Ptr to doc on "how end-entity authenticates cert_req to CA"

[Bill Doster <billdo@xxxxxxxxx>]

After looking through all the IETF PKIX drafts, I'm still in the dark as to what information is provided by the end-entity to authenticate itself as the entity named in the cert req
(as opposed to demonstrating possession of the cert's associated private key).

Perhaps my question is malformed to begin with?

Pointers anyone?