Are you aware of the work that's been going on within the Europeana
projects? A Europeana Data Model (EDM) has been developed that could be
considered as a overall ontology for the heritage domain, including archival
material. There is a first concept to describe EDM as RDF.
It might be of interest to your research since Europeana aims to ingest
different heritage collections described with heterogeneous metadata
schema's like EAD's, aggregating these and making them available as linked
Mapping EAD's to EDM is a challenge that's been working on within one of the subsidiary EU project called APEnet: the European Portal for Archives. I've
seen some examples of this.
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