Major dublincore fields that use a directory are not correctly defined in studio: dc:nature, dc:subjects, dc:coverage and dc:language. When using those in a layout, the default widget is "text" (or "list") instead of a selection widget where the directory is already set.
It makes it difficult to use those fields in layouts as it's not really clear which vocabulary should be used for each one (and the localized vocabs are missing).
