Question: ISO 3166-1 alpha-2 is a widely used country code system, along with what three-letter system?
Sentence (from "ISO 3166-1 alpha-2"): ISO 3166-1 alpha-2 codes are two-letter country codes defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest.
Relevant evidence: No