2 | sector must be fort with eff>5%, mil>5, gun>0, shell>0
21 | at sector that doesn't exist
23 | at ship that doesn't exist
25 | at valid target, but with insufficient mil
38 || fort firing nowhere (shell consumed)
42 | at ship out of range
44 | at sub, server pretends out of range
49 || fort firing at bogus target
51 | at sea, fractional range, ~50% chance
61 || fort firing at undefended target
62 | 5% fort with one gun
63 | 100% fort with one gun
64 | 100% fort with plenty of guns
65 | at own empty highway
70 | firing at bridges is covered in bridgefall-test
72 | at harbor with stuff
80 | at cs at sea, one sunk
85 | at cs in port, one sunk