function Dia(Data_DDMMYYYY)
{
	string_data = Data_DDMMYYYY.toString();
	posicao_barra = string_data.indexOf("/");
	if (posicao_barra!= -1)
	{
	dia = string_data.substring(0,posicao_barra);
	return dia;
	}
	else
	{
	return false;
	}
}

function Mes(Data_DDMMYYYY)
{
	string_data = Data_DDMMYYYY.toString();
	posicao_barra = string_data.indexOf("/");
	if (posicao_barra!= -1)
	{
	dia = string_data.substring(0,posicao_barra);
	string_mes = string_data.substring(posicao_barra+1,string_data.length);
	posicao_barra = string_mes.indexOf("/");
	if (posicao_barra!= -1)
	{
	mes = string_mes.substring(0,posicao_barra);
	mes = Math.floor(mes);
	return mes;
	}
	else
	{
	return false;
	}

	}
	else
	{
	return false;
	}
}

function Ano(Data_DDMMYYYY)
{
	string_data = Data_DDMMYYYY.toString();
	posicao_barra = string_data.indexOf("/");
	if (posicao_barra!= -1)
	{
	dia = string_data.substring(0,posicao_barra);
	string_mes = string_data.substring(posicao_barra+1,string_data.length);
	posicao_barra = string_mes.indexOf("/");
	if (posicao_barra!= -1)
	{
	mes = string_mes.substring(0,posicao_barra);
	mes = Math.floor(mes);
	ano = string_mes.substring(posicao_barra+1,string_mes.length);
	return ano;
	}
	else
	{
	return false;
	}

	}
	else
	{
	return false;
	}
}

function Calcula_Data(data_DDMMYYYY,semanas,dias,adicao)
{

	Var_Dia=Dia(data_DDMMYYYY);
	Var_Mes=Mes(data_DDMMYYYY);
	Var_Mes=Math.floor(Var_Mes)-1;
	Var_Ano=Ano(data_DDMMYYYY);

	if (1900 > Var_Ano)
	{
		Var_Ano = (Var_Ano*1) + 1900;
	}

	var data = new Date(Var_Ano,Var_Mes,Var_Dia);

	if (adicao == true)
	{
	operacao = '+'
	var diferenca = data.getTime() + (semanas * 7 * 1000 * 60 * 60 * 24) + (dias * 1000 * 60 * 60 * 24);
	}
	else
	{
	operacao = '-'
	var diferenca = data.getTime() - (dias * 1000 * 60 * 60 * 24);
	}
	var diferenca = new Date(diferenca);
	var year = diferenca.getYear();
	if (1900 > year)
	{
		year = (year*1) + 1900;
	}
	document.form_data.T22.value = diferenca.getDate()+'/'+(parseInt(diferenca.getMonth())+1)+'/'+year;

}

<!-- Original:  Richard Gorremans (RichardG@spiritwolfx.com) -->
<!-- Web Site:  http://www.spiritwolfx.com -->

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
// Check browser version
var isNav4 = false, isNav5 = false, isIE4 = false
var strSeperator = "/"; 

// If you are using any Java validation on the back side you will want to use the / because 
// Java date validations do not recognize the dash as a valid date separator.
var vDateType = 3; // Global value for type of date format

//                1 = mm/dd/yyyy
//                2 = yyyy/dd/mm  (Unable to do date check at this time)
//                3 = dd/mm/yyyy
var vYearType = 4; //Set to 2 or 4 for number of digits in the year for Netscape
var vYearLength = 2; // Set to 4 if you want to force the user to enter 4 digits for the year before validating.
var err = 0; // Set the error code to a default of zero

if(navigator.appName == "Netscape") {
if (navigator.appVersion < "5") {
isNav4 = true;
isNav5 = false;
}
else
if (navigator.appVersion > "4") {
isNav4 = false;
isNav5 = true;
   }
}
else {
isIE4 = true;
}

function DateFormat(vDateName, vDateValue, e, dateCheck, dateType) 
{
	vDateType = dateType;
	// vDateName = object name
	// vDateValue = value in the field being checked
	// e = event
	// dateCheck 
	// True  = Verify that the vDateValue is a valid date
	// False = Format values being entered into vDateValue only
	// vDateType
	// 1 = mm/dd/yyyy
	// 2 = yyyy/mm/dd
	// 3 = dd/mm/yyyy
	
	//Enter a tilde sign for the first number and you can check the variable information.
	if (vDateValue == "~") 
	{
		alert("AppVersion = "+navigator.appVersion+" \nNav. 4 Version = "+isNav4+" \nNav. 5 Version = "+isNav5+" \nIE Version = "+isIE4+" \nYear Type = "+vYearType+" \nDate Type = "+vDateType+" \nSeparator = "+strSeperator);
		vDateName.value = "";
		vDateName.focus();
		return true;
	}

	var whichCode = (window.Event) ? e.which : e.keyCode;
	
	// Check to see if a seperator is already present.
	// bypass the date if a seperator is present and the length greater than 8
	if (vDateValue.length > 8 && isNav4) 
	{
		if ((vDateValue.indexOf("-") >= 1) || (vDateValue.indexOf("/") >= 1))
		return true;
	}
	
	//Eliminate all the ASCII codes that are not valid
	var alphaCheck = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/-";
	if (alphaCheck.indexOf(vDateValue) >= 1) 
	{
		if (isNav4) 
		{
			vDateName.value = "";
			vDateName.focus();
			vDateName.select();
			return false;
		}
		else 
		{
			vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
			return false;
		}
	}
	
	if (whichCode == 8) //Ignore the Netscape value for backspace. IE has no value
		return false;
	else 
	{
	
	//Create numeric string values for 0123456789/
	//The codes provided include both keyboard and keypad values
	var strCheck = '47,48,49,50,51,52,53,54,55,56,57,58,59,95,96,97,98,99,100,101,102,103,104,105';
	if ((strCheck.indexOf(whichCode) != -1) || (dateCheck == true))
	{
		
		if (isNav4) 
		{
			//Wenn weniger als 6 oder genau 7 Ziffern eingegeben werden Fehler
			if (((vDateValue.length < 6 && dateCheck) || (vDateValue.length == 7 && dateCheck)) && (vDateValue.length >=1)) 
			{
				alert("Invalid Date\nPlease Re-Enter");
				vDateName.value = "";
				vDateName.focus();
				vDateName.select();
				return false;
			}
			//Wenn genau 6 Ziffern (Jahr zweistellig)
			if (vDateValue.length == 6 && dateCheck) 
			{
				var mDay = vDateName.value.substr(2,2);
				var mMonth = vDateName.value.substr(0,2);
				var mYear = vDateName.value.substr(4,4)
				//Turn a two digit year into a 4 digit year
				if (mYear.length == 2 && vYearType == 4) 
				{
					var mToday = new Date();
					//If the year is greater than 30 years from now use 19, otherwise use 20
					var checkYear = mToday.getFullYear() + 30; 
					var mCheckYear = '20' + mYear;
					if (mCheckYear >= checkYear)
						mYear = '19' + mYear;
					else
						mYear = '20' + mYear;
				}
				var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
				if (!dateValid(vDateValueCheck)) 
				{
					alert("Invalid Date\nPlease Re-Enter");
					vDateName.value = "";
					vDateName.focus();
					vDateName.select();
					return false;
				}
				return true;
			}
			else 
			{
				// Reformat the date for validation and set date type to a 1
				if (vDateValue.length >= 8  && dateCheck) 
				{
					if (vDateType == 1) // mmddyyyy
					{
						var mDay = vDateName.value.substr(2,2);
						var mMonth = vDateName.value.substr(0,2);
						var mYear = vDateName.value.substr(4,4)
						vDateName.value = mMonth+strSeperator+mDay+strSeperator+mYear;
					}
					if (vDateType == 2) // yyyymmdd
					{
						var mYear = vDateName.value.substr(0,4)
						var mMonth = vDateName.value.substr(4,2);
						var mDay = vDateName.value.substr(6,2);
						vDateName.value = mYear+strSeperator+mMonth+strSeperator+mDay;
					}
					if (vDateType == 3) // ddmmyyyy
					{
						var mMonth = vDateName.value.substr(2,2);
						var mDay = vDateName.value.substr(0,2);
						var mYear = vDateName.value.substr(4,4)
						vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;
					}
					//Create a temporary variable for storing the DateType and change
					//the DateType to a 1 for validation.
					var vDateTypeTemp = vDateType;
					vDateType = 1;
					var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
					if (!dateValid(vDateValueCheck)) 
					{
						alert("Invalid Date\nPlease Re-Enter");
						vDateType = vDateTypeTemp;
						vDateName.value = "";
						vDateName.focus();
						vDateName.select();
						return false;
					}
					vDateType = vDateTypeTemp;
					return true;
				}
				else 
				{
					if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1)) 
					{
						alert("Invalid Date\nPlease Re-Enter");
						vDateName.value = "";
						vDateName.focus();
						vDateName.select();
						return false;
					 }
				}
			}
		}
		
		//Wenn Browser nicht Nav4
		else 
		{
			// Non isNav Check
			if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1)) 
			{
				alert("Invalid Date\nPlease Re-Enter");
				vDateName.value = "";
				vDateName.focus();
				return true;
			}
			// Reformat date to format that can be validated. mm/dd/yyyy
			if (vDateValue.length >= 8 && dateCheck) 
			{
				// Additional date formats can be entered here and parsed out to
				// a valid date format that the validation routine will recognize.
				if (vDateType == 1) // mm/dd/yyyy
				{
					var mMonth = vDateName.value.substr(0,2);
					var mDay = vDateName.value.substr(3,2);
					var mYear = vDateName.value.substr(6,4)
				}
				if (vDateType == 2) // yyyy/mm/dd
				{
					var mYear = vDateName.value.substr(0,4)
					var mMonth = vDateName.value.substr(5,2);
					var mDay = vDateName.value.substr(8,2);
				}
				if (vDateType == 3) // dd/mm/yyyy
				{
					var mDay = vDateName.value.substr(0,2);
					var mMonth = vDateName.value.substr(3,2);
					var mYear = vDateName.value.substr(6,4)
				}
				if (vYearLength == 4) 
				{
					if (mYear.length < 4) 
					{
						alert("Invalid Date\nPlease Re-Enter");
						vDateName.value = "";
						vDateName.focus();
						return true;
					}
				}
				
				// Create temp. variable for storing the current vDateType
				var vDateTypeTemp = vDateType;
				
				// Change vDateType to a 1 for standard date format for validation
				// Type will be changed back when validation is completed.
				vDateType = 1;
				
				// Store reformatted date to new variable for validation.
				var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
				
				if (mYear.length == 2 && vYearType == 4 && dateCheck) 
				{
					//Turn a two digit year into a 4 digit year
					var mToday = new Date();
					//If the year is greater than 30 years from now use 19, otherwise use 20
					var checkYear = mToday.getFullYear() + 30; 
					var mCheckYear = '20' + mYear;
					
					if (mCheckYear >= checkYear)
						mYear = '19' + mYear;
					else
						mYear = '20' + mYear;
					
					vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
					
					// Store the new value back to the field.  This function will
					// not work with date type of 2 since the year is entered first.
					if (vDateTypeTemp == 1) // mm/dd/yyyy
						vDateName.value = mMonth+strSeperator+mDay+strSeperator+mYear;
					if (vDateTypeTemp == 3) // dd/mm/yyyy
						vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;
				} 
				
				if (!dateValid(vDateValueCheck)) 
				{
					alert("Invalid Date\nPlease Re-Enter");
					vDateType = vDateTypeTemp;
					vDateName.value = "";
					vDateName.focus();
					return true;
				}
				vDateType = vDateTypeTemp;
				return true;
			}
			
			//Wenn Datum nicht gecheckt wird (also während der Eingabe) - Separator einfügen
			else 
			{
				if (vDateType == 1) 
				{
					if (vDateValue.length == 2) 
					{
						vDateName.value = vDateValue+strSeperator;
					}
					if (vDateValue.length == 5) 
					{
						vDateName.value = vDateValue+strSeperator;
					}
				}
					if (vDateType == 2) 
					{
						if (vDateValue.length == 4) 
						{
							vDateName.value = vDateValue+strSeperator;
						}
						if (vDateValue.length == 7) 
						{
							vDateName.value = vDateValue+strSeperator;
						}
					} 
					if (vDateType == 3) 
					{
						if (vDateValue.length == 2) 
						{
							vDateName.value = vDateValue+strSeperator;
						}
						if (vDateValue.length == 5) 
						{
							vDateName.value = vDateValue+strSeperator;
						}
					}
					return true;
				}
			}
			
			if (vDateValue.length == 10 && dateCheck) 
			{
				if (!dateValid(vDateName)) 
				{
					// Un-comment the next line of code for debugging the dateValid() function error messages
					//alert(err);  
					alert("Invalid Date\nPlease Re-Enter");
					vDateName.focus();
					vDateName.select();
				}
			}
			return false;
		}
		
	
		else 
		{
			// If the value is not in the string return the string minus the last
			// key entered.
			if (isNav4) 
			{
				vDateName.value = "";
				vDateName.focus();
				vDateName.select();
				return false;
			}
			else
			{
				vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
				return false;
			}
		}
	}
}

function dateValid(objName) 
{
	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] = "Jan";
	strMonthArray[1] = "Feb";
	strMonthArray[2] = "Mar";
	strMonthArray[3] = "Apr";
	strMonthArray[4] = "May";
	strMonthArray[5] = "Jun";
	strMonthArray[6] = "Jul";
	strMonthArray[7] = "Aug";
	strMonthArray[8] = "Sep";
	strMonthArray[9] = "Oct";
	strMonthArray[10] = "Nov";
	strMonthArray[11] = "Dec";
	//strDate = datefield.value;
	strDate = objName;
	
	//Wenn nichts eingegeben wurde
	if (strDate.length < 1) 
	{
		return true;
	}
	
	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);
		}
	}
	
	//Adjustment for short years entered
	if (strYear.length == 2) 
	{
		strYear = '20' + strYear;
	}
	
	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 (LeapYear(intYear) == true) 
		{
			if (intday > 29) 
			{
				err = 9;
				return false;
			}
		}
		else 
		{
			if (intday > 28) 
			{
				err = 10;
				return false;
			}
		}
	}
	return true;
}

function LeapYear(intYear) 
{
	if (intYear % 100 == 0) {
	if (intYear % 400 == 0) { return true; }
	}
	else {
	if ((intYear % 4) == 0) { return true; }
	}
	return false;
}