In a nutshell, the concept this SAML profile is implementing, is about blinding IdPs in respect to the SP a user is authenticating to. The reason is, that connection data is PII, and in large systems should be minimized.

Attachments:

SAML PE-FIM Profile v1.2.pdf

SAML PE-FIM Profile v1.1.pdf

SAML PE-FIM Profile.pdf (V1.0)