[1] XQuery 3.1: An XML Query Language (2017-03-20 09:23:33 +09:00) <https://www.w3.org/TR/2017/REC-xquery-31-20170321/#dt-date-time>

[2] XML Path Language (XPath) 3.1 (2017-03-20 09:18:04 +09:00) <https://www.w3.org/TR/2017/REC-xpath-31-20170321/#dt-date-time>

[3] XPath and XQuery Functions and Operators 3.1 (2017-03-21 16:02:06 +09:00) <https://www.w3.org/TR/2017/REC-xpath-functions-31-20170321/#func-current-dateTime>