function showLay(Id){

        var temp="";
        var temp1="";
        
        
        
	for(var i=1;i<6;i++)
	{
	  

	   temp1 = "caidan"+i;
	   if (Id != i )
	   {
	        temp = "Layer"+i;
	   	objDiv = eval(temp);
	        eval("sp"+temp+".innerHTML='+'");
	        objDiv.style.display="none";
	        
	        objDiv = eval(temp1);
	        objDiv = eval(temp1);
                objDiv.style.color ="#999999";
             
	   }

        }
  
  
        divId = "Layer"+Id;           
	objDiv = eval(divId);

	if (objDiv.style.display=="none"){
		eval("sp"+divId+".innerHTML='--'");
		objDiv.style.display="";
	       
	       temp1 = "caidan"+Id;
	       objDiv = eval(temp1);
	       objDiv = eval(temp1);
               objDiv.style.color="#000000";
        		
	}else{
		eval("sp"+divId+".innerHTML='+'");
		objDiv.style.display="none";
	}
	
	
     
	
}