FPF Reference

    A.6.B:5.2 — Quadrant A: Admissibility & Gates

    Preface node heading:a-6-b-5-2-quadrant-a-admissibility-gates:9891

    What this page is

    This is generated FPF reference text from the specification preface or supporting sections. It helps interpret FPF; it is not FPF Reference product documentation.

    Methodology

    Use it to understand how the specification wants to be read, then return to a route, pattern, or work packet for active work. Cite generated IDs only when the wording changes the task decision.

    Content

    Intent. Specify when a mechanism application is admissible: runtime entry predicates, validity gates, and applicability checks that require context or execution environment. An A-* predicate may consume a result from another owner as one input, but it does not create or settle that result. If the sentence uses permission wording, choose its job with the branch in §8.4.1.

    Common mistake #0 — Applicability ≠ Admissibility (informative). Signature Applicability scopes intended use and bounded context; it is not a runtime entry gate. Runtime entry checks and admissibility predicates belong in U.Mechanism.AdmissibilityConditions as A-*. If your prose reads like “clients must satisfy the applicability”, you almost certainly want a D-* duty + an A-* gate (linked by ID) instead.

    Adjudication. In‑work: evaluated at mechanism entry (or operationally at the point the mechanism is applied).

    Canonical form. Predicate style, e.g.:

    • “A request is admissible iff …”
    • admissible(x) iff P(x) (conceptual form; no particular syntax is required)

    Prohibitions.

    • An A-* statement MUST NOT be placed in U.Signature.Laws.
    • An A-* statement MUST NOT use RFC deontic keywords as if it were an agent obligation. (It is a gate predicate, not a duty.)
    • An A-* statement MUST NOT claim that evidence exists (that is E-*) or that someone must enforce the gate (that is D-*).

    A.7 EntityOfConcern binding. A-* claims are Descriptions of a mechanism gate. They are not “what a client must do”; they are “what the mechanism admits”.

    Required references (explicit). If an A-* predicate relies on defined terms or invariants, it SHOULD reference the relevant L-* IDs (or at minimum the signature that defines them).

    Last Updated: 2026-07-28 — upstream FPF commit 17edd955 (github.com/ailev/FPF)