# Data Dictionary - World Country Reference Table (join-key crosswalk) - ISO codes, region, centroid

**Units:** stated per column in the descriptions below (this is a relational table; columns mix units).

| column | type | description |
|---|---|---|
| `iso_a3` | str | ISO 3166-1 alpha-3 code (primary key) |
| `iso_a2` | str | ISO 3166-1 alpha-2 code |
| `name` | str | Country name (long form where available) |
| `continent` | str | Continent |
| `region` | str | UN region (REGION_UN) |
| `subregion` | str | UN subregion |
| `pop_est` | int | Population estimate |
| `gdp_musd` | int | GDP estimate, million USD |
| `lat` | float | Centroid latitude (LABEL_Y / bbox center) |
| `lon` | float | Centroid longitude (LABEL_X / bbox center) |

*Source: Natural Earth (public domain).*