This class represents the list field. This is definitively detailed in:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 231, page 445.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 234, page 539.

This class is always an indirect object because it inherits from FieldElement which is always an indirect object.

System.Object
    WebSupergoo.ABCpdf14.Elements.Element
       WebSupergoo.ABCpdf14.Elements.FieldElement
          WebSupergoo.ABCpdf14.Elements.ListFieldElement

A list field presents a scrollable list of options from which the user selects one or more items. TI records the scroll position and I records the indices of all currently selected items. Whether multiple selection is allowed is controlled by the MultiSelect flag bit in Ff.