[arch-general] package name foo vs libfoo (eg. clutter vs libclutter)

Hello, this may be a minor issue, but it's bugging me so much that i had to write it here. and please link me to any previous discussion if this was asked before, i was kinda lazy to really search and http://wiki.archlinux.org/index.php/Arch_Packaging_Standards didn't mention anything about it. is there any rule on how to name packages ? lets take clutter as an example. it's named "clutter" everywhere in upstream, git, tarball, docs etc. but, it only builds libraries, and names those libclutter* (and really is only usable as library) so why are these (or only this?) packages named foo and not libfoo ? cheers .andre ps. im here to fix, not flame :)