"RPC" and "Messaging" style of SOAP

Hi

Soap can be used in two ways : "RPC" and "Messaging". I have questions
regarding this:

1) In the context of Web-Services, Soap seems to be used in "RPC" style
only. Can Web-Service potentially use "Messaging" style of SOAP?

2) According to my understanding, when used in "RPC" style, Soap
messages represent a call to a remote object. and when used in
"Messaging" style, soap messages represent a "XML document". How this
XML document  would be produced and consumed is up to the implementor. 

Thus Soap, when used in "RPC" style make the calls "truely
interoperable". But i could not see any "interoperability". if Soap is
used in "Messaging" style. Am i wrong somewhere?   

3) What are the scenerios, in which Soap can be used in "Messaging"
style?

i would appreciate any comments on the above.

thanks,

regards,
Naresh Agarwal