** from a method that may be accessed either from within the applet itself or when accessed via a shareable interface from an external applet, it shall check for **null** return before performing caller AID authentication.