Returns an xs:dateTime value created by combining an xs:date
and an xs:time.
fn:dateTime( $arg1 as xs:date?,$arg2 as xs:time?xs:dateTime?If either $arg1 or $arg2 is the empty sequence the function
returns the empty sequence.
Otherwise, the function returns an xs:dateTime whose date component is
equal to $arg1 and whose time component is equal to $arg2.
The timezone of the result is computed as follows:
If neither argument has a timezone, the result has no timezone.
If exactly one of the arguments has a timezone, or if both arguments have the same timezone, the result has this timezone.
The expression fn:dateTime(xs:date("1999-12-31"),
xs:time("12:00:00")) returns xs:dateTime("1999-12-31T12:00:00").
The expression fn:dateTime(xs:date("1999-12-31"),
xs:time("24:00:00")) returns xs:dateTime("1999-12-31T00:00:00").
A dynamic error is raised if the two arguments both have timezones and the timezones are different.