Digital archiving faces a dual challenge in making research data accessible: how to preserve their integrity, while opening up their assets for broader use. Data curation methods must acknowledge traditional approaches as well as be adaptable to recent social exigencies and technological innovation in rendering data interoperable. Our session explores the practices at various European archives in developing thematic metadata to explore their holdings and create bridges to connect with similar datasets in other repositories. Through exercises of labelling research documents the participants will receive experiential evidence of the ambiguity of meanings and the irreducible uncertainty of interpretation.