Abbreviations
Under the International Organization for Standardization's ISO 3166 standard, the two-letter code for Ireland is "IE" while the three-letter code is "IRL". The "IE" code is the basis for the choice of ".ie" for Irish internet addresses. The IRL code features on Irish driving licences, passports and is most visible on contemporary Irish EU style vehicle registration plates. Under the Convention on International Civil Aviation Irish registered aircraft carry the nationality mark "EI"
Read more about this topic: Names Of The Irish State