In 2.0 draft spec, the `<dita>` element https://github.com/oasis-tcs/dita/blob/DITA-2.0/specification/langRef/base/dita.dita is defined in the base DITA spec, but the schema for the element is only defined in the DITA Techcomm spec https://github.com/oasis-tcs/dita-techcomm/blob/DITA-2.0/doctypes/rng/technicalContent/ditabase.rng. IMO the prose description of an element should be in the same spec as the schema for that element.