function tab(tab_number)
{
	if(document.getElementById && document.getElementsByTagName)
	{
		/*** tabcontrol 1 ***/
		if(tab_number <= 2) {
			//hide all tabs except for the clicked one
			for (var t = 0; t <= 2; t++) {
				if(document.getElementById('tab_' + t + '_content')) {				
					if(t == tab_number) {
						document.getElementById('tab_' + t + '_content').style.display = 'block';
						document.getElementById('tab_' + t + '_link').className = 'active';
					} else {
						document.getElementById('tab_' + t + '_content').style.display = 'none';
						document.getElementById('tab_' + t + '_link').className = 'inactive';
					}
				}
			}
		}
		/*** tabcontrol 2 ***/
		if(tab_number > 2 && tab_number <= 5) {
			//hide all tabs except for the clicked one
			for (var t = 3; t <= 5; t++) {
				if(document.getElementById('tab_' + t + '_content')) {				
					if(t == tab_number) {
						document.getElementById('tab_' + t + '_content').style.display = 'block';
						document.getElementById('tab_' + t + '_link').className = 'active';
					} else {
						document.getElementById('tab_' + t + '_content').style.display = 'none';
						document.getElementById('tab_' + t + '_link').className = 'inactive';
					}
				}
			}
		}
		
	}
}