Apply GDPR-grade pseudonymization to clinical or personal text with OpenMed, keeping a separately-held re-linkage key so the data can be controlled-re-linked later. Use when the user must process EU personal/health data under GDPR, asks for pseudonymization vs anonymization, needs Art. 4(5) / Art. 9 / Recital 26 alignment, wants a reversible mapping/key vault held apart from the data, or needs controlled re-linkage. Covers openmed.deidentify(policy="gdpr_pseudonymization", keep_mapping=True), storing the mapping in a separate key vault, reidentify() for authorized re-linkage, and retention. Pairs after extracting-pii-entities and configuring-privacy-policies.