# Arxo population impact bank 0.1 / 0.2

A pinned population for the population-impact comparison: two sides — case packages with their own pins — rows mapping a row id to a case and a weight, and a single measure. It carries no legal meaning: weights and sums only orchestrate the comparison and are not a legal answer. The runner checks row id uniqueness, non-negative weights, the content hash self-pin, and equal case sets on both sides (rejection POPULATION_BANK_INVALID); the schema only holds the shape. Form 0.2 adds a distribution section — auxiliary rank and size queries, a pinned equivalence scale, and a group count — and provenance, an optional link to the materialization manifest. Auxiliary queries run as separate asks on the basis side.

## Versions

Accepted `schemaVersion`: `law.population.bank/0.1`, `law.population.bank/0.2`.

## Top-level fields

| name | type-or-$ref | required | description |
|---|---|---|---|
| `schemaVersion` | enum (2) | yes | — |
| `bankId` | [`#/$defs/Name`](#name) | yes | — |
| `worlds` | `object` | yes | — |
| `rows` | `array` | yes | — |
| `measure` | [`#/$defs/Measure`](#measure) | yes | — |
| `contentHash` | [`#/$defs/Digest`](#digest) | yes | Self-pin: sha256 of the bank's canonical bytes without the contentHash field, with rows ordered by the bytes of rowId: permuting the rows in the input does not change the hash. |
| `distribution` | [`#/$defs/Distribution`](#distribution) | no | — |
| `provenance` | [`#/$defs/Provenance`](#provenance) | no | — |

## Enumerations

| location | values |
|---|---|
| `properties/schemaVersion` | `"law.population.bank/0.1"`, `"law.population.bank/0.2"` |
| `$defs/Distribution/properties/basis` | `"before"` |
| `$defs/Provenance/properties/dataClass` | `"synthetic"`, `"real"` |
| `allOf/0/if/properties/schemaVersion` | `"law.population.bank/0.2"` |

## Raw schema

[`https://law.arxo.io/schema/population-bank.schema.json`](https://law.arxo.io/schema/population-bank.schema.json)

## `Digest`

Type: `string`.

## `Name`

Type: `string`.

## `CaseName`

Name of the case declaration, as recorded in the [[cases]] list of the case package.

Type: `string`.

## `Weight`

Decimal string not less than zero.

Type: `string`.

## `WorldPin`

A side of the bank: a case package and its pins. theoryHash and artifactHash are the hashes of the bound world W = root + closure C, the same hashes each row's evaluation manifest records.

Type: `object`.
Required: `package`, `manifestHash`, `lockHash`, `theoryHash`, `artifactHash`, `resources`.

| name | type-or-$ref | description |
|---|---|---|
| `package` | `string` | Path to the case package's law.toml relative to the bank file's directory. |
| `manifestHash` | [`#/$defs/Digest`](#digest) | sha256 of the exact bytes of law.toml. |
| `lockHash` | [`#/$defs/Digest`](#digest) | sha256 of the exact bytes of law.lock. |
| `theoryHash` | [`#/$defs/Digest`](#digest) | — |
| `artifactHash` | [`#/$defs/Digest`](#digest) | — |
| `resources` | `array` | Explicit resources of the side (calendars, documents, snapshots) — exactly the resources entries of the pinned law.lock, ordered by id and path. |

## `Row`

Type: `object`.
Required: `rowId`, `case`, `weight`.

| name | type-or-$ref | description |
|---|---|---|
| `rowId` | [`#/$defs/Name`](#name) | — |
| `case` | [`#/$defs/CaseName`](#casename) | — |
| `weight` | [`#/$defs/Weight`](#weight) | — |

## `ShortQueryId`

Short query name: the ask operation completes the full URN in the namespace of the case package and the row's case.

Type: `object`.

| name | type-or-$ref | description |
|---|---|---|
| `queryId` | `string` | — |

## `Measure`

A single measure per bank: a collect-all query (distinct: false) over Money literals, or a term query without an aggregate and with the empty-options flag; the stage is printed into the report verbatim. The schema deliberately does not constrain the distinct flag, the empty-options flag in a term query, side resolution, or an explicit non-Money variable type: those are the runner's POPULATION_MEASURE_INVALID rejection, and the bank's shape must not intercept them with a POPULATION_BANK_INVALID rejection.

Type: `object`.
Required: `name`, `stage`, `currency`, `query`.

| name | type-or-$ref | description |
|---|---|---|
| `name` | `string` | — |
| `stage` | `string` | — |
| `currency` | `string` | — |
| `query` | oneOf (2) | — |

## `PositiveDecimal`

Decimal string greater than zero (equivalence-scale weight).

Type: `string`.

## `ScalePin`

Equivalence scale, pinned as name + version + source + contentHash; weights — first adult, each subsequent adult, child. contentHash is a self-pin: sha256 of the object's canonical bytes without the contentHash field (checked by the runner, POPULATION_BANK_INVALID). The runner applies it as a statistical operation.

Type: `object`.
Required: `name`, `version`, `source`, `contentHash`, `weights`.

| name | type-or-$ref | description |
|---|---|---|
| `name` | `string` | — |
| `version` | `string` | — |
| `source` | `string` | — |
| `contentHash` | [`#/$defs/Digest`](#digest) | — |
| `weights` | `object` | — |

## `SizeQuery`

A term query with an Integer result of zero or more (number of adults or children); the empty-options flag in the term is a POPULATION_MEASURE_INVALID rejection.


## `Distribution`

Deciles for form 0.2 of the impact comparison: groups — number of groups; basis — the ranking side; scale — the pinned scale; rank — the ranking measure (Measure shape, executed as a separate ask on the basis side); size — queries for the number of adults (at least one) and children.

Type: `object`.
Required: `groups`, `basis`, `scale`, `rank`, `size`.

| name | type-or-$ref | description |
|---|---|---|
| `groups` | `integer` | — |
| `basis` | `"before"` | — |
| `scale` | [`#/$defs/ScalePin`](#scalepin) | — |
| `rank` | [`#/$defs/Measure`](#measure) | — |
| `size` | `object` | — |

## `Provenance`

Link to the materialization manifest: the manifest's contentHash and the data class; real data triggers the runner's rejection.

Type: `object`.
Required: `materializationHash`, `dataClass`.

| name | type-or-$ref | description |
|---|---|---|
| `materializationHash` | [`#/$defs/Digest`](#digest) | — |
| `dataClass` | enum (2) | — |