A system for delivering neurostimulation pulses to a patient using a plurality of electrodes (106, 206-1...N, 207, 406, 506, 606, 706, 707) and controlling the delivery of the neurostimulation pulses by a user, the system comprising: a programming control circuit configured to generate a plurality of stimulation parameters controlling delivery of neurostimulation pulses according to one or more stimulation waveforms; a user interface including: a display screen; and an interface control circuit configured to define the one or more stimulation waveforms, the interface control circuit including an impedance presentation module configured to receive values of impedances each between two electrodes of the plurality of electrodes for all of combinations of two electrodes available from the plurality of electrodes and display all of the received values of impedances on the display screen; an implantable stimulator (404, 504, 604, 704) including: a stimulation output circuit configured to deliver the neurostimulation pulses; and a stimulation control circuit (214, 714) configured to control the delivery of the neurostimulation pulses using the plurality of stimulation parameters; and an implantable lead (208, 408A, 408B, 508, 608A, 608B, 708) configured to be connected to the implantable stimulator and including a plurality of lead electrodes (106, 206-1...N, 207, 406, 506, 606, 706, 707) of the plurality of electrodes, wherein the stimulation output circuit comprises a plurality of timing channels each configured to deliver pulses of the neurostimulation pulses when being programmed to be active and not to deliver pulses of the neurostimulation pulses when being programmed to be inactive, and the interface control circuit comprises a channel timing module configured to identify one or more transition points in the one or more stimulation waveforms at which a timing channel of the plurality of timing channels becomes active or becomes inactive and apply a turn-off period during which none of the neurostimulation pulse is delivered from any active channel of the plurality of timing channels to each point of the identified one or more transition points, so that relative timing between the pulses delivered from channels that remain active before and after a point of the identified one or more transition points remain unchanged. a programming control circuit configured to generate a plurality of stimulation parameters controlling delivery of neurostimulation pulses according to one or more stimulation waveforms; a user interface including: a display screen; and an interface control circuit configured to define the one or more stimulation waveforms, the interface control circuit including an impedance presentation module configured to receive values of impedances each between two electrodes of the plurality of electrodes for all of combinations of two electrodes available from the plurality of electrodes and display all of the received values of impedances on the display screen; an implantable stimulator (404, 504, 604, 704) including: a stimulation output circuit configured to deliver the neurostimulation pulses; and a stimulation control circuit (214, 714) configured to control the delivery of the neurostimulation pulses using the plurality of stimulation parameters; and a stimulation output circuit configured to deliver the neurostimulation pulses; and a stimulation control circuit (214, 714) configured to control the delivery of the neurostimulation pulses using the plurality of stimulation parameters; and an implantable lead (208, 408A, 408B, 508, 608A, 608B, 708) configured to be connected to the implantable stimulator and including a plurality of lead electrodes (106, 206-1...N, 207, 406, 506, 606, 706, 707) of the plurality of electrodes, wherein the stimulation output circuit comprises a plurality of timing channels each configured to deliver pulses of the neurostimulation pulses when being programmed to be active and not to deliver pulses of the neurostimulation pulses when being programmed to be inactive, and the interface control circuit comprises a channel timing module configured to identify one or more transition points in the one or more stimulation waveforms at which a timing channel of the plurality of timing channels becomes active or becomes inactive and apply a turn-off period during which none of the neurostimulation pulse is delivered from any active channel of the plurality of timing channels to each point of the identified one or more transition points, so that relative timing between the pulses delivered from channels that remain active before and after a point of the identified one or more transition points remain unchanged.