Currently our set of validators in ValidatorBuilders does not validate the timezone. This is done in TimeValue, which limits it to an integer from -12 * 3600 to 14 * 3600.
I suggest to block all timezones other than 0, because:
- Almost all timezones we currently have in the database are errors/mistakes. Typically done by bots when creating an "imported from" reference. This is then the timezone where the bot is running, or anything else. We can't know.
- Having a timezone barely* makes sense when we do not support hour, minute and second. *You could argue that the timezone can be relevant even with day precision, but that's really vague and underspecified. Example: An event is know to happen on April 1st at 23:00 o'clock, but this is in a non-UTC timezone. It's April 2nd in UTC. People enter April 1st, which only makes sense with the timezone and the time. And that's the point: It does not make much sense without the time.
Query for http://query.wikidata.org:
# Dates with timezone are most probably a mistake
SELECT ?statementId ?c ?tz
WHERE {
# Keys: wikibase:timeValue (xsd:dateTime), wikibase:timePrecision (xsd:integer), wikibase:timeTimezone (xsd:integer), wikibase:timeCalendarModel
?dataValueId wikibase:timeTimezone ?tz .
FILTER (?tz != 0) .
?refId ?c ?dataValueId .
?statementId ?b ?refId
#SERVICE wikibase:label { bd:serviceParam wikibase:language "en" }
}
LIMIT 10