There are two different "modifiers" that can be applied to ranks, + and -. The "+" modifier represents the capacity of a temporary boost in power, allowing a weapon or ability of a lower rank to surpass a higher rank for a moment. While a B+ is generally weaker than an A, B+ may momentarily exceed A by doubling its own power. + indicates a two-times increase, ++ indicates a three-times increase, and +++ indicates a four-times increase. The "-" modifier indicates a rank which has a number that is not reliably stable, technically qualifying for that rank, but not quite reaching the rank in terms of power or ability and possibly being even closer to the next rank down.