[1] UTS #10: Unicode Collation Algorithm ( ( 版)) http://www.unicode.org/reports/tr10/
[2] XPath and XQuery Functions and Operators 3.1 () https://www.w3.org/TR/2017/REC-xpath-functions-31-20170321/
[3] XSL Transformations (XSLT) Version 3.0 () https://www.w3.org/TR/2017/REC-xslt-30-20170608/#uca-collations