[c-nsp] ASA failover - possible with a /30 ?

[Jeff Kell]

We are trying to move a customer behind our firewall (an active/active
pair of ASAs).  They are currently terminated on our edge via a /30
point-to-point link, and they would prefer to keep their addressing the
same.

The other inbound links to these ASAs are setup for failover, with the
"failover" and "standby" addresses in the failover configuration.

Is it possible to have this link "failover" without a configured standby
address?  or will this interface remain down if the primary goes down? 
Is the "standby" address only used for monitoring?

Jeff