function isNum(ExportData){

	var checkYear1 = window.document.ExportData.txtYear1.value;
	var checkYear2 = window.document.ExportData.txtYear2.value;
	var check10Year = checkYear2 - checkYear1
	var yearLength1 = window.document.ExportData.txtYear1.value.length;
	var yearLength2 = window.document.ExportData.txtYear2.value.length;
	if (checkYear1 == ""){
		alert("Year cannot be a blank.");
		ExportData.txtYear1.focus();
		return false;
	}
	if (checkYear2 == ""){
		alert("Year cannot be a blank.");
		ExportData.txtYear2.focus();
		return false;
	}
	if (checkYear1 > checkYear2){
		alert("The first year cannot be greater than the second year.");
		ExportData.txtYear1.focus();
		ExportData.txtYear1.select();
		return false;
	}
	if (check10Year > 10){
		alert("The range cannot be more than 10 years");
		ExportData.txtYear2.focus();
		ExportData.txtYear2.select();
		return false;
	}
	if (yearLength1 != 4){
		alert("The year must be in this format: YYYY");
		ExportData.txtYear1.focus();
		ExportData.txtYear1.select();
		return false;
	}	
	 if (yearLength2 != 4){
		alert("The year must be in this format: YYYY");
		ExportData.txtYear2.focus();
		ExportData.txtYear2.select();
		return false;
	}	
	for (i=0; i<checkYear1.length; i++){
		if (checkYear1.charAt(i) < "0"){
			alert("The year field is not numeric.");
			ExportData.txtYear1.focus();
			ExportData.txtYear1.select();
			return false;
		}
		if (checkYear1.charAt(i) > "9"){
			alert("The year field is not numeric.");
			ExportData.txtYear1.focus();
			ExportData.txtYear1.select();
			return false;
		}
	}
	for (i=0; i<checkYear2.length; i++){
		if (checkYear2.charAt(i) < "0"){
			alert("The year field is not numeric.");
			ExportData.txtYear2.focus();
			ExportData.txtYear2.select();
			return false;
		}
		if (checkYear2.charAt(i) > "9"){
			alert("The year field is not numeric.");
			ExportData.txtYear2.focus();
			ExportData.txtYear2.select();
			return false;
		}
		
		return true;	
	}
}

function annCheck(Annual){
	var checkAnnYear = window.document.Annual.txtAnnYear.value;
	var AnnYearLen = window.document.Annual.txtAnnYear.value.length;
	if (checkAnnYear == ""){
		alert("Year cannot be a blank.");
		Annual.txtAnnYear.focus();
		return false;
	}
	if (AnnYearLen != 4){
		alert("The year must be in this format: YYYY");
		Annual.txtAnnYear.focus();
		Annual.txtAnnYear.select();
		return false;
	}
	for (i=0; i<checkAnnYear.length; i++){
		if (checkAnnYear.charAt(i) < "0"){
			alert("The year field is not numeric.");
			Annual.txtAnnYear.focus();
			Annual.txtAnnYear.select();
			return false;
		}
		if (checkAnnYear.charAt(i) > "9"){
			alert("The year field is not numeric.");
			Annual.txtAnnYear.focus();
			Annual.txtAnnYear.select();
			return false;
		}
		
		return true;	
	}
}

function confirmSubmit(){
	var msg = "You have selected to graph data from an INACTIVE Ohio Observation well.\nOnly data available during the selected time period will be graphed.\nYou may need to select HISTORIC GRAPH to view data graphically for this observation well.\n\nClick OK to continue."
	var agree=confirm (msg);
	var browserType = navigator.appName
	var osType = navigator.platform
	var versionType = navigator.appVersion.match("4")

	if (agree){
		//if (browserType == "Microsoft Internet Explorer"){
		if (osType == "MacPPC" && browserType == "Netscape" && versionType <= 4){
			browserCheck();	
		}	
		else{
			return true;
		}
	}
	else{
		return false;
	}
}		
function browserCheck(){
	var browserType = navigator.appName
	var osType = navigator.platform
	var versionType = navigator.appVersion.match("4")
	var msg2 = "The graph will not work on a Mac Netscape 4.7 and below.  Please upgrade your browser to view the graph.\n\nCAUTION: Viewing the graph with the current version might lock up your system.\n\nClick OK to continue."
	
	if (osType == "MacPPC" && browserType == "Netscape" && versionType <= 4){
		var xx=confirm(msg2);
		if (xx){
			return true;
		}
		else{
			return false;	
		}	
	}
	else{
		return true;
	}	
}