The large body of data on the Mesozoic and Cenozoic sequence stratigraphy of European basins can be used as solid evidence to test the EXXON curve. The use of numbers to distinguish sequences leads to ambiguities, anomalies, and confusion. Different authors tend to use different numbers for the same sequences, often because there is disagreement on how many sequences there are. If a mistake occurs, all the other numbers for succeeding sequences have to be changed. There are also the problems of the insertion of extra sequences if they are discovered, and how to discard sequences that are no longer recognized.