CVS Tags

[David Fuchs]

Maybe I'm the only one confused by this, but would someone mind stating 
plainly what the difference is between the following CVS tags found at:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/cvs-tags.html:

RELENG_4
RELENG_4_10
RELENG_4_10_0_RELEASE

I assume RELENG_4_10_0_RELEASE is what the sources were tagged as at the 
time 4.10 was made an official release, and then development toward 4.11 
is made under the name RELENG_4.  If that's the case, then what is 
RELENG_4_10?  The page says that RELENG_4_10 is 'the release branch for 
FreeBSD-4.10, used only for security advisories and other critical 
fixes.'  Does this mean there are two lines of development here?

Thanks,
-David