Earlier quoted context omitted.
Just to clarify, what happens at Christmas is the first proper language release (as specified by the test suite) that will be accompanied by a conforming compiler release, ie the main focus is still semantics, not 'production readiness'. That said, Rakudo of today is more usable than Rakudo of days gone by, though there are still issues (my personal pet peeve: parsing speed; hopefully , automatic precompilation will…
Thanks for the clarification. So what does it mean to release "a language"? Is there a specification in addition to the test suite? Is the specification frozen from that point on? Or will it change, but only in backwards compatible ways?
The design documents at 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.