I also have been confused by the CVS version tags for FreeBSD. Richard Bejtlich's
comment about Dru's use of the wrong tag was a little too modest.
Check out his excellent article about keeping the OS up to date at:
In it you'll find the following (which is the best explanation I've seen:
The following examples begin with 5.3 RELEASE, the most recently published version of FreeBSD:
RELENG_5_3_0_RELEASE is FreeBSD 5.3 RELEASE, just as you might get on CD.
RELENG_5_3 is the "security" branch for 5.3, which is FreeBSD 5.3 RELEASE with patches for security advisories and critical fixes applied.
RELENG_5 is the development line of the FreeBSD 5 tree, also known as 5-STABLE
. ("dot"), also known as HEAD, is the development line of the next version of FreeBSD, 6.0, also known as 6-CURRENT or simply CURRENT