A choice field: a list of text options, of which one or (for a multi-select list box) several are selected.
public abstract class PdfChoiceField : PdfTerminalField
ISO 32000-2 §12.7.5.4, Tables 233 and 234; field type Ch. The Combo flag (bit 18) selects a PdfComboBoxField,
else a PdfListBoxField. Its text is variable text (§12.7.4.3).
kind:method, kind:property, kind:ctor. Press Esc to clear.DefaultValuesGets the items selected after a reset-form action (DV, inheritable); empty when there are none.IsCommitOnSelectionChangeGets a value indicating whether a new selection is committed as soon as it is made (Ff bit 27, CommitOnSelChange, PDF 1.5).IsMultiSelectGets a value indicating whether several options may be selected at once (Ff bit 22, MultiSelect, PDF 1.4).IsSortGets a value indicating whether the writer is asked to sort the options (Ff bit 20, Sort); readers keep Opt order.OptionsGets the options presented to the user, in Opt order (never sorted); empty when there is no Opt.SelectedIndicesGets the indices in Options of the selected items, ascending: each value matched against the options' export values, then their displayed text. I decides between options with the same text when it agrees with the value.StoredIndicesGets the indices of the selected options as stored in I (PDF 1.4); empty when absent. Entries that are not ascending in-range integers are left out.ValuesGets the selected items as stored (V, inheritable): one text string, or an array of them; empty when nothing is selected.GenerateAppearances()Regenerates the normal appearance of every widget from the field's current selection, as an interactive processor does for variable text.SetSelectedIndices(IEnumerable<Int32>)Selects the options at indices in Options (none when empty) and regenerates the widgets' appearances.SetValue(String?)Selects the option whose export value, else displayed text, is value (the text itself in an editable combo box when no option has it), or nothing with null, and regenerates the widgets' appearances.