While still many people use RELENG_4, it is End of Life (EOL) and End of Support (EOS). We encourage all users and developers to migrate to the FreeBSD 6.X branch, which is a stable and mature platform, and is now the 'reference' FreeBSD branch for the Ports Collection. The "last known good" tree has been tagged with the RELEASE_4_EOL tag as a convenience to those remaining users who intend to self-support their own 4.X installations. This tag is not supported in any way and security fixes will not be applied. Usage is therefore highly discouraged and should only be used as a last resort.
Support for RELENG_4 was removed from the ports infrastructure after the RELENG_4_EOL tag and the ports collection can no longer be used on that branch. Therefore maintainers are also no longer required to provide any form of support for running their ports on FreeBSD 4.X, and may also remove any legacy support code at their convenience.