beamed-power-interface

§7 BPI-A — Regulatory and Exposure Attestation

7.1 The principle

A conformant system declares the basis on which it operates, including the parts where no basis exists. It does not assert compliance with rules that do not apply to it, and it does not assert that rules exist where they do not.

This part exists because of a specific fact. There is no ITU Radio Regulations Article 21 space-to-Earth power flux-density row for 5.8 GHz. A system beaming power there is not in violation of that row; it is outside it. Those are different things, and a schema with no way to express the difference forces every implementer to pick a row that does not govern them and write it down as though it did.

The design insight: a schema with no way to say “there is no rule here” forces every implementer to lie. So the attestation has a positive half and a negative half, and the negative half is mandatory.

7.2 Spectrum and authorisation

spectrum {
  jurisdiction,                     // ISO 3166-1 alpha-2 (+ subdivision)
  authority,                        // "FCC", "Ofcom", "MIC", ...
  instrument: 'licence' | 'experimental_authorisation'
            | 'special_temporary_authority' | 'exemption'
            | 'notification' | 'under_application' | 'none_claimed',
  instrumentRef, issuedOn, expiresOn,
  band { centre_GHz, occupied_bandwidth_Hz, emissionDesignator? },
  allocationStatus: 'primary' | 'secondary'
                  | 'ism_not_allocated_for_this_use' | 'none',
  ituFilingRef?,
  article21 {
    applicability: 'exact' | 'analogue' | 'none',
    rowRef: string | null,
    declaredPfd_dBW_m2, refBandwidthHz, arrivalAngleDeg,
    marginDb, basis: 'screening' | 'modelled' | 'measured'
  }
}

[R-A-001] article21.applicability SHALL be exact only where a row of Article 21 covers this band and service. Where the nearest tabulated row is used as a yardstick, it SHALL be analogue. Where no row applies, it SHALL be none.

[R-A-002] article21.rowRef SHALL be null when applicability is none, and SHALL name the row otherwise. A null here is a legal, expected value.

[R-A-005] Where applicability is none, marginDb SHALL also be null.

A margin is a distance from a limit. Declaring that no limit applies and then reporting a distance from one is incoherent, and an earlier draft of this document did exactly that in its own worked example. If you screened against the nearest tabulated row, the applicability is analogue and the row is named — that is what “used as a yardstick” means. none is for a system reporting no screening at all.

[R-A-003] refBandwidthHz SHALL be present whenever declaredPfd_dBW_m2 is present, per [R-C-008]. There is no exception.

[R-A-004] marginDb MAY be negative. A negative margin is a disclosure, not an error, and SHALL NOT be suppressed or clamped.

7.3 Exposure

exposure {
  guideline: 'ICNIRP-2020' | 'IEEE-C95.1-2019' | 'national',
  nationalRef?,
  limitClass: 'general_public' | 'occupational',
  limit_W_m2, averagingTimeS, averagingAreaCm2,
  peakToMeanFactor, peakToMeanBasis,
  declaredPeak_W_m2, ratioToLimit,
  assessmentType: 'screening' | 'modelled' | 'measured',
  assessedBy { org, role, licensed },
  signed, reportRef?,
  localExposureBasis: 'SAR' | 'absorbed_power_density' | 'not_assessed'
}

[R-A-010] limit_W_m2 SHALL be accompanied by averagingTimeS and averagingAreaCm2, per [R-C-009].

[R-A-011] peakToMeanFactor SHALL be accompanied by peakToMeanBasis stating how it was obtained — for example, “2.5584, from a 10 dB Gaussian edge taper”.

A beam is not a top hat. Illuminating an aperture uniformly spills a large fraction of the power past its edge, so any real design tapers. An assessment that compares an aperture-average intensity against a limit written for the field a person stands in has compared the wrong two numbers.

[R-A-012] assessmentType: 'screening' SHALL NOT be used to support an L3 conformance claim. L3 requires modelled or measured, signed, with a named assessor.

[R-A-013] localExposureBasis SHALL be declared.

A known gap, disclosed rather than hidden. ICNIRP 2020 switches the local-exposure basis at 6 GHz: below it, specific absorption rate; above it, absorbed power density. A system operating at 5.8 GHz is therefore on the SAR side, and a power-density screening does not address local exposure at all. Declaring not_assessed is permitted and honest; claiming compliance on a power-density basis alone would not be. See OBJECTIONS.md §O-5.

7.4 Environmental, aviation and external authorities

environmentalReview { regime, status, ref, challengesPending }
aviation { coordinatingAuthority, restrictionType, ref,
           notamProcedure, externalAbortChannel }
externalAbortAuthorities[] { org, channel, credentialRef }

[R-A-020] Any party listed in externalAbortAuthorities[] SHALL have a working abort channel per [R-S-050].

7.5 unclaimed[] — the negative declaration

[R-A-030] unclaimed[] SHALL be present and SHALL enumerate every regulatory basis the operator is explicitly not claiming.

[R-A-031] operatingPosture SHALL be one of authorised, authorised_experimental, or operating_without_specific_authorisation_by_declaration.

For a 5.8 GHz space-to-Earth system as of 2026-08, an honest bundle reads:

"unclaimed": [
  "itu-rr-art21-space-to-earth-pfd-limit-for-this-band",
  "primary-allocation-for-space-to-earth-wireless-power-transfer",
  "itu-r-recommendation-governing-this-application",
  "national-type-approval-for-transmitter-at-rated-power"
],
"operatingPosture": "operating_without_specific_authorisation_by_declaration"

This does three things nothing else in the specification does.

  1. It makes the honest position machine-readable, and therefore aggregatable. A regulator could diff the unclaimed[] arrays of every declared system and see the shape of the gap in a single query. That is precisely the evidence an ITU-R work-item proposal needs, and precisely what nobody currently has.
  2. It converts an omission into an affirmative statement. Failing to mention that you hold no allocation is an omission. Declaring it and being wrong is a misstatement, with all the consequences that carries.
  3. It makes conformance orthogonal to authorisation. A 200 m laboratory demonstration under an experimental licence can be fully BPI-conformant while declaring it holds no space-to-Earth authorisation whatsoever. The protocol’s job is to make that visible, not to prevent it.

[R-A-032] An empty unclaimed[] SHALL be accompanied by operatingPosture: 'authorised' and a resolvable instrumentRef for every applicable regime. An empty array is a strong claim and is treated as one.