Use of <local-last> in jboss-deployment-structure.xml

Issue

• What is the use of <local-last value="true"/> in jboss-deployment-structure.xml ?
• How can I make the local-resource present in a sub-deployment (WAR or an EJB Jar) have the lowest priority ?
• If the same class is present both in the sub deployment as myappA.war and in another sub deployment myAppB.war ,that is visible to the myAppA.war, then how to ensure that the Class from the other deployment i.e myAppB.war will be loaded, rather than the class actually packaged in the myappA.war.