function checkform()
 {
   //var patrn=/^[a-zA-Z0-9]|[ ._-]$/; //letters,digita," ",".","-","_" are only permitted 
   var patrn=/^[^*/\\?"';:@!&<>|+~`=%$#{}\[\]]+$/g; 
  if (!patrn.exec(document.formSear.searWords.value)||document.formSear.searWords.value=='') 
      {
        alert('please only enter letters,digits,space or -');
        document.formSear.searWords.focus();
         return false;
       }
   return true; 
  }