The DDI-RDF Discovery Vocabulary (Disco) is an RDF Schema vocabulary that enables discovery of research and survey data on the Web. The issue of its integration into the future DDI 4 is complex, and requires some coherence controls between the actual disco vocabulary and the upcoming RDF representation of the DDI information model. Widely accepted and adopted vocabularies are reused to a large extend in the disco vocabulary. The first step for the integration of disco is the identification and the validation of those external RDF properties and classes currently used in disco. This is the purpose of this view.