*
* @return <code>null</code> if the tag represents a file which is not a
* asf file, or no copyright has been entered.
*/
public static TagTextField getCopyright(Tag tag) {
TagTextField result = null;
List list = tag.get(FIELD_ID);
if (list != null && list.size() > 0) {
TagField field = (TagField) list.get(0);
if (field instanceof TagTextField) {
result = (TagTextField) field;