xs:dateTime that is current at some time during the
evaluation of a query or transformation in which
fn:current-dateTime() is executed. This function is
*stable*. The precise instant during the query or transformation
represented by the value of fn:current-dateTime() is
*implementation dependent*.
fn:current-dateTime() returns an xs:dateTime
corresponding to the current date and time. For example, an invocation
of fn:current-dateTime() might return
2004-05-12T18:17:15.125Z corresponding to the current
time on May 12, 2004 in timezone Z.
fn.currentDateTime() => 2014-10-29T21:13:49.437147