Where do I look for the reason for the removal of a package from the Ubuntu repositories

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http://askubuntu.com – I have seen that when a new Ubuntu version is released, sometimes a particular application that I had used till the previous Ubuntu versions would have been removed from the Ubuntu repositories for the latest release. Who can makes such decisions( a particular Launchpad team/individual,etc..), and which mailing-list(or other resource) should I look to find the exact reason for removal of the package from the latest Ubuntu release. e.g: Kompozer has been removed from the repository for Quantal (HowTos)