function chgQty(tFieldName,delta) {
	   tField = document.getElementById(tFieldName); 
        qty = parseFloat(tField.value) + delta;
        if (isNaN(qty) || qty < 1.0) {
            qty = 0;
        } else if (qty >= 99.0) {
            qty = 99.0;
        }
        qty = Math.floor( (qty-1.0)/1.0 )*1.0  + 1.0;
        tField.value= qty;
    }