OWL-Time [[owl-time]] is an ontology for temporal entities and relations between them.
OWL-Time defines simple temporal entities (intervals and instants).
This note adds one new class time:Era, two properties time:era and time:reignOf, and an instance time:CommonEra to allow for the description of eras.
The namespace for OWL-Time terms is http://www.w3.org/2006/time#
The suggested prefix for the OWL-Time namespace is time
The OWL-Time ontology is available here.
The OWL-Time ontology with these extensions is available here.
This is a Public Draft of a document prepared by Elie Roux. The document is prepared following W3C conventions. This document is not an OGC Standard. This document is distributed for review and comment. This document is subject to change without notice and may not be referred to as an OGC Standard. Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
New classes and properties are introduced in this extension to OWL-Time. The new elements concern temporal entities which cannot be expressed in OWL-Time. The ontology document imports OWL-Time, and adds the new elements and axioms. IRIs denoting the new elements are placed in the OWL-Time namespace since it is expected that they could be added to the normative ontology in a future revision of OWL-Time.
OWL-Time is an ontology for describing temporal information. As part of its mission it implements ways to encode dates in the Gregorian calendar.
This extension answers a need by Digital Humanists to encode dates in other types of calendar using different eras.
Classes and properties are denoted in this specification using Compact URIs [[?curie]].
The namespace for all classes and properties in OWL-Time and this extension is
http://www.w3.org/2006/time#.
The table below indicates the full list of namespaces and prefixes used in this document.
| Prefix | Namespace |
|---|---|
ex |
http://example.org/time/ |
owl |
http://www.w3.org/2002/07/owl# |
time |
http://www.w3.org/2006/time# |
xs |
http://www.w3.org/2001/XMLSchema# |
Where class descriptions include local restrictions on properties, these are described using the OWL 2 Manchester Syntax [[owl2-manchester-syntax]].
Examples and other code fragments are serialized using RDF 1.1 Turtle notation [[turtle]].
| Class: | time:Era |
|---|---|
| IRI: |
http://www.w3.org/2006/time#Era
|
| Definition: | A linear (non-cyclic) frame of reference used to assign numbers to years.
This class can be used for any year numbering system, even if the definition of "year" in that system doesn't match the one of the Gregorian calendar.
For instance Roman reigns (like they reign of Claudius) or Japanese eras (like the Reiwa era) can be encoded as instances of time:Era.
This specification makes no assumption about the possibility of a year 0, or of years with negative indexes. An era can correspond to a temporal entity (ex: a Roman Emperor reign) but does not have to (ex: the Common Era, which doesn't have an upper limit). |
| Instance of: | owl:Class |
| Property: | time:era |
|---|---|
| IRI: |
http://www.w3.org/2006/time#era
|
| Definition: | Era indication |
| Instance of: | owl:ObjectProperty |
| Domain: | time:GeneralDateTimeDescription
|
| Range: | time:Era
|
| Property: | time:reignOf |
|---|---|
| IRI: |
http://www.w3.org/2006/time#era
|
| Definition: | The object of this property is the person whose reign is associated with the era. In some cases multiple eras are associated with the same reign (especially in the late Chinese context). No range is indicated so that the associated person can have any relevant type. |
| Instance of: | owl:ObjectProperty |
| Domain: | time:Era
|
The Era of the modern gregorian calendar, so that a time:generalYear associated with this era is roughly equivalent to a xs:gYear.
The general year associated with this era can be a non-gregorian year. For example, some Chinese calendars may indicate years in the Common Era, even though the Chinese year starts and ends after the gregorian one.
| Class | Individual |
|---|---|
time:Era |
time:CommonEra |
The Reiwa era (associated with the reign of Naruhito) is used to indicate years in the official Japanese calendar since May 2019. The 11th of July 2020 could be encoded as follows:
Some documents refer to the sixth year in the reign of Claudius, which occured in 45-46 in the Common Era. It can be encoded as: