From SELinux Wiki
The SELinux Reference Policy (refpolicy) is a complete SELinux policy that can be used as the system policy for a variety of systems and used as the basis for many Linux distributions, including Red Hat Enterprise Linux, Fedora, Ubuntu, Debian, and Gentoo. It is rigorously structured using computer science concepts, making it simpler to maintain and use. The goal is to allow greater adaptation and adoption of SELinux while maintaining the knowledge gained through the years of policy evolution, while increasing the ability to validate the security properties of a given SELinux policy.
The following pages describe concepts in Reference Policy and guides for using it.