The ITIC curve plots the magnitude of the disturbance (in percentage) on the Y-axis and the duration of the disturbance on the X-axis. Disturbances that fall within the envelope defined by the upper and the lower curve are typically not harmful to electrical equipment; disturbances that fall outside the envelope may disrupt or damage the equipment. Both the CBEMA and ITIC curves also plot voltage with respect to duration, but as a percentage of absolute voltage. Electronic equipment can withstand high voltages provided they last for less than 1 millisecond in duration, but voltage cannot be greater than +10 percent or -20 percent for between 0.5 seconds and 10 seconds duration. These curves also offer a convenient way to define acceptable power-quality limits. However, the standard curves should be used only as guides.