This paper explores the persistent challenges in achieving interoperability within public procurement, emphasizing the critical transitions between organizational, semantic, and technical layers. While existing general frameworks such as the Framework for Interoperable Service Architecture Development (FISAD) and the European Interoperability Framework (EIF) provide structured approaches to interoperability, they often lack mechanisms for effectively translating domain-driven requirements into technical data standard specifications. To address this gap, the paper examines Simple Semantic Modeling in XML (SeMoX) as a method to enhance interoperability by bridging these layers. Drawing from a Design Science Research approach, the study integrates SeMoX into FISAD, creating a holistic architectural framework that incorporates data standardization as a core enabler of interoperability. Practical use cases, including SeMoX's application in public procurement, demonstrate its effectiveness. The paper concludes with an analysis of SeMoX’s contributions and outlines future research directions to evaluate its scalability and potential in developing interoperable, holistic architectures.