Both enemy soldiers and vehicles may be targeted. Soldiers will fire their weapons regardless of the amount of cartridges in the magazine, so they will shoot those last rounds and then resume normal combat. Bazookas, Snipers, Flamethrowers and Mechanized units do not display this behavior.
The advantage to this command is to suppress most of the enemy and kill a few. The drawback is that this is an inefficient command due to the fact that the soldier with a pistol will shoot at a tank and the other soldier with a bazooka will shoot at a Volkssturm. Another drawback is that bazookas don't always fire at this command.