OK, right, the 200-499 bits are less or more mixed up to me. Myself I align 100s with Dublin, 200s with Cork, 300s with Limerick and 400s with Galway/Sligo.
BTW. The highest route number is 495 Ballyshannon - Manorhamilton, which does an astonishing 4 runs a week! It actually isn't even in the map of Bus Eireann routes...
I wonder what in Heaven's name is 8xx for? Possibly some sort of "charging routes" for ticket vending machines. I have three tickets from the "venders" for Galway - Belfast month returns, which display I suppose 865 as the route number! What's the deal here?