In part 2 chapter 1 of the AMD64 installation handbook ("A Portage introduction") there are some references to the "world" set, but there is no @ sign prefix. As far as I know commands still work if you forget the @ sign, but it's deprecated syntax. emerge(1) man page says: "When used as arguments to emerge sets have to be prefixed with @ to be recognized." In particular, in http://www.gentoo.org/doc/en/handbook/handbook-amd64.xml?part=2&chap=1#doc_chap3_sect5 there are 5 instances of "world" without the @ prefix. In http://www.gentoo.org/doc/en/handbook/handbook-amd64.xml?part=2&chap=1#doc_chap3_sect6 there is another instance, too. Of course this bug is not AMD64 specific. The file to edit is xml/htdocs/doc/en/handbook/hb-working-portage.xml. Reproducible: Always
"world" is a special case; it's built into portage. also, sets with the @ prefix are a portage-2.2 feature, which is still hardmasked and thus not documented.
