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var nn6 = (navigator.appName == 'Netscape' && document.getElementById)? true: false;
var ie4 = (navigator.appName == 'Microsoft Internet Explorer' && document.all)? true: false;
var ie5 = (navigator.appName == 'Microsoft Internet Explorer' && document.all)? true: false;
var ie6 = (navigator.appName == 'Microsoft Internet Explorer' && document.getElementById)? true: false;