associated. The two letter code appears in the first two, middle, or last two positions of the four character code. The use of the FAA identifier system in meteorology ended in 1996 when airways reporting code was replaced by METAR code. The METAR code is dependent wholly on the ICAO identifier system. Transport Canada identifier Transport Canada assigns two, three, and four character identifiers, including three letter identifiers beginning with letters Y and Z, for its areas of jurisdiction. These identifiers are designed to mesh with the FAA Identifier system described above, though a few conflicts exist. Direction General of Civil Aeronautics Code The airfields code of Direction General of Civil Aeronautics of Mexico is a designator airfields code compound 3 alphabetic characters used to identify all fields of civil aviation in Mexico (these characters are chosen with the same methodology for IATA Code, i.e. , taking 3 letters of the airfield, for example ZPU Zacapu Airstrip), these airfields can be airports, regional airports, private airstrips, heliports, boat-heliports and helipads platform-; if more substantial airports IATA designator code is used, for example TLC for Toluca International Airport, although there are some exceptions, such IATA: XAL and DGAC: ALA to Alamos National Airport, Sonora. Russian location identifier Within Russia (and before 1991 within the Soviet Union), there are airport identifiers (внутренний код - internal code) having three Cyrillic letters. They are used for e.g. ticket sales. Some small airports with scheduled flights have no IATA code, only this code and an ICAO code. Unlike the IATA codes, they changed when renaming some cities of the former USSR in the 1990s, e.g. Saint Petersburg (was Leningrad) - was ЛЕД, became СПТ. As of 2009, about 3,000 code combinations of internal code are in use. WMO station identifiers The World Meteorological Organization used a system of five-digit numeric station codes to represent synoptic weather stations. An example is 72295 for Los Angeles International Airport (LAX). The first number specifies the region: 0 to 1 for Europe, 2 to 3 for Russia, 4 for Asia, 5 for the Far East, 6 for Africa, 7 for North America, 8 for South America and Antarctica, and 9 for the Pacific. The remainder of the numbers are set at the regional and national level. A modernization of WMO station id's was performed as part of the WMO Integrated Global Observing System (WIGOS). Previously, observing stations were registered