A system may include electrodes on at least one lead configured to be operationally positioned for use in modulating a volume of neural tissue, a neural modulation generator configured to deliver energy using at least some electrodes to modulate the volume of neural tissue, a programming system configured to program the programmed modulation parameter set, including determine electrode fractionalizations for the electrodes based on a target multipole. The programmed parameter set may include the determined electrode fractionalizations. The target multipole may be used to determine electrode fractionalizations having at least three target poles that directionally and progressively stack fractionalizations of target poles to provide a linear electric field over the volume of tissue. The neural modulation generator may be configured to use the programmed modulation parameter set to provide the linear electric field over the volume of tissue.