Abstract
The CELINE Core Ontology is a lightweight orchestration profile for Renewable Energy Communities (RECs) and Digital Twin workflows. It connects established standards -- PECO, SAREF, SAREF4ENER, SOSA/SSN -- without redefining their domain semantics, providing a minimal coordination layer for simulation scenarios, dataset references, KPI definition and evaluation, flexibility commitment and settlement, grid topology, and member classification within the CELINE platform.