Identifying a service

I'm soemewhat not sure what the group thinks about identifying a service
(this is not about identifying WSDL components themselves!). I remember
some discussions at F2F, but can't extrapolate it to the whole group.
Here is my informal strawpoll question.

The following is uniquely identifies a service for any client:
	1) URL of a WSDL document that has a single <service>
	2) QName of the following form:
<WSDL-target-namespace>:<service-name>
	3) URL where SOAP messages go
	4) URI of the following form:
<URL-of-the-WSDL>#<Xpath-expression-to-a-service-element>
	5) URI of the following form:
<URL-of-the-WSDL>#<service-element-ID>

What's your choice?

-- Igor Sedukhin .. (igor.sedukhin@ca.com)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11788