ok there is nothing in airbus manuals about this, but this is a good example when you have to use your common sense, during t/o below 72knots on a320 at least we have no auto brake so, if we are taking off and we need to stop for any reason wee will neeed to use manual brakes and in order to apply we need to use the top of the pedals ,so we need to mantain our feet on the pedals durign t/o.