Time Instants or Time Points

[Tara Athan <taraathan@gmail.com>]

There is a relatively recent date-time ontology published by OMG (http://www.nist.gov/customcf/get_pdf.cfm?pub_id=911074) that addresses time scale granularity and also solves the problem of duration (is 1 month greater, equal or less than 30 days?)

While LegalRuleML is not supposed to be dependent on any particular ontology, this work does provide a useful conceptualization that allows certain intervals of time to be specified with a single datum. For example the date 2012-10-12 corresponds to a particular interval of time which can be specialized to a particular 24 hr interval when a timezone is added. This general concept of a point on a time scale with a particular granularity is called "time point". It is more general than a "point in time" or "time instant", but could include that concept if the time scale is continuous.

I proposed that we adopt this terminology, (but not the ontology) by referring to a collection of <ruleml:Time> elements as <lrml:TimePoints>

This also avoids the unfortunate plural "Times", which could be confused with multiplication or repitition, while retaining generality regarding the granularity, if any, of the time scale.

Example

<lrml:TimePoints>
  <ruleml:Time key="t1"> <ruleml:Data xsi:type="xs:dateTime">2012-07-21T00:00:00Z</ruleml:Data> </ruleml:Time>
  <ruleml:Time key="t2"> <ruleml:Data xsi:type="xs:date">2012-07-21</ruleml:Data> </ruleml:Time>
</lrml:TimePoints>

Tara