code: protected function storeValue($type, $data, $delim = false)
       {
           $dataMember = &$this->$type;
           // If array or object full of data was passed in, add all data
           // to appropriate data member.
           if (is_array($data) || is_object($data)) {
               foreach ($data as $value) {
                   if ($value !== false) {
                       if ($delim) {
                           $value = $delim.$value.$delim;
                       }
                   }
                   else {
                       $value = 'NULL';
                   }
                   array_push($dataMember, $value);
               }
           }
  
           // Add singular data item to data member.
           else {
               if ($data !== false) {
                   if ($delim) {
                       $data = $delim.$data.$delim;
                   }
               }
               else {
                   $data = 'NULL';
               }
               array_push($dataMember, $data);
           }
       }
docs: For storing a single value or flat list of values.
  STORAGE FORMAT:
  [item1, item2, item3]