This page was printed on Nov 20, 2019. For the current version, visit https://help.shopify.com/en/themes/liquid/objects/all-country-option-tags.
The all_country_option_tags object creates an <option> tag for each country.
An attribute called data-provinces is set for each <option>, and contains a JSON-encoded array of the country's subregions. If a country doesn't have any subregions, then an empty array is set for its data-provinces attribute.