function isNotEmpty(elem){
		var str=elem.value;
		if(str==null || str=="")
		{ 
			return true;
		}
	}
	

  function isTime(obj){
  var timePat=/^(\d{1,2})(:)(\d{1,2})$/;
  var timeStr=obj.value;
  var matchArray = timeStr.match(timePat);
  
  if(matchArray==null)
	 {
		 obj.value="";
		 obj.focus();
		 return false;
	 }
	 
	if(matchArray[1]>24||matchArray[1]<0||matchArray[3]>59||matchArray[3]<0){
	  
	  return false;
	}	 
      return true; 
	}
 
  function isDate(obj,ShowMsg)
{
 var show = true ;
 
 if(obj.value==null)
 {
 if (show) alert(ShowMsg);
 return false;
 }
 if(obj.value=="")
    {
 if (show) alert(ShowMsg);
 return false;
 }
    
    var datePat=/^(\d{2}|\d{4})(\-)(\d{1,2})(\-)(\d{1,2})$/;
    
    var dateStr=obj.value;
    // is the format ok?
 var matchArray = dateStr.match(datePat); 
    if (matchArray==null)
    {
  if (show) alert(ShowMsg);
        return false;
    }
    year=matchArray[1];
    month=matchArray[3];
    day=matchArray[5];  
     if (year.length!=4 || month.length!=2 || day.length!=2)
    {
  if (show) alert(ShowMsg);
        return false;
    }
    if (month < 1 || month > 12)
    {
  if (show) alert(ShowMsg);
        return false;
    }
    if (day < 1 || day > 31)
    {
  if (show) alert(ShowMsg);
        return false;
    }     if ((month==4 || month==6 || month==9 || month==11) && day==31)
    {
  if (show) alert(ShowMsg);
        return false;
    }     if (month==2)
    {
        var isleap=(year % 4==0 && (year % 100 !=0 || year % 400==0));
        if (day>29 || ((day==29) && (!isleap)))
        {
   if (show) alert(ShowMsg);
            return false;
        }
    }
    return true;
}