> 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.