`.^language-revision` is ENODOC
.^language-revision is specced in S14-roles/versioning.t and implemented in https://github.com/rakudo/rakudo/blob/5c4f9efe11cbcd1911341bacee7f917bc19406d6/src/Perl6/Metamodel/LanguageRevision.nqp#L82 but not documented. In fact type/Metamodel/LanguageRevision is missing entirely. It should be cross-referenced with /type/Version and referenced in /language/pragmas#v6.x and /language/typesystem .
Related: #3711
It's better not to rush with documenting it. Perhaps, it would make sense to reconsider the meaning of the method.
It's in roast, and so should be documented: S14-roles/versioning.t