FreeBSD: Which branch is supported for longer?

Can someone help explain the FreeBSD support policy? I'm looking at http://security.freebsd.org/#sup , which says: Branch Release Type Release Date Estimated EoL RELENG_6 n/a n/a n/a November 30, 2010 RELENG_6_4 6.4-RELEASE Extended November 28, 2008 November 30, 2010 RELENG_7 n/a n/a n/a last release + 2 years RELENG_7_1 7.1-RELEASE Extended January 4, 2009 January 31, 2011 RELENG_7_3 7.3-RELEASE Extended March 23, 2010 March 31, 2012 RELENG_8 n/a n/a n/a last release + 2 years RELENG_8_0 8.0-RELEASE Normal November 25, 2009 November 30, 2010 RELENG_8_1 8.1-RELEASE Extended July 23, 2010 July 31, 2012 We haven't decided between FreeBSD 7.x and FreeBSD 8.x yet. We want to go with a FreeBSD branch which is supported for a while. Which release will be supported for longer? RELENG_7, or RELENG_7_3 ? RELENG_7 says "last release", which is a big ambiguous.