A great part of JSONiq is directly inherited from XQuery -- everything that is orthogonal to XML.

If you would like to know more about JSONiq, you can browse http://www.jsoniq.org/.

If you are interested in knowing the semantics of the expressions more in depth, you can find most of them on the XQuery 3.0 specification at http://www.w3.org/TR/xquery-30.

If you are interested in knowing the semantics of the builtin functions more in depth, you can find most of them on the XPath and XQuery Functions and Operators 3.0 specification at http://www.w3.org/TR/xpath-functions-30.