adfs-initiated sso to shib sp ?

[Tom Zeller]

With idp-initiated sso, somehow a saml authentication response from
the idp should be posted to the saml2 http-post assertion consumer
service url on the shibboleth sp, correct ?

More of an adfs question than a shib question : the user will click on
a link that url-decodes to something like the one below, where the
RPID parameter is the sp entityID and RelayState is the target web app
url, correct ?

https://adfs.com/adfs/ls/idpInitiatedSignon.aspx?RelayState=RPID=<sp
entity id>&RelayState=http://webapp.sp.com

Did I get this right ? close ?

Thanks,
Tom