The first link ( http://www.gentoo.org/proj/en/releng/docs/cascading-profiles.xml) in the Description section of the man page for portage is broken. Observed this while "man portage" on bash.
There's no such link in portage(5) man page according to https://gitweb.gentoo.org/proj/portage.git/tree/man/portage.5 Which version of portage are you using?
Created attachment 473668 [details] The link underlined in the screenshot (attachement) man portage was used in the live USB, may be that's outdated. Portage(5) is what the output shows, guess that's the version.
Sorry I mean Live DVD "livedvd-amd64-multilib-20160704.iso"