I have an Application using shareable running on a JCOB 2.4.2R2. Once I am in a Shareable JCSystem.getAid() returns the AID of the Applet providing the Shareable (which also is consitent with the JCRE spec, as far as I understood it). On jcardsim it returns the AID of the Applet calling into the Shareable if I am not mistaken.