The Vf is the forward voltage across the diode, that voltage was measured with a current of 10ma's. Different forward currents are going to result in slight changes in the voltage dropped by the diode. That diode can actually pass 400ma's of current repetativly, as long as the average forward current is only 200ma's. It will even allow 1 amp pulses for 1 second (non repeating) or 4amp pulses for 1 micro second, again only if these pulses do not recur frequently.