function changeCategories()
{
	var index = top.document.register.sport.selectedIndex;
	top.document.getElementById("c0").style.display ='none';
	top.document.getElementById("c1").style.display ='none';
	top.document.getElementById("c2").style.display ='none';
	top.document.getElementById("c3").style.display ='none';
	top.document.getElementById("c4").style.display ='none';
	top.document.getElementById("c5").style.display ='none';
	top.document.getElementById("c6").style.display ='none';
	
	if(index != 0)
	{
		try
		{
			top.document.getElementById("c0").style.display = "table-row";
			top.document.getElementById("c"+index).style.display = "table-row";
		}
		catch(e)
		{
			top.document.getElementById("c0").style.display = "block";
			top.document.getElementById("c"+index).style.display = "block";
		}
	}
}