# Decision record: EAI-D1 - tariff as twenty-two strict rules

## Status

accepted

## Context

Article 17 pairs twenty-two risk classes with rates from 0.12 percent (class 1) through 2.96 percent (class 22, rate 0.0296), and the premium base multiplies the contract insured sum by the derived rate. (Amended by EAI-R3: the base read payroll before; see EAI-D4. This record's representation position is unchanged.)

## Question

One decision table or twenty-two strict rules for the tariff?

## Options considered

- Decision table routing class to rate under a uniqueness policy: compact, but a wrong row hides inside one table and the table form adds policy machinery the article never mentions.
- Twenty-two strict rules, each guarded by one class: longer, but each pair stands alone with its own source label.

## Position

Twenty-two strict rules, one per class, with the premium computation as a separate rule reading the derived tariff.

## Justification

Each class-rate pair carries its own source label, so a wrong row fails and reads alone. Strict fits because the article admits no exceptions. The premium stays separate because the article states the tariff table and the premium formula as distinct norms.

## Distinguishing scenario

The tariff suite pins all twenty-two rows: each class carries its own premium check with the expectation derived from the source percent (percent times a one-million insured sum), not copied from the rule literal. Remove the class-7 rule on a scratch copy and exactly EAI-TARIFF-CLASS-07-PREMIUM fails while the other thirty-six checks pass — per-row independence, not one row standing for the table. The class-22 check alone proves only class 22; the synthetic revisit demo flips class 22 to 0.0310 and trips exactly the three class-22 checks (core, tariff row, sum-distinguishes).

This choice of representation has no distinguishing scenario against an equivalent decision table: a correctly written table answers every admissible input identically. The position is judged by traceability instead — each pair carries its own source label and fails alone — not by a test the table form would fail.

## Assumptions

- Each employer carries exactly one risk class, assigned outside the package; the package never derives or validates the assignment.
- Rates are exact decimals as printed; no half-way rounding policy exists in the article.
- Every class the act lists appears exactly once in the rules (twenty-two rules, classes 1–22, each guarded by one class).

## Consequences

Adding a class means adding a rule. The premium rule reads the derived tariff, so tariff edits propagate to premiums without touching the premium rule.

## Open questions

none — the table is transcribed in full and the premium formula is separate, as the article states them.

## Review

Agent-reviewed with the EAI dossier on the candidate snapshot: position stands, per-row tripwire confirmed by the row-7 removal. No human subject-matter approval.