The document discusses different modes of mechanical ventilation: 1) Volume-controlled ventilation (VCV) targets a set flow and cycles based on a set volume, with the pressure waveform determined by the respiratory system and patient effort. 2) Pressure-controlled ventilation (PCV) targets a set pressure and cycles based on a set time, with the flow waveform again determined by the respiratory system and patient effort. 3) Pressure support ventilation (PSV) is pressure-targeted and flow-cycled, with the inspiratory time varying and the flow waveform determined by set variables and the respiratory system.