====== P4-REQ-21-3-003 ======

[[dido:99_annexes:annex-d-requirements:part-04:start| Return to Requirements]]

===== Statement =====

The Phase 0 Implementation Profile / PSM SHALL identify IDL as the selected Phase 0 data definition mechanism.

===== Source =====

Part 4, Section 21.3: Technology Selection Requirements.

===== Rationale =====

IDL provides the governed implementation-level mechanism for defining data structures used by the selected Phase 0 DDS implementation.

Identifying IDL as the selected data definition mechanism provides a consistent source for generated implementation types while preserving traceability to the FX logical information structures those IDL definitions realise.

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

This requirement applies to:

  * governed Phase 0 IDL files;
  * IDL structures;
  * generated types;
  * DDS Topic data representations; and
  * FX logical information-structure mappings.

===== Verification =====

Verification SHALL confirm that IDL is identified as the selected Phase 0 data definition mechanism.

Verification activities should include review checks confirming that:

  * applicable Phase 0 data structures are defined through governed IDL;
  * IDL structures trace to applicable FX logical information structures;
  * generated types identify their source IDL structures; and
  * IDL remains an implementation representation rather than a redefinition of logical information.

===== Traceability =====

This requirement connects FX logical information structures to their selected Phase 0 IDL representations.

Related requirement identifiers:

  * [[dido:99_annexes:annex-d-requirements:part-04:p4-req-21-3-002]]
  * [[dido:99_annexes:annex-d-requirements:part-04:p4-req-21-3-005]]

Related source section:

  * [[fxdemo:04-part:21-phase-0-implementation-requirements:21-3-technology-selection-requirements:start]]

===== Status =====

Draft

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