Changes the technical settings. Send only the fields you want to change. Changing `app_hosts` changes where your shop answers. Settings are kept per mode: a test token works on the test settings, a live token on the live ones. Secret and trusted tokens may call it when their permissions include `settings_technical`. Limited tokens may not.

List countries GET

Lists every country Comecero knows, sorted by name, with its currency and what an address form needs (postal code, states). Use it to build country and state pickers. This needs no token. Every country comes in one response, so there is no paging.