A set of radio buttons: widgets of which at most one is on, unless several share an on state and turn on in unison.
public sealed class PdfRadioButtonField : PdfToggleButtonField
ISO 32000-2 §12.7.5.2.4; Radio flag set, Pushbutton clear.
kind:method, kind:property, kind:ctor. Press Esc to clear.IsNoToggleToOffGets a value indicating whether exactly one button shall be on at all times (Ff bit 15, NoToggleToOff).IsRadiosInUnisonGets a value indicating whether buttons with the same on state turn on and off together (Ff bit 26, RadiosInUnison, PDF 1.5).