 its materials uniquely and persistently for use both in and outside the 
AUDIT AND CERTIFICATION OF TRUSTWORTHY DIGITAL REPOSITORIES 
CCSDS 652.0-M-1 
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September 2011 
repository. The ‘visibility’ requirement here means ‘visible’ to repository managers and 
auditors. It does not imply that these unique identifiers need to be visible to end users or that 
they serve as the primary means of access to digital objects. Ideally, the unique ID lives as 
long as the AIP; if it does not, there must be tr