<P> The VFL changed its name to the Australian Football League (AFL) for the 1990 season, and over the next decade, three non-Victorian clubs gained entry: Adelaide (1991), Fremantle (1995) and the SANFL's Port Adelaide (1997), the only pre-existing club outside Victoria to join the league . In 2011 and 2012 respectively, two new non-Victorian clubs were added to the competition: Gold Coast and Greater Western Sydney . The AFL, currently with 18 member clubs, is the sport's elite competition and most powerful body . Following the emergence of the AFL, state leagues were quickly relegated to a second - tier status . The VFA merged with the former VFL reserves competition in 1998, adopting the VFL name . State of Origin also declined in importance, especially after an increasing number of player withdrawals . The AFL turned its focus to the annual International Rules Series against Ireland in 1998 before abolishing State of Origin the following year . State and territorial leagues still contest interstate matches, as do AFL Women players . </P> <P> Although a Tasmanian AFL bid is ongoing, the AFL's focus has been on expanding into markets outside Australian football's traditional heartlands . The AFL regularly schedules pre-season exhibition matches in all Australian states and territories as part of the Regional Challenge . The AFL signalled further attempts at expansion in the 2010s by hosting home - and - away matches in New Zealand, followed by China . </P> <P> Australian rules football playing fields have no fixed dimensions but at senior level are typically between 135 and 185 metres long and 110 and 155 metres wide wing - to - wing . The field, like the ball, is oval - shaped, and in Australia, cricket grounds are often used . No more than 18 players of each team are permitted to be on the field at any time . </P> <P> Up to four interchange (reserve) players may be swapped for those on the field at any time during the game . In Australian rules terminology, these players wait for substitution "on the bench"--an area with a row of seats on the sideline . Players must interchange through a designated interchange "gate" with strict penalties for too many players from one team on the field . In addition, some leagues like the AFL have each team designate one player as a substitute who can be used to make a single permanent exchange of players during a game . </P>

How many players in an afl team on the field