2 | ship must have mil>0, glim>0, gun>0, shell>0, eff>=60
17 | at sector that doesn't exist
19 | at ship that doesn't exist
21 | at valid target, but no mil
37 || ship firing nowhere (shells consumed)
41 | at ship out of range
43 | at sub, server pretends out of range
48 || ship firing at bogus target
55 || ship firing at undefended target
56 | 100% bb with 1, 2, 3 guns
65 | likewise 1, 2 shell (take care to avoid automatic supply)
74 | likewise 1, 2, 3 mil
92 | at ship, fractional range, ~50% chance