In Ireland the shamrock is used as a badge for sports teams, state organizations, and troops abroad. The IRFU, Shamrock Rovers FC, Aer Lingus, IDA Ireland, University College Dublin, University of Notre Dame, the Northern Ireland Tourist Board and Fáilte Ireland use it as part of their identity. Legend says that it was used by Saint Patrick to illustrate the doctrine of the Trinity, and it has become an emblem of Ireland (no official status in Northern Ireland or the Republic of Ireland).