heavymap

Parcel Identity Spine

Status: architecture sketch, 2026-09-23. Linear NA-11. Docs only.

Purpose

The spine is how a piece of land is known. It produces the unit that the Context Band Ladder fills, that PCDP presents, and that the Claim & Refusal Contract is allowed to speak about.

A spine record has four jobs:

  1. Give the unit a stable HeavyMap key that does not change when a publisher renames a field.
  2. Say what geometry grain that key is (parcel polygon, footprint, or address point).
  3. Record native keys beside it when a publisher has them, and record the join that attached each one.
  4. Name the jurisdiction precisely enough that a coverage refusal is checkable.

The spine does not interpret use, constraint, activity, or a reading. Those are later bands.

Non-goals

Hamilton now has a tested ID registry (heavymap/ids/, first geography). That code is the unit index for Hamilton. It is not a public database and it does not publish. Other jurisdictions are not minted here.

How it relates to the other three

The HeavyMap key

Every unit in v1 gets one key of the form:

hm:{country}:{region}:{jurisdiction}:{grain}:{local}
Part Meaning
country ca or us
region on or ny for v1
jurisdiction The publishing government the grain comes from, in a stable slug. For a Niagara Region lower-tier municipality, the slug is the lower tier (for example welland), not the word Niagara.
grain parcel, footprint, or address
local A unique token inside that jurisdiction and grain. Synthetic examples use a SYN- prefix. Hamilton, which publishes no parcel key, mints an opaque Crockford ULID; see ADR 0003. Rochester still follows the SBL20 recommendation in rochester-parcel-local-token.md.

The key is HeavyMap’s. Publishers keep their own keys in native_keys. A native key is never silently promoted to the spine key, because municipal parcel identifiers, assessment roll numbers, New York SWIS/SBL print keys, nei_id, and street addresses fail in different ways and do not survive a border crossing.

Hamilton (first geography)

City of Hamilton parcels have no published stable id (OBJECTID only; Q-002). The registry mints one hm:ca:on:hamilton:parcel:{ULID} per distinct City geometry, collapses stacked duplicates as aliases, shifts NPCA geometry by the Q-004 translation before attaching ARN, and reconciles a re-pull by fingerprint then IoU ≥ 0.9. IDs are never reused. Operator notes: heavymap-id-registry.md. Evidence: SPINE-BASE-PULL-2026-10-17.md.

A joining concept is a second handle for the job a native field does. The publisher’s field name stays on the claim. The closed catalog, the relation set, and authority_scale are in ADR 0002 and vocab/joining-concepts.vocab.json. Spine grain stays parcel, footprint, or address. Claim grain is a wider set and adds register_unit, zone_polygon, and jurisdiction_aggregate. The nei_id class is premises_register_key; establishment_register_key is an alias of that id. Two fields that share a concept still need their own join before either table can be linked.

Grain

Grain is part of identity, because area and containment mean different things at each tier.

Grain When it is the unit
parcel A publisher in v1 releases a parcel polygon HeavyMap is licensed to use, and the polygon is the thing the reader would point at.
footprint Building outline is the best licensed geometry. There is no joined parcel polygon.
address Only a point or a normalized address is licensed and joined.

A municipality that publishes no parcel fabric still has units. Their grain is footprint or address, and the identity band says the parcel polygon is not_in_coverage or not_licensed. The unit is not dropped, and it is not drawn as a parcel.

One physical site may be knowable at more than one grain. v1 does not require those grains to be fused into a single polygon. If two keys refer to the same ground, each keeps its own key, and any link between them is a join with a method and a grade. An unfused pair is not_joined, which is a true description of the index.

Canada — join and key problems

These are conceptual. Counts and field names below are prior-art observations in first-attempts/niagara-atlas/, not a claim that Beta has loaded the layers.

No single public provincial parcel key. Ontario’s assessment roll (MPAC) is the usual cross-municipality parcel identifier, and it is fee-based. For v1 that native key was not_licensed; HARD-RULES 4 (amended 2026-10-17) lifts that, so the roll number may be carried as a native key, and shown publicly, where an MPAC-derived source (for example NPCA assessment parcels) provides it. The Welland illustrations now refuse the roll as not_joined (no accepted join yet) and assessed value as not_in_coverage (no source read so far carries a value field). Neither refusal is about licence, and neither says whether the land has an assessment.

Municipal fabrics are uneven inside Niagara-12. Prior reconnaissance found public parcel polygons for some lower-tier cities (St. Catharines, Niagara Falls) and none for others (Welland’s open data had no parcel fabric; Hamilton’s open catalogue had no parcel layer). Haldimand, Norfolk, Brantford, and Brant are inside geography v1 and are not assumed to match either pattern. Until a layer is joined, those jurisdictions are not_joined at parcel grain, not “no industry” and not “no parcels in the world.”

The Region is both a government and a publisher. Niagara Region is the upper-tier municipality of twelve lower tiers, and it publishes regional layers such as the Niagara Employment Inventory. A spine key names the lower tier the geometry sits in. “Niagara” alone is not a jurisdiction slug. The glossary rule in first-attempts/niagara-atlas/GLOSSARY.md is the pattern: Niagara Region, the peninsula, and the study area are different claims.

Activity joins are not parcel joins. Where the NEI is the activity source, the stable native key on that register is nei_id. Address text drifts across editions; an identifier join is a stronger method than a normalized address. Hamilton publishes no comparable business inventory. That gap is not_in_coverage for the activity band. It does not mean the spine has no Hamilton units, and it does not mean employment is zero.

Upper tier, single tier, county. Hamilton, Haldimand, and Norfolk are single-tier. Brantford and Brant County are distinct. A join must name which of those governments published the geometry. Point-in-polygon against the wrong boundary is a bad join, not a small spelling issue.

United States — join and key problems

County parcel keys, not an ARN. New York tax parcels are keyed by county geography plus a section-block-lot (SBL) print key, with SWIS identifying the municipality. That pair does not match an Ontario roll number. The HeavyMap key may be minted from a county parcel id; the SBL stays in native_keys.

Rochester local token (recommendation, not locked). How a City of Rochester parcel gets its permanent local token is specified in rochester-parcel-local-token.md (Linear NA-80). The recommendation is the 20-character text SBL, not the print key. The Erie illustration below still uses a print-key-shaped local. It is not rewritten by that note. The SWIS reading of Monroe’s six-digit countysbl prefix remains unconfirmed.

The state parcel layer is not the map of v1. Prior reconnaissance of NYS Tax Parcels Public found Erie County present and Niagara County, New York absent from that service, with Niagara County publishing its own parcel layer. The other v1 counties — Chautauqua, Cattaraugus, Wyoming, Genesee, Orleans, Monroe — each need their own coverage stamp: state layer, county layer, or neither. A county missing from the state service still has land. The identity band says which layer was not in coverage or not joined.

Property class is not a parcel id and not zoning. The 700-series industrial class is an assessment classification. It may later fill land_use, with the stamp saying it is property class. It does not identify the parcel, and it does not stand in for a zoning by-law.

No shared code across the border. SWIS is New York’s. Ontario municipalities do not use it. Cross-border grouping, when it is warranted, is geometric, and the method is part of the stamp. v1 does not require a cross-border link to show either parcel.

Units and owner fields. New York area fields are often in square feet and acres. Canadian sources often use square metres. The spine stores the published unit on the native attribute. Conversion is a derived reading, not a quiet rewrite of the source. Public owner-name fields are out of presentation scope for this sketch; the spine does not need an owner to be complete.

Geography v1 is the coverage fence

The jurisdiction list is fixed in README.md. A spine key may be minted only inside that fence. A well-known industrial site outside it can be named in a note elsewhere; it is not given a v1 key. Halton and Burlington stay out of core unless a later lock moves them.

Inside the fence, missing data is still a key plus a refusal. Outside the fence, there is no key.

The two synthetic units

Full presentations are in PCDP.md. The table is the spine at the maximum illustration, after the joins that PCDP’s maximum walkthrough accepts. PCDP’s minimum is the earlier moment: key, grain, jurisdiction, and refusals, before those joins.

  Canadian illustration American illustration
Spine key hm:ca:on:welland:footprint:SYN-0142 hm:us:ny:erie:parcel:SYN-999.00-1-1.1
Why this grain Illustration of a lower-tier city whose open data, in prior art, had no parcel fabric. Grain is the footprint. Illustration of a v1 county where a public tax-parcel polygon is the pattern. Grain is the parcel.
Jurisdiction sentence City of Welland, lower-tier municipality of Niagara Region, Ontario Erie County, New York. The municipality slug stays erie until a SWIS join names a city or town.
Native keys Parcel PIN: not_in_coverage (no fabric in the illustration). nei_id: SYN-8130 joined by identifier. SBL: SYN-999.00-1-1.1. SWIS: not_joined.
What the key refuses MPAC roll number: not_joined; assessed value: not_in_coverage. Other v1 counties stay outside this key. Wyoming, Niagara County NY, and Monroe are unstated.

The Welland footprint and the Erie parcel are both complete spine records. Completeness means the key, the grain, the jurisdiction, and the refusals are explicit.

Prior art

Patterns, not the product root:

Beta does not inherit that folder’s study-area boundary. Geography v1 is the list in the architecture index, which is wider than the old Hamilton-plus-Niagara-Region study area and includes the named New York counties.