ISO 18232:2006

Overview

ISO 18232:2006 defines a common, length-limited alphanumeric format for exchanging globally unique string identifiers (GUSI) for healthcare data objects. It standardizes how both ISO/IEC object identifiers (OIDs) and 128‑bit universal unique identifiers (UUIDs) are represented as character strings so that different healthcare systems can reliably reference, verify and merge data objects exchanged electronically.

Key topics and technical requirements

• Field constraints
  • GUSI field length: maximum 64 octets.
  • Field type: alphanumeric encoded per ISO/IEC 646 (basic ISO 7‑bit character set).
• OID (ISO/IEC data object identifier) format
  • Logical format: sequence of integer components per ISO/IEC 8824‑1 and registration rules in ISO/IEC 9834.
  • Character set: digits 0–9 and the dot “.” as separator.
  • Component rule: no leading zero in an integer component unless the value is zero.
  • Separator: single full stop (.) with no leading or trailing dot.
  • Applications must not infer semantic meaning from OID components.
• 128‑bit UUID format
  • Logical format: 128‑bit binary value represented in hexadecimal text.
  • Character set: digits 0–9, letters a–f, and hyphen “-”.
  • Canonical layout: five hyphen‑separated components of lengths 8-4-4-4-12 characters.
  • Encoded as alphanumeric octets per ISO/IEC 646.

Practical applications

• Verification of referenced objects: Confirm that a retrieved image, waveform or report matches the identifier embedded in the reference/pointer.
• Record merging: Use globally unique identifiers as reliable keys when combining data from multiple institutions.
• Archival indexing and access control: Link GUSIs to storage paths for retrieval and rights management within archives and PACS.
• Interoperability across systems: Facilitate exchange between EHRs, imaging systems and GP systems that may differ in native identifier models.

Who should use this standard

• Healthcare IT architects and system integrators
• EHR, PACS, LIS and imaging software vendors
• Developers implementing DICOM, HL7 or other healthcare messaging
• Standards bodies and registries issuing OID roots

Related standards

• ISO/IEC 8824‑1 (ASN.1 object identifier rules)
• ISO/IEC 9834 (registration authorities)
• DICOM (PS 3.x references for medical imaging object/UID usage)
• UUID specifications referenced in the standard

ISO 18232:2006 helps ensure consistent, interoperable string representations of global identifiers in healthcare data exchange, improving data integrity, traceability and system integration.