What is the difference among thos tags in the  buildsystem web of Fedora http://koji.fedoraproject.org/koji?
There are 13 tags for Fedora 15,and I'm confused with the relationship among those tags.I know dist-f15-updates
is inherited from dist-f15,and dist-f15-override is   inherited from dist-f15-updates.I what to know which package should
goes to dist-f15-updates? In what situation, a package should goes to dist-f15-override but not dist-f15-updates?
Where can I find some relevant docs?I'm new here.