The test suite is the actual specification; for the language release, it will be cleaned up of things that aren't yet ironed out. The design documents at http:

The test suite is the actual specification; for the language release, it will be cleaned up of things that aren't yet ironed out. The design documents at http://design.perl6.org/ http://design.perl6.org/ are companion documents to the test suite, but where the two are in conflict, the test suite is authoritative. As for changes: backward incompatible changes will result in a new language version.