Lists IPTC Application Object Types.

Values:

IGMDTAG_ID_IPTC_OBJTYPE_NEWS	Object type is News (default).
IGMDTAG_ID_IPTC_OBJTYPE_DATA	Object type is Data (intended for tables such as statistics or lists, as opposed to narrative text).
IGMDTAG_ID_IPTC_OBJTYPE_ADVISORY	Object type is Advisory (content provider messages, generally not published).