Deep Semantic Mapping governs advanced cross-ontology and cross-system semantic mappings within MyHealth@MyHands that cannot be expressed as simple 1:1 terminological mappings. Deep Semantic Mappings include multi-step concept transformations involving intermediate concept resolution.. It performs complex cross-domain semantic comparisons to establish meaning-level equivalences between national clinical data representations and the pan-European normalised health dataset.The mechanism draws on inputs from multiple European health projects and is supported by a dedicated knowledge graph processing component. Required particularly for preparing Normalised Health Datasets for secondary use research and digital twin feature set construction.