The deviation of the reference voltage, Vref, over the full temperature range is known as VI(dev). The parameter of VI(dev) can be used to find the temperature coefficient of the device. The average full-range temperature coefficient of the reference input voltage, αVref, is defined as:
αVref is positive or negative, depending on whether minimum Vref or maximum Vref, respectively, occurs at the lower temperature. The full-range temperature coefficient is an average and therefore any subsection of the rated operating temperature range can yield a value that is greater or less than the average. For more details on temperature coefficient, check out Voltage Reference Selection Basics.