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Library / First Principles Framework (FPF) - Core Conceptual Specification
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Source changed 2026-10-03 08:25:59 UTC · snapshot created 2026-10-03 08:26:43 UTC · last check 2026-10-03 09:05:10 UTC

E.17.ID.CR:5.4.6.e - Functional versus constructive-description comparison

Source slice. A functional-description publication and a constructive publication or product-description publication describe the same pumping skid. The functional description foregrounds flow relation and method-selection relation; the constructive description foregrounds module composition and installed equipment.

Comparative review unit. For design review, the functional description foregrounds what the skid is supposed to do in the declared flow relation, while the constructive description foregrounds what parts are present. This contrast helps the engineer keep function and construction separate, but it is not a module-equivalence claim, a performed-work record, or a gate decision.

Why it stays here:

  • both source publications keep source references and remain inspectable;
  • the same pumping skid remains the EntityOfConcernRef;
  • the bounded comparative lift is the function-versus-construction contrast for one review task;
  • module equivalence, work occurrence, evidence, and gate claims remain blocked downstream uses.