The SOVO simply states 'International Orange' (or 'Orange International', depending on where it appears). The further reference is DEF(AUST) 1000C - Packaging, part 5, section A, which might have the paint specifications for the various colours, but I don't have a copy of that Defence standard, so cannot help.
In practice, I've seen the word 'ARMY' and the Kangaroo in different shades of orange, and even in yellow. There are three examples on Leopard tanks provided as colour images on page 168 of my book 'Leopard AS1 in Australian Service' from Trackpad Publishing.
Mike