The national chess championship of Mexico has been organized annually since 1973 by (Spanish: Federación Nacional de Ajedrez de Mexico A.C.), the Mexican chess federation. Known since 1997 as the National Absolute Championship (Campeonato Nacional Absoluto) and previously as the National Closed Championship (Campeonato Nacional Cerrado), it was initially organized as a round-robin tournament. However, several editions in the 1990s were organized as a series of elimination matches, and the championship is currently run as a Swiss-system tournament. In some years it serves as a qualifying stage for the FIDE World Chess Championship and is designated as sub-Zonal tournament 2.3.1 in such cases. A different tournament is the Mexican Open Championship (Campeonato Nacional Abierto), which is no