Thanks Florent,
Do you have any result of the W3C test suites, in order to see the coverage of the current support?
we are frequently running the W3 XQuery and Q3 Test Suites to check our conformance (the test classes are part of the open source code, too). Currently, most pending bugs are due to the extended regular expression features that (..unfortunately..) are not supported by Java's standard regex library. Michael Kay decided to embed a new Regex library for that in Saxon [1], which is something we may do as well. It will be exciting to see which implementation will first reach 100%.
Christian