Gazetteer Overhaul: ISO-3166 country coding and ADM1 codings

[mubaldino]

Type of Feature:

• Collaboration or partnership
• Improvement or clarification
• New Processing

Description of Feature

• NGA gazetteer has now moved to using ISO, and revamped entire schema
• Geonames.org gazetteer remains using FIPS ADM1 codings, despite using ISO country codings.

Solution:

• Use NGA 2021 version (Xponents 3.5 data) to map equivalences to NGA 2022 version, that is CC.ADM1 == CC.ADM1 for a given Place ID across standards
• Use ISO country code and ADM1 consistently within Xponents API. non-ISO codings we'll sacrifice for now.
• Solve missing ADM1 tiers in GB, IRL and other countries.