Abstract: Methods are disclosed for providing certain operational instructions to a hemodialysis machine. The hemodialysis machine possesses a programmable memory and a capability of operating according to a time-varying parameter such as variable ultrafiltration. According to the methods, the machine operator enters into the memory a desired time period, a target cumulative value of the time-varying parameter, such as target UF volume, and a proposed time-varying profile of the time-varying parameter that is representable as a plot of coordinates in a region defined by an ordinate of values of the parameter and a time-based abscissa, wherein the plot defines a profile cumulative value of the parameter. If the profile cumulative value is not equal to the target cumulative value, then the proposed time-varying profile is changed along the ordinate so that the profile cumulative value is made equal to the target cumulative value.