function toggleVisibility(nr)
        {
	        if (document.layers)
	        {
		        vista = (document.layers[nr].visibility == 'hide') ? 'show' : 'hide'
		        document.layers[nr].visibility = vista;
	        }
	        else if (document.all)
	        {
		        vista = (document.all[nr].style.visibility == 'hidden') ? 'visible'	: 'hidden';
		        document.all[nr].style.visibility = vista;
	        }
	        else if (document.getElementById)
	        {
		        vista = (document.getElementById(nr).style.visibility == 'hidden') ? 'visible' : 'hidden';
		        document.getElementById(nr).style.visibility = vista;

	        }
        }


/* 
styTog() -- a function to toggle CSS style attributes
This function accepts four parameters from the calling event:
targ_id, which is the id of the target element;
sty_attrJ, which is the style attribute's name in JavaScript syntax;
sty_attrC, which is the style attribute's name in CSS syntax;
set_val, which is the second toggle state value;

The element id, "zedSpan" is reserved for this function's use.
*/
function styTog(targ_id,sty_attrJ,sty_attrC,set_val){ 
	var targ=document.getElementById(targ_id);
	var targ_stat="";
	var targ_sty="";
	var attr_chk=sty_attrC.toLowerCase()
	var excp_flag=0;
	
	if(attr_chk.indexOf("color")!=-1 || attr_chk.indexOf("font")!=-1){
		excp_flag=1;
		
		if(!document.getElementById("zedSpan")){
			var insSpan=document.createElement("span");
			insSpan.setAttribute("id","zedSpan");
			document.body.appendChild(insSpan);
		}
		var zS=document.getElementById("zedSpan").style
		zS[sty_attrJ]=set_val;
	}
	
	if(targ.currentStyle){ //code for IE
		if(excp_flag==1)
			set_val=zS[sty_attrJ];
		
		targ_stat=targ.currentStyle[sty_attrJ];
	}
	else{ //code for W3C-spec-compatible
		if(excp_flag==1){
			var tst_span=document.getElementById("zedSpan");
			var tst_sty=document.defaultView.getComputedStyle(tst_span,"");
			set_val=tst_sty.getPropertyValue(sty_attrC);
			excp_flag=0;
		}
		
		targ_sty=document.defaultView.getComputedStyle(targ,"");
		targ_stat=targ_sty.getPropertyValue(sty_attrC);
	}
	
	if(set_val == "block") {
		var opposite="none";
	}
	else {
		var opposite="block";
	}
	
	targ_stat!=set_val ? targ.style[sty_attrJ]=set_val : targ.style[sty_attrJ]=opposite;
}