About dates and times

[Fabio Vitali <fabio@cs.unibo.it>]

Dear all, 

on the verge of publishing (in an hour or so) a new draft release of Akoma Ntoso, I would like to re-assert my conclusions about the discussion we had last time on the specification of time annotations on dates, and why Grant's solution actually simplifies things a lot. 

First of all, we have to remember that dates and timed dates expressed in a legal text point to a specific point in time. This can be fully expressed (e.g., "1 August 2013 at 0:00 CET") or have implicit parts: almost always the time zone, and very often the actual hour. Sometimes the legislator provides multiple representations for the same point in tie (e.g.: "1 August 2013 at 0:00 (31 July 2013 @ 23:00 UCT)" ). 

It must be remembered that these representation describe (in different ways) a single point in time, which is THE concept that needs disambiguation and formalization through a date element. Therefore, whenever the same point in time is expressed using a multitude of textual representations, only one encompassing date element needs to be used. 

As Grant suggested, the union of elements from the xsd:date and xdd:dateTime predefined simple types works just fine. For this reason, it will be possible, in the date attribute of elements such as date, docDate, etc., to use either a simple date value in the format 

YYYY-MM-DD

or a full dateTime value in the formats

YYYY-MM-DDThh-mm-ss
YYYY-MM-DDThh-mm-ss+zzzzz
YYYY-MM-DDThh-mm-ss-zzzzz

where YYYY is a four digit year in the Julian calendar, MM is a 1 to 12 number of the month, DD is a 1 to 31 number of the day, hh is a 00 to 23 number for the hour, ss is a 00 to 59 number for the second, and zzzzz is EITHER the letter Z (to signify UTC) or a five letter string to signify the offset of the time zone wrt UTC (thus, +01:00 is CET, -05:00 is EST, etc.). 

I hope we all agree on this

Ciao

Fabio



--

Fabio Vitali                            Tiger got to hunt, bird got to fly,
Dept. of Computer Science        Man got to sit and wonder "Why, why, why?'
Univ. of Bologna  ITALY               Tiger got to sleep, bird got to land,
phone:  +39 051 2094872              Man got to tell himself he understand.
e-mail: fabio@cs.unibo.it         Kurt Vonnegut (1922-2007), "Cat's cradle"
http://vitali.web.cs.unibo.it/