We use nobuild files to indicate releases we shouldn't build a package for. They sit in the directory you run da* from. So, for instance

builder@zulu:/mit/debathena/packages/config/debathena-cluster-login-config$ cat nobuild
etch lenny squeeze

They're not kept in version control anywhere, which is unfortunate. You also have to edit them when you add a new release if the package shouldn't be built for that release. 

'''TODO: Except we don't, docuyment X-Debathena-No-Build and friends'''