How this classloading settings work ?

[Rr Kumaran]

a.ear
-|-------- axis.war (web module)
-|-------- c.jar (ejb module)

say I have below set of jars under axis.war\WEB-INF\lib:

axis-ant.jar, axis.jar, bcel.jar, commons-discovery.jar, commons-logging.jar, jaxrpc.jar, jibx-bind.jar, jibx-extras.jar, jibx-run.jar, log4j-1.2.8.jar, saaj.jar, wsdl4j.jar, xerces.jar, xercesImpl.jar, xml-apis.jar, xpp3-later.jar, xpp3.jar

Now with below settings

a.ear Classloader mode: PARENT_FIRST
a.ear WAR classloader policy: APPLICATION
b.war Classloader mode : PARENT_FIRST or PARENT_LAST

I am successfully able to run AXIS 1.2 RC2 Web Module inside a EAR deployed on WSAD 5.1.2's WebSphere 5.0 Test Environment. Actually I faced a JiBX classloading issue if I keep any other settings other than above. I am not even sure why the above setting works for me. Can anyone please clarify ...