<u>Codominance.</u> This is shown by the calico cats, who have both black and orange phenotypic expression; the black and orange are not mixed like incomplete dominance, and one is not entirely dominant over the other. (A common example is the roan cow, whose fur is a bit red, a bit white.)
<u>Sex-linked inheritance.</u> Since calico cats are said to always be female (which actually isn't entirely accurate, by the way) this means that the coat color is sex-linked. It's found on the X chromosome, so a female cat can have one X black and one X orange chromosome. This is only possible in males when they are nondisjunct and inherit two Xs along with their Y... but that's a completely different story. :)
