DOCBOOK: Possible bug in dbpoolx (V4.1.2)

Is this content model really correct?

<!ELEMENT segmentedlist ((%formalobject.title.content;)?,
                         segtitle, segtitle+,
                         seglistitem+)>

A segmented list consists of an optional title
followed by at least 2 segment titles
followes by at least 1 segment list item.


Dieter