Software repositories in Ubuntu are divided into four categories or components - main, restricted, universe and multiverse, according to support offered by Ubuntu and free and open source: how well it meets the goals of Ubuntu's free software philosophy.
In my source file, I saw that all the ppa's belong to main, e.g.:
deb http://ppa.launchpad.net/kalakris/okular/ubuntu precise main deb-src http://ppa.launchpad.net/kalakris/okular/ubuntu precise main
While both being free and open source, Main is officially supported by the Ubuntu security and distribution team. and Universe is community maintained, but not officially supported.
Shouldn't a ppa belong to Universe instead of Main?