function doA (){
document.getElementById('a').className='activetab';
document.getElementById('b').className='tab';
document.getElementById('c').className='tab';
/*document.getElementById('d').className='tab';*/
MM_showHideLayers('toptext2','','none','toptext1','','block','toptext3','','none','toptext4','','none');
}

function doB (){
document.getElementById('b').className='activetab';
document.getElementById('a').className='tab';
document.getElementById('c').className='tab';
/*document.getElementById('d').className='tab';*/
MM_showHideLayers('toptext2','','block','toptext1','','none','toptext3','','none','toptext4','','none');
}

function doC (){
document.getElementById('c').className='activetab';
document.getElementById('a').className='tab';
document.getElementById('b').className='tab';
/*document.getElementById('d').className='tab';*/
MM_showHideLayers('toptext3','','block','toptext1','','none','toptext2','','none','toptext4','','none');
}




function MM_showHideLayers() {
	var i,p,v,obj,args=MM_showHideLayers.arguments;
  for (i=0; i<(args.length-2); i+=3) 
  with (document) if (getElementById && ((obj=getElementById(args[i]))!=null)) { v=args[i+2];
    if (obj.style) { obj=obj.style; v=(v=='block')?'block':(v=='none')?'none':v; }
    obj.display=v; }
}