current limit

For 6700K (and likely other CPUs too) there is a CPU current limit option that can be set to 255.5 which means no current throttling But why 255.5 and not 256 or 300? What's the deal with that 0.5? So really what is the "physical" meaning of 255.5? Is it in Amps? Like If i set it to 100 does...