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