The documentation now has an Alphabetical index.
At the time of writing, W3C has published draft specifications under the titles XQuery 1.1, XPath 2.1, and XSLT 2.1. However, W3C has also announced its intent to change the numbering, so that the final specifications will be XQuery 3.0, XPath 3.0, and XSLT 3.0. Saxon 9.3 anticipates this change by using the version number 3.0 to refer to the new set of draft specifications.
The current state of implementation of all standard functions is now documented here.