The test suite is the actual specification; for the language release, it will be cleaned up of things that aren&#x27;t yet ironed out.<p>The design documents at <a href="http:&#x2F;&#x2F;design.perl6.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;design.perl6.org&#x2F;</a> are companion documents to the test suite, but where the two are in conflict, the test suite is authoritative.<p>As for changes: backward incompatible changes will result in a new language version.