Return value is 0 for failure. Otherwise a numeric value is returned which tells the evaluation cost. Bigger number means higher cost. The evaluation cost is approximately the number of LPC machine code instructions executed.
In native mode, command() can effect only the calling object. If native mode is not enabled, command() can get an optional second arg, that specifies the object that the command is to be applied to. If command() is called on another object, it is not possible to call static functions in this way, to give some protection against illegal forces.