http://docs.oracle.com/javafx/2/deployment/javafx_ant_task_reference.htm does not contain a description for the macro expansion $APPDIR.
For instance
<fx:platform>
<fx:jvmarg value="-Djava.policy.file=$APPDIR/app/whatever.policy"/>
</fx:platform>
would get expanded during launch to something like
-Djava.policy.file=/Users/cooluse/mydev/TestPackager/dist/bundles/Test Packager.app/Contents/app/whatever.policy
For instance
<fx:platform>
<fx:jvmarg value="-Djava.policy.file=$APPDIR/app/whatever.policy"/>
</fx:platform>
would get expanded during launch to something like
-Djava.policy.file=/Users/cooluse/mydev/TestPackager/dist/bundles/Test Packager.app/Contents/app/whatever.policy