From: Saašha Metsärantala > Maybe we should clarify that > > (A B) | C > > means the same that > > A B | C > > even without line break, doesn't it? No, not unless we add to the rules section a rule for evaluation of "|" over tokens. As it is, A B | C is ambiguous, that is, it isn't clear whether it means (A B) | C or A (B|C) > > Several productions exclude negative years. Maybe, that is what we want. > I suggest to clarify this point. It is true that for some of the definition, for example, where 'u' is a placeholder, I haven't bothered to allow negative years. I don't see the need for that level of complexity. If someone has a concrete use case, I'll add it. > Furthermore, I can not find the production with > > > dateWithInternalUncertaintly Right, I've added dateWithInternalUncertainty = internalUncertainOrApproximate | internalUnspecified > A problem in today's BNF is that it allows dates such as > > 2011-02-31 We have ensured that months and days match up for basic dates. To ensure this for the whacky dates is going to impose extreme complexity and I don't see why it's needed. Thanks. --Ray