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Responses to missed comments

From: <Simon.Cox@csiro.au>
Date: Mon, 20 Feb 2017 03:56:03 +0000
To: <public-sdw-wg@w3.org>
CC: <cowan@mercury.ccil.org>
Message-ID: <8ee5bc5723df442e9d5ca11c674a6194@exch1-mel.nexus.csiro.au>
John Cowan provided some comments on the draft of OWL-Time more than half a year ago, which slipped through the cracks.
Here are some responses:

1)      I'll continue to call it Unix time since that is the vernacular and is also the name used in Wikipedia/DBPedia from where we have taken a linked data identifier for use in the examples. However, I'll add a note that it is also known as Posix time.

2)      AFAICT it is OK to say that it is the count of seconds since that is what it is - a count. The issue of leap-seconds only comes up when you try to convert into another calendar, such as our conventional (Gregorian) calendar with leap-second adjustments. We didn't make any statement about that and don't propose to.

3)      I suggest that a discussion of leap-seconds is now out-of-scope since we have decided not to provide any model for temporal references systems, and are silent on the matter of conversions from one system to another.

4)      Yes, maybe. However, they are best known in the context of temporal relations, and in the case of OWL-Time we are not making backward incompatible changes. There are different views on modularization and how this should be reflected in 'namespaces' (really: URI stems). There are also different views on whether it is wise to aim at generality or specificity in ontologies, and the fashion changes! Furthermore, having the predicates available in a particular namespace does not preclude their use in other applications. Will leave as is for now.

5)      Hmm. Not sure that defining specific predicates for components all calendars are in scope.  Note that the only property which is cardinality=1 is hasTRS. If the TRS is a calendar which needs different names for its elements, then the user of that calendar will need to define them. The DateTimeDescription class supports day/week/month/year calendars, since they are the most common. If other calendars need other elements, the go for it!

6)      Now fixed.

7)      Please see Cox & Richard 2005, 2015 mentioned in the bibliography. These explain how the geological timescale model is based in the practice of the ICS.

8)      Timezone model now dropped from this specification. The IANA database is now mentioned.


From: John Cowan <cowan@mercury.ccil.org>
Date: Wed, 13 Jul 2016 21:57:13 -0400
To: Phil Archer <phila@w3.org>
Cc: www-international@w3.org, SDW WG Public List <public-sdw-wg@w3.org>
Message-ID: <20160714015713.GB32561@mercury.ccil.org>
Phil Archer scripsit:

> The original work only supported the Gregorian calendar and a major
> motivation for the New WG to take up the work has been to handle
> other calendars or Temporal Reference Systems. These include things
> like geological time but also other calendars in use around the
> world - hence this request for your review.

The following comments reflect only my personal views, and have nothing
to do with the I18n WG or anybody else.

1) Unix time should rightly be known as Posix time..

2) Posix time is not a count of seconds since a particular epoch,
because it excludes leap seconds.

3) There is no discussion of leap seconds anywhere.

4) The Allen and Ferguson interval relations are not specific to temporal
relations, and ought to be put in their own namespace so that they can
apply to arbitrary intervals (spatial intervals, numeric intervals, etc.)

5) The Maya Tzolk'in (ritual) calendar does not fit the ontology.
It separately counts the days of a 13-day period and the names of a
20-day period.  As an analogy, it is as if we numbered the days of
2012 as Sunday 1, Monday 2, Tuesday 3, etc. without any month names.
When both cycles come back into concurrency after 260 days, the next
ritual year starts.

6) Typos in the geological epoch chart:  Quanternary for Quaternary,
Creataceous for Cretaceous.

7) The whole idea that there is an identifiable instant separating
geological periods is Just Wrong.  Even if we knew when these transitions
happened, we wouldn't be able to describe them.  In the Devonian, for
example, the year had 400 days.  The transitions are inherently vague.

8) The time zone system is too complex as well as too simple.  It should
be aligned with the IANA time zone system, which divides the world into
some 400 zones, each of which (except the purely oceanic zones) occupies
part or all of a given country, and which is based on timezone as well
as DST transitions at various instants.

John Cowan          http://www.ccil.org/~cowan        cowan@ccil.org
        Is it not written, "That which is written, is written"?

Simon J D Cox
Research Scientist
Environmental Informatics
CSIRO Land and Water<http://www.csiro.au/Research/LWF>

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Received on Monday, 20 February 2017 03:57:20 UTC

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