Determines whether a given date/time is in summer-time (daylight savings time).
in-summer-time($date as xs:dateTime, $region as xs:string) ➔ xs:boolean?
The input date/time
The country code or Olson timezone name
Notes on the Saxon implementation
Available since Saxon 9.1.
$region argument may either be an ISO two-letter country code (for
es), or an Olson timezone name (such as
Europe/Lisbon). The function returns
true if the given date/time is in summer time (daylight savings time) in that country or
timezone, as far as can be determined from the Java timezone database. If the
information is not available the function returns an empty sequence.
If a country code is specified for a country that spans different timezones with different daylight savings rules (for example, the US), then one timezone in that country is chosen arbitrarily.
For reliable results, the supplied date/time should include a timezone. This does not
need to correspond to the timezone named in the second argument; it is there purely to
$date represents a single point in time unambiguously.