Just playing around with things....

Thinking more.. do we perhaps want to toss the whole u model and instead introduce a direct system of
specifying precision.

1985 <- implicit year precision
1985-12 <- implicit month precision
1985-12-12 <- implicit day precision
1985-12-12T12 <- implicit hour precision
1985-12-12T12:12 <- impliciut min. precision
1985-W3  <- implicit week precision

How would we express "20th century"? That's century precision.
[In u format:  NNuu where N is 0-9, e.g. 19uu  ]

Just for the sake of discussion lets call this Pn.

P1 would mean 1-unit precision. A year
P1(1955) would be 1955--- 1955 as date is implicitly in year precision.

P100(1985) -> 100 year precision of 1985 -> 20 the century

P100(1985) = P100(1910) etc.

P10 (1955) -> 10 year precision of 1955 -> The 1950s.
[In u format:   195u]

We can apply this to months and even days

1955-12- P10(1)  would be 1-9 in Dec. 1955 with 10-day precision.
[What in u format as 1955-12-0u]

This format tosses out things like  1uu9 (see previous mail) but now includes some more interesting cases where we have
Pn where n is not limited (as in the u case) to  1,10,100 etc. but can be any natural number.

Recall that we also have week dates... YYYY-Www-D

1955-WP4(23)-2

This is a precision of 4 weeks--- contrast to month-- but also a specification that its Mondays.

1955-WP54(1)-2 would say the event took place on Monday in 1955.

1955-WP26(1)-2 would say the event took place on Monday in the first half of  1955.

Here there is no talk anymore about "unknown" but directly precision.

On Fri, 26 Nov 2010 13:02:09 +0000, Simon Grant wrote
> "Hammer this into the ground" sounds unwarrantedly rough, but, well, let's try to finish the discussion positively...
>
> On 26 November 2010 12:28, Edward C. Zimmermann wrote:
>
Pragmatically:
>

> [...]
>
195u means the event took place in the 1950s (its unit of precision is 10 years)
>

> = [1950...1959]
>
19uu means that the event took place in the 20th century (its unit of precision is 100 years)
>

> = [1900...1999]
>
1uuu means that the event took place in the second milennia (its unit of precision is 1000 years)
>

> = [1000...1999]
>
uuuu means that we don't know when the event took place
>
[...]
>
But the 'u' delivers more:
>
> uu59 means that we know the event took place in the year 59 but don't know the century
>

> A very unlikely case, extending as it does into the future.
> = [1059, 1159, 1259, ..., 9959] (sorry, needed to shorten that one :-)]
>
1u59 means that we know the event took place in the year 59 in the second milennia but don't know which century.
>

> Slightly less unlikely, though the only reason I can think of is that we have found a book with a ripped-off page. Do we really want to be dealing with these edge cases?
>
> = [1059, 1159, 1259, 1359, 1459, 1559, 1659, 1759, 1859, 1959]
>

> [...]
>
> > However, in both cases this states a claim or belief that the actual value
> is one of the set running all the way from 1980 to 1989. I don't see any
> *pragmatic*, *operational* reason for making a distinction. Furthermore, I
> believe that if such a distinction were made, in practice people would argue
> over or confuse the two, leading to inconsistency of semantics. The
> consequence would be that in practice, both forms would have to be treated
> equally in any case.
> >
>
> The extended date system has not provision at this time for |.
>
> In our systems (matching and searching dates) we would all probably handle
> them as the same but the sentence
>
> But.. just to hammer this into the ground...
>
> 195u is expressing something known (1950s)
> 195| is expressing more: Not only is it known that the event took place in the
> 1950s but we claim to be able (at some future time) to increase the precision.
>

>
> This is an important distinction. I would strongly advise *against* trying to include in a standard like EDTF any implication of a claim that precision may increase in the future. It seems much too vague a concept to be representing in a standardized way.
>
>

> 195| is essentially claiming a year precision but expressing that the year is
> not yet collected. Its a kind of "volatile" flag announcing that the precision
> might increase at some future time.
>

>
> Would people really agree on exactly what such a "volatile" flag might mean? I suggest going through the process of finding out, from real people, what they agree on here. My guess is that what they will actually consistently agree on is that the value is not known now :-) Glad this is not in the EDTF proposal: I would oppose it in carefully and forcefully argued terms.
>
> Really, you can't just include something in a public standard because it seems like a good idea to a few people. To be useful, it has to express a concept that there is genuine common agreement about. Otherwise, write a private or proprietary standard to be used among the group of believers. No one will stop you doing that. :-)
>
> Simon

> --
> Simon Grant
> +44 7710031657
> http://www.simongrant.org/home.html

--

Edward C. Zimmermann, NONMONOTONIC LAB
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