e4x javascript references

I must confess my ignorance on this subject.
The example:
http://wso2.org/project/esb/java/1.7/docs/ESB_Samples.html#Sample350
makes use of some syntax in javascript that I don't understand, nor can find a good reference on.
Specifically:
var symbol = mc.getPayloadXML()..*::Code.toString();
What does this "..*::" do?
Are there any references online that explain it?

>I realize now it is related to e4x, and I'm looking for an exact explanation of the above syntax. If you have one, please post reply, but I'll keep looking.

>>Ok, here we go:
http://www.ibm.com/developerworks/webservices/library/ws-ajax1/

" resp..*::getQuoteReturn

This syntax takes a second to digest if you are new to E4X. The .. means search down the tree for the named element. The *:: means any Namespace, and so the value will be the value of any element called getQuoteReturn in any Namespace in the response SOAP envelope. "

Yes, I'm definitely new to e4x.