function swapit(whichLayer)
{
  var elem, vis;
  //if(document.getElementById) // this is the way the standards work
    elem = document.getElementById( whichLayer );
  	elem1 = document.getElementById('maincontent1');
  	elem2 = document.getElementById('maincontent2');
	elem3 = document.getElementById('maincontent3');
  	elem4 = document.getElementById('maincontent4');
  	elem5 = document.getElementById('maincontent5');
  	elem6 = document.getElementById('maincontent6');
  	elem7 = document.getElementById('maincontent7'); 
  	   
  	
  //else if(document.all) // this is the way old msie versions work
  //  elem = document.all[whichLayer];
  //  elem1 = document.all['maincontent1'];
  //  elem2 = document.all['maincontent2'];
  //  elem3 = document.all['maincontent3'];
  //  elem4 = document.all['maincontent4'];
  //  elem5 = document.all['maincontent5'];
  //  elem6 = document.all['maincontent6'];
  //  elem7 = document.all['maincontent7'];
  
  	
  	
  //else if(document.layers) // this is the way nn4 works
  //  elem1 = document.layers['maincontent1'];
  //  elem2 = document.layers['maincontent2'];
  //  elem3 = document.layers['maincontent3'];
  //  elem4 = document.layers['maincontent4'];
  //  elem5 = document.layers['maincontent5'];
  //  elem6 = document.layers['maincontent6'];
  //  elem7 = document.layers['maincontent7'];
  
  
  
  vis = elem.style;
  
  vis1 = elem1.style;
  vis2 = elem2.style;
  vis3 = elem3.style;
  vis4 = elem4.style;
  vis5 = elem5.style;
  vis6 = elem6.style;
  vis7 = elem7.style;
  
  
  vis1.display = 'none';
  vis2.display = 'none';
  vis3.display = 'none';
  vis4.display = 'none';
  vis5.display = 'none';
  vis6.display = 'none';
  vis7.display = 'none';
  
  
  vis.display = 'block';
}