Closing Gaps: A Model of Cumulative Curation and Preservation Levels for Trustworthy Digital Repositories

Curation and preservation measures carried out by digital repository staff are an important building block in maintaining the accessibility and usability of digital resources over time. The measures adequate to achieve long-term usability for a given audience strongly depend on scenarios of (re)use, the (intended) users’ needs and skills, the organisational setting (e.g., mission, resources, policies), as well as the characteristics of the digital objects to be preserved. The assessment of curation and preservation measures also forms an important part of existing certification procedures for trustworthy digital repositories (TDRs) as offered, for example, by the CoreTrustSeal foundation, the nestor network, or ISO. The digital curation community is presented with the challenge of finding community-, organisation-, and object-specific approaches to curation and preservation at the same time as defining the minimum level of curation and preservation measures expected from a TDR in sufficiently generic terms to ensure applicability to a wide array of repositories. Against this backdrop, this paper discusses the need for and benefits of community-agreed levels of curation and preservation to address this challenge, and considers the tiered model proposed by the CoreTrustSeal Board as an example. The proposed model is then applied in an analysis of successful CoreTrustSeal applications from 2018–2022 in an effort to better understand the capacity of the curation and preservation levels to capture the respective practices of repositories and to identify potential gaps.