Bugs should be listed here if their version field is invalid (i.e. it is listed as "unspecified") or they are still present in KDE 4, so that the version field can be corrected. The version should be set to the newest version of KDE that the bug is reproducable, or to the version it was reported if it is listed as "unspecified" and it's not reproducable.
If a bug fits another category, put it there and add the notation that the version field needs changing.