Players can play 'up' with an older age group than they are categorized in. However, players cannot play 'down' with a younger age group than they are categorized in.
Based on the chart below, a player born in 2005 or 2006, which is categorized as U18, could play in U19 as it is an older age group. However, a player born in 2004, which is categorized as U19 cannot play in U18, as it is a younger age group than they are.
|2005 & 2006||U18|