//FUNCTION isValidDate()

function isValidDate(theField)
 { if(theField=="" ||theField=="//" ) return true;
   var leap;
   var dateString=new String(theField);
   var day=dateString.substring(0,dateString.indexOf("/"));
   var month=dateString.substring(dateString.indexOf("/")+1,dateString.lastIndexOf("/"));
   var year=dateString.substring(dateString.lastIndexOf("/")+1,dateString.length);
   var f_two_char_year=dateString.substring(dateString.lastIndexOf("/")+1,dateString.length-2);
   if (f_two_char_year=="00") return false;
   var YR=new Number(year);
   if(YR<=0) return false;
  // var regexp=/(0[1-9]|[1-9]|[1-2][0-9]|3[0-1])[/](0[1-9]|[1-9]|1[0-2])[/]\d{4}$/;
      
  //if (!regexp.test(theField)) 
   //  {
    //   return false;
    // } 
 else
 if ((month==4)||(month==6)||(month==9)||(month==11))
     {
        if(day>30) return false;
      }
 else
 if(month==2)
   {
             
       if((year%400)==0) leap=true;
       else
         {
          if((year%100)==0) leap=false;   
          else
          if((year%4)==0) leap=true;
         }
      if(leap)
        {
         if(day>29) return false;
        }
      else  
        if(day>28) return false;        
     }    
  return true;
 }