assert bookmark != null;
	public TOCEntry startEntry( TOCEntry parent, String displayString, String bookmark )	{		assert displayString != null;		assert bookmark != null;		if ( parent == null )		{			parent = rootEntry;		}				TOCNode parentNode = parent.node;		TOCNode node = new TOCNode( );		String id = parentNode.getNodeID( );		if ( id == null )		{			id = "toc";		}		id = id + "_" + parentNode.getChildren( ).size( );		// entry.nodeid is null		node.setNodeID( id );		node.setDisplayString( displayString );		node.setBookmark( bookmark == null ? id : bookmark );		node.setParent( parentNode );		parentNode.getChildren( ).add( node );				TOCEntry entry = new TOCEntry( parent, parent.getRoot( ), node );		return entry;	}