$ROOT needs to be documented inn man 5 ebuild. running Portage 2.1.1_pre4-r1 (default-linux/amd64/2006.0, gcc-3.4.6/amd64-vanilla, glibc-2.4-r3, 2.6.17-gentoo-r1 x86_64)
now documented in svn
This has been released in 2.1.1_pre5-r3.