//browser detection
	var strUserAgent = navigator.userAgent.toLowerCase(); 
	var isIE = strUserAgent.indexOf("msie") > -1; 
	var isNS6 = strUserAgent.indexOf("netscape6") > -1; 
	var isNS4 = !isIE && !isNS6  && parseFloat(navigator.appVersion) < 5; 
	
	//regular expressions
			
	var reValidChars;
	var reValidString;
	var reKeyboardChars = /[\x00\x03\x08\x0D\x16\x18\x1A]/;
	var reClipboardChars = /[cvxz]/i;
			
	//mask functions
	function maskKeyPress(objEvent,InputData) {
		var iKeyCode, strKey, objInput;  
		if (isIE) {
			iKeyCode = objEvent.keyCode;
			objInput = objEvent.srcElement;
		} else {
			iKeyCode = objEvent.which;
			objInput = objEvent.target;
		}
				
		strKey = String.fromCharCode(iKeyCode);
			
		if (isValid(objInput.value,InputData)) {
			objInput.validValue = objInput.value;
			if (!reValidChars.test(strKey) && !reKeyboardChars.test(strKey) && !checkClipboardCode(objEvent, strKey)) {
				return false;
			}
			} else {
				alert("Invalid Data");
				objInput.value = objInput.validValue;
				objInput.focus();
				return false;
			}
		}
			
		function checkClipboardCode(objEvent, strKey) {
		  	if (isNS6)
			    	return objEvent.ctrlKey && reClipboardChars.test(strKey);
			else
			   	return false;
		}
			
		function isValid(strValue,InputData) {
			if (InputData.toUpperCase() == 'N') {
				reValidChars = /\d/;
				reValidString = /^\d*$/;
			} else {
				reValidChars = /[a-zA-Z. ]/;
				reValidString = /^[a-zA-Z. ]*$/;				
			}				
			return reValidString.test(strValue) || strValue.length == 0;			
		}
			
		function maskChange(objEvent,InputData) {
		  	var objInput;
		
		  	if (isIE) {
			    	objInput = objEvent.srcElement; 
		  	} else {
		    		objInput = objEvent.target;
			}
			 
			if (!isValid(objInput.value,InputData)) {
				alert("Invalid data");
				objInput.value = objInput.validValue || "";
				objInput.focus();
			    	objInput.select(); 
			} else {
				objInput.validValue = objInput.value;
			}
		}
			
		function maskPaste(objEvent,InputData) {
			var strPasteData = window.clipboardData.getData("Text");
			var objInput = objEvent.srcElement;
			
			if (!isValid(strPasteData,InputData)) {
				alert("Invalid data");
		    		objInput.focus();
				return false;
		  	}
		}