function initialize() {
      document.getElementById('sec1').style.display = "block";      
      document.getElementById('sec2').style.display = "none";
      document.getElementById('sec3').style.display = "none";
      document.getElementById('sec4').style.display = "none";
      document.getElementById('sec5').style.display = "none";
      document.getElementById('sec6').style.display = "none";                      
    }
    
    var shown = "sec1";
        
		function section_show(item) {
			
      if ( document.getElementById ) {
				document.getElementById(shown).style.display = "none";
				document.getElementById(item).style.display = "block";      												
				
				shown = item;
				return false;
			}	
      		 
		}
		
		window.onload=initialize;