FPF Reference

    C.3.A:A.5 Design guidance & pitfalls [I]

    Preface node heading:c-3-a-a-5-design-guidance-pitfalls-i:40473

    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

    Do this.

    • Treat regulatory categories as Kinds. Put the definition into KindSignature (aim for F4 predicates where practical).
    • Make time explicit. In guards, require a time selector (Γ_time) for effective dates and grace periods. Forbid “latest”.
    • Publish bridges with loss notes. If two jurisdictions’ categories are “almost the same,” say how, rate CL^k, and note what is lost.
    • Split “where” from “what.” Keep Scope (G) over U.ContextSlice (jurisdiction, plant, Standard versions) separate from MemberOf on the kind.
    • Route uncertainty to R. Use Ψ(CL^k) and Φ(CL); never modify F/G to hide ambiguity.

    Avoid this.

    • Synonym games. Don’t alias “Adult” to local AdultPatient in prose. Use a KindBridge.
    • Scope by labels. “Domain = EU” is not a guard. Use explicit U.ContextSlice fields (jurisdiction, version, time selector) and Scope predicates.
    • Hiding time. Never rely on “current law”; always fix Γ_time (point/window/policy).
    • Widening G to compensate for type gaps. If kinds don’t line up, introduce a subkind, add a mask/adapter, or narrow; don’t “make the scope bigger”.

    Last Updated: 2026-06-17 — upstream FPF commit 646b0b9b (github.com/ailev/FPF)