function isPosInteger(inputVal)
{
	inputStr = inputVal.toString()
	for (var i = 0; i < inputStr.length; i++)
	{
	  	var oneChar = inputStr.charAt(i)
	    if ((oneChar < "1" || oneChar > "9")&&(i==0))
	    {
	    	return false
	    }
	    if ((oneChar < "0" || oneChar > "9")&&(i!=0))
	    {
	    	return false
	    }
	}
	return true
}

function isYearString(sDate){	
	if (!isPosInteger(sDate)) return false
	if (sDate < 1989 || sDate > (new Date()).getYear()) return false
	return true;
}

function isYearString_unlimited(sDate){	
	if (!isPosInteger(sDate)) return false
	if (sDate < 1900 ||sDate > (new Date()).getYear()) return false
	return true;
}