CADJ is recommended to improve ripple rejection. It prevents amplification of the ripple as the output voltage is adjusted higher.
Ci is recommended, particularly if the regulator is not in close proximity to the power-supply filter capacitors. A 0.1-µF or 1-µF ceramic or tantalum capacitor provides sufficient bypassing for most applications, especially when adjustment and output capacitors are used.
CO improves transient response, but is not needed for stability.
Protection diode D2 is recommended if CADJ is used. The diode provides a low-impedance discharge path to prevent the capacitor from discharging into the output of the regulator.
Protection diode D1 is recommended if CO is used. The diode provides a low-impedance discharge path to prevent the capacitor from discharging into the output of the regulator.