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Achieving Metadata Registry Content Consistency: CAN/CSA‑ISO/IEC TR 20943‑3‑06 – Value Domains
Technical Guidelines for Value Domain Design and Documentation in Accordance with ISO/IEC 11179
CAN/CSA‑ISO/IEC TR 20943‑3‑06 is the Canadian adoption of ISO/IEC TR 20943‑3:2004, a Technical Report that provides guidelines for achieving content consistency in metadata registries (MDRs), specifically regarding value domains. It is part of the ISO/IEC 20943 series, which supports implementers of ISO/IEC 11179 — the international standard for the representation of metadata. This report focuses on the consistent specification, documentation, and maintenance of value domains, ensuring that metadata within and across registries remains interpretable, comparable, and reusable.
Scope
CAN/CSA‑ISO/IEC TR 20943‑3‑06 defines a value domain as a set of permissible values for a data element or a data attribute. The report offers practical techniques for describing value domains, including:
- Enumerated value domains – explicit lists of permissible values (e.g., codes or terms).
- Non-enumerated value domains – described through a description or a rule (e.g., a range, regex pattern, or external reference).
- Value meaning – the conceptual definition associated with each permissible value.
The scope extends to all phases of a metadata registry life cycle: creation, validation, versioning, and mapping between value domains. It is intended for data architects, metadata managers, and system developers who need to ensure that values are unambiguous and consistently interpreted across systems.
Key point: The report is not an alternative to ISO/IEC 11179 but rather a complementary guide that shows how to achieve the consistency objectives of the 11179 series when dealing with value domains.
Technical Guidelines for Value Domain Consistency
While the report does not prescribe mandatory requirements (as it is a Technical Report), it provides detailed recommended practices. The following are the core guidelines presented in CAN/CSA‑ISO/IEC TR 20943‑3‑06, grouped by theme.
3.1 Value Domain Representation
Every value domain should be defined by:
- Data type (e.g., string, integer, code).
- Unit of measure if applicable (e.g., kg, m).
- Permissible values – either enumerated (explicit list) or non-enumerated (description or rule).
- Value meanings – textual definitions for each permissible value that capture semantics independent of the representation.
The report emphasizes that the same value meaning can appear in multiple value domains, enabling cross‑domain consistency.
3.2 Enumerated Value Domain Specification
For enumerated domains, the report recommends structuring each item as a trio:
- Permissible Value – the actual signifier (e.g., “F”).
- Value Meaning – the meaning (e.g., “Female”).
- Value Meaning Description – additional context if needed.
It also advises that value meanings should be defined once and reused, rather than re‑described for each domain, to avoid ambiguity.
3.3 Consistency Across Domains
A major contribution of the report is the framework for mapping between value domains. When two data elements use different coded representations for the same conceptual value (e.g., “M” vs. “Male”), the registry must record a correspondence between the permissible values. CAN/CSA‑ISO/IEC TR 20943‑3‑06 outlines several mapping scenarios:
- One‑to‑one equivalence
- Value aggregation (e.g., many codes mapping to one meaning)
- Semantic overlap with no exact match
For each scenario, the report describes how to document the mapping in the MDR to maintain consistency.
Common pitfall: Relying solely on the permissible value (code) without recording the value meaning often leads to misinterpretation when the same code is used in a different context. Always capture the meaning explicitly.
Key Technical Aspects in Summary
The following table summarises the essential elements for documenting a value domain according to the report’s guidance.
| Aspect | Required Attribute | Example |
|---|---|---|
| Name | Value Domain Name | Gender Code |
| Data type | Type of permissible values | String (length 1) |
| Representation class | Enumerated / Non‑enumerated | Enumerated |
| Permissible value | Value itself | F |
| Value meaning | Meaning of the value | Female |
| Value meaning description | Definition of the meaning (optional) | Indicates a person of female gender |
| Domain classification | Conceptual domain reference | GenderConcept |
Implementation Highlights
Applying the guidelines of CAN/CSA‑ISO/IEC TR 20943‑3‑06 within an organisation typically involves the following steps:
- Inventory existing value sets – Collect all coded lists and value ranges currently used in databases, messages, and interfaces.
- Extract value meanings – For each permissible value, document what it means, not just what it looks like. This often requires interviews with domain experts.
- Map to a conceptual domain – Group value domains that share a common meaning (e.g., all colour code sets map to the concept “Colour”). This is a key requirement in ISO/IEC 11179‑3.
- Record in a registry – Populate an MDR with the value domain attributes, including origin, steward, and version history as recommended by the report.
- Establish cross‑domain mappings – Where equivalent meanings exist in different coding schemes, record the correspondence in the registry.
Implementation tip: Start with a small set of high‑value domains (e.g., country codes, currency codes, gender) to build momentum. Use the report’s templates for documenting permissible value/meaning pairs.
Compliance Notes
CAN/CSA‑ISO/IEC TR 20943‑3‑06 is a Technical Report, not a normative International Standard. Consequently, “compliance” is not a pass/fail certification but a measure of how closely an MDR implementation follows the recommended practices. Organisations seeking alignment with the ISO/IEC 11179 series can use this report as an authoritative reference for value domain consistency.
Important considerations for compliance assessment:
- Traceability: Each value domain should be linked to an identified conceptual domain (as defined in ISO/IEC 11179‑3).
- Meaning persistence: Value meanings must be documented and versioned independently from the permissible values.
- Mapping completeness: When two value domains are known to overlap, the registry should contain an explicit mapping, even if the overlap is only partial.
- Adherence to 11179‑6: The Technical Report complements the registration process described in ISO/IEC 11179‑6; consider using both together for a full conformance framework.
Warning: An MDR that stores only permissible values without their meanings or domain context is non‑conformant with the spirit of the report. This can lead to costly data inconsistency and misinterpretation across systems.
Relationship to Other Standards
This Technical Report is tightly coupled with:
- CAN/CSA‑ISO/IEC 11179‑1‑18 – Framework for metadata registries.
- CAN/CSA‑ISO/IEC 11179‑3‑18 – Metamodel and basic attributes (value domains are defined in clause 9).
- ISO/IEC TR 20943‑1 – Part 1: Data elements (guidance for data element consistency).
- ISO/IEC TR 20943‑2 – Part 2: Classification schemes.
Together, these documents form a comprehensive toolkit for building interoperable metadata registries.
FAQs
Q: Is CAN/CSA‑ISO/IEC TR 20943‑3‑06 a mandatory standard?
A: No. It is a Technical Report (TR), meaning it provides guidance and best practices rather than normative requirements. However, many organisations adopt it to ensure their metadata registries align with the ISO/IEC 11179 framework.
A: No. It is a Technical Report (TR), meaning it provides guidance and best practices rather than normative requirements. However, many organisations adopt it to ensure their metadata registries align with the ISO/IEC 11179 framework.
Q: How does this report differ from ISO/IEC 11179‑3?
A: ISO/IEC 11179‑3 defines the metamodel and attributes for value domains at a conceptual level. The TR gives concrete, step‑by‑step guidance on how to document, manage, and map value domains to achieve consistency in practice.
A: ISO/IEC 11179‑3 defines the metamodel and attributes for value domains at a conceptual level. The TR gives concrete, step‑by‑step guidance on how to document, manage, and map value domains to achieve consistency in practice.
Q: Can I use the report for non‑enumerated value domains?
A: Yes. The report addresses both enumerated and non‑enumerated domains. For non‑enumerated domains, it recommends a rule‑based description (e.g., “positive integer between 1 and 999”) and encourages documenting the rule in a standardised format.
A: Yes. The report addresses both enumerated and non‑enumerated domains. For non‑enumerated domains, it recommends a rule‑based description (e.g., “positive integer between 1 and 999”) and encourages documenting the rule in a standardised format.
Q: Does complying with this TR guarantee interoperability?
A: Strict adherence significantly improves the chances of interoperability because it ensures that value meanings are unambiguously captured and traceable. However, interoperability also depends on other factors such as agreement on conceptual domains and use of common data element identifiers.
A: Strict adherence significantly improves the chances of interoperability because it ensures that value meanings are unambiguously captured and traceable. However, interoperability also depends on other factors such as agreement on conceptual domains and use of common data element identifiers.