This year’s annual conference on the Preservation of Digital Objects, iPRES-2013, will be held at the Lisbon Technical University (IST) from the 2nd – 6th of September. EUDAT will be participating in the workshop on the Interoperability of Persistent Identifier (PI) Systems across PI domains. The use of persistent identifiers is core to EUDAT's philosophy of creating a collaborative data infrastructure for the domain of globally registered data. Interoperability between PI systems is essential so that data objects are globally findable and verifiable.