function showhide (tr1) 
{ 
var style1 = document.getElementById(tr1).style
if(style1.display=='none')
	{
	style1.display = '';
	}
else
	{
	style1.display = 'none';
	}
} 

function uncheckAll(field)
{
for (i = 0; i < field.length; i++)
	field[i].checked = false ;
}