meta {
    title: "Country Code Check";
    version: "1.1_2023-04-09";
    author: "CjMalone";
    link: "https://josm.openstreetmap.de/wiki/Rules/CountryCodeCheck";
    baselanguage: "en";
}

*[addr:country][addr:country!~/^[A-Z]{2}$/] {
    throwWarning: "addr:country should be a valid country code, e.g. DE, GB or US";
}