"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

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Simon Grant
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