Mandatory
Core

The Mandatory Core Is Now Testable

Specification Sections 01–07 now define a deterministic candidate profile sufficient to establish a concrete Mandatory Core for executable Conformance work.

Conformance shall test the solved Specification profile exactly as written. It shall not infer, regularize, approximate, or privately define behavior for capabilities whose canonical semantics remain open.

Establish the Minimum Claim of Compatibility

The Mandatory Core defines the minimum canonical capabilities and behaviors every implementation must demonstrate before claiming compatibility with the current Foundational Survey Fabric candidate profile.

An implementation that fails any required Mandatory Core behavior shall not claim full compatibility with that profile, regardless of how many optional features or higher-layer capabilities it provides.

The Solved Candidate Profile Must Be Implemented as One Body

The current candidate Mandatory Core includes at minimum: CRPC parsing and normalization; canonical frame interpretation; Point validation; parameterized Survey Domain validation under D_H; Segment validation; SCPE validation; exact geometry predicates; canonical geometry normalization; canonical validity-state behavior; FSF-CJSON-1.0 parsing and serialization; ECEM-compatible precision behavior; no silent snapping; deterministic canonical results; and independent reproducibility.

These capabilities form one common foundational proof surface. Selective success does not establish Mandatory Core conformance.

No Competing Foundational Truth

All Mandatory Core behavior shall resolve to the same canonical Survey meaning defined by the governing Specification.

Implementations may differ internally, but the Mandatory Core shall not permit alternate interpretations of coordinate meaning, frame orientation, geometry, validity, normalization, serialization, precision semantics, or authoritative result.

Canonical Inputs Must Resolve Correctly

Every conforming implementation shall correctly interpret canonical CRPC coordinates, canonical Points, Segments, SCPEs, frame-relative meaning, and other expressions included in the Mandatory Core.

Correct interpretation includes preserving permanent spatial meaning, respecting the canonical frame, preserving exact Point meaning under ECEM, and resolving valid expressions without dependence on hidden implementation state.

Valid and Invalid States Must Be Distinguished

The Mandatory Core shall require deterministic validation of every included expression and operation.

The current core shall distinguish at least: canonical valid, valid noncanonical, and invalid.

Invalid conditions may include malformed CRPC values, coordinates outside the governed Survey Domain under the applicable parameterized or adopted Domain-capacity rule, zero-length Segments, invalid or self-intersecting SCPEs, unsupported operation results, malformed canonical serialization, and other failures defined by the integrated Specification.

Invalid input shall not be silently repaired, guessed, rounded, snapped, or reinterpreted into canonical truth.

Equivalent Meaning Must Normalize Identically

Where the Specification permits multiple equivalent valid representations, every conforming implementation shall resolve them to the same authoritative canonical meaning and canonical normal form.

For the current core this includes CRPC normalization, lexicographic Segment endpoint ordering, and deterministic SCPE normalization.

Canonicalization shall preserve place exactly and shall not silently move, snap, approximate, simplify by tolerance, or reinterpret spatial meaning.

Canonical Truth Is Not Tolerance-Based

Mandatory Core operations shall use the exact comparison, orientation, incidence, containment, equivalence, normalization, and other exact behavior established by the Specification.

Tolerance-based equality, floating approximation, hidden snapping, device-dependent precision, or implementation-specific convergence shall not substitute for canonical exactness.

Point · Segment · SCPE Must Behave Deterministically

A Mandatory Core implementation shall correctly validate and evaluate the current primitive geometry profile: Point, Segment, and Simple Closed Polygonal Extent (SCPE).

Applicable exact predicate behavior includes Point equality and order, orientation, Point-on-Segment, Segment intersection, Point-on-boundary, Point-in-SCPE, polygon validity, connectedness, containment, and geometric equivalence as defined by the Specification.

Exact Coordinate Extension Must Preserve Place

Mandatory Core implementations shall preserve the Exact Coordinate Extension Model.

A canonical Point denotes one exact position. It shall not be interpreted as a coarse cell, uncertainty region, parent Point, rounded reference, or set of descendants.

Compatible representational extension may expand what can be expressed, but shall not change the meaning of previously valid canonical Points.

Representations may evolve. Canonical place may not drift.

Identical Inputs, Identical Authoritative Results

Independent implementations receiving identical valid canonical inputs shall produce the same authoritative canonical result for every Mandatory Core operation within scope.

Where the governing Specification requires a unique canonical representation, normalized structure, or canonical byte sequence, those outputs shall also be identical.

Performance, programming language, storage model, cache strategy, internal representation, and optimization may differ without altering the canonical answer.

FSF-CJSON-1.0 Is Mandatory for the Current Machine-Interchange Core

Every implementation claiming Mandatory Core serialization compatibility shall satisfy the current canonical machine-interchange rules defined by FSF-CJSON-1.0.

This includes deterministic UTF-8 canonical bytes, exact structured CRPC values, required normalization before serialization, deterministic key ordering, duplicate-key rejection, unknown-field rejection where required by the format, and the other canonical encoding rules defined by Specification 06.

Proprietary internal or presentation formats shall not substitute for required canonical interchange.

The Governing Standard Must Be Explicit

A Mandatory Core conformance claim shall identify the governing Foundational Survey Fabric Specification profile and applicable serialization identity or version information that is formally defined.

For current machine interchange, FSF-CJSON-1.0 shall be identified where serialization conformance is claimed.

Final top-level FSF Specification identifier syntax remains open and shall not be invented by Conformance.

Specification identity governs interpretation and proof scope. It does not become the spatial identity of a Point, Segment, SCPE, or Survey location. Representation identity and format identity likewise remain distinct from the underlying mathematical object.

The Mandatory Core Must Be Executably Demonstrable

Mandatory Core capabilities shall be associated with applicable Reference Vectors or equivalent executable proof obligations derived from the governing Specification.

Such proof shall cover both success and failure behavior, including canonical inputs, valid noncanonical normalization, invalid inputs, exact predicate outcomes, and canonical serialization results where applicable.

Reference Vectors demonstrate the Specification. They do not create missing semantics.

The Core Must Be Open to Independent Proof

Mandatory Core conformance shall be independently testable from openly inspectable Specifications, Conformance rules, and applicable Reference Vectors or proof fixtures.

No proprietary software, unpublished algorithm, exclusive service, secret convention, institutional permission, or shared hidden implementation state shall be required to understand or reproduce the canonical result.

Unresolved Specification Mathematics Are Outside the Mandatory Core

The Mandatory Core shall not claim support for canonical behavior that the Specification has not yet defined.

For Survey Domain behavior, FMD-04A already resolves the closed-square geometry and boundary semantics and may be tested parametrically through D_H = {(x,y) : -H ≤ x ≤ H and -H ≤ y ≤ H}. FMD-04B leaves the numerical Survey Domain half-span H open. The earlier ±1,000,000 Pang half-span is a superseded working candidate and shall not be used as a canonical Mandatory Core limit.

Other current exclusions include general Boolean/composite output closure, arbitrary exact rotation closure, unresolved exact general distance and path-length scalar forms, future geometry not yet selected, and other explicitly open operation-result domains.

Implementations may experiment with such capabilities, but experimental behavior shall not be represented as canonical FSF conformance.

Optional Features May Extend, Never Replace

Optional conformance classes, representations, accelerators, extensions, or implementation conveniences may provide additional capabilities above the Mandatory Core where the Specification defines them.

Such capabilities shall not alter Mandatory Core semantics, weaken exactness, bypass validation, replace canonical interchange, or create an alternate source of canonical spatial truth.

Core Failure Prevents Compatibility Claim

Failure of any required Mandatory Core behavior shall prevent an implementation from claiming full Foundational Survey Fabric compatibility with the candidate Mandatory Core profile.

Examples include accepting invalid input, producing noncanonical geometry after required normalization, returning an incorrect exact predicate result, emitting incorrect canonical bytes, silently snapping a coordinate, or disagreeing with required cross-implementation results.

Partial implementation may be described accurately for development or testing purposes, but shall not be represented as conforming.

The Mandatory Core Has Crossed From Principle to Executable Scope

The original section correctly established Finding #84 as requiring one common minimum conformance core. The integrated Specification now provides enough deterministic mathematics to identify the present candidate Mandatory Core explicitly.

This section still does not finalize every future FSF capability, every test identifier, or every declaration mechanism. It defines the current mandatory proof surface while preserving open Specification gates outside canonical conformance.

Primary Referenced Finding

This Conformance section directly realizes Requirements Finding #84 — Mandatory Conformance Core — and references supporting requirements governing exactness, deterministic canonicalization, independent implementation, normative serialization and interchange, finite computability, and authoritative results.