The code depends on who you are getting the paint from ie Manufacture. If you let me now i can give yo the code the name is Rosso and you are correct there are different types of red used at present i have 7 in my collection and only 3 Yellows. But will gladly help if you can tell me the paint manufacture i will get you the code. Most used one on Ducati is Lechler who funny enough are Italian and supply Ducati with there paint.
Take a look at this page on Ducati.com. Answer to question 20 gives you the codes you need. Apparently PPG are the original paint suppliers, easy enough to get from most car paint suppliers.