This Standard outlines how government institutions and other stakeholders can harmonise data definitions, structures, and exchange protocols to enable seamless interoperability across various IT systems in Nigeria. Beginning with an overview of semantic interoperability where systems share a precise, mutual understanding of data, the document highlights common incompatibilities at domain, entity, and abstraction levels. It then prescribes uniform approaches to naming, structuring, and standardising data elements (e.g., naming conventions for addresses, personal names, or biometric information) so agencies can avoid duplication and misinterpretation of records. Providing detailed tables, appendices, and practical use cases, the Standards emphasise consistent data modelling practices, unified naming rules, and rigorous validation methods. Ultimately, this prevents fragmentation of government databases, fosters accurate data analysis, and enhances service delivery in the public sector.