So, I have two "roans". I haven't tested yet. They say it's not in the Arabians, but roan is an acceptable colour on the registration application.
I say rabicano, but they both have every indicator or roan (dark legs, face, ears, etc) and my rabicanos are "roaned" throughout - butt, head, face, legs, etc.
Pink Floyd, Stallion:
And Tessa, Mare. She isn't as extreme, but definitely "roaned".