2 | ship must have mil>0, glim>0, gun>0, shell>0, eff>=60
20 | at sector that doesn't exist
22 | at ship that doesn't exist
26 | at valid target, but no mil
42 || ship firing nowhere (shells consumed)
46 | at ship out of range
48 | at sub, server pretends out of range
53 || ship firing at bogus target
60 || ship firing at undefended target
61 | 100% bb with 1, 2, 3 guns
70 | likewise 1, 2 shell (take care to avoid automatic supply)
79 | likewise 1, 2, 3 mil
97 | at ship, fractional range, ~50% chance