[gentoo-user] Understanding sets

[Zeerak Waseem]

Hey guys,

I have some questions about sets:
1) Sets are just files with one package per line in /usr/portage/sets,  
right?
2) Can a set be included in the world file?
3) With set files in /usr/portage/sets and running "emerge -u @foo"  
portage yields that @foo isn't a valid package atom, any idea why this is?

Thanks for any help :-)

-- 
Zeerak