# Map lexicon (v1)

The controlled vocabulary of the Map standard. Terms are stable; their IRIs live in [`v1.ttl`](v1.ttl) under `https://maps.transaction.science/vocab/v1#`.

| Term | Meaning |
|------|---------|
| **Place** | The cargo Map carries: a region of the world at a position, altitude, instant, and fidelity. |
| **Tile** | A content-addressed, signed unit of place at a single cell, with its energy cost intrinsic. The unit of cargo. |
| **Cell key** | The 4D address of a tile: `(s2, alt, time, lod)`. |
| **S2 cell** | The horizontal axis: a hierarchical, Hilbert-ordered cell on the sphere. Its level is the horizontal LOD. |
| **Altitude band** | The vertical axis: a signed band index against the tileset's declared schedule. Band 0 = datum. |
| **Time bucket** | The temporal axis: a half-open `[start, start+width)` TAI interval. Bucket 0 = atemporal. First-class. |
| **LOD** | The within-tier detail level, independent of the S2 level. |
| **Content id** | `blake3(canonical_cbor(x))` — the 32-byte address every structure cross-references through. |
| **Tileset** | The single range-requestable archive: header + Hilbert-ordered directory + payloads. "It's just a file." |
| **Directory** | The `CellKey → (offset, len, content_id)` map, sorted by the S2 key so a viewport is a near-contiguous byte range. |
| **Manifest** | The signed root of a tileset; commits to the directory Merkle root under a publisher key. |
| **Revision** | A signed, dated transition `prev_root → new_root`. Append-only; a new forecast hour / AIRAC cycle is a revision. |
| **Fidelity cascade** | `F0:Cache → F1:Base → F2:Field → F3:Feature → F4:Photoreal`. The highest tier ≤ the request that holds data closes it. |
| **Base floor** | F1 — terrain + coastlines + borders, defined everywhere; the guaranteed fallback. |
| **Receipt** | The signed per-resolve energy record (`measured + estimated` µJ, provenance-tagged), sealed as JCR-1. |
| **Provenance** | `HwShunt` (hardware-measured) \| `ModelBased` (calibrated model) \| `Estimator` (constant). The honesty tag on every reading. |
| **Steward** | Transaction Science: publishes the spec, ships the reference, runs optional services. Not the owner — Map carries no token. |