Hi Philipp,
the OAI-PMH unique identifier ( https://www.openarchives.org/OAI/openarchivesprotocol.html#UniqueIdentifier ) is very useful and is used in different ways to process metadata. If this could be a global _persistent_ unique identifier would be nice.
We see global unique identifiers but are not persistent from an aggregator perspective.
Best, Andreas
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Andreas Czerniak
OpenAIRE-NEXUS
www.openaire.eu
Bielefeld University - Library
Universitätsstr. 25 - 33615 Bielefeld - Germany (Winter:UTC+1, Summer:UTC+2)
Tel: +49.521.106.2694
Fax: +49.521.106.4052
www.uni-bielefeld.de
ORCID: https://orcid.org/0000-0003-3883-4169
ResearchGate: https://www.researchgate.net/profile/Andreas_Czerniak