In the Debian Bug Tracking System, a bug can be tagged to denote a particular aspect.
In can be the specific version of Debian that is suffering from the bug :
Tags: woody Tags: sid
In can tell the state of the bug, like when it won't be fixed, or when the upstream author of the package has been told of the bug, and will attempt to correct it in its source :
Tags: wontfix Tags: upstream
It can also link the bug to a particular subject, whose bugs can be found in several packages :
Tags: lfs Tags: ipv6