{HEAD ~ The challenge response application} can be administered by an issuer or by {TAIL ~ a third party} on behalf of an issuer 
{ HEAD ~ The challenge response application } can be administered by an issuer or by { TAIL ~ a third party } on behalf of an issuer
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH