> From: Saašha Metsärantala > In all the examples in #204, the x replaces the last digit of a year. > Is such a limitation part of the EDTF specification? Or should we > assume that x's may be placed on other digits anywhere in a date? As far as I recall (or can tell) there was only one advocate for x-replacement; that was Ed, who argued strongly for it. (Nobody else that I recall claimed a need for it (but nobody argued against it, at least not loudly). So I suppose Ed should weigh in on that question. I think that Ed wanted only the single 'x' and only at the end of a year. > 1) Assuming that x's are only allowed to replace the last digit of a > year: > > I wonder whether there is a need for such a construction. Ed claims that there is. > 196x > > is easily (and more legibly) rewritten as > > {1960..1969} I don't know if that's easier or more legible. > {1958..1959, 196x, 1970} > > is probably better rewritten as > > {1958..1970} > > which is both shorter and more legible. Ok but it isn't hard to come up with a counter-example. In fact change the above only slightly to: {1957..1958, 196x, 1971} Which without the x-notation would be: {1957..1958, 1960-1969, 1971} Which is more complex, though, I agree, only marginally so. > 2) Assuming that x's are allowed on other digits that the last digit of > a > year: > > I think that we should make clear that x's are allowed to replace any > digit, anywhere in a date. So 1x90 would mean: the years 1190, 1290, 1390, 1490, 1590, 1690, 1790,1890, 1990 What would be a use case for this? > {1xx0, 2000} > > which would mean all years ending with a zero from 1000 inclusive to > 2000 inclusive and obviously is MUCH shorter than what it would be if > we do not allow x's on other digits than the last one in a year. I > wonder whether there are enough use cases for such constructions. > > In some cases, x's are maybe useful. Let's consider > > 2011-06-xxT12:00:00 > > which means at twelve o'clock every day during june 2011. According to > the BNF, such a construction is not unambigously allowed, though. I do > not how many use cases there are for such constructions. > Yes as you note, this is all about whether there are real use cases for these notions. Lacking any, I would not want to pursue this beyond the single 'x' at the end of a year. --Ray