var browser     = '';
var version     = '';
var entrance    = '';
var cond        = '';

function captaentorno() {
	if (browser == ''){
		if (navigator.appName.indexOf('Microsoft') != -1)
		browser = 'IE'
		else if (navigator.appName.indexOf('Netscape') != -1)
		browser = 'Netscape'
		else browser = 'IE';
	}

	if (version == ''){
		version= navigator.appVersion;
		paren = version.indexOf('MSIE');
		version = navigator.appVersion.substring(paren+5, paren+8);
	}
}

function aclara(objeto) {
	captaentorno();
	if (browser == 'IE' && version >= 5.5) objeto.filters.alpha.opacity=30;
}

function oscurece(objeto) {
	captaentorno();
	if (browser == 'IE' && version >= 5.5) objeto.filters.alpha.opacity=100;
}