ECHOES Interoperability Requirements and Guidelines (D6.2)

This deliverable defines the interoperability requirements and implementation guidelines for the European Collaborative Cloud for Cultural Heritage (ECCCH). It establishes a structured interoperability framework covering technical, semantic, organizational, and legal dimensions necessary to enable reliable exchange, reuse, and federation of cultural heritage data, services, workflows, and applications across distributed infrastructures.
The document introduces three cumulative interoperability levels (L1–L3), providing a progressive onboarding and maturity path for providers while ensuring consistent validation, security, and operational readiness across the CH Cloud ecosystem. These interoperability levels are 
aligned with the integration model defined in the ECHOES Integration Strategy (D3.1), ensuring that interoperability readiness enables corresponding levels of integration within the federated architecture.
The deliverable specifies testable technical requirements, provider guidelines, validation and monitoring mechanisms, and federation-readiness expectations for datasets, APIs, applications, workflows, semantic artefacts, and infrastructure nodes. Together, these elements form the normative interoperability framework supporting the development of a coherent, secure, and sustainable Cultural Heritage Cloud.