I have been giving that some thought, particularly because some extensions have separate dev packages and
some extensions include their dev headers and libs in the same package. In both cases the packager is free
to add optional tags, such as dev or headers for example.
If dev, doc, and locale are submitted separately, I think that using the same tags as the main extension is a
good way to go, since that way they would all show up on a search, and their name should make their
purpose obvious.