`<serialize>` can be one of the following values `PHP`, `JSON`, `SEPARATOR_BOOKEND`, `SEPARATOR_TRIMMED`, `SERIALIZE_COMMA`. The Accepted values can be found in `CRM_Core_DAO` Class
`<serialize>` can be one of the following values `PHP`, `JSON`, `SEPARATOR_BOOKEND`, `SEPARATOR_TRIMMED`, `COMMA`. The Accepted values can be found in `CRM_Core_DAO` Class