I have a dataset that has two different date-time datatypes; timestamps and from-to dates (lifespan data, formatted as yyyy–yyyy).
I'm considering issues related to the formatting of these data, reuse and linking (such as linking to DBPedia dates).
I'm aware that there are datatypes for dateTime and calendar data, but I wonder if there is an "accepted" way of representing these data.
If your data is suited to it then it may be best to use xsd:dateTime and xsd:date rather than a more complex ontology/type since this is one of the standard types that is supported by SPARQL engines and allows you to do value based equality and comparison on them e.g. all items that occurred in January:
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX ex: <http://example.org>
SELECT * WHERE
?item ex:start ?start ;
ex:end ?end .
FILTER (?start >= "2010-01-01"^^xsd:date && ?end <= "2010-01-31"^^xsd:date)
While an ontology like the time ontology may allow you to be far more expressive it would tend to make the queries you have to write far more complex