Locations

Almost every view in Atlas can be sliced by place, and the Locations group is where that vocabulary is defined and maintained.

Three vocabularies, and which wins where

Atlas uses three overlapping systems for naming places. Knowing which one a view is using saves a lot of confusion:

Vocabulary	Source	Used for
Country codes	ISO two-letter	The coarse key almost everywhere — coverage, filters, rollups
Cities	GeoNames	City names and coordinates
UN/LOCODE	UNECE	Stable codes that disambiguate places sharing a name

Regions sit above all three: they are groupings you define.

Regions

/regions · public

Regions are user-defined groups of countries — "EU", "APNIC", "our customers" — created and edited here with a grouped two-pane country picker.

They are worth setting up early, because once a region exists it becomes a filter option across the rest of the site. A region you use often turns a repeated multi-select into one click.

The search and which panels are open are both reflected in the URL (?open= takes a comma-separated list of region IDs), so a specific view of the region tree is shareable.

Countries

/countries · public

The per-country view, searchable and filterable by region. This is where a country's probe and anchor picture lives — the reference page behind every country code you click elsewhere.

Cities

/cities · public

Search GeoNames cities by name prefix and country, with a detail page per city.

City data is reference data, not measurement data: it tells you what and where a city is, so that probe and anchor locations have something to resolve against. When a probe's city looks wrong, the problem is almost always the probe's declared location rather than this table — see Geofeeds and geolocation.

UN/LOCODE lookup

/unlocode · requires an account

Search UN/LOCODE by country, name or code.

UN/LOCODE earns its place when a name is ambiguous. There are dozens of places called Springfield and several called London; a UN/LOCODE resolves exactly one of them. If you are reconciling location data between systems, this is the identifier to reconcile on rather than a city name.

The lookup includes a neighbours map, for checking that a code sits where you think it does.

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Background reading: Geofeeds and geolocation