function validafecha(objName) {
	var datefield = objName;
	if (valfecha(objName) == false) {
		datefield.select();
		alert("La fecha ingresada es incorrecta.");
		datefield.focus();
		return false;
	}
	else {
		return true;
	   }
}

function valfecha(objName) {
	//var strDatestyle = "US"; //Tipo de fecha yanki
	//alert(objName);
	var strDatestyle = "EU";  //Formato europeo (el que usamos aca)
	var strDate;
	var strDateArray;
	var strDay;
	var strMonth;
	var strYear;
	var intday;
	var intMonth;
	var intYear;
	var booFound = false;
	var datefield = objName;
	var strSeparatorArray = new Array("-"," ","/",".");
	var intElementNr;
	var err = 0;
	var strMonthArray = new Array(12);
	strMonthArray[0] = "01";
	strMonthArray[1] = "02";
	strMonthArray[2] = "03";
	strMonthArray[3] = "04";
	strMonthArray[4] = "05";
	strMonthArray[5] = "06";
	strMonthArray[6] = "07";
	strMonthArray[7] = "08";
	strMonthArray[8] = "09";
	strMonthArray[9] = "10";
	strMonthArray[10] = "11";
	strMonthArray[11] = "12";
	strDate = datefield.value;
	
	if (strDate.length < 1) {
		return true;
	}
	else {
		if (strDate.length < 6) {
			return false;
		}
	}
	
	for (intElementNr = 0; intElementNr < strSeparatorArray.length; intElementNr++) {
		if (strDate.indexOf(strSeparatorArray[intElementNr]) != -1) {
			strDateArray = strDate.split(strSeparatorArray[intElementNr]);
			if (strDateArray.length != 3) {
				err = 1;
				return false;
			}
			else {
				strDay = strDateArray[0];
				strMonth = strDateArray[1];
				strYear = strDateArray[2];
			}
			booFound = true;
	   	}
	}
	if (booFound == false) {
		if (strDate.length > 5) {
			strDay = strDate.substr(0, 2);
			strMonth = strDate.substr(2, 2);
			strYear = strDate.substr(4);
	   	}
	}
	if (strYear.length == 2) {
		if (parseInt(strYear) > 20){
			strYear = '19' + strYear;
		}
		else {
			strYear = '20' + strYear;
		}
	}
	if (strYear.length == 3) {
		return false;
	}
	if (strYear.length > 4){
		return false;
	}
	// Estilo de fecha yankie
	if (strDatestyle == "US") {
		strTemp = strDay;
		strDay = strMonth;
		strMonth = strTemp;
	}
	intday = parseInt(strDay, 10);
	if (isNaN(intday)) {
		err = 2;
		return false;
	}
	intMonth = parseInt(strMonth, 10);
	if (isNaN(intMonth)) {
		for (i = 0;i<12;i++) {
			if (strMonth.toUpperCase() == strMonthArray[i].toUpperCase()) {
				intMonth = i+1;
				strMonth = strMonthArray[i];
				i = 12;
	 		}
		}
		if (isNaN(intMonth)) {
			err = 3;
			return false;
	   	}
	}
	intYear = parseInt(strYear, 10);
	if (isNaN(intYear)) {
		err = 4;
		return false;
	}
	if (intMonth>12 || intMonth<1) {
		err = 5;
		return false;
	}
	if ((intMonth == 1 || intMonth == 3 || intMonth == 5 || intMonth == 7 || intMonth == 8 || intMonth == 10 || intMonth == 12) && (intday > 31 || intday < 1)) {
		err = 6;
		return false;
	}
	if ((intMonth == 4 || intMonth == 6 || intMonth == 9 || intMonth == 11) && (intday > 30 || intday < 1)) {
		err = 7;
		return false;
	}
	if (intMonth == 2) {
		if (intday < 1) {
			err = 8;
			return false;
		}
		if (bisiesto(intYear) == true) {
			if (intday > 29) {
				err = 9;
				return false;
			}
		}
		else {
			if (intday > 28) {
				err = 10;
				return false;
			}
		}
	}
	if (strDatestyle == "US") {
		datefield.value = strMonthArray[intMonth-1] + "/" + intday+"/" + strYear;
	}
	else {
		if (intday > 9){
			datefield.value = intday + "/" + strMonthArray[intMonth-1] + "/" + strYear;
		}
		else{
			datefield.value = "0" + intday + "/" + strMonthArray[intMonth-1] + "/" + strYear;
		}	
	}
	return true;
}
	
	
function bisiesto(intYear) {
	if (intYear % 100 == 0) {
		if (intYear % 400 == 0) {
			return true; 
		}
	}
	else {
		if ((intYear % 4) == 0) {
			return true;
		}
	}
	return false;
}