In the effort of Governments worldwide to effectively transform manual into electronic services, semantic interoperability issues pose as a key challenge: system-to-system interaction asks for standardized data definitions, codification of existing unstructured information and a framework for managing governmental data in a unified way. Integrating and extending recent developments in Germany, Hong-Kong, UK and US governments - but also eBusiness interoperability research results in Europe, the proposed approach is applied within the Greek e-Government Framework and bears the following steps: (a) Gathering and analysis of governmental service forms at field level, so that common structures can be identified, (b) Customization of UN/CEFACT Core Components, (c) Semiautomatic XML Schema Definition (XSD) files creation, using sets of naming, structuring and verification rules, (d) Adoption of international or development of country-specific Codelists, (e) Development of guidance material for the application of the approach by government officials at central or local level. Discussion on the results is targeting best practice examples that can be drawn at scientific and organizational level, but also the key difficulties that have to be tackled - in relevance with the administrations and industry readiness in each country. Future steps include enhancing the paradigm in orderto cover vertical data standards and applying the approach to other EU or associated countries.