====== P1-REQ-13-4-012 ======

[[dido:99_annexes:annex-d-requirements:part-01:start|Return to Part 1 Requirements]]

===== Statement =====

The Conceptual Architecture SHALL distinguish a [[dido:99_annexes:annex-b-terms-and-definitions:d:data_structure_definition|Data Structure Definition]] from a [[dido:99_annexes:annex-b-terms-and-definitions:d:data_structure_instance|Data Structure Instance]].

===== Source =====

Part 1, Section 13.4: Core Conceptual Element Requirements.

===== Rationale =====

A Data Structure Definition describes the structure, meaning, and constraints of a class of information. A Data Structure Instance identifies a populated occurrence of that definition.

Distinguishing definition from instance prevents a single occurrence of information from redefining the class of information and supports consistent interpretation, validation, and traceability.

===== Applies To =====

This requirement applies to Data Structure Definition and Data Structure Instance references within the Conceptual Architecture.

It applies specifically to:

  * Definition-to-instance relationships
  * Information classes
  * Populated occurrences
  * Information interpretation
  * Information traceability

===== Verification =====

Verification SHALL confirm that the Conceptual Architecture distinguishes Data Structure Definitions from Data Structure Instances.

Verification activities include review checks confirming that:

  * Data Structure Definitions describe classes of information
  * Data Structure Instances identify populated occurrences
  * Instances reference definitions without redefining them
  * Diagrams and text preserve the distinction between definition and instance

===== Traceability =====

Related source section:

  * [[fxdemo:01-part:13-conceptual-requirements:13-4-core-conceptual-element-requirements]]

Related requirement identifiers:

  * [[dido:99_annexes:annex-d-requirements:part-01:p1-req-13-4-001:start]]
  * [[dido:99_annexes:annex-d-requirements:part-01:p1-req-13-4-007:start]]
  * [[dido:99_annexes:annex-d-requirements:part-01:p1-req-13-4-008:start]]
  * [[dido:99_annexes:annex-d-requirements:part-01:p1-req-13-4-011:start]]

===== Status =====

Draft

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