function showhide(what){
        if (document.getElementById(what).style.display=='none'){
            document.getElementById(what).style.display='';
        }else{
            document.getElementById(what).style.display='none'
        }
    }

    function ClearOptions(sel){
		sel.options.length=0;
	}

    function PopulateSelect(sel,optsArray){
		for (var i=0,len=optsArray.length;i<len;i++) sel.options[i]=optsArray[i];
	}

    function UpdateOptions(sel, elem){
		var destSel = document.getElementById(elem);
		ClearOptions(destSel);
		if (sel.value=="_xx_") return;
		var opts = [];
		var srcObjs = availVals[sel.value];
		for (var i=0,len=srcObjs.length;i<len;i++) opts[i]=new Option(srcObjs[i],srcObjs[i]);
		PopulateSelect(destSel,opts);
	}