I posted a similar question yesterday..got a reply also. For people who would like to follow, here is the reply
As for your LinkRef question, javax.naming.Reference does not permit to link an object to an external JNDI but it allows one to link to objects which themselves are not directly bound to the naming/directory system. This means outside of JNDI (on the same server) and not to an external JNDI (on a different server), which is different. You get the nuance?