Part 3 of the Technical Report describes a data-centric view of a Spatial Data Infrastructure (SDI). The Data Centric view addresses the concepts of semantic interoperability, the methodology for developing data specifications through the application of the relevant International Standards, and the content of such specifications including Application Schemas, Feature Catalogues, General Feature Model, Data Lifecycle Management and Data Quality, Data Access and Data Transformation. The intended readership of this Technical Report are those people who are responsible for creating frameworks for SDI, experts contributing to INSPIRE, experts in information and communication technologies and e-government that need to familiarise themselves with geographic information and SDI concepts, and standards developers and writers.