The name of the field in the listname working list that contains item tags. This is the non-visible, unique identifier of the tree item that can be used to identify it when selected or expanded.
$list_caption_field. The field used to store the tag information is the same field used for the caption.
The name of a valid field, in single quotes. A list of fields in the listname working list can be chosen from by clicking the corresponding dropdown button in the property sheet.