This feature is invisible ink printed on the surface of the banknote and is only visible when the note is placed under an ultra violet light.
$100 and $50 Banknotes
When held under ultra violet light the front of these banknotes show two blinks (blocks of invisible ink) with the numeral of the denomination and the jabiru. The back shows one blink with the numeral of the denomination.
$20, $10, $5 and $2 Banknotes
These banknotes have a blink with the numeral of the denomination and the jabiru and one blink with the numeral of the denomination on the back.