p6 libraries follow the guidelines published at http://perlsix.org/guidelines/. Each p6-* project maintains a page at http://code.launchpad.net/projects, however, *anyone* is free to commit to their own branch in the upstream repositories. Each p6-* project maintains its specifications as Launchpad "blueprints", so there can be multiple *implementations* of a single blueprint. Once a release of a blueprint implementation is cut, that blueprint is frozen as an API (and bug!) specification. Any releases of implementations of that specification must not add any features, and must remain fully backward-compatible with the associated specification. This allows developers to rely upon frozen APIs for module dependencies, but still allow for bugfixes. The recommended way to add new features is to implement "plugins", "extensions", "subclasses", "interfaces", or "submodules". This encourages properly modular design from the initial release of a specification.