More than one IPL 6 ?

[Janos Mohacsi <mohacsi%fsz.bme.hu@localhost>]

Hi,

If there are more than one Zorro card that can generate interrupt 
IPL 6 (External interrupts) how is it handled in NetBSD-Amiga? Are they 
chained ? How the interrupt sources polled? Even, Is it a real condition 
( which zorro cards are open-collectors ?) to able to cooperate more 
than one device in the same interrupt ?
Thanks,
        Janos Mohacsi