loading . . . International Metadata Recommendations, and Platform-Specific Requirements for Open Access Books and Chapters With a review of recent policies and recommendations, an overview of metadata formats used in long-form publishing, specific metadata requirements mandated by international aggregators, and a formulation of a two-tiered metadata framework for books and chapters. Executive Summary This report provides a comprehensive review of international metadata standards and requirements for open access books and chapters. It aims to support small-to-medium sized independent scholar-led, as well as institutional, publishers of open access books in implementing effective metadata management practices, thereby improving the discoverability, interoperability and sustainability of open access books. The report situates Thoth Open Metadata within a broader movement towards open, community-owned infrastructure for scholarly publishing, responding to persistent challenges faced by independent and institutional publishers navigating proprietary metadata systems and fragmented technical standards. By consolidating research from major initiatives, including the ongoing work within the Copim Community as well as now-completed European initiatives such as DIAMAS, CRAFT-OA, and PALOMERA, and the corresponding emergence of the journals-focused Diamond Open Access Standard (DOAS), the report outlines current policy landscapes, identifies key gaps, and proposes a harmonised approach to metadata for open access books. Key findings include: Metadata openness and interoperability are critical for inclusion of books (open access and non-open access) in research assessment, policy development and monitoring, and equitable dissemination. Legal and accessibility frameworks (e.g. EU GPSR, Americans With Disabilities Act) increasingly necessitate the provision of richer metadata, including funder data, licensing, and accessibility fields, flowing through degradation-free metadata supply chains. Fragmentation of metadata standards and formats (ONIX, MARC, KBART, etc) in use across stakeholders and intermediaries active in the supply chain impedes visibility and reuse of open access books, while also impinging on the reuse of the metadata itself Persistent Identifiers (PIDs) such as DOI, ORCID, and ROR are essential for tracking, attribution, and interoperability – yet adoption remains uneven, particularly in the Humanities and Social Sciences, and particularly within the wide archipelago of small-to-medium-sized publishers across the globe. The highly fragmented nature of the book supply chain – with an existing multiplicity of distribution channels and correspondingly fragmented metadata requirements that is substantially different to that of journal publishing – means that policy and technical maturity for open access books has traditionally lagged behind that of journals. In response, the report proposes a two-tiered metadata framework: Essential: essential bibliographic and access data including information on title and subtitle, contributors, copyright holders, subjects classifications, landing page and full-text URLs and/or DOIs at book and chapter level, licence, publisher details, publication date. Releasing metadata into the public domain and making this explicit in the metadata record (e.g. via a CC0 dedication) to facilitate easy re-use e.g. across libraries. Desirable: includes elements such as a fuller set of Persistent Identifiers (ORCID, ROR), usage of a broader set of controlled vocabularies, multilingual metadata, abstracts, cover images, tables of contents, and funder details. A fuller description of the two-tiered metadata framework is available in Section X of this report, and the PDF attached here as a supplement. The proposed metadata framework aligns with emerging international quality standards and policy documents (e.g., Diamond Open Access Standard (DOAS), the German Working Group of University Publishers’ [AG Universitätsverlage] Quality Criteria, NISO recommendations, and policies such as the Swedish National Open Access or UKRI Open Access policy ). The report at hand also provides guidance for stakeholders, and with a particular view on small-to-medium-sized publishers of open access books, to facilitate integration with key discovery platforms and aggregators such as OAPEN, DOAB, Google Books, JSTOR, and Project MUSE, while also looking at traditional as well as alternative distribution mechanisms to academic libraries. This is pertinent as library research has shown that traditional library supply chains and distribution mechanisms are not up to the task of properly disseminating open access titles. Hence, alternative open mechanisms are needed to embed open access books more fully within library collections. In essence, the report calls for coordination between stakeholders across open scholarly infrastructure to foster interoperability via a broader adoption of a common open metadata framework, with an overarching goal to empower independent as well as institutional small-to-medium-sized publishers, to enhance discoverability, and to strengthen bibliodiversity. Ultimately, by proposing a future-proof enhanced metadata framework, the report provides a pathway to more centrally position open access long-form publishing in the global scholarly communication ecosystem. Acknowledgement: The authors are indebted to Christina Drummond (OAeBU DT), Arnaud Gingolt (OpenEdition), and Ludo Waltman (Leiden University), who have provided invaluable feedback on sections of this report. Supporting documents: Report document, in multiple file formats; Graphic `Overview of metadata formats, particular specifications, and platforms for open access books'. CC BY 4.0, 2026, Thoth Open Metadata; Spreadsheet `Overview of International Aggregators' Metadata Requirements for Books`, including the proposed framework of Essential and Desired Metadata for OA Books and Chapters (2026). This also available as a live online spreadsheet; and the full bibliography of referenced works in BibTeX and Zotero RDF formats. The extended bibliography can also be accessed via this open Zotero collection. https://zenodo.org/records/18173982
