Issues with the ical ontologies

1. The older ical ontology

http://www.w3.org/2002/12/cal/ical

....doesn't contain the properties ical:component, ical:standard and 
ical:daylight. Why? They are explicitly mentioned in the W3C note 
(http://www.w3.org/TR/rdfcal/) and the ical2rdf.pl script uses them in 
generated files.

2. The newer ontology

http://www.w3.org/2002/12/cal/icaltzd

contains many elements that are multiply defined like:

<owl:ObjectProperty rdf:ID="standard">
     <rdfs:label>STANDARD</rdfs:label>
   </owl:ObjectProperty>
   <owl:ObjectProperty rdf:ID="daylight">
     <rdfs:label>DAYLIGHT</rdfs:label>
   </owl:ObjectProperty>
   <owl:ObjectProperty rdf:ID="standard">
     <rdfs:label>STANDARD</rdfs:label>
   </owl:ObjectProperty>
   <owl:ObjectProperty rdf:ID="daylight">
     <rdfs:label>DAYLIGHT</rdfs:label>
   </owl:ObjectProperty>
   <owl:ObjectProperty rdf:ID="standard">
     <rdfs:label>STANDARD</rdfs:label>
   </owl:ObjectProperty>
   <owl:ObjectProperty rdf:ID="daylight">
     <rdfs:label>DAYLIGHT</rdfs:label>
   </owl:ObjectProperty>

This causes problems with the Sesame RIO library.
org.openrdf.rio.ParseException: ID 'standard' has already been defined

I had to remove those multiple definitions manually.

3. What do you think about adjusting the ical ontology to use the new 
owl-time vocabulary.
http://www.w3.org/TR/2006/WD-owl-time-20060927/
It has become a w3c working-draft two weeks ago and seems to be on the 
best way to become a w3c recomendation.

Antoni Mylka
mylka@dfki.uni-kl.de