Status-bydesign is the response to a bug/feature request stating that this is the intended behavior.
Status-completed means the feature/bug fix has been implemented.
Status-declined means the feature request is "rejected" and will not be implemented.
Status-norepro means a bug cannot be duplicated
Status-planned is a feature that is being planned.
Status-review is a bug/feature being reviewed.
Status-reproduced is a bug that has been successfully reproduced.
I'm not sure what status-deffered is intended to mean.
I believe there is also a status-accepted (though there are none currently) which would be when a feature request has been accepted, but has not been completed yet.