On Tue, 21 Dec 2010 21:29:50 +0000, Simon Grant wrote 
> There is nothing universal about any particular time interval. Why
prioritise a decade in a decimal calendar over some other interval of years in

There is nothing "universal" but there is much that is central to our
Occidental culture just as there is nothing "universal" about the measure
of months and years (in my daily life I use two: both the International
normed and Hebrew calendars) but to deny the significance of 1 Jan, the
concepts (as pointed out in previous mails, national and local) of seasons
and the trend in Northern America and Western Europe to speak of decades as
milestones would be to deny anything other than "Universal culture" and among
Homo sapiens that probably boils down to only as much as one can ascribe to
apes and monkeys.

> some other calendar? The closer I consider things, the more arbitrary a
decade or a century appears. Hence my preference (and willingness to argue)
for a primary, general system of points and intervals, and only secondary and
less important (and only if trouble-free) some notations for selecting ranges
of years etc. etc. 

But a Westerner measures things in years. It defines the life cycle from
when to start school, what age one can vote and when to retire. With few
exceptions most Americans, for example, see the recurrence of their birth
day and month ("birthday") as special (milestone). In Jewish culture great
significance is placed upon Jahrzeit.
Jews too measure things in years but the years are different--- and there are
multiple concepts even of year between time as we see it, time in the Torah 
and time in the Messianic Era (where there is no linear time but where history
and future appear to intersect). Australian aborigines has a concept of time
but its non-linear.

> The precisions mentioned here are fully dependent on the time system and
calendar, and therefore only "scientific" inasmuch as our current science uses
these units and this numbering system. I do *not* believe they are worthy of

Precision are always dependent upon the measurement system (here "calendar").

On Tue, 21 Dec 2010 16:48:18 -0500, Ray Denenberg, Library of Congress wrote 
> I would be happy with '19' meaning 1900 through 1999, 

I think we can address that differently. We have--- like it or not--- an
Occidental concept of century. We could dismiss it but its like dismissing
the Christian calendar that forms the basis of "International" dates.
While the concept of "century" is, unfortunately, commonly used.

Alone in today's news the phrase "19th century" was found by my engine
in 34 news stories. Google News (which covers also non-news sources) claims
6,320 results (but only lists around 30).
"British Prime Minister, Benjamin Disraeli's 19th century aphorism: Lies,
damned lies, and statistics in descending order."

Please observe, however, that the phrase 19th century and the concept of
100 years 1800 to 1899 are not really different on the level of century.
On a precision of year 1900 belongs to the 19th century and 1800 to the 18th
but if we view century with a readability of century... Think of a
glass thermometer example. I have 10 marking between 20 and 21. The
distance between 20 and 21 is 20 mm (e.g. between markings is 2 mm) and
the bevel is 2mm. What temp. do I have if the mercury is a tiny hair above
20? A tiny hair below?  

>  I would be fine just saying it means 1900 through 1999 and then striking
"century" from our spec. But then I don't know how others feel about that,
those who may have a need to refer to specific centuries. Perhaps nobody does.
I would not want to come up with an alternative syntax for a century since
8601 attempts to provide one, though flawed. 

On Tue, 14 Dec 2010 12:19:24 -0500, Ray Denenberg, Library of Congress wrote
> Ed-- 
> By your view, 1960/1969 (and 1960--1969) is "an interval with 
> precision of year", while 196x is "the decade of the 60s, with 
> precision of decade".
> The problem I see is that "decade" is pretty specialized. I mean, suppose

Agree. Its, however, one of the precisions that people tend to often use
in conversation. "50s Rock and Roll", "1970s Fashion", "the Roaring 20s". 

> instead you have the interval 1958/1969 (equivalent to 1958--1969),
> similarly, in your terms, "an interval with precision of year" but 
> there is no corresponding x representation.

Correct. These are all implicit precisions just like 1981 is implicitly
year precision. 1958/1969 is an interval of year precision. 

To extend things we could use a precision operand. This could let us have
something to talk about periods such as the FD Roosevelt Era (1933/1945 with
year precision, 1933-03-04/1945-04-12 with day precision or some expression to
describe the era in a precision of its dozen years), The Belle Epoche (started
sometime in the late 19th century and ended with WW-I), Victorian era, the
Thirty Years War, the Exodus from Egypt .. etc.

Again: the key to these is also their meaning with "approximate" attached.

Some notation for decade (with decade precision) I think is needed. Even
with precision I think its difficult to express something that is as simple
to express in common speech "the 1950s decade".

> So how useful is this x representation really (when it can only represent
> intervals of powers of ten), and how useful is the "precision of decade"?

Its main use, I think, is to get a compact representation for decade. 

> I would just as well then leave out the x notation alltogether.  Personally
> I think it is more useful applied as "discrete years", but that's 
> just my view, and as Simon suggests, it's best to avoid notatations 
> that people want to use in divergent ways.

Introducing a P (for precision) operand.   
  1965PY5  (1965 += 5 years -> 10 year to a precision of 10 years)
  this would be the 1960s decade.

PY := precision year
PW := precision week,  example PW2 := precision of +- 2 weeks
PM := precision month
P  := precision day, example P5 := precision of 7 days
PD := precision day (just for consistency)

An expression such as 1960PY1 is 1959/1960 but viewed as a point (3 years)

We could add accuracy as well:
AY := accuracy year etc.

I don't have a burning need for these.. the only one I current use in my
own software is decade precision. Lacking a standardized manner to express
it I accept (in my date parser I accept more than just ISO 8601 but try hard
to accept all kinds of well defined date formats that are used in the
  This Decade (this current decade, e.g. 2010-2019)
  1950s (for the decade of the 1950s)
and for intervals expressions like:
   During the 1950s
   Within the 1950s


Edward C. Zimmermann, NONMONOTONIC LAB
Basis Systeme netzwerk, Munich Ges. des buergerl. Rechts
Office Leo (R&D):
  Leopoldstrasse 53-55, D-80802 Munich,
  Federal Republic of Germany
Umsatz-St-ID: DE130492967