Although range expressions (N to M) are not used in XPath 1.0, the XPath 2.0 specification states that the operands are handled like arguments to a function expecting xs:integer, which means that backwards compatibility rules apply: if a sequence of integers is supplied as an argument, then the first integer in the sequence should be used. That is (1 to (3,4)) is not an error in 1.0 mode, it returns the sequence (1,2,3). The WG resolution of bug 7424 confirms this interpretation. A patch is being raised to Saxon 9.1 and 9.2 to implement this decision. A test backwards074 has been added to the W3C XSLT 2.0 test suite.