C.31.RSA:4 - Solution

C.31.RSA governs reusable-structure accounting as a typed description over declared structures and structural aspects. It starts with ReusableStructureTriage; it uses ReusableStructureAccountingDescription@Context only when the accounting basis is declared.

C.31.RSA:4.1 - Typed accounting description

ReusableStructureAccountingDescription@Context:
  accountingBasisRef:
  structureRefs: FinSet(U.StructureRef)
  structuralAspectRefs: FinSet(StructuralAspectDescriptionRef)
  reusableStructureSlots:
  bespokeResidueSlots:
  hiddenOrResidualUncertaintySlots:
  slotBasisRefs?:
  admissibleAggregationRuleRef?:
  reportOnlyShares?:
  sourceReturnCondition?:
  admissibleUse:
  nonAdmissibleUse:

accountingBasisRef identifies the accounting rule. The rule may concern description length, dependency edges, work items, evidence package count, cost share, template instances, interface variants, regulatory case sections, or another declared basis. The accounting rule is not implied by the word “reuse”.

Well-formedness: every slot is over declared structureRefs, declared structuralAspectRefs, and one declared accounting basis. Slot labels are explanatory; they are not root kinds and are not automatically commensurable.

C.31.RSA:4.2 - Explanatory slot labels

A local accounting description may use explanatory slot labels such as:

S_function
S_flow
S_control
S_type
S_interface
S_scale
S_work
S_evidence
S_changePolicy
S_unique
S_crossScopeUnique
H_residual

These labels are local slots, not FPF ontology. H_residual is residual uncertainty or unmodelled variance under the accounting basis. Its value is not automatically commensurable with counts or other measures of interface grammars, work templates, evidence packages, or regulatory arguments.

C.31.RSA:4.3 - Report-only shares

ReusableStructureShare:
  report-only share over declared structureRefs and structuralAspectRefs
  under accountingBasisRef; not an architecture amount

BespokeResidueShare:
  report-only share under accountingBasisRef

HiddenOrResidualShare:
  report-only uncertainty or residue interpretation under accountingBasisRef

Numeric shares require a declared accountingBasisRef, declared scale or unitless-value rule, unit when relevant, polarity when relevant, admissible comparability relation, and comparator admission named by value such as CG-Spec, ComparatorSetRef, or a comparator-governing reference named by value before they can guide outside-RSA use such as comparison, ranking, selection, gate use, or decision use. Without that, the share remains local report-only guidance.

C.31.RSA:4.4 - Pseudo-sum boundary

An explanatory decomposition may be useful:

total-described-structure under accountingBasisRef:
  reusable slots
  bespoke residue slots
  hidden or residual uncertainty slots

This is a readable decomposition of one declared accounting description, not an equation defining an architecture amount. If the slots do not share a declared accounting basis and comparability rule, they cannot be summed or ranked.

C.31.RSA:4.5 - Structure-relocation actions

RSA is useful because it points to relocation and repair actions:

A high reusable-structure share is not always good. The architecture question is where structure lives—for example, in reusable templates, interfaces, flows, control relations, work methods, evidence packages, or unique exception networks and hidden coupling—and what action follows.

After a relocation or reuse move, ask what got worse:

A conforming RSA move states the reusable locus, the bespoke or residual locus, the accounting basis, the first repair direction, and the first cost, loss, or source-return condition that can make the move inadmissible.

C.31.RSA:4.6 - Triage and accounting use boundary

Use only ReusableStructureTriage when:

• there is one local case;
• no outside-RSA use is being made;
• the practitioner only needs a repair direction;
• no numeric share is being relied on.

Use ReusableStructureAccountingDescription@Context when:

• the accounting basis is declared;
• a report-only share is useful;
• structure refs or structural aspects need to be compared inside one declared accountingBasisRef;
• source-return conditions matter;
• reusable structure or bespoke residue is used for outside-RSA use such as cross-case report, publication, assurance, architecture scale preference, or decision.

C.31.RSA:4.7 - Reopen and lowering conditions

An RSA result remains valid only inside its declared accounting basis, structure edition, source-return condition, and comparator admission. Reopen the triage or lower the admissible use when any of the following changes:

• a hidden source distinction becomes action-relevant;
• the accounting basis changes or proves heterogeneous;
• the selected structure, structural aspect, interface grammar, evidence package, work method, or assurance argument changes edition;
• a comparator set, CG-Spec, or outside-RSA use is added after a report-only share was recorded;
• downstream reliance uses the RSA result for outside-RSA evidence, assurance, gate, causal-use, scale-preference, or decision work that the RSA note did not admit;
• evidence validity, assurance window, or source-return condition decays;
• a local bounded exception becomes repeated enough to require refactoring;
• a reuse move improves one locus while worsening interface cost, variation loss, evidence decay, assurance work, source-return cost, or hidden bespoke residue.

Lower the result to report-only when outside-RSA comparison, ranking, selection, gate use, or decision use lacks comparator admission named by value. Lower it to quote-only or source cue when the accounting basis cannot be recovered. Mark it blocked when the reusable locus and bespoke-residue locus cannot be separated.