The XML Query Working Group has published a Proposed Recommendation for two documents:
XQuery 3.1: An XML Query Language: XML is a versatile markup language, capable of labeling the information content of diverse data sources including structured and semi-structured documents, relational databases, and object repositories. A query language that uses the structure of XML intelligently can express queries across all these kinds of data, whether physically stored in XML or viewed as XML via middleware. This specification describes a query language called XQuery, which is designed to be broadly applicable across many types of XML data sources.
XQueryX 3.1: XQueryX is an XML representation of an XQuery. It was created by mapping the productions of the XQuery grammar into XML productions. The result is not particularly convenient for humans to read and write, but it is easy for programs to parse, and because XQueryX is represented in XML, standard XML tools can be used to create, interpret, or modify queries.
Comments are welcome through 28 February 2017.