Playing 8 ball an ERO is in the first inning and all ofthe balls are on the table at the beginning of your turn. So either break and run or opponents breaks dry and then you run out. If you make an opponents ball while performing an ERO it is still an ERO. Thus you can have a score of 10-1 or 10-2 whatever and still have an ERO it does not have to be a 10-0 which is something different. They track zip matches in the valley rule book, the 50-zip club is full of prime players. I have shot many 50's but never a 50-zip.