The following is a matrix of the primary country subdivisions. It shows which types of entities, e.g. province, exist in which countries and at what level. To keep the matrix as compact as possible and to illustrate distribution, countries are represented by ISO 3166-1 alpha-2 country code, followed by the number of units present. Not included in the matrix are federal districts, capital districts, interstate compacts, or other special-purpose districts that exist in AR, BR, DO, MX, NG, US. * effective from 2007