Initializes a new instance of the PdfChoiceFieldKeys class

(Sometimes required, otherwise optional; inheritable; PDF 1.4) For choice fields that allow multiple selection (MultiSelect flag set), an array of integers, sorted in ascending order, representing the zero-based indices in the Opt array of the currently selected option items. This entry is required when two or more elements in the Opt array have different names but the same export value, or when the value of the choice field is an array; in other cases, it is permitted but not required. If the items identified by this entry differ from those in the V entry of the field dictionary (see below), the V entry takes precedence.

(Required; inheritable) An array of options to be presented to the user. Each element of the array is either a text string representing one of the available options or a two-element array consisting of a text string together with a default appearance string for constructing the item’s appearance dynamically at viewing time.

(Optional; inheritable) For scrollable list boxes, the top index (the index in the Opt array of the first option visible in the list).