The world rankings were formerly based on point tariffs set by the governing body, but this system transitioned to a prize money list for the 2014–15 season.
The revised system was now based on only the two previous seasons, and updated annually after the World Championship.
While the ranking point allocations have undergone modifications down the years the basic system remained the same up until the 2009–10 season.
Various "cut-off" points are selected at convenient stages during the season where the rankings are "frozen" and used as seedings for the next few tournaments, until the next revision.
Subsequent tournaments that were assigned ranking status worked on the same system but with the World Championship from 1983 onwards carrying double points.
When the game went open for the 1991–92 season, the ranking point allocations (devised by the WPBSA chairman on the back of a cigarette pack)[14] were altered by several factors to accommodate the influx of new players.
The tie-break system was dropped but the system remained basically the same with players awarded incrementally more points for each successive round; should a seeded player lose their first match they would receive only half the points allocated to the non-seeded losers in that round.