单向双向：某些产品的手续费只在开仓时收取，有些则在开仓和平仓时都收取； The Sensitivities strategy [two] entails to start with calculating alternative sensitivities known as the Greeks because of the frequent exercise of symbolizing the sensitivities working with Greek letters. On ne improve rien à ce qui est en practice de se passer, mais on modifie seulement son sens. En PNL, Successfully Submitted (Awaiting Approval)